Merge pull request #450 from OxygenCobalt/dev

Version 3.1.0

.github/workflows/android.yml

@@ -15,10 +15,10 @@ jobs:
       uses: actions/checkout@v3
     - name: Clone submodules
       run: git submodule update --init --recursive
-    - name: Set up JDK 11
+    - name: Set up JDK 17
       uses: actions/setup-java@v3
       with:
-        java-version: '11'
+        java-version: '17'
         distribution: 'temurin'
         cache: gradle
     - name: Grant execute permission for gradlew

.gitmodules

@@ -1,4 +1,3 @@
-[submodule "ExoPlayer"]
+[submodule "media"]
-	path = ExoPlayer
+	path = media
-	url = https://github.com/OxygenCobalt/ExoPlayer.git
+	url = https://github.com/OxygenCobalt/media.git
-	branch = auxio

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## 3.1.0
+
+#### What's New
+- Added playlist functionality
+
+#### What's Improved
+- Sorting now handles numbers of arbitrary length
+- Punctuation is now ignored in sorting with intelligent sort names disabled
+
+#### What's Fixed
+- Fixed issue where vorbis comments in the form of `metadata_block_picture` (lowercase) would not
+be parsed as images
+- Fixed issue where searches would match song file names case-sensitively
+- Fixed issue where the notification would not respond to changes in the album cover setting
+- Fixed issue where short names starting with an article would not be correctly sorted (ex. "the 1")
+- Fixed incorrect item arrangement on landscape
+- Fixed disappearing dividers in search view
+- Reduced likelihood that images (eg. album covers) would not update when the music library changed
+
+#### Dev/Meta
+- Switched to androidx media3 (New Home of ExoPlayer) for backing player components
+
 ## 3.0.5
 
 #### What's Fixed
@@ -11,23 +33,23 @@ screen
 ## 3.0.4
 
 #### What's New
-- Added support for `COMPILATION` and `ITUNESCOMPILATION` flags.
+- Added support for `COMPILATION` and `ITUNESCOMPILATION` flags
 
 #### What's Improved
 - Accept `REPLAYGAIN_*` adjustment information on OPUS files alongside
 `R128_*` adjustments
 - List updates are now consistent across the app
 - Fixed jarring header update in detail view
-- Search view now trims search queries
+- Searching now ignores punctuation and trailing whitespace
 - Audio effect (equalizer) session is now broadcast when playing/pausing
 rather than on start/stop
-- Searching now ignores punctuation
 - Numeric names are now logically sorted (i.e 7 before 15)
 
 #### What's Fixed
 - Fixed MP4-AAC files not playing due to an accidental audio extractor
 deletion
 - Fix "format" not appearing in song properties view
+- Fix visual bugs when editing duplicate songs in the queue
 
 #### What's Changed
 - "Ignore articles when sorting" is now "Intelligent sorting"

ExoPlayer

@@ -1 +0,0 @@
-Subproject commit fef2bb3af622f235d98549ffe2efd8f7f7d2aa41

README.md

@@ -2,8 +2,8 @@
 <h1 align="center"><b>Auxio</b></h1>
 <h4 align="center">A simple, rational music player for android.</h4>
 <p align="center">
-    <a href="https://github.com/oxygencobalt/Auxio/releases/tag/v3.0.5">
+    <a href="https://github.com/oxygencobalt/Auxio/releases/tag/v3.1.0">
-        <img alt="Latest Version" src="https://img.shields.io/static/v1?label=tag&message=v3.0.5&color=64B5F6&style=flat">
+        <img alt="Latest Version" src="https://img.shields.io/static/v1?label=tag&message=v3.1.0&color=64B5F6&style=flat">
     </a>
     <a href="https://github.com/oxygencobalt/Auxio/releases/">
         <img alt="Releases" src="https://img.shields.io/github/downloads/OxygenCobalt/Auxio/total.svg?color=4B95DE&style=flat">
@@ -21,7 +21,7 @@
 
 ## About
 
-Auxio is a local music player with a fast, reliable UI/UX without the many useless features present in other music players. Built off of <a href="https://exoplayer.dev/">Exoplayer</a>, Auxio has superior library support and listening quality compared to other apps that use outdated android functionality. In short, **It plays music.**
+Auxio is a local music player with a fast, reliable UI/UX without the many useless features present in other music players. Built off of [ExoPlayer](https://exoplayer.dev/), Auxio has superior library support and listening quality compared to other apps that use outdated android functionality. In short, **It plays music.**
 
 I primarily built Auxio for myself, but you can use it too, I guess.
 
@@ -42,7 +42,7 @@ I primarily built Auxio for myself, but you can use it too, I guess.
 
 ## Features
 
-- [ExoPlayer](https://exoplayer.dev/) based playback
+- [ExoPlayer](https://exoplayer.dev/)-based playback
 - Snappy UI derived from the latest Material Design guidelines
 - Opinionated UX that prioritizes ease of use over edge cases
 - Customizable behavior
@@ -50,7 +50,8 @@ I primarily built Auxio for myself, but you can use it too, I guess.
 precise/original dates, sort tags, and more
 - Advanced artist system that unifies artists and album artists
 - SD Card-aware folder management
-- Reliable playback state persistence
+- Reliable playlisting functionality
+- Playback state persistence
 - Full ReplayGain support (On MP3, FLAC, OGG, OPUS, and MP4 files)
 - External equalizer support (ex. Wavelet)
 - Edge-to-edge

app/build.gradle

@@ -20,8 +20,8 @@ android {
 
     defaultConfig {
         applicationId namespace
-        versionName "3.0.5"
+        versionName "3.1.0"
-        versionCode 29
+        versionCode 30
 
         minSdk 21
         targetSdk 33
@@ -30,12 +30,12 @@ android {
     }
 
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_11
+        sourceCompatibility JavaVersion.VERSION_17
-        targetCompatibility JavaVersion.VERSION_11
+        targetCompatibility JavaVersion.VERSION_17
     }
 
     kotlinOptions {
-        jvmTarget = "11"
+        jvmTarget = "17"
         freeCompilerArgs += "-Xjvm-default=all"
     }
 
@@ -56,15 +56,16 @@ android {
             }
         }
     }
-
     packagingOptions {
-        exclude "DebugProbesKt.bin"
+        jniLibs {
-        exclude "kotlin-tooling-metadata.json"
+            excludes += ['**/kotlin/**', '**/okhttp3/**']
-        exclude "**/kotlin/**"
+        }
-        exclude "**/okhttp3/**"
+        resources {
-        exclude "META-INF/*.version"
+            excludes += ['DebugProbesKt.bin', 'kotlin-tooling-metadata.json', '**/kotlin/**', '**/okhttp3/**', 'META-INF/*.version']
+        }
     }
 
+
     buildFeatures {
         viewBinding true
     }
@@ -75,26 +76,27 @@ dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4"
+
-    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-guava:1.6.4"
+    def coroutines_version = '1.7.1'
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-guava:$coroutines_version"
 
     // --- SUPPORT ---
 
     // General
-    // 1.4.0 is used in order to avoid a ripple bug in material components
     implementation "androidx.appcompat:appcompat:1.6.1"
-    implementation "androidx.core:core-ktx:1.9.0"
+    implementation "androidx.core:core-ktx:1.10.1"
-    implementation "androidx.activity:activity-ktx:1.6.1"
+    implementation "androidx.activity:activity-ktx:1.7.1"
-    implementation "androidx.fragment:fragment-ktx:1.5.5"
+    implementation "androidx.fragment:fragment-ktx:1.5.7"
 
     // UI
     implementation "androidx.recyclerview:recyclerview:1.3.0"
     implementation "androidx.constraintlayout:constraintlayout:2.1.4"
     implementation "androidx.viewpager2:viewpager2:1.1.0-beta01"
-    implementation 'androidx.core:core-ktx:1.9.0'
+    implementation 'androidx.core:core-ktx:1.10.1'
 
     // Lifecycle
-    def lifecycle_version = "2.6.0"
+    def lifecycle_version = "2.6.1"
     implementation "androidx.lifecycle:lifecycle-common:$lifecycle_version"
     implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"
     implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
@@ -111,7 +113,7 @@ dependencies {
     implementation "androidx.preference:preference-ktx:1.2.0"
 
     // Database
-    def room_version = '2.5.0'
+    def room_version = '2.6.0-alpha01'
     implementation "androidx.room:room-runtime:$room_version"
     kapt "androidx.room:room-compiler:$room_version"
     implementation "androidx.room:room-ktx:$room_version"
@@ -119,27 +121,27 @@ dependencies {
     // --- THIRD PARTY ---
 
     // Exoplayer (Vendored)
-    implementation project(":exoplayer-library-core")
+    implementation project(":media-lib-exoplayer")
-    implementation project(":exoplayer-extension-ffmpeg")
+    implementation project(":media-lib-decoder-ffmpeg")
 
     // Image loading
-    implementation 'io.coil-kt:coil-base:2.2.2'
+    implementation 'io.coil-kt:coil-base:2.3.0'
 
     // Material
-    // TODO: Stuck on 1.8.0-alpha01 until ripple bug with tab layout can be worked around
+    // TODO: Stuck on 1.8.0-alpha01 until ripple bug with tab layout is actually available
+    //  in a version that I can build with
     // TODO: Exactly figure out the conditions that the 1.7.0 ripple bug occurred so you can just
     //  PR a fix.
     implementation "com.google.android.material:material:1.8.0-alpha01"
 
     // Dependency Injection
-    def dagger_version = '2.45'
+    implementation "com.google.dagger:dagger:$hilt_version"
-    implementation "com.google.dagger:dagger:$dagger_version"
+    kapt "com.google.dagger:dagger-compiler:$hilt_version"
-    kapt "com.google.dagger:dagger-compiler:$dagger_version"
     implementation "com.google.dagger:hilt-android:$hilt_version"
     kapt "com.google.dagger:hilt-android-compiler:$hilt_version"
 
     // Testing
-    debugImplementation 'com.squareup.leakcanary:leakcanary-android:2.10'
+    debugImplementation 'com.squareup.leakcanary:leakcanary-android:2.11'
     testImplementation "junit:junit:4.13.2"
     androidTestImplementation 'androidx.test.ext:junit:1.1.5'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'

app/proguard-rules.pro

@@ -23,3 +23,14 @@
 # Obsfucation is what proprietary software does to keep the user unaware of it's abuses.
 # Also it's easier to fix issues if the stack trace symbols remain unmangled.
 -dontobfuscate
+
+# Make AGP shut up about classes that aren't even used.
+-dontwarn org.bouncycastle.jsse.BCSSLParameters
+-dontwarn org.bouncycastle.jsse.BCSSLSocket
+-dontwarn org.bouncycastle.jsse.provider.BouncyCastleJsseProvider
+-dontwarn org.conscrypt.Conscrypt$Version
+-dontwarn org.conscrypt.Conscrypt
+-dontwarn org.conscrypt.ConscryptHostnameVerifier
+-dontwarn org.openjsse.javax.net.ssl.SSLParameters
+-dontwarn org.openjsse.javax.net.ssl.SSLSocket
+-dontwarn org.openjsse.net.ssl.OpenJSSE

app/src/androidTest/java/org/oxycblt/auxio/StubTest.kt

@@ -35,6 +35,6 @@ class StubTest {
     @Test
     fun useAppContext() {
         val appContext = InstrumentationRegistry.getInstrumentation().targetContext
-        assertEquals("org.oxycblt.auxio", appContext.packageName)
+        assertEquals("org.oxycblt.auxio.debug", appContext.packageName)
     }
 }

app/src/main/java/org/oxycblt/auxio/Auxio.kt

@@ -25,6 +25,7 @@ import androidx.core.content.pm.ShortcutManagerCompat
 import androidx.core.graphics.drawable.IconCompat
 import dagger.hilt.android.HiltAndroidApp
 import javax.inject.Inject
+import org.oxycblt.auxio.home.HomeSettings
 import org.oxycblt.auxio.image.ImageSettings
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.ui.UISettings
@@ -39,6 +40,7 @@ class Auxio : Application() {
     @Inject lateinit var imageSettings: ImageSettings
     @Inject lateinit var playbackSettings: PlaybackSettings
     @Inject lateinit var uiSettings: UISettings
+    @Inject lateinit var homeSettings: HomeSettings
 
     override fun onCreate() {
         super.onCreate()
@@ -46,6 +48,7 @@ class Auxio : Application() {
         imageSettings.migrate()
         playbackSettings.migrate()
         uiSettings.migrate()
+        homeSettings.migrate()
         // Adding static shortcuts in a dynamic manner is better than declaring them
         // manually, as it will properly handle the difference between debug and release
         // Auxio instances.

app/src/main/java/org/oxycblt/auxio/IntegerTable.kt

@@ -33,18 +33,26 @@ object IntegerTable {
     const val VIEW_TYPE_ARTIST = 0xA002
     /** GenreViewHolder */
     const val VIEW_TYPE_GENRE = 0xA003
+    /** PlaylistViewHolder */
+    const val VIEW_TYPE_PLAYLIST = 0xA004
     /** BasicHeaderViewHolder */
-    const val VIEW_TYPE_BASIC_HEADER = 0xA004
+    const val VIEW_TYPE_BASIC_HEADER = 0xA005
+    /** DividerViewHolder */
+    const val VIEW_TYPE_DIVIDER = 0xA006
     /** SortHeaderViewHolder */
-    const val VIEW_TYPE_SORT_HEADER = 0xA005
+    const val VIEW_TYPE_SORT_HEADER = 0xA007
     /** AlbumSongViewHolder */
-    const val VIEW_TYPE_ALBUM_SONG = 0xA007
+    const val VIEW_TYPE_ALBUM_SONG = 0xA008
     /** ArtistAlbumViewHolder */
     const val VIEW_TYPE_ARTIST_ALBUM = 0xA009
     /** ArtistSongViewHolder */
     const val VIEW_TYPE_ARTIST_SONG = 0xA00A
     /** DiscHeaderViewHolder */
-    const val VIEW_TYPE_DISC_HEADER = 0xA00C
+    const val VIEW_TYPE_DISC_HEADER = 0xA00B
+    /** EditHeaderViewHolder */
+    const val VIEW_TYPE_EDIT_HEADER = 0xA00C
+    /** PlaylistSongViewHolder */
+    const val VIEW_TYPE_PLAYLIST_SONG = 0xA00E
     /** "Music playback" notification code */
     const val PLAYBACK_NOTIFICATION_CODE = 0xA0A0
     /** "Music loading" notification code */
@@ -65,34 +73,36 @@ object IntegerTable {
     const val PLAYBACK_MODE_IN_ALBUM = 0xA105
     /** PlaybackMode.ALL_SONGS */
     const val PLAYBACK_MODE_ALL_SONGS = 0xA106
-    /** DisplayMode.NONE (No Longer used but still reserved) */
-    // const val DISPLAY_MODE_NONE = 0xA107
-    /** MusicMode._GENRES */
-    const val MUSIC_MODE_GENRES = 0xA108
-    /** MusicMode._ARTISTS */
-    const val MUSIC_MODE_ARTISTS = 0xA109
-    /** MusicMode._ALBUMS */
-    const val MUSIC_MODE_ALBUMS = 0xA10A
     /** MusicMode.SONGS */
     const val MUSIC_MODE_SONGS = 0xA10B
-    /** Sort.ByName */
+    /** MusicMode.ALBUMS */
+    const val MUSIC_MODE_ALBUMS = 0xA10A
+    /** MusicMode.ARTISTS */
+    const val MUSIC_MODE_ARTISTS = 0xA109
+    /** MusicMode.GENRES */
+    const val MUSIC_MODE_GENRES = 0xA108
+    /** MusicMode.PLAYLISTS */
+    const val MUSIC_MODE_PLAYLISTS = 0xA107
+    /** Sort.Mode.ByName */
     const val SORT_BY_NAME = 0xA10C
-    /** Sort.ByArtist */
+    /** Sort.Mode.ByArtist */
     const val SORT_BY_ARTIST = 0xA10D
-    /** Sort.ByAlbum */
+    /** Sort.Mode.ByAlbum */
     const val SORT_BY_ALBUM = 0xA10E
-    /** Sort.ByYear */
+    /** Sort.Mode.ByYear */
     const val SORT_BY_YEAR = 0xA10F
-    /** Sort.ByDuration */
+    /** Sort.Mode.ByDuration */
     const val SORT_BY_DURATION = 0xA114
-    /** Sort.ByCount */
+    /** Sort.Mode.ByCount */
     const val SORT_BY_COUNT = 0xA115
-    /** Sort.ByDisc */
+    /** Sort.Mode.ByDisc */
     const val SORT_BY_DISC = 0xA116
-    /** Sort.ByTrack */
+    /** Sort.Mode.ByTrack */
     const val SORT_BY_TRACK = 0xA117
-    /** Sort.ByDateAdded */
+    /** Sort.Mode.ByDateAdded */
     const val SORT_BY_DATE_ADDED = 0xA118
+    /** Sort.Mode.None */
+    const val SORT_BY_NONE = 0xA11F
     /** ReplayGainMode.Off (No longer used but still reserved) */
     // const val REPLAY_GAIN_MODE_OFF = 0xA110
     /** ReplayGainMode.Track */

app/src/main/java/org/oxycblt/auxio/MainActivity.kt

@@ -48,6 +48,10 @@ import org.oxycblt.auxio.util.systemBarInsetsCompat
  * TODO: Use proper material attributes (Not the weird dimen attributes I currently have)
  * TODO: Migrate to material animation system
  * TODO: Unit testing
+ * TODO: Fix UID naming
+ * TODO: Leverage FlexibleListAdapter more in dialogs (Disable item anims)
+ * TODO: Add more logging
+ * TODO: Try to move on from synchronized and volatile in shared objs
  */
 @AndroidEntryPoint
 class MainActivity : AppCompatActivity() {

app/src/main/java/org/oxycblt/auxio/MainFragment.kt

@@ -38,14 +38,17 @@ import dagger.hilt.android.AndroidEntryPoint
 import kotlin.math.max
 import kotlin.math.min
 import org.oxycblt.auxio.databinding.FragmentMainBinding
+import org.oxycblt.auxio.detail.DetailViewModel
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.Music
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.Playlist
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.navigation.MainNavigationAction
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackBottomSheetBehavior
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.queue.QueueBottomSheetBehavior
-import org.oxycblt.auxio.ui.MainNavigationAction
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.ui.ViewBindingFragment
 import org.oxycblt.auxio.util.*
 
@@ -60,9 +63,11 @@ class MainFragment :
     ViewBindingFragment<FragmentMainBinding>(),
     ViewTreeObserver.OnPreDrawListener,
     NavController.OnDestinationChangedListener {
-    private val playbackModel: PlaybackViewModel by activityViewModels()
     private val navModel: NavigationViewModel by activityViewModels()
+    private val musicModel: MusicViewModel by activityViewModels()
+    private val playbackModel: PlaybackViewModel by activityViewModels()
     private val selectionModel: SelectionViewModel by activityViewModels()
+    private val detailModel: DetailViewModel by activityViewModels()
     private val callback = DynamicBackPressedCallback()
     private var lastInsets: WindowInsets? = null
     private var elevationNormal = 0f
@@ -132,6 +137,10 @@ class MainFragment :
         collect(navModel.mainNavigationAction.flow, ::handleMainNavigation)
         collect(navModel.exploreNavigationItem.flow, ::handleExploreNavigation)
         collect(navModel.exploreArtistNavigationItem.flow, ::handleArtistNavigationPicker)
+        collect(musicModel.newPlaylistSongs.flow, ::handleNewPlaylist)
+        collect(musicModel.playlistToRename.flow, ::handleRenamePlaylist)
+        collect(musicModel.playlistToDelete.flow, ::handleDeletePlaylist)
+        collect(musicModel.songsToAdd.flow, ::handleAddToPlaylist)
         collectImmediately(playbackModel.song, ::updateSong)
         collect(playbackModel.artistPickerSong.flow, ::handlePlaybackArtistPicker)
         collect(playbackModel.genrePickerSong.flow, ::handlePlaybackGenrePicker)
@@ -258,7 +267,7 @@ class MainFragment :
             initialNavDestinationChange = true
             return
         }
-        selectionModel.consume()
+        selectionModel.drop()
     }
 
     private fun handleMainNavigation(action: MainNavigationAction?) {
@@ -268,8 +277,8 @@ class MainFragment :
         }
 
         when (action) {
-            is MainNavigationAction.Expand -> tryExpandSheets()
+            is MainNavigationAction.OpenPlaybackPanel -> tryOpenPlaybackPanel()
-            is MainNavigationAction.Collapse -> tryCollapseSheets()
+            is MainNavigationAction.ClosePlaybackPanel -> tryClosePlaybackPanel()
             is MainNavigationAction.Directions ->
                 findNavController().navigateSafe(action.directions)
         }
@@ -279,7 +288,7 @@ class MainFragment :
 
     private fun handleExploreNavigation(item: Music?) {
         if (item != null) {
-            tryCollapseSheets()
+            tryClosePlaybackPanel()
         }
     }
 
@@ -300,6 +309,40 @@ class MainFragment :
         }
     }
 
+    private fun handleNewPlaylist(songs: List<Song>?) {
+        if (songs != null) {
+            findNavController()
+                .navigateSafe(
+                    MainFragmentDirections.actionNewPlaylist(songs.map { it.uid }.toTypedArray()))
+            musicModel.newPlaylistSongs.consume()
+        }
+    }
+
+    private fun handleRenamePlaylist(playlist: Playlist?) {
+        if (playlist != null) {
+            findNavController()
+                .navigateSafe(MainFragmentDirections.actionRenamePlaylist(playlist.uid))
+            musicModel.playlistToRename.consume()
+        }
+    }
+
+    private fun handleDeletePlaylist(playlist: Playlist?) {
+        if (playlist != null) {
+            findNavController()
+                .navigateSafe(MainFragmentDirections.actionDeletePlaylist(playlist.uid))
+            musicModel.playlistToDelete.consume()
+        }
+    }
+
+    private fun handleAddToPlaylist(songs: List<Song>?) {
+        if (songs != null) {
+            findNavController()
+                .navigateSafe(
+                    MainFragmentDirections.actionAddToPlaylist(songs.map { it.uid }.toTypedArray()))
+            musicModel.songsToAdd.consume()
+        }
+    }
+
     private fun handlePlaybackArtistPicker(song: Song?) {
         if (song != null) {
             navModel.mainNavigateTo(
@@ -318,22 +361,33 @@ class MainFragment :
         }
     }
 
-    private fun tryExpandSheets() {
+    private fun tryOpenPlaybackPanel() {
         val binding = requireBinding()
         val playbackSheetBehavior =
             binding.playbackSheet.coordinatorLayoutBehavior as PlaybackBottomSheetBehavior
+
         if (playbackSheetBehavior.state == BackportBottomSheetBehavior.STATE_COLLAPSED) {
             // Playback sheet is not expanded and not hidden, we can expand it.
             playbackSheetBehavior.state = BackportBottomSheetBehavior.STATE_EXPANDED
+            return
+        }
+
+        val queueSheetBehavior =
+            (binding.queueSheet.coordinatorLayoutBehavior ?: return) as QueueBottomSheetBehavior
+        if (playbackSheetBehavior.state == BackportBottomSheetBehavior.STATE_EXPANDED &&
+            queueSheetBehavior.state == BackportBottomSheetBehavior.STATE_EXPANDED) {
+            // Queue sheet and playback sheet is expanded, close the queue sheet so the
+            // playback panel can eb shown.
+            queueSheetBehavior.state = BackportBottomSheetBehavior.STATE_COLLAPSED
         }
     }
 
-    private fun tryCollapseSheets() {
+    private fun tryClosePlaybackPanel() {
         val binding = requireBinding()
         val playbackSheetBehavior =
             binding.playbackSheet.coordinatorLayoutBehavior as PlaybackBottomSheetBehavior
         if (playbackSheetBehavior.state == BackportBottomSheetBehavior.STATE_EXPANDED) {
-            // Make sure the queue is also collapsed here.
+            // Playback sheet (and possibly queue) needs to be collapsed.
             val queueSheetBehavior =
                 binding.queueSheet.coordinatorLayoutBehavior as QueueBottomSheetBehavior?
             playbackSheetBehavior.state = BackportBottomSheetBehavior.STATE_COLLAPSED
@@ -406,8 +460,13 @@ class MainFragment :
                 return
             }
 
+            // Clear out pending playlist edits.
+            if (detailModel.dropPlaylistEdit()) {
+                return
+            }
+
             // Clear out any prior selections.
-            if (selectionModel.consume().isNotEmpty()) {
+            if (selectionModel.drop()) {
                 return
             }
 
@@ -435,6 +494,7 @@ class MainFragment :
             isEnabled =
                 queueSheetBehavior?.state == BackportBottomSheetBehavior.STATE_EXPANDED ||
                     playbackSheetBehavior.state == BackportBottomSheetBehavior.STATE_EXPANDED ||
+                    detailModel.editedPlaylist.value != null ||
                     selectionModel.selected.value.isNotEmpty() ||
                     exploreNavController.currentDestination?.id !=
                         exploreNavController.graph.startDestinationId

app/src/main/java/org/oxycblt/auxio/detail/AlbumDetailFragment.kt

@@ -26,6 +26,7 @@ import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
 import androidx.navigation.fragment.navArgs
 import androidx.recyclerview.widget.ConcatAdapter
+import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.LinearSmoothScroller
 import com.google.android.material.transition.MaterialSharedAxis
 import dagger.hilt.android.AndroidEntryPoint
@@ -34,6 +35,8 @@ import org.oxycblt.auxio.databinding.FragmentDetailBinding
 import org.oxycblt.auxio.detail.header.AlbumDetailHeaderAdapter
 import org.oxycblt.auxio.detail.list.AlbumDetailListAdapter
 import org.oxycblt.auxio.detail.list.DetailListAdapter
+import org.oxycblt.auxio.list.Divider
+import org.oxycblt.auxio.list.Header
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.Sort
@@ -43,9 +46,11 @@ import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.music.info.Disc
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.*
 
 /**
@@ -61,6 +66,7 @@ class AlbumDetailFragment :
     private val detailModel: DetailViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     // Information about what album to display is initially within the navigation arguments
     // as a UID, as that is the only safe way to parcel an album.
@@ -87,17 +93,27 @@ class AlbumDetailFragment :
         super.onBindingCreated(binding, savedInstanceState)
 
         // --- UI SETUP --
-        binding.detailToolbar.apply {
+        binding.detailNormalToolbar.apply {
             inflateMenu(R.menu.menu_album_detail)
             setNavigationOnClickListener { findNavController().navigateUp() }
             setOnMenuItemClickListener(this@AlbumDetailFragment)
         }
 
-        binding.detailRecycler.adapter = ConcatAdapter(albumHeaderAdapter, albumListAdapter)
+        binding.detailRecycler.apply {
+            adapter = ConcatAdapter(albumHeaderAdapter, albumListAdapter)
+            (layoutManager as GridLayoutManager).setFullWidthLookup {
+                if (it != 0) {
+                    val item = detailModel.albumList.value[it - 1]
+                    item is Divider || item is Header || item is Disc
+                } else {
+                    true
+                }
+            }
+        }
 
         // -- VIEWMODEL SETUP ---
         // DetailViewModel handles most initialization from the navigation argument.
-        detailModel.setAlbumUid(args.albumUid)
+        detailModel.setAlbum(args.albumUid)
         collectImmediately(detailModel.currentAlbum, ::updateAlbum)
         collectImmediately(detailModel.albumList, ::updateList)
         collectImmediately(
@@ -108,7 +124,7 @@ class AlbumDetailFragment :
 
     override fun onDestroyBinding(binding: FragmentDetailBinding) {
         super.onDestroyBinding(binding)
-        binding.detailToolbar.setOnMenuItemClickListener(null)
+        binding.detailNormalToolbar.setOnMenuItemClickListener(null)
         binding.detailRecycler.adapter = null
         // Avoid possible race conditions that could cause a bad replace instruction to be consumed
         // during list initialization and crash the app. Could happen if the user is fast enough.
@@ -136,6 +152,10 @@ class AlbumDetailFragment :
                 onNavigateToParentArtist()
                 true
             }
+            R.id.action_playlist_add -> {
+                musicModel.addToPlaylist(currentAlbum)
+                true
+            }
             else -> false
         }
     }
@@ -159,8 +179,10 @@ class AlbumDetailFragment :
 
     override fun onOpenSortMenu(anchor: View) {
         openMenu(anchor, R.menu.menu_album_sort) {
+            // Select the corresponding sort mode option
             val sort = detailModel.albumSongSort
             unlikelyToBeNull(menu.findItem(sort.mode.itemId)).isChecked = true
+            // Select the corresponding sort direction option
             val directionItemId =
                 when (sort.direction) {
                     Sort.Direction.ASCENDING -> R.id.option_sort_asc
@@ -171,8 +193,10 @@ class AlbumDetailFragment :
                 item.isChecked = !item.isChecked
                 detailModel.albumSongSort =
                     when (item.itemId) {
+                        // Sort direction options
                         R.id.option_sort_asc -> sort.withDirection(Sort.Direction.ASCENDING)
                         R.id.option_sort_dec -> sort.withDirection(Sort.Direction.DESCENDING)
+                        // Any other option is a sort mode
                         else -> sort.withMode(unlikelyToBeNull(Sort.Mode.fromItemId(item.itemId)))
                     }
                 true
@@ -190,7 +214,7 @@ class AlbumDetailFragment :
             findNavController().navigateUp()
             return
         }
-        requireBinding().detailToolbar.title = album.resolveName(requireContext())
+        requireBinding().detailNormalToolbar.title = album.name.resolve(requireContext())
         albumHeaderAdapter.setParent(album)
     }
 
@@ -289,6 +313,13 @@ class AlbumDetailFragment :
 
     private fun updateSelection(selected: List<Music>) {
         albumListAdapter.setSelected(selected.toSet())
-        requireBinding().detailSelectionToolbar.updateSelectionAmount(selected.size)
+
+        val binding = requireBinding()
+        if (selected.isNotEmpty()) {
+            binding.detailSelectionToolbar.title = getString(R.string.fmt_selected, selected.size)
+            binding.detailToolbar.setVisible(R.id.detail_selection_toolbar)
+        } else {
+            binding.detailToolbar.setVisible(R.id.detail_normal_toolbar)
+        }
     }
 }

app/src/main/java/org/oxycblt/auxio/detail/ArtistDetailFragment.kt

@@ -26,6 +26,7 @@ import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
 import androidx.navigation.fragment.navArgs
 import androidx.recyclerview.widget.ConcatAdapter
+import androidx.recyclerview.widget.GridLayoutManager
 import com.google.android.material.transition.MaterialSharedAxis
 import dagger.hilt.android.AndroidEntryPoint
 import org.oxycblt.auxio.R
@@ -34,6 +35,8 @@ import org.oxycblt.auxio.detail.header.ArtistDetailHeaderAdapter
 import org.oxycblt.auxio.detail.header.DetailHeaderAdapter
 import org.oxycblt.auxio.detail.list.ArtistDetailListAdapter
 import org.oxycblt.auxio.detail.list.DetailListAdapter
+import org.oxycblt.auxio.list.Divider
+import org.oxycblt.auxio.list.Header
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.Sort
@@ -42,9 +45,10 @@ import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicParent
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.*
 
 /**
@@ -60,6 +64,7 @@ class ArtistDetailFragment :
     private val detailModel: DetailViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     // Information about what artist to display is initially within the navigation arguments
     // as a UID, as that is the only safe way to parcel an artist.
@@ -86,18 +91,31 @@ class ArtistDetailFragment :
         super.onBindingCreated(binding, savedInstanceState)
 
         // --- UI SETUP ---
-        binding.detailToolbar.apply {
+        binding.detailNormalToolbar.apply {
-            inflateMenu(R.menu.menu_genre_artist_detail)
+            inflateMenu(R.menu.menu_parent_detail)
             setNavigationOnClickListener { findNavController().navigateUp() }
             setOnMenuItemClickListener(this@ArtistDetailFragment)
         }
 
-        binding.detailRecycler.adapter = ConcatAdapter(artistHeaderAdapter, artistListAdapter)
+        binding.detailRecycler.apply {
+            adapter = ConcatAdapter(artistHeaderAdapter, artistListAdapter)
+            (layoutManager as GridLayoutManager).setFullWidthLookup {
+                if (it != 0) {
+                    val item =
+                        detailModel.artistList.value.getOrElse(it - 1) {
+                            return@setFullWidthLookup false
+                        }
+                    item is Divider || item is Header
+                } else {
+                    true
+                }
+            }
+        }
 
         // --- VIEWMODEL SETUP ---
         // DetailViewModel handles most initialization from the navigation argument.
-        detailModel.setArtistUid(args.artistUid)
+        detailModel.setArtist(args.artistUid)
-        collectImmediately(detailModel.currentArtist, ::updateItem)
+        collectImmediately(detailModel.currentArtist, ::updateArtist)
         collectImmediately(detailModel.artistList, ::updateList)
         collectImmediately(
             playbackModel.song, playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
@@ -107,7 +125,7 @@ class ArtistDetailFragment :
 
     override fun onDestroyBinding(binding: FragmentDetailBinding) {
         super.onDestroyBinding(binding)
-        binding.detailToolbar.setOnMenuItemClickListener(null)
+        binding.detailNormalToolbar.setOnMenuItemClickListener(null)
         binding.detailRecycler.adapter = null
         // Avoid possible race conditions that could cause a bad replace instruction to be consumed
         // during list initialization and crash the app. Could happen if the user is fast enough.
@@ -131,6 +149,10 @@ class ArtistDetailFragment :
                 requireContext().showToast(R.string.lng_queue_added)
                 true
             }
+            R.id.action_playlist_add -> {
+                musicModel.addToPlaylist(currentArtist)
+                true
+            }
             else -> false
         }
     }
@@ -171,8 +193,10 @@ class ArtistDetailFragment :
 
     override fun onOpenSortMenu(anchor: View) {
         openMenu(anchor, R.menu.menu_artist_sort) {
+            // Select the corresponding sort mode option
             val sort = detailModel.artistSongSort
             unlikelyToBeNull(menu.findItem(sort.mode.itemId)).isChecked = true
+            // Select the corresponding sort direction option
             val directionItemId =
                 when (sort.direction) {
                     Sort.Direction.ASCENDING -> R.id.option_sort_asc
@@ -184,8 +208,10 @@ class ArtistDetailFragment :
 
                 detailModel.artistSongSort =
                     when (item.itemId) {
+                        // Sort direction options
                         R.id.option_sort_asc -> sort.withDirection(Sort.Direction.ASCENDING)
                         R.id.option_sort_dec -> sort.withDirection(Sort.Direction.DESCENDING)
+                        // Any other option is a sort mode
                         else -> sort.withMode(unlikelyToBeNull(Sort.Mode.fromItemId(item.itemId)))
                     }
 
@@ -194,13 +220,13 @@ class ArtistDetailFragment :
         }
     }
 
-    private fun updateItem(artist: Artist?) {
+    private fun updateArtist(artist: Artist?) {
         if (artist == null) {
             // Artist we were showing no longer exists.
             findNavController().navigateUp()
             return
         }
-        requireBinding().detailToolbar.title = artist.resolveName(requireContext())
+        requireBinding().detailNormalToolbar.title = artist.name.resolve(requireContext())
         artistHeaderAdapter.setParent(artist)
     }
 
@@ -260,6 +286,13 @@ class ArtistDetailFragment :
 
     private fun updateSelection(selected: List<Music>) {
         artistListAdapter.setSelected(selected.toSet())
-        requireBinding().detailSelectionToolbar.updateSelectionAmount(selected.size)
+
+        val binding = requireBinding()
+        if (selected.isNotEmpty()) {
+            binding.detailSelectionToolbar.title = getString(R.string.fmt_selected, selected.size)
+            binding.detailToolbar.setVisible(R.id.detail_selection_toolbar)
+        } else {
+            binding.detailToolbar.setVisible(R.id.detail_normal_toolbar)
+        }
     }
 }

app/src/main/java/org/oxycblt/auxio/detail/DetailAppBarLayout.kt

@@ -44,9 +44,6 @@ import org.oxycblt.auxio.util.lazyReflectedField
  * and thus scrolling past them should make the toolbar show the name in order to give context on
  * where the user currently is.
  *
- * This task should nominally be accomplished with CollapsingToolbarLayout, but I have not figured
- * out how to get that working sensibly yet.
- *
  * @author Alexander Capehart (OxygenCobalt)
  */
 class DetailAppBarLayout
@@ -72,7 +69,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
 
         // Assume that we have a Toolbar with a detail_toolbar ID, as this view is only
         // used within the detail layouts.
-        val toolbar = findViewById<Toolbar>(R.id.detail_toolbar)
+        val toolbar = findViewById<Toolbar>(R.id.detail_normal_toolbar)
 
         // The Toolbar's title view is actually hidden. To avoid having to create our own
         // title view, we just reflect into Toolbar and grab the hidden field.

app/src/main/java/org/oxycblt/auxio/detail/DetailViewModel.kt

@@ -30,16 +30,17 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.yield
 import org.oxycblt.auxio.R
+import org.oxycblt.auxio.detail.list.EditHeader
 import org.oxycblt.auxio.detail.list.SortHeader
 import org.oxycblt.auxio.list.BasicHeader
+import org.oxycblt.auxio.list.Divider
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.UpdateInstructions
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.metadata.AudioInfo
+import org.oxycblt.auxio.music.info.Disc
-import org.oxycblt.auxio.music.metadata.Disc
+import org.oxycblt.auxio.music.info.ReleaseType
-import org.oxycblt.auxio.music.metadata.ReleaseType
+import org.oxycblt.auxio.music.metadata.AudioProperties
-import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.util.*
 
@@ -54,22 +55,22 @@ class DetailViewModel
 @Inject
 constructor(
     private val musicRepository: MusicRepository,
-    private val audioInfoProvider: AudioInfo.Provider,
+    private val audioPropertiesFactory: AudioProperties.Factory,
     private val musicSettings: MusicSettings,
     private val playbackSettings: PlaybackSettings
-) : ViewModel(), MusicRepository.Listener {
+) : ViewModel(), MusicRepository.UpdateListener {
-    private var currentSongJob: Job? = null
-
     // --- SONG ---
     
+    private var currentSongJob: Job? = null
+
     private val _currentSong = MutableStateFlow<Song?>(null)
     /** The current [Song] to display. Null if there is nothing to show. */
     val currentSong: StateFlow<Song?>
         get() = _currentSong
 
-    private val _songAudioInfo = MutableStateFlow<AudioInfo?>(null)
+    private val _songAudioProperties = MutableStateFlow<AudioProperties?>(null)
-    /** The [AudioInfo] of the currently shown [Song]. Null if not loaded yet. */
+    /** The [AudioProperties] of the currently shown [Song]. Null if not loaded yet. */
-    val songAudioInfo: StateFlow<AudioInfo?> = _songAudioInfo
+    val songAudioProperties: StateFlow<AudioProperties?> = _songAudioProperties
 
     // --- ALBUM ---
 
@@ -144,6 +145,29 @@ constructor(
             currentGenre.value?.let { refreshGenreList(it, true) }
         }
 
+    // --- PLAYLIST ---
+
+    private val _currentPlaylist = MutableStateFlow<Playlist?>(null)
+    /** The current [Playlist] to display. Null if there is nothing to do. */
+    val currentPlaylist: StateFlow<Playlist?>
+        get() = _currentPlaylist
+
+    private val _playlistList = MutableStateFlow(listOf<Item>())
+    /** The current list data derived from [currentPlaylist] */
+    val playlistList: StateFlow<List<Item>> = _playlistList
+    private val _playlistInstructions = MutableEvent<UpdateInstructions>()
+    /** Instructions for updating [playlistList] in the UI. */
+    val playlistInstructions: Event<UpdateInstructions>
+        get() = _playlistInstructions
+
+    private val _editedPlaylist = MutableStateFlow<List<Song>?>(null)
+    /**
+     * The new playlist songs created during the current editing session. Null if no editing session
+     * is occurring.
+     */
+    val editedPlaylist: StateFlow<List<Song>?>
+        get() = _editedPlaylist
+
     /**
      * The [MusicMode] to use when playing a [Song] from the UI, or null to play from the currently
      * shown item.
@@ -152,126 +176,218 @@ constructor(
         get() = playbackSettings.inParentPlaybackMode
 
     init {
-        musicRepository.addListener(this)
+        musicRepository.addUpdateListener(this)
     }
 
     override fun onCleared() {
-        musicRepository.removeListener(this)
+        musicRepository.removeUpdateListener(this)
     }
 
-    override fun onLibraryChanged(library: Library?) {
+    override fun onMusicChanges(changes: MusicRepository.Changes) {
-        if (library == null) {
-            // Nothing to do.
-            return
-        }
-
         // If we are showing any item right now, we will need to refresh it (and any information
         // related to it) with the new library in order to prevent stale items from showing up
         // in the UI.
+        val deviceLibrary = musicRepository.deviceLibrary
+        if (changes.deviceLibrary && deviceLibrary != null) {
+            val song = currentSong.value
+            if (song != null) {
+                _currentSong.value = deviceLibrary.findSong(song.uid)?.also(::refreshAudioInfo)
+                logD("Updated song to ${currentSong.value}")
+            }
 
-        val song = currentSong.value
+            val album = currentAlbum.value
-        if (song != null) {
+            if (album != null) {
-            _currentSong.value = library.sanitize(song)?.also(::refreshAudioInfo)
+                _currentAlbum.value = deviceLibrary.findAlbum(album.uid)?.also(::refreshAlbumList)
-            logD("Updated song to ${currentSong.value}")
+                logD("Updated album to ${currentAlbum.value}")
+            }
+
+            val artist = currentArtist.value
+            if (artist != null) {
+                _currentArtist.value =
+                    deviceLibrary.findArtist(artist.uid)?.also(::refreshArtistList)
+                logD("Updated artist to ${currentArtist.value}")
+            }
+
+            val genre = currentGenre.value
+            if (genre != null) {
+                _currentGenre.value = deviceLibrary.findGenre(genre.uid)?.also(::refreshGenreList)
+                logD("Updated genre to ${currentGenre.value}")
+            }
         }
 
-        val album = currentAlbum.value
+        val userLibrary = musicRepository.userLibrary
-        if (album != null) {
+        if (changes.userLibrary && userLibrary != null) {
-            _currentAlbum.value = library.sanitize(album)?.also(::refreshAlbumList)
+            val playlist = currentPlaylist.value
-            logD("Updated genre to ${currentAlbum.value}")
+            if (playlist != null) {
-        }
+                logD("Updated playlist to ${currentPlaylist.value}")
-
+                _currentPlaylist.value =
-        val artist = currentArtist.value
+                    userLibrary.findPlaylist(playlist.uid)?.also(::refreshPlaylistList)
-        if (artist != null) {
+            }
-            _currentArtist.value = library.sanitize(artist)?.also(::refreshArtistList)
-            logD("Updated genre to ${currentArtist.value}")
-        }
-
-        val genre = currentGenre.value
-        if (genre != null) {
-            _currentGenre.value = library.sanitize(genre)?.also(::refreshGenreList)
-            logD("Updated genre to ${currentGenre.value}")
         }
     }
 
     /**
-     * Set a new [currentSong] from it's [Music.UID]. If the [Music.UID] differs, [currentSong] and
+     * Set a new [currentSong] from it's [Music.UID]. [currentSong] and [songAudioProperties] will
-     * [songAudioInfo] will be updated to align with the new [Song].
+     * be updated to align with the new [Song].
      *
      * @param uid The UID of the [Song] to load. Must be valid.
      */
-    fun setSongUid(uid: Music.UID) {
+    fun setSong(uid: Music.UID) {
-        if (_currentSong.value?.uid == uid) {
-            // Nothing to do.
-            return
-        }
         logD("Opening Song [uid: $uid]")
-        _currentSong.value = requireMusic<Song>(uid)?.also(::refreshAudioInfo)
+        _currentSong.value = musicRepository.deviceLibrary?.findSong(uid)?.also(::refreshAudioInfo)
     }
 
     /**
-     * Set a new [currentAlbum] from it's [Music.UID]. If the [Music.UID] differs, [currentAlbum]
+     * Set a new [currentAlbum] from it's [Music.UID]. [currentAlbum] and [albumList] will be
-     * and [albumList] will be updated to align with the new [Album].
+     * updated to align with the new [Album].
      *
      * @param uid The [Music.UID] of the [Album] to update [currentAlbum] to. Must be valid.
      */
-    fun setAlbumUid(uid: Music.UID) {
+    fun setAlbum(uid: Music.UID) {
-        if (_currentAlbum.value?.uid == uid) {
-            // Nothing to do.
-            return
-        }
         logD("Opening Album [uid: $uid]")
-        _currentAlbum.value = requireMusic<Album>(uid)?.also(::refreshAlbumList)
+        _currentAlbum.value =
+            musicRepository.deviceLibrary?.findAlbum(uid)?.also(::refreshAlbumList)
     }
 
     /**
-     * Set a new [currentArtist] from it's [Music.UID]. If the [Music.UID] differs, [currentArtist]
+     * Set a new [currentArtist] from it's [Music.UID]. [currentArtist] and [artistList] will be
-     * and [artistList] will be updated to align with the new [Artist].
+     * updated to align with the new [Artist].
      *
      * @param uid The [Music.UID] of the [Artist] to update [currentArtist] to. Must be valid.
      */
-    fun setArtistUid(uid: Music.UID) {
+    fun setArtist(uid: Music.UID) {
-        if (_currentArtist.value?.uid == uid) {
-            // Nothing to do.
-            return
-        }
         logD("Opening Artist [uid: $uid]")
-        _currentArtist.value = requireMusic<Artist>(uid)?.also(::refreshArtistList)
+        _currentArtist.value =
+            musicRepository.deviceLibrary?.findArtist(uid)?.also(::refreshArtistList)
     }
 
     /**
-     * Set a new [currentGenre] from it's [Music.UID]. If the [Music.UID] differs, [currentGenre]
+     * Set a new [currentGenre] from it's [Music.UID]. [currentGenre] and [genreList] will be
-     * and [genreList] will be updated to align with the new album.
+     * updated to align with the new album.
      *
      * @param uid The [Music.UID] of the [Genre] to update [currentGenre] to. Must be valid.
      */
-    fun setGenreUid(uid: Music.UID) {
+    fun setGenre(uid: Music.UID) {
-        if (_currentGenre.value?.uid == uid) {
-            // Nothing to do.
-            return
-        }
         logD("Opening Genre [uid: $uid]")
-        _currentGenre.value = requireMusic<Genre>(uid)?.also(::refreshGenreList)
+        _currentGenre.value =
+            musicRepository.deviceLibrary?.findGenre(uid)?.also(::refreshGenreList)
     }
 
-    private fun <T : Music> requireMusic(uid: Music.UID) = musicRepository.library?.find<T>(uid)
+    /**
+     * Set a new [currentPlaylist] from it's [Music.UID]. If the [Music.UID] differs,
+     * [currentPlaylist] and [currentPlaylist] will be updated to align with the new album.
+     *
+     * @param uid The [Music.UID] of the [Playlist] to update [currentPlaylist] to. Must be valid.
+     */
+    fun setPlaylist(uid: Music.UID) {
+        logD("Opening Playlist [uid: $uid]")
+        _currentPlaylist.value =
+            musicRepository.userLibrary?.findPlaylist(uid)?.also(::refreshPlaylistList)
+    }
+
+    /** Start a playlist editing session. Does nothing if a playlist is not being shown. */
+    fun startPlaylistEdit() {
+        val playlist = _currentPlaylist.value ?: return
+        logD("Starting playlist edit")
+        _editedPlaylist.value = playlist.songs
+        refreshPlaylistList(playlist)
+    }
+
+    /**
+     * End a playlist editing session and commits it to the database. Does nothing if there was no
+     * prior editing session.
+     */
+    fun savePlaylistEdit() {
+        val playlist = _currentPlaylist.value ?: return
+        val editedPlaylist = _editedPlaylist.value ?: return
+        viewModelScope.launch {
+            musicRepository.rewritePlaylist(playlist, editedPlaylist)
+            // TODO: The user could probably press some kind of button if they were fast enough.
+            //  Think of a better way to handle this state.
+            _editedPlaylist.value = null
+        }
+    }
+
+    /**
+     * End a playlist editing session and keep the prior state. Does nothing if there was no prior
+     * editing session.
+     *
+     * @return true if the session was ended, false otherwise.
+     */
+    fun dropPlaylistEdit(): Boolean {
+        val playlist = _currentPlaylist.value ?: return false
+        if (_editedPlaylist.value == null) {
+            // Nothing to do.
+            return false
+        }
+        _editedPlaylist.value = null
+        refreshPlaylistList(playlist)
+        return true
+    }
+
+    /**
+     * (Visually) move a song in the current playlist. Does nothing if not in an editing session.
+     *
+     * @param from The start position, in the list adapter data.
+     * @param to The destination position, in the list adapter data.
+     * @return true if the song was moved, false otherwise.
+     */
+    fun movePlaylistSongs(from: Int, to: Int): Boolean {
+        // TODO: Song re-sorting
+        val playlist = _currentPlaylist.value ?: return false
+        val editedPlaylist = (_editedPlaylist.value ?: return false).toMutableList()
+        val realFrom = from - 2
+        val realTo = to - 2
+        if (realFrom !in editedPlaylist.indices || realTo !in editedPlaylist.indices) {
+            return false
+        }
+        editedPlaylist.add(realFrom, editedPlaylist.removeAt(realTo))
+        _editedPlaylist.value = editedPlaylist
+        refreshPlaylistList(playlist, UpdateInstructions.Move(from, to))
+        return true
+    }
+
+    /**
+     * (Visually) remove a song in the current playlist. Does nothing if not in an editing session.
+     *
+     * @param at The position of the item to remove, in the list adapter data.
+     */
+    fun removePlaylistSong(at: Int) {
+        val playlist = _currentPlaylist.value ?: return
+        val editedPlaylist = (_editedPlaylist.value ?: return).toMutableList()
+        val realAt = at - 2
+        if (realAt !in editedPlaylist.indices) {
+            return
+        }
+        editedPlaylist.removeAt(realAt)
+        _editedPlaylist.value = editedPlaylist
+        refreshPlaylistList(
+            playlist,
+            if (editedPlaylist.isNotEmpty()) {
+                UpdateInstructions.Remove(at, 1)
+            } else {
+                UpdateInstructions.Remove(at - 2, 3)
+            })
+    }
 
     private fun refreshAudioInfo(song: Song) {
         // Clear any previous job in order to avoid stale data from appearing in the UI.
         currentSongJob?.cancel()
-        _songAudioInfo.value = null
+        _songAudioProperties.value = null
         currentSongJob =
             viewModelScope.launch(Dispatchers.IO) {
-                val info = audioInfoProvider.extract(song)
+                val info = audioPropertiesFactory.extract(song)
                 yield()
-                _songAudioInfo.value = info
+                _songAudioProperties.value = info
             }
     }
 
     private fun refreshAlbumList(album: Album, replace: Boolean = false) {
-        logD("Refreshing album data")
+        logD("Refreshing album list")
         val list = mutableListOf<Item>()
-        list.add(SortHeader(R.string.lbl_songs))
+        val header = SortHeader(R.string.lbl_songs)
+        list.add(Divider(header))
+        list.add(header)
         val instructions =
             if (replace) {
                 // Intentional so that the header item isn't replaced with the songs
@@ -301,7 +417,7 @@ constructor(
     }
 
     private fun refreshArtistList(artist: Artist, replace: Boolean = false) {
-        logD("Refreshing artist data")
+        logD("Refreshing artist list")
         val list = mutableListOf<Item>()
         val albums = Sort(Sort.Mode.ByDate, Sort.Direction.DESCENDING).albums(artist.albums)
 
@@ -329,7 +445,9 @@ constructor(
         logD("Release groups for this artist: ${byReleaseGroup.keys}")
 
         for (entry in byReleaseGroup.entries.sortedBy { it.key }) {
-            list.add(BasicHeader(entry.key.headerTitleRes))
+            val header = BasicHeader(entry.key.headerTitleRes)
+            list.add(Divider(header))
+            list.add(header)
             list.addAll(entry.value)
         }
 
@@ -337,7 +455,9 @@ constructor(
         var instructions: UpdateInstructions = UpdateInstructions.Diff
         if (artist.songs.isNotEmpty()) {
             logD("Songs present in this artist, adding header")
-            list.add(SortHeader(R.string.lbl_songs))
+            val header = SortHeader(R.string.lbl_songs)
+            list.add(Divider(header))
+            list.add(header)
             if (replace) {
                 // Intentional so that the header item isn't replaced with the songs
                 instructions = UpdateInstructions.Replace(list.size)
@@ -350,12 +470,17 @@ constructor(
     }
 
     private fun refreshGenreList(genre: Genre, replace: Boolean = false) {
-        logD("Refreshing genre data")
+        logD("Refreshing genre list")
         val list = mutableListOf<Item>()
         // Genre is guaranteed to always have artists and songs.
-        list.add(BasicHeader(R.string.lbl_artists))
+        val artistHeader = BasicHeader(R.string.lbl_artists)
+        list.add(Divider(artistHeader))
+        list.add(artistHeader)
         list.addAll(genre.artists)
-        list.add(SortHeader(R.string.lbl_songs))
+
+        val songHeader = SortHeader(R.string.lbl_songs)
+        list.add(Divider(songHeader))
+        list.add(songHeader)
         val instructions =
             if (replace) {
                 // Intentional so that the header item isn't replaced with the songs
@@ -368,6 +493,25 @@ constructor(
         _genreList.value = list
     }
 
+    private fun refreshPlaylistList(
+        playlist: Playlist,
+        instructions: UpdateInstructions = UpdateInstructions.Diff
+    ) {
+        logD("Refreshing playlist list")
+        val list = mutableListOf<Item>()
+
+        val songs = editedPlaylist.value ?: playlist.songs
+        if (songs.isNotEmpty()) {
+            val header = EditHeader(R.string.lbl_songs)
+            list.add(Divider(header))
+            list.add(header)
+            list.addAll(songs)
+        }
+
+        _playlistInstructions.put(instructions)
+        _playlistList.value = list
+    }
+
     /**
      * A simpler mapping of [ReleaseType] used for grouping and sorting songs.
      *

app/src/main/java/org/oxycblt/auxio/detail/GenreDetailFragment.kt

@@ -26,6 +26,7 @@ import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
 import androidx.navigation.fragment.navArgs
 import androidx.recyclerview.widget.ConcatAdapter
+import androidx.recyclerview.widget.GridLayoutManager
 import com.google.android.material.transition.MaterialSharedAxis
 import dagger.hilt.android.AndroidEntryPoint
 import org.oxycblt.auxio.R
@@ -34,18 +35,15 @@ import org.oxycblt.auxio.detail.header.DetailHeaderAdapter
 import org.oxycblt.auxio.detail.header.GenreDetailHeaderAdapter
 import org.oxycblt.auxio.detail.list.DetailListAdapter
 import org.oxycblt.auxio.detail.list.GenreDetailListAdapter
+import org.oxycblt.auxio.list.Divider
+import org.oxycblt.auxio.list.Header
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.selection.SelectionViewModel
-import org.oxycblt.auxio.music.Album
+import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.Artist
+import org.oxycblt.auxio.navigation.NavigationViewModel
-import org.oxycblt.auxio.music.Genre
-import org.oxycblt.auxio.music.Music
-import org.oxycblt.auxio.music.MusicParent
-import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.PlaybackViewModel
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.*
 
 /**
@@ -61,6 +59,7 @@ class GenreDetailFragment :
     private val detailModel: DetailViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     // Information about what genre to display is initially within the navigation arguments
     // as a UID, as that is the only safe way to parcel an genre.
@@ -85,18 +84,31 @@ class GenreDetailFragment :
         super.onBindingCreated(binding, savedInstanceState)
 
         // --- UI SETUP ---
-        binding.detailToolbar.apply {
+        binding.detailNormalToolbar.apply {
-            inflateMenu(R.menu.menu_genre_artist_detail)
+            inflateMenu(R.menu.menu_parent_detail)
             setNavigationOnClickListener { findNavController().navigateUp() }
             setOnMenuItemClickListener(this@GenreDetailFragment)
         }
 
-        binding.detailRecycler.adapter = ConcatAdapter(genreHeaderAdapter, genreListAdapter)
+        binding.detailRecycler.apply {
+            adapter = ConcatAdapter(genreHeaderAdapter, genreListAdapter)
+            (layoutManager as GridLayoutManager).setFullWidthLookup {
+                if (it != 0) {
+                    val item =
+                        detailModel.genreList.value.getOrElse(it - 1) {
+                            return@setFullWidthLookup false
+                        }
+                    item is Divider || item is Header
+                } else {
+                    true
+                }
+            }
+        }
 
         // --- VIEWMODEL SETUP ---
         // DetailViewModel handles most initialization from the navigation argument.
-        detailModel.setGenreUid(args.genreUid)
+        detailModel.setGenre(args.genreUid)
-        collectImmediately(detailModel.currentGenre, ::updateItem)
+        collectImmediately(detailModel.currentGenre, ::updatePlaylist)
         collectImmediately(detailModel.genreList, ::updateList)
         collectImmediately(
             playbackModel.song, playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
@@ -106,7 +118,7 @@ class GenreDetailFragment :
 
     override fun onDestroyBinding(binding: FragmentDetailBinding) {
         super.onDestroyBinding(binding)
-        binding.detailToolbar.setOnMenuItemClickListener(null)
+        binding.detailNormalToolbar.setOnMenuItemClickListener(null)
         binding.detailRecycler.adapter = null
         // Avoid possible race conditions that could cause a bad replace instruction to be consumed
         // during list initialization and crash the app. Could happen if the user is fast enough.
@@ -130,6 +142,10 @@ class GenreDetailFragment :
                 requireContext().showToast(R.string.lng_queue_added)
                 true
             }
+            R.id.action_playlist_add -> {
+                musicModel.addToPlaylist(currentGenre)
+                true
+            }
             else -> false
         }
     }
@@ -154,7 +170,7 @@ class GenreDetailFragment :
 
     override fun onOpenMenu(item: Music, anchor: View) {
         when (item) {
-            is Artist -> openMusicMenu(anchor, R.menu.menu_artist_actions, item)
+            is Artist -> openMusicMenu(anchor, R.menu.menu_parent_actions, item)
             is Song -> openMusicMenu(anchor, R.menu.menu_song_actions, item)
             else -> error("Unexpected datatype: ${item::class.simpleName}")
         }
@@ -170,8 +186,10 @@ class GenreDetailFragment :
 
     override fun onOpenSortMenu(anchor: View) {
         openMenu(anchor, R.menu.menu_genre_sort) {
+            // Select the corresponding sort mode option
             val sort = detailModel.genreSongSort
             unlikelyToBeNull(menu.findItem(sort.mode.itemId)).isChecked = true
+            // Select the corresponding sort direction option
             val directionItemId =
                 when (sort.direction) {
                     Sort.Direction.ASCENDING -> R.id.option_sort_asc
@@ -182,8 +200,10 @@ class GenreDetailFragment :
                 item.isChecked = !item.isChecked
                 detailModel.genreSongSort =
                     when (item.itemId) {
+                        // Sort direction options
                         R.id.option_sort_asc -> sort.withDirection(Sort.Direction.ASCENDING)
                         R.id.option_sort_dec -> sort.withDirection(Sort.Direction.DESCENDING)
+                        // Any other option is a sort mode
                         else -> sort.withMode(unlikelyToBeNull(Sort.Mode.fromItemId(item.itemId)))
                     }
                 true
@@ -191,13 +211,13 @@ class GenreDetailFragment :
         }
     }
 
-    private fun updateItem(genre: Genre?) {
+    private fun updatePlaylist(genre: Genre?) {
         if (genre == null) {
             // Genre we were showing no longer exists.
             findNavController().navigateUp()
             return
         }
-        requireBinding().detailToolbar.title = genre.resolveName(requireContext())
+        requireBinding().detailNormalToolbar.title = genre.name.resolve(requireContext())
         genreHeaderAdapter.setParent(genre)
     }
 
@@ -233,7 +253,7 @@ class GenreDetailFragment :
             is Genre -> {
                 navModel.exploreNavigationItem.consume()
             }
-            null -> {}
+            else -> {}
         }
     }
 
@@ -243,6 +263,13 @@ class GenreDetailFragment :
 
     private fun updateSelection(selected: List<Music>) {
         genreListAdapter.setSelected(selected.toSet())
-        requireBinding().detailSelectionToolbar.updateSelectionAmount(selected.size)
+
+        val binding = requireBinding()
+        if (selected.isNotEmpty()) {
+            binding.detailSelectionToolbar.title = getString(R.string.fmt_selected, selected.size)
+            binding.detailToolbar.setVisible(R.id.detail_selection_toolbar)
+        } else {
+            binding.detailToolbar.setVisible(R.id.detail_normal_toolbar)
+        }
     }
 }

app/src/main/java/org/oxycblt/auxio/detail/PlaylistDetailFragment.kt

@@ -0,0 +1,318 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistDetailFragment.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.detail
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.MenuItem
+import android.view.View
+import androidx.fragment.app.activityViewModels
+import androidx.navigation.NavController
+import androidx.navigation.NavDestination
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import androidx.recyclerview.widget.ConcatAdapter
+import androidx.recyclerview.widget.GridLayoutManager
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.RecyclerView
+import com.google.android.material.transition.MaterialSharedAxis
+import dagger.hilt.android.AndroidEntryPoint
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.FragmentDetailBinding
+import org.oxycblt.auxio.detail.header.DetailHeaderAdapter
+import org.oxycblt.auxio.detail.header.PlaylistDetailHeaderAdapter
+import org.oxycblt.auxio.detail.list.PlaylistDetailListAdapter
+import org.oxycblt.auxio.detail.list.PlaylistDragCallback
+import org.oxycblt.auxio.list.Divider
+import org.oxycblt.auxio.list.Header
+import org.oxycblt.auxio.list.Item
+import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.selection.SelectionViewModel
+import org.oxycblt.auxio.music.*
+import org.oxycblt.auxio.navigation.NavigationViewModel
+import org.oxycblt.auxio.playback.PlaybackViewModel
+import org.oxycblt.auxio.util.*
+
+/**
+ * A [ListFragment] that shows information for a particular [Playlist].
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+@AndroidEntryPoint
+class PlaylistDetailFragment :
+    ListFragment<Song, FragmentDetailBinding>(),
+    DetailHeaderAdapter.Listener,
+    PlaylistDetailListAdapter.Listener,
+    NavController.OnDestinationChangedListener {
+    private val detailModel: DetailViewModel by activityViewModels()
+    override val navModel: NavigationViewModel by activityViewModels()
+    override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
+    override val selectionModel: SelectionViewModel by activityViewModels()
+    // Information about what playlist to display is initially within the navigation arguments
+    // as a UID, as that is the only safe way to parcel an playlist.
+    private val args: PlaylistDetailFragmentArgs by navArgs()
+    private val playlistHeaderAdapter = PlaylistDetailHeaderAdapter(this)
+    private val playlistListAdapter = PlaylistDetailListAdapter(this)
+    private var touchHelper: ItemTouchHelper? = null
+    private var initialNavDestinationChange = false
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        enterTransition = MaterialSharedAxis(MaterialSharedAxis.X, true)
+        returnTransition = MaterialSharedAxis(MaterialSharedAxis.X, false)
+        exitTransition = MaterialSharedAxis(MaterialSharedAxis.X, true)
+        reenterTransition = MaterialSharedAxis(MaterialSharedAxis.X, false)
+    }
+
+    override fun onCreateBinding(inflater: LayoutInflater) = FragmentDetailBinding.inflate(inflater)
+
+    override fun getSelectionToolbar(binding: FragmentDetailBinding) =
+        binding.detailSelectionToolbar
+
+    override fun onBindingCreated(binding: FragmentDetailBinding, savedInstanceState: Bundle?) {
+        super.onBindingCreated(binding, savedInstanceState)
+
+        // --- UI SETUP ---
+        binding.detailNormalToolbar.apply {
+            inflateMenu(R.menu.menu_playlist_detail)
+            setNavigationOnClickListener { findNavController().navigateUp() }
+            setOnMenuItemClickListener(this@PlaylistDetailFragment)
+        }
+
+        binding.detailEditToolbar.apply {
+            setNavigationOnClickListener { detailModel.dropPlaylistEdit() }
+            setOnMenuItemClickListener(this@PlaylistDetailFragment)
+        }
+
+        binding.detailRecycler.apply {
+            adapter = ConcatAdapter(playlistHeaderAdapter, playlistListAdapter)
+            touchHelper =
+                ItemTouchHelper(PlaylistDragCallback(detailModel)).also {
+                    it.attachToRecyclerView(this)
+                }
+            (layoutManager as GridLayoutManager).setFullWidthLookup {
+                if (it != 0) {
+                    val item =
+                        detailModel.playlistList.value.getOrElse(it - 1) {
+                            return@setFullWidthLookup false
+                        }
+                    item is Divider || item is Header
+                } else {
+                    true
+                }
+            }
+        }
+
+        // --- VIEWMODEL SETUP ---
+        // DetailViewModel handles most initialization from the navigation argument.
+        detailModel.setPlaylist(args.playlistUid)
+        collectImmediately(detailModel.currentPlaylist, ::updatePlaylist)
+        collectImmediately(detailModel.playlistList, ::updateList)
+        collectImmediately(detailModel.editedPlaylist, ::updateEditedPlaylist)
+        collectImmediately(
+            playbackModel.song, playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
+        collect(navModel.exploreNavigationItem.flow, ::handleNavigation)
+        collectImmediately(selectionModel.selected, ::updateSelection)
+    }
+
+    override fun onStart() {
+        super.onStart()
+        // Once we add the destination change callback, we will receive another initialization call,
+        // so handle that by resetting the flag.
+        initialNavDestinationChange = false
+        findNavController().addOnDestinationChangedListener(this)
+    }
+
+    override fun onStop() {
+        super.onStop()
+        findNavController().removeOnDestinationChangedListener(this)
+    }
+
+    override fun onDestroyBinding(binding: FragmentDetailBinding) {
+        super.onDestroyBinding(binding)
+        binding.detailNormalToolbar.setOnMenuItemClickListener(null)
+        touchHelper = null
+        binding.detailRecycler.adapter = null
+        // Avoid possible race conditions that could cause a bad replace instruction to be consumed
+        // during list initialization and crash the app. Could happen if the user is fast enough.
+        detailModel.playlistInstructions.consume()
+    }
+
+    override fun onDestinationChanged(
+        controller: NavController,
+        destination: NavDestination,
+        arguments: Bundle?
+    ) {
+        // Drop the initial call by NavController that simply provides us with the current
+        // destination. This would cause the selection state to be lost every time the device
+        // rotates.
+        if (!initialNavDestinationChange) {
+            initialNavDestinationChange = true
+            return
+        }
+        // Drop any pending playlist edits when navigating away. This could actually happen
+        // if the user is quick enough.
+        detailModel.dropPlaylistEdit()
+    }
+
+    override fun onMenuItemClick(item: MenuItem): Boolean {
+        if (super.onMenuItemClick(item)) {
+            return true
+        }
+
+        val currentPlaylist = unlikelyToBeNull(detailModel.currentPlaylist.value)
+        return when (item.itemId) {
+            R.id.action_play_next -> {
+                playbackModel.playNext(currentPlaylist)
+                requireContext().showToast(R.string.lng_queue_added)
+                true
+            }
+            R.id.action_queue_add -> {
+                playbackModel.addToQueue(currentPlaylist)
+                requireContext().showToast(R.string.lng_queue_added)
+                true
+            }
+            R.id.action_rename -> {
+                musicModel.renamePlaylist(currentPlaylist)
+                true
+            }
+            R.id.action_delete -> {
+                musicModel.deletePlaylist(currentPlaylist)
+                true
+            }
+            R.id.action_save -> {
+                detailModel.savePlaylistEdit()
+                true
+            }
+            else -> false
+        }
+    }
+
+    override fun onRealClick(item: Song) {
+        playbackModel.playFromPlaylist(item, unlikelyToBeNull(detailModel.currentPlaylist.value))
+    }
+
+    override fun onPickUp(viewHolder: RecyclerView.ViewHolder) {
+        requireNotNull(touchHelper) { "ItemTouchHelper was not available" }.startDrag(viewHolder)
+    }
+
+    override fun onOpenMenu(item: Song, anchor: View) {
+        openMusicMenu(anchor, R.menu.menu_playlist_song_actions, item)
+    }
+
+    override fun onPlay() {
+        playbackModel.play(unlikelyToBeNull(detailModel.currentPlaylist.value))
+    }
+
+    override fun onShuffle() {
+        playbackModel.shuffle(unlikelyToBeNull(detailModel.currentPlaylist.value))
+    }
+
+    override fun onStartEdit() {
+        detailModel.startPlaylistEdit()
+    }
+
+    override fun onOpenSortMenu(anchor: View) {}
+
+    private fun updatePlaylist(playlist: Playlist?) {
+        if (playlist == null) {
+            // Playlist we were showing no longer exists.
+            findNavController().navigateUp()
+            return
+        }
+        val binding = requireBinding()
+        binding.detailNormalToolbar.title = playlist.name.resolve(requireContext())
+        binding.detailEditToolbar.title = "Editing ${playlist.name.resolve(requireContext())}"
+        playlistHeaderAdapter.setParent(playlist)
+    }
+
+    private fun updatePlayback(song: Song?, parent: MusicParent?, isPlaying: Boolean) {
+        // Prefer songs that might be playing from this playlist.
+        if (parent is Playlist &&
+            parent.uid == unlikelyToBeNull(detailModel.currentPlaylist.value).uid) {
+            playlistListAdapter.setPlaying(song, isPlaying)
+        } else {
+            playlistListAdapter.setPlaying(null, isPlaying)
+        }
+    }
+
+    private fun handleNavigation(item: Music?) {
+        when (item) {
+            is Song -> {
+                logD("Navigating to another song")
+                findNavController()
+                    .navigateSafe(PlaylistDetailFragmentDirections.actionShowAlbum(item.album.uid))
+            }
+            is Album -> {
+                logD("Navigating to another album")
+                findNavController()
+                    .navigateSafe(PlaylistDetailFragmentDirections.actionShowAlbum(item.uid))
+            }
+            is Artist -> {
+                logD("Navigating to another artist")
+                findNavController()
+                    .navigateSafe(PlaylistDetailFragmentDirections.actionShowArtist(item.uid))
+            }
+            is Playlist -> {
+                navModel.exploreNavigationItem.consume()
+            }
+            else -> {}
+        }
+    }
+
+    private fun updateList(list: List<Item>) {
+        playlistListAdapter.update(list, detailModel.playlistInstructions.consume())
+    }
+
+    private fun updateEditedPlaylist(editedPlaylist: List<Song>?) {
+        playlistListAdapter.setEditing(editedPlaylist != null)
+        playlistHeaderAdapter.setEditedPlaylist(editedPlaylist)
+        selectionModel.drop()
+
+        if (editedPlaylist != null) {
+            requireBinding().detailEditToolbar.menu.findItem(R.id.action_save).apply {
+                isEnabled = editedPlaylist != detailModel.currentPlaylist.value?.songs
+            }
+        }
+
+        updateMultiToolbar()
+    }
+
+    private fun updateSelection(selected: List<Music>) {
+        playlistListAdapter.setSelected(selected.toSet())
+
+        val binding = requireBinding()
+        if (selected.isNotEmpty()) {
+            binding.detailSelectionToolbar.title = getString(R.string.fmt_selected, selected.size)
+        }
+        updateMultiToolbar()
+    }
+
+    private fun updateMultiToolbar() {
+        val id =
+            when {
+                detailModel.editedPlaylist.value != null -> R.id.detail_edit_toolbar
+                selectionModel.selected.value.isNotEmpty() -> R.id.detail_selection_toolbar
+                else -> R.id.detail_normal_toolbar
+            }
+
+        requireBinding().detailToolbar.setVisible(id)
+    }
+}

app/src/main/java/org/oxycblt/auxio/detail/SongDetailDialog.kt

@@ -34,7 +34,8 @@ import org.oxycblt.auxio.detail.list.SongPropertyAdapter
 import org.oxycblt.auxio.list.adapter.UpdateInstructions
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.metadata.AudioInfo
+import org.oxycblt.auxio.music.info.Name
+import org.oxycblt.auxio.music.metadata.AudioProperties
 import org.oxycblt.auxio.music.resolveNames
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
@@ -66,11 +67,11 @@ class SongDetailDialog : ViewBindingDialogFragment<DialogSongDetailBinding>() {
         super.onBindingCreated(binding, savedInstanceState)
         binding.detailProperties.adapter = detailAdapter
         // DetailViewModel handles most initialization from the navigation argument.
-        detailModel.setSongUid(args.itemUid)
+        detailModel.setSong(args.songUid)
-        collectImmediately(detailModel.currentSong, detailModel.songAudioInfo, ::updateSong)
+        collectImmediately(detailModel.currentSong, detailModel.songAudioProperties, ::updateSong)
     }
 
-    private fun updateSong(song: Song?, info: AudioInfo?) {
+    private fun updateSong(song: Song?, info: AudioProperties?) {
         if (song == null) {
             // Song we were showing no longer exists.
             findNavController().navigateUp()
@@ -123,12 +124,14 @@ class SongDetailDialog : ViewBindingDialogFragment<DialogSongDetailBinding>() {
         }
     }
 
-    private fun <T : Music> T.zipName(context: Context) =
+    private fun <T : Music> T.zipName(context: Context): String {
-        if (rawSortName != null) {
+        val name = name
-            getString(R.string.fmt_zipped_names, resolveName(context), rawSortName)
+        return if (name is Name.Known && name.sort != null) {
+            getString(R.string.fmt_zipped_names, name.resolve(context), name.sort)
         } else {
-            resolveName(context)
+            name.resolve(context)
         }
+    }
 
     private fun <T : Music> List<T>.zipNames(context: Context) =
         concatLocalized(context) { it.zipName(context) }

app/src/main/java/org/oxycblt/auxio/detail/header/AlbumDetailHeaderAdapter.kt

@@ -33,6 +33,7 @@ import org.oxycblt.auxio.util.inflater
 /**
  * A [DetailHeaderAdapter] that shows [Album] information.
  *
+ * @param listener [DetailHeaderAdapter.Listener] to bind interactions to.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class AlbumDetailHeaderAdapter(private val listener: Listener) :
@@ -76,7 +77,7 @@ private constructor(private val binding: ItemDetailHeaderBinding) :
         // The type text depends on the release type (Album, EP, Single, etc.)
         binding.detailType.text = binding.context.getString(album.releaseType.stringRes)
 
-        binding.detailName.text = album.resolveName(binding.context)
+        binding.detailName.text = album.name.resolve(binding.context)
 
         // Artist name maps to the subhead text
         binding.detailSubhead.apply {

app/src/main/java/org/oxycblt/auxio/detail/header/ArtistDetailHeaderAdapter.kt

@@ -33,6 +33,7 @@ import org.oxycblt.auxio.util.inflater
 /**
  * A [DetailHeaderAdapter] that shows [Artist] information.
  *
+ * @param listener [DetailHeaderAdapter.Listener] to bind interactions to.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class ArtistDetailHeaderAdapter(private val listener: Listener) :
@@ -62,7 +63,18 @@ private constructor(private val binding: ItemDetailHeaderBinding) :
     fun bind(artist: Artist, listener: DetailHeaderAdapter.Listener) {
         binding.detailCover.bind(artist)
         binding.detailType.text = binding.context.getString(R.string.lbl_artist)
-        binding.detailName.text = artist.resolveName(binding.context)
+        binding.detailName.text = artist.name.resolve(binding.context)
+
+        // Song and album counts map to the info
+        binding.detailInfo.text =
+            binding.context.getString(
+                R.string.fmt_two,
+                binding.context.getPlural(R.plurals.fmt_album_count, artist.albums.size),
+                if (artist.songs.isNotEmpty()) {
+                    binding.context.getPlural(R.plurals.fmt_song_count, artist.songs.size)
+                } else {
+                    binding.context.getString(R.string.def_song_count)
+                })
 
         if (artist.songs.isNotEmpty()) {
             // Information about the artist's genre(s) map to the sub-head text
@@ -71,13 +83,6 @@ private constructor(private val binding: ItemDetailHeaderBinding) :
                 text = artist.genres.resolveNames(context)
             }
 
-            // Song and album counts map to the info
-            binding.detailInfo.text =
-                binding.context.getString(
-                    R.string.fmt_two,
-                    binding.context.getPlural(R.plurals.fmt_album_count, artist.albums.size),
-                    binding.context.getPlural(R.plurals.fmt_song_count, artist.songs.size))
-
             // In the case that this header used to he configured to have no songs,
             // we want to reset the visibility of all information that was hidden.
             binding.detailPlayButton.isVisible = true
@@ -87,10 +92,8 @@ private constructor(private val binding: ItemDetailHeaderBinding) :
             // ex. Play and Shuffle, Song Counts, and Genre Information.
             // Artists are always guaranteed to have albums however, so continue to show those.
             binding.detailSubhead.isVisible = false
-            binding.detailInfo.text =
+            binding.detailPlayButton.isEnabled = false
-                binding.context.getPlural(R.plurals.fmt_album_count, artist.albums.size)
+            binding.detailShuffleButton.isEnabled = false
-            binding.detailPlayButton.isVisible = false
-            binding.detailShuffleButton.isVisible = false
         }
 
         binding.detailPlayButton.setOnClickListener { listener.onPlay() }

app/src/main/java/org/oxycblt/auxio/detail/header/DetailHeaderAdapter.kt

@@ -48,10 +48,17 @@ abstract class DetailHeaderAdapter<T : MusicParent, VH : RecyclerView.ViewHolder
      */
     fun setParent(parent: T) {
         currentParent = parent
+        rebindParent()
+    }
+
+    /**
+     * Forces the parent [RecyclerView.ViewHolder] to rebind as soon as possible, with no animation.
+     */
+    protected fun rebindParent() {
         notifyItemChanged(0, PAYLOAD_UPDATE_HEADER)
     }
 
-    /** An extended listener for [DetailHeaderAdapter] implementations. */
+    /** A listener for [DetailHeaderAdapter] implementations. */
     interface Listener {
         /**
          * Called when the play button in a detail header is pressed, requesting that the current

app/src/main/java/org/oxycblt/auxio/detail/header/GenreDetailHeaderAdapter.kt

@@ -24,7 +24,6 @@ import androidx.core.view.isVisible
 import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.ItemDetailHeaderBinding
-import org.oxycblt.auxio.detail.list.DetailListAdapter
 import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.getPlural
@@ -33,6 +32,7 @@ import org.oxycblt.auxio.util.inflater
 /**
  * A [DetailHeaderAdapter] that shows [Genre] information.
  *
+ * @param listener [DetailHeaderAdapter.Listener] to bind interactions to.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class GenreDetailHeaderAdapter(private val listener: Listener) :
@@ -57,15 +57,15 @@ private constructor(private val binding: ItemDetailHeaderBinding) :
      * Bind new data to this instance.
      *
      * @param genre The new [Genre] to bind.
-     * @param listener A [DetailListAdapter.Listener] to bind interactions to.
+     * @param listener A [DetailHeaderAdapter.Listener] to bind interactions to.
      */
     fun bind(genre: Genre, listener: DetailHeaderAdapter.Listener) {
         binding.detailCover.bind(genre)
         binding.detailType.text = binding.context.getString(R.string.lbl_genre)
-        binding.detailName.text = genre.resolveName(binding.context)
+        binding.detailName.text = genre.name.resolve(binding.context)
         // Nothing about a genre is applicable to the sub-head text.
         binding.detailSubhead.isVisible = false
-        // The song count of the genre maps to the info text.
+        // The song and artist count of the genre maps to the info text.
         binding.detailInfo.text =
             binding.context.getString(
                 R.string.fmt_two,

app/src/main/java/org/oxycblt/auxio/detail/header/PlaylistDetailHeaderAdapter.kt

@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistDetailHeaderAdapter.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.detail.header
+
+import android.view.View
+import android.view.ViewGroup
+import androidx.core.view.isVisible
+import androidx.recyclerview.widget.RecyclerView
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.ItemDetailHeaderBinding
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.playback.formatDurationMs
+import org.oxycblt.auxio.util.context
+import org.oxycblt.auxio.util.getPlural
+import org.oxycblt.auxio.util.inflater
+
+/**
+ * A [DetailHeaderAdapter] that shows [Playlist] information.
+ *
+ * @param listener [DetailHeaderAdapter.Listener] to bind interactions to.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class PlaylistDetailHeaderAdapter(private val listener: Listener) :
+    DetailHeaderAdapter<Playlist, PlaylistDetailHeaderViewHolder>() {
+    private var editedPlaylist: List<Song>? = null
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+        PlaylistDetailHeaderViewHolder.from(parent)
+
+    override fun onBindHeader(holder: PlaylistDetailHeaderViewHolder, parent: Playlist) =
+        holder.bind(parent, editedPlaylist, listener)
+
+    /**
+     * Indicate to this adapter that editing is ongoing with the current state of the editing
+     * process. This will make the header immediately update to reflect information about the edited
+     * playlist.
+     */
+    fun setEditedPlaylist(songs: List<Song>?) {
+        if (editedPlaylist == songs) {
+            // Nothing to do.
+            return
+        }
+        editedPlaylist = songs
+        rebindParent()
+    }
+}
+
+/**
+ * A [RecyclerView.ViewHolder] that displays the [Playlist] header in the detail view. Use [from] to
+ * create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class PlaylistDetailHeaderViewHolder
+private constructor(private val binding: ItemDetailHeaderBinding) :
+    RecyclerView.ViewHolder(binding.root) {
+    /**
+     * Bind new data to this instance.
+     *
+     * @param playlist The new [Playlist] to bind.
+     * @param editedPlaylist The current edited state of the playlist, if it exists.
+     * @param listener A [DetailHeaderAdapter.Listener] to bind interactions to.
+     */
+    fun bind(
+        playlist: Playlist,
+        editedPlaylist: List<Song>?,
+        listener: DetailHeaderAdapter.Listener
+    ) {
+        // TODO: Debug perpetually re-binding images
+        binding.detailCover.bind(playlist, editedPlaylist)
+        binding.detailType.text = binding.context.getString(R.string.lbl_playlist)
+        binding.detailName.text = playlist.name.resolve(binding.context)
+        // Nothing about a playlist is applicable to the sub-head text.
+        binding.detailSubhead.isVisible = false
+
+        val songs = editedPlaylist ?: playlist.songs
+        val durationMs = editedPlaylist?.sumOf { it.durationMs } ?: playlist.durationMs
+        // The song count of the playlist maps to the info text.
+        binding.detailInfo.text =
+            if (songs.isNotEmpty()) {
+                binding.context.getString(
+                    R.string.fmt_two,
+                    binding.context.getPlural(R.plurals.fmt_song_count, songs.size),
+                    durationMs.formatDurationMs(true))
+            } else {
+                binding.context.getString(R.string.def_song_count)
+            }
+
+        binding.detailPlayButton.apply {
+            isEnabled = playlist.songs.isNotEmpty() && editedPlaylist == null
+            setOnClickListener { listener.onPlay() }
+        }
+        binding.detailShuffleButton.apply {
+            isEnabled = playlist.songs.isNotEmpty() && editedPlaylist == null
+            setOnClickListener { listener.onShuffle() }
+        }
+    }
+
+    companion object {
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) =
+            PlaylistDetailHeaderViewHolder(ItemDetailHeaderBinding.inflate(parent.context.inflater))
+    }
+}

app/src/main/java/org/oxycblt/auxio/detail/list/AlbumDetailListAdapter.kt

@@ -33,7 +33,7 @@ import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.adapter.SimpleDiffCallback
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.metadata.Disc
+import org.oxycblt.auxio.music.info.Disc
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.inflater
@@ -69,15 +69,6 @@ class AlbumDetailListAdapter(private val listener: Listener<Song>) :
         }
     }
 
-    override fun isItemFullWidth(position: Int): Boolean {
-        if (super.isItemFullWidth(position)) {
-            return true
-        }
-        // The album and disc headers should be full-width in all configurations.
-        val item = getItem(position)
-        return item is Album || item is Disc
-    }
-
     private companion object {
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
@@ -171,7 +162,7 @@ private class AlbumSongViewHolder private constructor(private val binding: ItemA
             }
         }
 
-        binding.songName.text = song.resolveName(binding.context)
+        binding.songName.text = song.name.resolve(binding.context)
 
         // Use duration instead of album or artist for each song, as this text would
         // be homogenous otherwise.
@@ -204,7 +195,7 @@ private class AlbumSongViewHolder private constructor(private val binding: ItemA
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Song>() {
                 override fun areContentsTheSame(oldItem: Song, newItem: Song) =
-                    oldItem.rawName == newItem.rawName && oldItem.durationMs == newItem.durationMs
+                    oldItem.name == newItem.name && oldItem.durationMs == newItem.durationMs
             }
     }
 }

app/src/main/java/org/oxycblt/auxio/detail/list/ArtistDetailListAdapter.kt

@@ -65,14 +65,6 @@ class ArtistDetailListAdapter(private val listener: Listener<Music>) :
         }
     }
 
-    override fun isItemFullWidth(position: Int): Boolean {
-        if (super.isItemFullWidth(position)) {
-            return true
-        }
-        // Artist headers should be full-width in all configurations.
-        return getItem(position) is Artist
-    }
-
     private companion object {
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
@@ -106,7 +98,7 @@ private class ArtistAlbumViewHolder private constructor(private val binding: Ite
     fun bind(album: Album, listener: SelectableListListener<Album>) {
         listener.bind(album, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(album)
-        binding.parentName.text = album.resolveName(binding.context)
+        binding.parentName.text = album.name.resolve(binding.context)
         binding.parentInfo.text =
             // Fall back to a friendlier "No date" text if the album doesn't have date information
             album.dates?.resolveDate(binding.context)
@@ -139,7 +131,7 @@ private class ArtistAlbumViewHolder private constructor(private val binding: Ite
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Album>() {
                 override fun areContentsTheSame(oldItem: Album, newItem: Album) =
-                    oldItem.rawName == newItem.rawName && oldItem.dates == newItem.dates
+                    oldItem.name == newItem.name && oldItem.dates == newItem.dates
             }
     }
 }
@@ -161,8 +153,8 @@ private class ArtistSongViewHolder private constructor(private val binding: Item
     fun bind(song: Song, listener: SelectableListListener<Song>) {
         listener.bind(song, this, menuButton = binding.songMenu)
         binding.songAlbumCover.bind(song)
-        binding.songName.text = song.resolveName(binding.context)
+        binding.songName.text = song.name.resolve(binding.context)
-        binding.songInfo.text = song.album.resolveName(binding.context)
+        binding.songInfo.text = song.album.name.resolve(binding.context)
     }
 
     override fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean) {
@@ -191,8 +183,7 @@ private class ArtistSongViewHolder private constructor(private val binding: Item
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Song>() {
                 override fun areContentsTheSame(oldItem: Song, newItem: Song) =
-                    oldItem.rawName == newItem.rawName &&
+                    oldItem.name == newItem.name && oldItem.album.name == newItem.album.name
-                        oldItem.album.rawName == newItem.album.rawName
             }
     }
 }

app/src/main/java/org/oxycblt/auxio/detail/list/DetailListAdapter.kt

@@ -27,6 +27,7 @@ import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.IntegerTable
 import org.oxycblt.auxio.databinding.ItemSortHeaderBinding
 import org.oxycblt.auxio.list.BasicHeader
+import org.oxycblt.auxio.list.Divider
 import org.oxycblt.auxio.list.Header
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.list.SelectableListListener
@@ -47,13 +48,12 @@ import org.oxycblt.auxio.util.inflater
 abstract class DetailListAdapter(
     private val listener: Listener<*>,
     private val diffCallback: DiffUtil.ItemCallback<Item>
-) :
+) : SelectionIndicatorAdapter<Item, RecyclerView.ViewHolder>(diffCallback) {
-    SelectionIndicatorAdapter<Item, RecyclerView.ViewHolder>(diffCallback),
-    AuxioRecyclerView.SpanSizeLookup {
 
     override fun getItemViewType(position: Int) =
         when (getItem(position)) {
             // Implement support for headers and sort headers
+            is Divider -> DividerViewHolder.VIEW_TYPE
             is BasicHeader -> BasicHeaderViewHolder.VIEW_TYPE
             is SortHeader -> SortHeaderViewHolder.VIEW_TYPE
             else -> super.getItemViewType(position)
@@ -61,6 +61,7 @@ abstract class DetailListAdapter(
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
         when (viewType) {
+            DividerViewHolder.VIEW_TYPE -> DividerViewHolder.from(parent)
             BasicHeaderViewHolder.VIEW_TYPE -> BasicHeaderViewHolder.from(parent)
             SortHeaderViewHolder.VIEW_TYPE -> SortHeaderViewHolder.from(parent)
             else -> error("Invalid item type $viewType")
@@ -73,12 +74,6 @@ abstract class DetailListAdapter(
         }
     }
 
-    override fun isItemFullWidth(position: Int): Boolean {
-        // Headers should be full-width in all configurations.
-        val item = getItem(position)
-        return item is BasicHeader || item is SortHeader
-    }
-
     /** An extended [SelectableListListener] for [DetailListAdapter] implementations. */
     interface Listener<in T : Music> : SelectableListListener<T> {
         /**
@@ -94,6 +89,8 @@ abstract class DetailListAdapter(
             object : SimpleDiffCallback<Item>() {
                 override fun areContentsTheSame(oldItem: Item, newItem: Item): Boolean {
                     return when {
+                        oldItem is Divider && newItem is Divider ->
+                            DividerViewHolder.DIFF_CALLBACK.areContentsTheSame(oldItem, newItem)
                         oldItem is BasicHeader && newItem is BasicHeader ->
                             BasicHeaderViewHolder.DIFF_CALLBACK.areContentsTheSame(oldItem, newItem)
                         oldItem is SortHeader && newItem is SortHeader ->
@@ -114,8 +111,8 @@ abstract class DetailListAdapter(
 data class SortHeader(@StringRes override val titleRes: Int) : Header
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [SortHeader], a variation on [BasicHeader] that adds
+ * A [RecyclerView.ViewHolder] that displays a [SortHeader] and it's actions. Use [from] to create
- * a button opening a menu for sorting. Use [from] to create an instance.
+ * an instance.
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -129,7 +126,7 @@ private class SortHeaderViewHolder(private val binding: ItemSortHeaderBinding) :
      */
     fun bind(sortHeader: SortHeader, listener: DetailListAdapter.Listener<*>) {
         binding.headerTitle.text = binding.context.getString(sortHeader.titleRes)
-        binding.headerButton.apply {
+        binding.headerSort.apply {
             // Add a Tooltip based on the content description so that the purpose of this
             // button can be clear.
             TooltipCompat.setTooltipText(this, contentDescription)

app/src/main/java/org/oxycblt/auxio/detail/list/GenreDetailListAdapter.kt

@@ -30,7 +30,7 @@ import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.Song
 
 /**
- * An [DetailListAdapter] implementing the header and sub-items for the [Genre] detail view.
+ * A [DetailListAdapter] implementing the header and sub-items for the [Genre] detail view.
  *
  * @param listener A [DetailListAdapter.Listener] to bind interactions to.
  * @author Alexander Capehart (OxygenCobalt)
@@ -60,14 +60,6 @@ class GenreDetailListAdapter(private val listener: Listener<Music>) :
         }
     }
 
-    override fun isItemFullWidth(position: Int): Boolean {
-        if (super.isItemFullWidth(position)) {
-            return true
-        }
-        // Genre headers should be full-width in all configurations
-        return getItem(position) is Genre
-    }
-
     private companion object {
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Item>() {

app/src/main/java/org/oxycblt/auxio/detail/list/PlaylistDetailListAdapter.kt

@@ -0,0 +1,281 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistDetailListAdapter.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.detail.list
+
+import android.annotation.SuppressLint
+import android.graphics.drawable.LayerDrawable
+import android.view.View
+import android.view.ViewGroup
+import androidx.annotation.StringRes
+import androidx.appcompat.widget.TooltipCompat
+import androidx.core.view.isInvisible
+import androidx.core.view.isVisible
+import androidx.recyclerview.widget.RecyclerView
+import com.google.android.material.shape.MaterialShapeDrawable
+import org.oxycblt.auxio.IntegerTable
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.ItemEditHeaderBinding
+import org.oxycblt.auxio.databinding.ItemEditableSongBinding
+import org.oxycblt.auxio.list.EditableListListener
+import org.oxycblt.auxio.list.Header
+import org.oxycblt.auxio.list.Item
+import org.oxycblt.auxio.list.adapter.PlayingIndicatorAdapter
+import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.adapter.SimpleDiffCallback
+import org.oxycblt.auxio.list.recycler.MaterialDragCallback
+import org.oxycblt.auxio.list.recycler.SongViewHolder
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.music.resolveNames
+import org.oxycblt.auxio.util.context
+import org.oxycblt.auxio.util.getAttrColorCompat
+import org.oxycblt.auxio.util.getDimen
+import org.oxycblt.auxio.util.inflater
+
+/**
+ * A [DetailListAdapter] implementing the header, sub-items, and editing state for the [Playlist]
+ * detail view.
+ *
+ * @param listener A [DetailListAdapter.Listener] to bind interactions to.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class PlaylistDetailListAdapter(private val listener: Listener) :
+    DetailListAdapter(listener, DIFF_CALLBACK) {
+    private var isEditing = false
+
+    override fun getItemViewType(position: Int) =
+        when (getItem(position)) {
+            is EditHeader -> EditHeaderViewHolder.VIEW_TYPE
+            is Song -> PlaylistSongViewHolder.VIEW_TYPE
+            else -> super.getItemViewType(position)
+        }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+        when (viewType) {
+            EditHeaderViewHolder.VIEW_TYPE -> EditHeaderViewHolder.from(parent)
+            PlaylistSongViewHolder.VIEW_TYPE -> PlaylistSongViewHolder.from(parent)
+            else -> super.onCreateViewHolder(parent, viewType)
+        }
+
+    override fun onBindViewHolder(
+        holder: RecyclerView.ViewHolder,
+        position: Int,
+        payloads: List<Any>
+    ) {
+        super.onBindViewHolder(holder, position, payloads)
+
+        if (payloads.isEmpty()) {
+            when (val item = getItem(position)) {
+                is EditHeader -> (holder as EditHeaderViewHolder).bind(item, listener)
+                is Song -> (holder as PlaylistSongViewHolder).bind(item, listener)
+            }
+        }
+
+        if (holder is ViewHolder) {
+            holder.updateEditing(isEditing)
+        }
+    }
+
+    fun setEditing(editing: Boolean) {
+        if (editing == isEditing) {
+            // Nothing to do.
+            return
+        }
+        this.isEditing = editing
+        notifyItemRangeChanged(1, currentList.size - 1, PAYLOAD_EDITING_CHANGED)
+    }
+
+    /** An extended [DetailListAdapter.Listener] for [PlaylistDetailListAdapter]. */
+    interface Listener : DetailListAdapter.Listener<Song>, EditableListListener {
+        /** Called when the "edit" option is selected in the edit header. */
+        fun onStartEdit()
+    }
+
+    /**
+     * A [RecyclerView.ViewHolder] extension required to respond to changes in the editing state.
+     */
+    interface ViewHolder {
+        /**
+         * Called when the editing state changes. Implementations should update UI options as needed
+         * to reflect the new state.
+         *
+         * @param editing Whether the data is currently being edited or not.
+         */
+        fun updateEditing(editing: Boolean)
+    }
+
+    private companion object {
+        val PAYLOAD_EDITING_CHANGED = Any()
+
+        val DIFF_CALLBACK =
+            object : SimpleDiffCallback<Item>() {
+                override fun areContentsTheSame(oldItem: Item, newItem: Item) =
+                    when {
+                        oldItem is Song && newItem is Song ->
+                            PlaylistSongViewHolder.DIFF_CALLBACK.areContentsTheSame(
+                                oldItem, newItem)
+                        oldItem is EditHeader && newItem is EditHeader ->
+                            EditHeaderViewHolder.DIFF_CALLBACK.areContentsTheSame(oldItem, newItem)
+                        else -> DetailListAdapter.DIFF_CALLBACK.areContentsTheSame(oldItem, newItem)
+                    }
+            }
+    }
+}
+
+/**
+ * A [Header] variant that displays an edit button.
+ *
+ * @param titleRes The string resource to use as the header title
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+data class EditHeader(@StringRes override val titleRes: Int) : Header
+
+/**
+ * Displays an [EditHeader] and it's actions. Use [from] to create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+private class EditHeaderViewHolder private constructor(private val binding: ItemEditHeaderBinding) :
+    RecyclerView.ViewHolder(binding.root), PlaylistDetailListAdapter.ViewHolder {
+    /**
+     * Bind new data to this instance.
+     *
+     * @param editHeader The new [EditHeader] to bind.
+     * @param listener An [PlaylistDetailListAdapter.Listener] to bind interactions to.
+     */
+    fun bind(editHeader: EditHeader, listener: PlaylistDetailListAdapter.Listener) {
+        binding.headerTitle.text = binding.context.getString(editHeader.titleRes)
+        // Add a Tooltip based on the content description so that the purpose of this
+        // button can be clear.
+        binding.headerEdit.apply {
+            TooltipCompat.setTooltipText(this, contentDescription)
+            setOnClickListener { listener.onStartEdit() }
+        }
+    }
+
+    override fun updateEditing(editing: Boolean) {
+        binding.headerEdit.isEnabled = !editing
+    }
+
+    companion object {
+        /** A unique ID for this [RecyclerView.ViewHolder] type. */
+        const val VIEW_TYPE = IntegerTable.VIEW_TYPE_EDIT_HEADER
+
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) =
+            EditHeaderViewHolder(ItemEditHeaderBinding.inflate(parent.context.inflater))
+
+        /** A comparator that can be used with DiffUtil. */
+        val DIFF_CALLBACK =
+            object : SimpleDiffCallback<EditHeader>() {
+                override fun areContentsTheSame(oldItem: EditHeader, newItem: EditHeader) =
+                    oldItem.titleRes == newItem.titleRes
+            }
+    }
+}
+
+/**
+ * A [PlayingIndicatorAdapter.ViewHolder] that displays a queue [Song] which can be re-ordered and
+ * removed. Use [from] to create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+private class PlaylistSongViewHolder
+private constructor(private val binding: ItemEditableSongBinding) :
+    SelectionIndicatorAdapter.ViewHolder(binding.root),
+    MaterialDragCallback.ViewHolder,
+    PlaylistDetailListAdapter.ViewHolder {
+    override val enabled: Boolean
+        get() = binding.songDragHandle.isVisible
+    override val root = binding.root
+    override val body = binding.body
+    override val delete = binding.background
+    override val background =
+        MaterialShapeDrawable.createWithElevationOverlay(binding.root.context).apply {
+            fillColor = binding.context.getAttrColorCompat(R.attr.colorSurface)
+            elevation = binding.context.getDimen(R.dimen.elevation_normal)
+            alpha = 0
+        }
+
+    init {
+        binding.body.background =
+            LayerDrawable(
+                arrayOf(
+                    MaterialShapeDrawable.createWithElevationOverlay(binding.context).apply {
+                        fillColor = binding.context.getAttrColorCompat(R.attr.colorSurface)
+                    },
+                    background))
+    }
+
+    /**
+     * Bind new data to this instance.
+     *
+     * @param song The new [Song] to bind.
+     * @param listener A [PlaylistDetailListAdapter.Listener] to bind interactions to.
+     */
+    @SuppressLint("ClickableViewAccessibility")
+    fun bind(song: Song, listener: PlaylistDetailListAdapter.Listener) {
+        listener.bind(song, this, binding.interactBody, menuButton = binding.songMenu)
+        listener.bind(this, binding.songDragHandle)
+        binding.songAlbumCover.bind(song)
+        binding.songName.text = song.name.resolve(binding.context)
+        binding.songInfo.text = song.artists.resolveNames(binding.context)
+        // Not swiping this ViewHolder if it's being re-bound, ensure that the background is
+        // not visible. See MaterialDragCallback for why this is done.
+        binding.background.isInvisible = true
+    }
+
+    override fun updateSelectionIndicator(isSelected: Boolean) {
+        binding.interactBody.isActivated = isSelected
+        binding.songAlbumCover.isActivated = isSelected
+    }
+
+    override fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean) {
+        binding.interactBody.isSelected = isActive
+        binding.songAlbumCover.isPlaying = isPlaying
+    }
+
+    override fun updateEditing(editing: Boolean) {
+        binding.songDragHandle.isInvisible = !editing
+        binding.songMenu.isInvisible = editing
+        binding.interactBody.isEnabled = !editing
+    }
+
+    companion object {
+        /** A unique ID for this [RecyclerView.ViewHolder] type. */
+        const val VIEW_TYPE = IntegerTable.VIEW_TYPE_PLAYLIST_SONG
+
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) =
+            PlaylistSongViewHolder(ItemEditableSongBinding.inflate(parent.context.inflater))
+
+        /** A comparator that can be used with DiffUtil. */
+        val DIFF_CALLBACK = SongViewHolder.DIFF_CALLBACK
+    }
+}

app/src/main/java/org/oxycblt/auxio/detail/list/PlaylistDragCallback.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistDragCallback.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.detail.list
+
+import androidx.recyclerview.widget.RecyclerView
+import org.oxycblt.auxio.detail.DetailViewModel
+import org.oxycblt.auxio.list.recycler.MaterialDragCallback
+
+/**
+ * A [MaterialDragCallback] extension for playlist-specific item editing.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class PlaylistDragCallback(private val detailModel: DetailViewModel) : MaterialDragCallback() {
+    override fun onMove(
+        recyclerView: RecyclerView,
+        viewHolder: RecyclerView.ViewHolder,
+        target: RecyclerView.ViewHolder
+    ) =
+        detailModel.movePlaylistSongs(
+            viewHolder.bindingAdapterPosition, target.bindingAdapterPosition)
+
+    override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
+        detailModel.removePlaylistSong(viewHolder.bindingAdapterPosition)
+    }
+}

app/src/main/java/org/oxycblt/auxio/home/FlipFloatingActionButton.kt

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * FlipFloatingActionButton.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.home
+
+import android.content.Context
+import android.util.AttributeSet
+import androidx.annotation.DrawableRes
+import androidx.annotation.StringRes
+import com.google.android.material.floatingactionbutton.FloatingActionButton
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.util.logD
+
+/**
+ * An extension of [FloatingActionButton] that enables the ability to fade in and out between
+ * several states, as in the Material Design 3 specification.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class FlipFloatingActionButton
+@JvmOverloads
+constructor(
+    context: Context,
+    attrs: AttributeSet? = null,
+    defStyleAttr: Int = R.attr.floatingActionButtonStyle
+) : FloatingActionButton(context, attrs, defStyleAttr) {
+    private var pendingConfig: PendingConfig? = null
+    private var flipping = false
+
+    override fun show() {
+        // Will already show eventually, need to do nothing.
+        if (flipping) return
+        // Apply the new configuration possibly set in flipTo. This should occur even if
+        // a flip was canceled by a hide.
+        pendingConfig?.run {
+            setImageResource(iconRes)
+            contentDescription = context.getString(contentDescriptionRes)
+            setOnClickListener(clickListener)
+        }
+        pendingConfig = null
+        super.show()
+    }
+
+    override fun hide() {
+        // Not flipping anymore, disable the flag so that the FAB is not re-shown.
+        flipping = false
+        // Don't pass any kind of listener so that future flip operations will not be able
+        // to show the FAB again.
+        super.hide()
+    }
+
+    /**
+     * Flip to a new FAB state.
+     *
+     * @param iconRes The resource of the new FAB icon.
+     * @param contentDescriptionRes The resource of the new FAB content description.
+     */
+    fun flipTo(
+        @DrawableRes iconRes: Int,
+        @StringRes contentDescriptionRes: Int,
+        clickListener: OnClickListener
+    ) {
+        // Avoid doing a flip if the given config is already being applied.
+        if (tag == iconRes) return
+        tag = iconRes
+        pendingConfig = PendingConfig(iconRes, contentDescriptionRes, clickListener)
+
+        // Already hiding for whatever reason, apply the configuration when the FAB is shown again.
+        if (!isOrWillBeHidden) {
+            flipping = true
+            // We will re-show the FAB later, assuming that there was not a prior flip operation.
+            super.hide(FlipVisibilityListener())
+        }
+    }
+
+    private data class PendingConfig(
+        @DrawableRes val iconRes: Int,
+        @StringRes val contentDescriptionRes: Int,
+        val clickListener: OnClickListener
+    )
+
+    private inner class FlipVisibilityListener : OnVisibilityChangedListener() {
+        override fun onHidden(fab: FloatingActionButton) {
+            if (!flipping) return
+            logD("Showing for a flip operation")
+            flipping = false
+            show()
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/home/HomeFragment.kt

@@ -46,20 +46,15 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.MainFragmentDirections
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeBinding
-import org.oxycblt.auxio.home.list.AlbumListFragment
+import org.oxycblt.auxio.home.list.*
-import org.oxycblt.auxio.home.list.ArtistListFragment
-import org.oxycblt.auxio.home.list.GenreListFragment
-import org.oxycblt.auxio.home.list.SongListFragment
 import org.oxycblt.auxio.home.tabs.AdaptiveTabStrategy
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.selection.SelectionFragment
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.model.Library
+import org.oxycblt.auxio.navigation.MainNavigationAction
-import org.oxycblt.auxio.music.system.Indexer
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
-import org.oxycblt.auxio.ui.MainNavigationAction
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.*
 
 /**
@@ -73,8 +68,8 @@ class HomeFragment :
     SelectionFragment<FragmentHomeBinding>(), AppBarLayout.OnOffsetChangedListener {
     override val playbackModel: PlaybackViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     private val homeModel: HomeViewModel by activityViewModels()
-    private val musicModel: MusicViewModel by activityViewModels()
     private val navModel: NavigationViewModel by activityViewModels()
     private var storagePermissionLauncher: ActivityResultLauncher<String>? = null
 
@@ -107,7 +102,7 @@ class HomeFragment :
 
         // --- UI SETUP ---
         binding.homeAppbar.addOnOffsetChangedListener(this)
-        binding.homeToolbar.apply {
+        binding.homeNormalToolbar.apply {
             setOnMenuItemClickListener(this@HomeFragment)
             MenuCompat.setGroupDividerEnabled(menu, true)
         }
@@ -152,13 +147,11 @@ class HomeFragment :
         // re-creating the ViewPager.
         setupPager(binding)
 
-        binding.homeFab.setOnClickListener { playbackModel.shuffleAll() }
-
         // --- VIEWMODEL SETUP ---
         collect(homeModel.recreateTabs.flow, ::handleRecreate)
         collectImmediately(homeModel.currentTabMode, ::updateCurrentTab)
         collectImmediately(homeModel.songsList, homeModel.isFastScrolling, ::updateFab)
-        collectImmediately(musicModel.indexerState, ::updateIndexerState)
+        collectImmediately(musicModel.indexingState, ::updateIndexerState)
         collect(navModel.exploreNavigationItem.flow, ::handleNavigation)
         collectImmediately(selectionModel.selected, ::updateSelection)
     }
@@ -176,7 +169,7 @@ class HomeFragment :
         super.onDestroyBinding(binding)
         storagePermissionLauncher = null
         binding.homeAppbar.removeOnOffsetChangedListener(this)
-        binding.homeToolbar.setOnMenuItemClickListener(null)
+        binding.homeNormalToolbar.setOnMenuItemClickListener(null)
     }
 
     override fun onOffsetChanged(appBarLayout: AppBarLayout, verticalOffset: Int) {
@@ -185,8 +178,7 @@ class HomeFragment :
         // Fade out the toolbar as the AppBarLayout collapses. To prevent status bar overlap,
         // the alpha transition is shifted such that the Toolbar becomes fully transparent
         // when the AppBarLayout is only at half-collapsed.
-        binding.homeSelectionToolbar.alpha =
+        binding.homeToolbar.alpha = 1f - (abs(verticalOffset.toFloat()) / (range.toFloat() / 2))
-            1f - (abs(verticalOffset.toFloat()) / (range.toFloat() / 2))
         binding.homeContent.updatePadding(
             bottom = binding.homeAppbar.totalScrollRange + verticalOffset)
     }
@@ -250,7 +242,7 @@ class HomeFragment :
         binding.homePager.adapter =
             HomePagerAdapter(homeModel.currentTabModes, childFragmentManager, viewLifecycleOwner)
 
-        val toolbarParams = binding.homeSelectionToolbar.layoutParams as AppBarLayout.LayoutParams
+        val toolbarParams = binding.homeToolbar.layoutParams as AppBarLayout.LayoutParams
         if (homeModel.currentTabModes.size == 1) {
             // A single tab makes the tab layout redundant, hide it and disable the collapsing
             // behavior.
@@ -273,6 +265,7 @@ class HomeFragment :
     }
 
     private fun updateCurrentTab(tabMode: MusicMode) {
+        val binding = requireBinding()
         // Update the sort options to align with those allowed by the tab
         val isVisible: (Int) -> Boolean =
             when (tabMode) {
@@ -280,16 +273,8 @@ class HomeFragment :
                 MusicMode.SONGS -> { id -> id != R.id.option_sort_count }
                 // Disallow sorting by album for albums
                 MusicMode.ALBUMS -> { id -> id != R.id.option_sort_album }
-                // Only allow sorting by name, count, and duration for artists
+                // Only allow sorting by name, count, and duration for parents
-                MusicMode.ARTISTS -> { id ->
+                else -> { id ->
-                        id == R.id.option_sort_asc ||
-                            id == R.id.option_sort_dec ||
-                            id == R.id.option_sort_name ||
-                            id == R.id.option_sort_count ||
-                            id == R.id.option_sort_duration
-                    }
-                // Only allow sorting by name, count, and duration for genres
-                MusicMode.GENRES -> { id ->
                         id == R.id.option_sort_asc ||
                             id == R.id.option_sort_dec ||
                             id == R.id.option_sort_name ||
@@ -299,8 +284,7 @@ class HomeFragment :
             }
 
         val sortMenu =
-            unlikelyToBeNull(
+            unlikelyToBeNull(binding.homeNormalToolbar.menu.findItem(R.id.submenu_sorting).subMenu)
-                requireBinding().homeToolbar.menu.findItem(R.id.submenu_sorting).subMenu)
         val toHighlight = homeModel.getSortForTab(tabMode)
 
         for (option in sortMenu) {
@@ -321,13 +305,24 @@ class HomeFragment :
         // Update the scrolling view in AppBarLayout to align with the current tab's
         // scrolling state. This prevents the lift state from being confused as one
         // goes between different tabs.
-        requireBinding().homeAppbar.liftOnScrollTargetViewId =
+        binding.homeAppbar.liftOnScrollTargetViewId =
             when (tabMode) {
                 MusicMode.SONGS -> R.id.home_song_recycler
                 MusicMode.ALBUMS -> R.id.home_album_recycler
                 MusicMode.ARTISTS -> R.id.home_artist_recycler
                 MusicMode.GENRES -> R.id.home_genre_recycler
+                MusicMode.PLAYLISTS -> R.id.home_playlist_recycler
             }
+
+        if (tabMode != MusicMode.PLAYLISTS) {
+            binding.homeFab.flipTo(R.drawable.ic_shuffle_off_24, R.string.desc_shuffle_all) {
+                playbackModel.shuffleAll()
+            }
+        } else {
+            binding.homeFab.flipTo(R.drawable.ic_add_24, R.string.desc_new_playlist) {
+                musicModel.createPlaylist()
+            }
+        }
     }
 
     private fun handleRecreate(recreate: Unit?) {
@@ -340,14 +335,14 @@ class HomeFragment :
         homeModel.recreateTabs.consume()
     }
 
-    private fun updateIndexerState(state: Indexer.State?) {
+    private fun updateIndexerState(state: IndexingState?) {
         // TODO: Make music loading experience a bit more pleasant
         //  1. Loading placeholder for item lists
         //  2. Rework the "No Music" case to not be an error and instead result in a placeholder
         val binding = requireBinding()
         when (state) {
-            is Indexer.State.Complete -> setupCompleteState(binding, state.result)
+            is IndexingState.Completed -> setupCompleteState(binding, state.error)
-            is Indexer.State.Indexing -> setupIndexingState(binding, state.indexing)
+            is IndexingState.Indexing -> setupIndexingState(binding, state.progress)
             null -> {
                 logD("Indexer is in indeterminate state")
                 binding.homeIndexingContainer.visibility = View.INVISIBLE
@@ -355,77 +350,77 @@ class HomeFragment :
         }
     }
 
-    private fun setupCompleteState(binding: FragmentHomeBinding, result: Result<Library>) {
+    private fun setupCompleteState(binding: FragmentHomeBinding, error: Throwable?) {
-        if (result.isSuccess) {
+        if (error == null) {
             logD("Received ok response")
             binding.homeFab.show()
             binding.homeIndexingContainer.visibility = View.INVISIBLE
-        } else {
+            return
-            logD("Received non-ok response")
+        }
-            val context = requireContext()
+
-            val throwable = unlikelyToBeNull(result.exceptionOrNull())
+        logD("Received non-ok response")
-            binding.homeIndexingContainer.visibility = View.VISIBLE
+        val context = requireContext()
-            binding.homeIndexingProgress.visibility = View.INVISIBLE
+        binding.homeIndexingContainer.visibility = View.VISIBLE
-            when (throwable) {
+        binding.homeIndexingProgress.visibility = View.INVISIBLE
-                is Indexer.NoPermissionException -> {
+        when (error) {
-                    logD("Updating UI to permission request state")
+            is NoAudioPermissionException -> {
-                    binding.homeIndexingStatus.text = context.getString(R.string.err_no_perms)
+                logD("Updating UI to permission request state")
-                    // Configure the action to act as a permission launcher.
+                binding.homeIndexingStatus.text = context.getString(R.string.err_no_perms)
-                    binding.homeIndexingAction.apply {
+                // Configure the action to act as a permission launcher.
-                        visibility = View.VISIBLE
+                binding.homeIndexingAction.apply {
-                        text = context.getString(R.string.lbl_grant)
+                    visibility = View.VISIBLE
-                        setOnClickListener {
+                    text = context.getString(R.string.lbl_grant)
-                            requireNotNull(storagePermissionLauncher) {
+                    setOnClickListener {
-                                    "Permission launcher was not available"
+                        requireNotNull(storagePermissionLauncher) {
-                                }
+                                "Permission launcher was not available"
-                                .launch(Indexer.PERMISSION_READ_AUDIO)
+                            }
-                        }
+                            .launch(PERMISSION_READ_AUDIO)
                     }
                 }
-                is Indexer.NoMusicException -> {
+            }
-                    logD("Updating UI to no music state")
+            is NoMusicException -> {
-                    binding.homeIndexingStatus.text = context.getString(R.string.err_no_music)
+                logD("Updating UI to no music state")
-                    // Configure the action to act as a reload trigger.
+                binding.homeIndexingStatus.text = context.getString(R.string.err_no_music)
-                    binding.homeIndexingAction.apply {
+                // Configure the action to act as a reload trigger.
-                        visibility = View.VISIBLE
+                binding.homeIndexingAction.apply {
-                        text = context.getString(R.string.lbl_retry)
+                    visibility = View.VISIBLE
-                        setOnClickListener { musicModel.refresh() }
+                    text = context.getString(R.string.lbl_retry)
-                    }
+                    setOnClickListener { musicModel.refresh() }
                 }
-                else -> {
+            }
-                    logD("Updating UI to error state")
+            else -> {
-                    binding.homeIndexingStatus.text = context.getString(R.string.err_index_failed)
+                logD("Updating UI to error state")
-                    // Configure the action to act as a reload trigger.
+                binding.homeIndexingStatus.text = context.getString(R.string.err_index_failed)
-                    binding.homeIndexingAction.apply {
+                // Configure the action to act as a reload trigger.
-                        visibility = View.VISIBLE
+                binding.homeIndexingAction.apply {
-                        text = context.getString(R.string.lbl_retry)
+                    visibility = View.VISIBLE
-                        setOnClickListener { musicModel.rescan() }
+                    text = context.getString(R.string.lbl_retry)
-                    }
+                    setOnClickListener { musicModel.rescan() }
                 }
             }
         }
     }
 
-    private fun setupIndexingState(binding: FragmentHomeBinding, indexing: Indexer.Indexing) {
+    private fun setupIndexingState(binding: FragmentHomeBinding, progress: IndexingProgress) {
         // Remove all content except for the progress indicator.
         binding.homeIndexingContainer.visibility = View.VISIBLE
         binding.homeIndexingProgress.visibility = View.VISIBLE
         binding.homeIndexingAction.visibility = View.INVISIBLE
 
-        when (indexing) {
+        when (progress) {
-            is Indexer.Indexing.Indeterminate -> {
+            is IndexingProgress.Indeterminate -> {
                 // In a query/initialization state, show a generic loading status.
                 binding.homeIndexingStatus.text = getString(R.string.lng_indexing)
                 binding.homeIndexingProgress.isIndeterminate = true
             }
-            is Indexer.Indexing.Songs -> {
+            is IndexingProgress.Songs -> {
                 // Actively loading songs, show the current progress.
                 binding.homeIndexingStatus.text =
-                    getString(R.string.fmt_indexing, indexing.current, indexing.total)
+                    getString(R.string.fmt_indexing, progress.current, progress.total)
                 binding.homeIndexingProgress.apply {
                     isIndeterminate = false
-                    max = indexing.total
+                    max = progress.total
-                    progress = indexing.current
+                    this.progress = progress.current
                 }
             }
         }
@@ -450,7 +445,8 @@ class HomeFragment :
                 is Album -> HomeFragmentDirections.actionShowAlbum(item.uid)
                 is Artist -> HomeFragmentDirections.actionShowArtist(item.uid)
                 is Genre -> HomeFragmentDirections.actionShowGenre(item.uid)
-                else -> return
+                is Playlist -> HomeFragmentDirections.actionShowPlaylist(item.uid)
+                null -> return
             }
 
         setupAxisTransitions(MaterialSharedAxis.X)
@@ -459,11 +455,15 @@ class HomeFragment :
 
     private fun updateSelection(selected: List<Music>) {
         val binding = requireBinding()
-        if (binding.homeSelectionToolbar.updateSelectionAmount(selected.size) &&
+        if (selected.isNotEmpty()) {
-            selected.isNotEmpty()) {
+            binding.homeSelectionToolbar.title = getString(R.string.fmt_selected, selected.size)
-            // New selection started, show the AppBarLayout to indicate the new state.
+            if (binding.homeToolbar.setVisible(R.id.home_selection_toolbar)) {
-            logD("Significant selection occurred, expanding AppBar")
+                // New selection started, show the AppBarLayout to indicate the new state.
-            binding.homeAppbar.expandWithScrollingRecycler()
+                logD("Significant selection occurred, expanding AppBar")
+                binding.homeAppbar.expandWithScrollingRecycler()
+            }
+        } else {
+            binding.homeToolbar.setVisible(R.id.home_normal_toolbar)
         }
     }
 
@@ -499,6 +499,7 @@ class HomeFragment :
                 MusicMode.ALBUMS -> AlbumListFragment()
                 MusicMode.ARTISTS -> ArtistListFragment()
                 MusicMode.GENRES -> GenreListFragment()
+                MusicMode.PLAYLISTS -> PlaylistListFragment()
             }
     }
 

app/src/main/java/org/oxycblt/auxio/home/HomeSettings.kt

@@ -24,6 +24,7 @@ import dagger.hilt.android.qualifiers.ApplicationContext
 import javax.inject.Inject
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.home.tabs.Tab
+import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
@@ -64,10 +65,32 @@ class HomeSettingsImpl @Inject constructor(@ApplicationContext context: Context)
     override val shouldHideCollaborators: Boolean
         get() = sharedPreferences.getBoolean(getString(R.string.set_key_hide_collaborators), false)
 
+    override fun migrate() {
+        if (sharedPreferences.contains(OLD_KEY_LIB_TABS)) {
+            val oldTabs =
+                Tab.fromIntCode(sharedPreferences.getInt(OLD_KEY_LIB_TABS, Tab.SEQUENCE_DEFAULT))
+                    ?: unlikelyToBeNull(Tab.fromIntCode(Tab.SEQUENCE_DEFAULT))
+
+            // The playlist tab is now parsed, but it needs to be made visible.
+            val playlistIndex = oldTabs.indexOfFirst { it.mode == MusicMode.PLAYLISTS }
+            if (playlistIndex > -1) { // Sanity check
+                oldTabs[playlistIndex] = Tab.Visible(MusicMode.PLAYLISTS)
+            }
+            sharedPreferences.edit {
+                putInt(getString(R.string.set_key_home_tabs), Tab.toIntCode(oldTabs))
+                remove(OLD_KEY_LIB_TABS)
+            }
+        }
+    }
+
     override fun onSettingChanged(key: String, listener: HomeSettings.Listener) {
         when (key) {
             getString(R.string.set_key_home_tabs) -> listener.onTabsChanged()
             getString(R.string.set_key_hide_collaborators) -> listener.onHideCollaboratorsChanged()
         }
     }
+
+    companion object {
+        const val OLD_KEY_LIB_TABS = "auxio_lib_tabs"
+    }
 }

app/src/main/java/org/oxycblt/auxio/home/HomeViewModel.kt

@@ -27,7 +27,6 @@ import org.oxycblt.auxio.home.tabs.Tab
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.list.adapter.UpdateInstructions
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.model.Library
 import org.oxycblt.auxio.playback.PlaybackSettings
 import org.oxycblt.auxio.util.Event
 import org.oxycblt.auxio.util.MutableEvent
@@ -46,7 +45,7 @@ constructor(
     private val playbackSettings: PlaybackSettings,
     private val musicRepository: MusicRepository,
     private val musicSettings: MusicSettings
-) : ViewModel(), MusicRepository.Listener, HomeSettings.Listener {
+) : ViewModel(), MusicRepository.UpdateListener, HomeSettings.Listener {
 
     private val _songsList = MutableStateFlow(listOf<Song>())
     /** A list of [Song]s, sorted by the preferred [Sort], to be shown in the home view. */
@@ -88,6 +87,15 @@ constructor(
     val genresInstructions: Event<UpdateInstructions>
         get() = _genresInstructions
 
+    private val _playlistsList = MutableStateFlow(listOf<Playlist>())
+    /** A list of [Playlist]s, sorted by the preferred [Sort], to be shown in the home view. */
+    val playlistsList: StateFlow<List<Playlist>>
+        get() = _playlistsList
+    private val _playlistsInstructions = MutableEvent<UpdateInstructions>()
+    /** Instructions for how to update [genresList] in the UI. */
+    val playlistsInstructions: Event<UpdateInstructions>
+        get() = _playlistsInstructions
+
     /** The [MusicMode] to use when playing a [Song] from the UI. */
     val playbackMode: MusicMode
         get() = playbackSettings.inListPlaybackMode
@@ -117,37 +125,45 @@ constructor(
     val isFastScrolling: StateFlow<Boolean> = _isFastScrolling
 
     init {
-        musicRepository.addListener(this)
+        musicRepository.addUpdateListener(this)
         homeSettings.registerListener(this)
     }
 
     override fun onCleared() {
         super.onCleared()
-        musicRepository.removeListener(this)
+        musicRepository.removeUpdateListener(this)
         homeSettings.unregisterListener(this)
     }
 
-    override fun onLibraryChanged(library: Library?) {
+    override fun onMusicChanges(changes: MusicRepository.Changes) {
-        if (library != null) {
+        val deviceLibrary = musicRepository.deviceLibrary
-            logD("Library changed, refreshing library")
+        logD(changes.deviceLibrary)
-            // FIXME: Sort name setting changes result in incorrect list updates
+        if (changes.deviceLibrary && deviceLibrary != null) {
+            logD("Refreshing library")
             // Get the each list of items in the library to use as our list data.
             // Applying the preferred sorting to them.
             _songsInstructions.put(UpdateInstructions.Diff)
-            _songsList.value = musicSettings.songSort.songs(library.songs)
+            _songsList.value = musicSettings.songSort.songs(deviceLibrary.songs)
             _albumsInstructions.put(UpdateInstructions.Diff)
-            _albumsLists.value = musicSettings.albumSort.albums(library.albums)
+            _albumsLists.value = musicSettings.albumSort.albums(deviceLibrary.albums)
             _artistsInstructions.put(UpdateInstructions.Diff)
             _artistsList.value =
                 musicSettings.artistSort.artists(
                     if (homeSettings.shouldHideCollaborators) {
                         // Hide Collaborators is enabled, filter out collaborators.
-                        library.artists.filter { !it.isCollaborator }
+                        deviceLibrary.artists.filter { !it.isCollaborator }
                     } else {
-                        library.artists
+                        deviceLibrary.artists
                     })
             _genresInstructions.put(UpdateInstructions.Diff)
-            _genresList.value = musicSettings.genreSort.genres(library.genres)
+            _genresList.value = musicSettings.genreSort.genres(deviceLibrary.genres)
+        }
+
+        val userLibrary = musicRepository.userLibrary
+        if (changes.userLibrary && userLibrary != null) {
+            logD("Refreshing playlists")
+            _playlistsInstructions.put(UpdateInstructions.Diff)
+            _playlistsList.value = musicSettings.playlistSort.playlists(userLibrary.playlists)
         }
     }
 
@@ -160,7 +176,7 @@ constructor(
     override fun onHideCollaboratorsChanged() {
         // Changes in the hide collaborator setting will change the artist contents
         // of the library, consider it a library update.
-        onLibraryChanged(musicRepository.library)
+        onMusicChanges(MusicRepository.Changes(deviceLibrary = true, userLibrary = false))
     }
 
     /**
@@ -175,6 +191,7 @@ constructor(
             MusicMode.ALBUMS -> musicSettings.albumSort
             MusicMode.ARTISTS -> musicSettings.artistSort
             MusicMode.GENRES -> musicSettings.genreSort
+            MusicMode.PLAYLISTS -> musicSettings.playlistSort
         }
 
     /**
@@ -206,6 +223,11 @@ constructor(
                 _genresInstructions.put(UpdateInstructions.Replace(0))
                 _genresList.value = sort.genres(_genresList.value)
             }
+            MusicMode.PLAYLISTS -> {
+                musicSettings.playlistSort = sort
+                _playlistsInstructions.put(UpdateInstructions.Replace(0))
+                _playlistsList.value = sort.playlists(_playlistsList.value)
+            }
         }
     }
 

app/src/main/java/org/oxycblt/auxio/home/list/AlbumListFragment.kt

@@ -37,10 +37,10 @@ import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.recycler.AlbumViewHolder
 import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.*
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.playback.secsToMs
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.collectImmediately
 
 /**
@@ -56,6 +56,7 @@ class AlbumListFragment :
     private val homeModel: HomeViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     private val albumAdapter = AlbumAdapter(this)
     // Save memory by re-using the same formatter and string builder when creating popup text
@@ -94,10 +95,10 @@ class AlbumListFragment :
         // Change how we display the popup depending on the current sort mode.
         return when (homeModel.getSortForTab(MusicMode.ALBUMS).mode) {
             // By Name -> Use Name
-            is Sort.Mode.ByName -> album.sortName?.thumbString
+            is Sort.Mode.ByName -> album.name.thumb
 
             // By Artist -> Use name of first artist
-            is Sort.Mode.ByArtist -> album.artists[0].sortName?.thumbString
+            is Sort.Mode.ByArtist -> album.artists[0].name.thumb
 
             // Date -> Use minimum date (Maximum dates are not sorted by, so showing them is odd)
             is Sort.Mode.ByDate -> album.dates?.run { min.resolveDate(requireContext()) }

app/src/main/java/org/oxycblt/auxio/home/list/ArtistListFragment.kt

@@ -38,9 +38,10 @@ import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.collectImmediately
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.nonZeroOrNull
@@ -58,6 +59,7 @@ class ArtistListFragment :
     private val homeModel: HomeViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     private val artistAdapter = ArtistAdapter(this)
 
@@ -93,7 +95,7 @@ class ArtistListFragment :
         // Change how we display the popup depending on the current sort mode.
         return when (homeModel.getSortForTab(MusicMode.ARTISTS).mode) {
             // By Name -> Use Name
-            is Sort.Mode.ByName -> artist.sortName?.thumbString
+            is Sort.Mode.ByName -> artist.name.thumb
 
             // Duration -> Use formatted duration
             is Sort.Mode.ByDuration -> artist.durationMs?.formatDurationMs(false)
@@ -115,7 +117,7 @@ class ArtistListFragment :
     }
 
     override fun onOpenMenu(item: Artist, anchor: View) {
-        openMusicMenu(anchor, R.menu.menu_artist_actions, item)
+        openMusicMenu(anchor, R.menu.menu_parent_actions, item)
     }
 
     private fun updateArtists(artists: List<Artist>) {

app/src/main/java/org/oxycblt/auxio/home/list/GenreListFragment.kt

@@ -38,9 +38,10 @@ import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.collectImmediately
 import org.oxycblt.auxio.util.logD
 
@@ -57,6 +58,7 @@ class GenreListFragment :
     private val homeModel: HomeViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     private val genreAdapter = GenreAdapter(this)
 
@@ -92,7 +94,7 @@ class GenreListFragment :
         // Change how we display the popup depending on the current sort mode.
         return when (homeModel.getSortForTab(MusicMode.GENRES).mode) {
             // By Name -> Use Name
-            is Sort.Mode.ByName -> genre.sortName?.thumbString
+            is Sort.Mode.ByName -> genre.name.thumb
 
             // Duration -> Use formatted duration
             is Sort.Mode.ByDuration -> genre.durationMs.formatDurationMs(false)
@@ -114,7 +116,7 @@ class GenreListFragment :
     }
 
     override fun onOpenMenu(item: Genre, anchor: View) {
-        openMusicMenu(anchor, R.menu.menu_artist_actions, item)
+        openMusicMenu(anchor, R.menu.menu_parent_actions, item)
     }
 
     private fun updateGenres(genres: List<Genre>) {

app/src/main/java/org/oxycblt/auxio/home/list/PlaylistListFragment.kt

@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistListFragment.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.home.list
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.activityViewModels
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.FragmentHomeListBinding
+import org.oxycblt.auxio.home.HomeViewModel
+import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
+import org.oxycblt.auxio.list.*
+import org.oxycblt.auxio.list.ListFragment
+import org.oxycblt.auxio.list.Sort
+import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.PlaylistViewHolder
+import org.oxycblt.auxio.list.selection.SelectionViewModel
+import org.oxycblt.auxio.music.Music
+import org.oxycblt.auxio.music.MusicMode
+import org.oxycblt.auxio.music.MusicParent
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.navigation.NavigationViewModel
+import org.oxycblt.auxio.playback.PlaybackViewModel
+import org.oxycblt.auxio.playback.formatDurationMs
+import org.oxycblt.auxio.util.collectImmediately
+import org.oxycblt.auxio.util.logD
+
+/**
+ * A [ListFragment] that shows a list of [Playlist]s.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ *
+ * TODO: Show a placeholder when there are no playlists.
+ */
+class PlaylistListFragment :
+    ListFragment<Playlist, FragmentHomeListBinding>(),
+    FastScrollRecyclerView.PopupProvider,
+    FastScrollRecyclerView.Listener {
+    private val homeModel: HomeViewModel by activityViewModels()
+    override val navModel: NavigationViewModel by activityViewModels()
+    override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
+    override val selectionModel: SelectionViewModel by activityViewModels()
+    private val playlistAdapter = PlaylistAdapter(this)
+
+    override fun onCreateBinding(inflater: LayoutInflater) =
+        FragmentHomeListBinding.inflate(inflater)
+
+    override fun onBindingCreated(binding: FragmentHomeListBinding, savedInstanceState: Bundle?) {
+        super.onBindingCreated(binding, savedInstanceState)
+
+        binding.homeRecycler.apply {
+            id = R.id.home_playlist_recycler
+            adapter = playlistAdapter
+            popupProvider = this@PlaylistListFragment
+            listener = this@PlaylistListFragment
+        }
+
+        collectImmediately(homeModel.playlistsList, ::updatePlaylists)
+        collectImmediately(selectionModel.selected, ::updateSelection)
+        collectImmediately(playbackModel.parent, playbackModel.isPlaying, ::updatePlayback)
+    }
+
+    override fun onDestroyBinding(binding: FragmentHomeListBinding) {
+        super.onDestroyBinding(binding)
+        binding.homeRecycler.apply {
+            adapter = null
+            popupProvider = null
+            listener = null
+        }
+    }
+
+    override fun getPopup(pos: Int): String? {
+        val playlist = homeModel.playlistsList.value[pos]
+        // Change how we display the popup depending on the current sort mode.
+        return when (homeModel.getSortForTab(MusicMode.GENRES).mode) {
+            // By Name -> Use Name
+            is Sort.Mode.ByName -> playlist.name.thumb
+
+            // Duration -> Use formatted duration
+            is Sort.Mode.ByDuration -> playlist.durationMs.formatDurationMs(false)
+
+            // Count -> Use song count
+            is Sort.Mode.ByCount -> playlist.songs.size.toString()
+
+            // Unsupported sort, error gracefully
+            else -> null
+        }
+    }
+
+    override fun onFastScrollingChanged(isFastScrolling: Boolean) {
+        homeModel.setFastScrolling(isFastScrolling)
+    }
+
+    override fun onRealClick(item: Playlist) {
+        navModel.exploreNavigateTo(item)
+    }
+
+    override fun onOpenMenu(item: Playlist, anchor: View) {
+        openMusicMenu(anchor, R.menu.menu_playlist_actions, item)
+    }
+
+    private fun updatePlaylists(playlists: List<Playlist>) {
+        playlistAdapter.update(
+            playlists, homeModel.playlistsInstructions.consume().also { logD(it) })
+    }
+
+    private fun updateSelection(selection: List<Music>) {
+        playlistAdapter.setSelected(selection.filterIsInstanceTo(mutableSetOf()))
+    }
+
+    private fun updatePlayback(parent: MusicParent?, isPlaying: Boolean) {
+        // If a playlist is playing, highlight it within this adapter.
+        playlistAdapter.setPlaying(parent as? Playlist, isPlaying)
+    }
+
+    /**
+     * A [SelectionIndicatorAdapter] that shows a list of [Playlist]s using [PlaylistViewHolder].
+     *
+     * @param listener An [SelectableListListener] to bind interactions to.
+     */
+    private class PlaylistAdapter(private val listener: SelectableListListener<Playlist>) :
+        SelectionIndicatorAdapter<Playlist, PlaylistViewHolder>(PlaylistViewHolder.DIFF_CALLBACK) {
+        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+            PlaylistViewHolder.from(parent)
+
+        override fun onBindViewHolder(holder: PlaylistViewHolder, position: Int) {
+            holder.bind(getItem(position), listener)
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/home/list/SongListFragment.kt

@@ -39,11 +39,12 @@ import org.oxycblt.auxio.list.selection.SelectionViewModel
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.MusicParent
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.playback.secsToMs
-import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.util.collectImmediately
 
 /**
@@ -59,6 +60,7 @@ class SongListFragment :
     private val homeModel: HomeViewModel by activityViewModels()
     override val navModel: NavigationViewModel by activityViewModels()
     override val playbackModel: PlaybackViewModel by activityViewModels()
+    override val musicModel: MusicViewModel by activityViewModels()
     override val selectionModel: SelectionViewModel by activityViewModels()
     private val songAdapter = SongAdapter(this)
     // Save memory by re-using the same formatter and string builder when creating popup text
@@ -100,13 +102,13 @@ class SongListFragment :
         // based off the names of the parent objects and not the child objects.
         return when (homeModel.getSortForTab(MusicMode.SONGS).mode) {
             // Name -> Use name
-            is Sort.Mode.ByName -> song.sortName?.thumbString
+            is Sort.Mode.ByName -> song.name.thumb
 
             // Artist -> Use name of first artist
-            is Sort.Mode.ByArtist -> song.album.artists[0].sortName?.thumbString
+            is Sort.Mode.ByArtist -> song.album.artists[0].name.thumb
 
             // Album -> Use Album Name
-            is Sort.Mode.ByAlbum -> song.album.sortName?.thumbString
+            is Sort.Mode.ByAlbum -> song.album.name.thumb
 
             // Year -> Use Full Year
             is Sort.Mode.ByDate -> song.album.dates?.resolveDate(requireContext())

app/src/main/java/org/oxycblt/auxio/home/tabs/AdaptiveTabStrategy.kt

@@ -58,6 +58,10 @@ class AdaptiveTabStrategy(context: Context, private val tabs: List<MusicMode>) :
                 icon = R.drawable.ic_genre_24
                 string = R.string.lbl_genres
             }
+            MusicMode.PLAYLISTS -> {
+                icon = R.drawable.ic_playlist_24
+                string = R.string.lbl_playlists
+            }
         }
 
         // Use expected sw* size thresholds when choosing a configuration.

app/src/main/java/org/oxycblt/auxio/home/tabs/Tab.kt

@@ -49,7 +49,7 @@ sealed class Tab(open val mode: MusicMode) {
         //
         // 0bTAB1_TAB2_TAB3_TAB4_TAB5
         //
-        // Where TABN is a chunk representing a tab at position N. TAB5 is reserved for playlists.
+        // Where TABN is a chunk representing a tab at position N.
         // Each chunk in a sequence is represented as:
         //
         // VTTT
@@ -57,18 +57,23 @@ sealed class Tab(open val mode: MusicMode) {
         // Where V is a bit representing the visibility and T is a 3-bit integer representing the
         // MusicMode for this tab.
 
-        /** The length a well-formed tab sequence should be. */
+        /** The maximum index that a well-formed tab sequence should be. */
-        private const val SEQUENCE_LEN = 4
+        private const val MAX_SEQUENCE_IDX = 4
 
         /**
          * The default tab sequence, in integer form. This represents a set of four visible tabs
-         * ordered as "Song", "Album", "Artist", and "Genre".
+         * ordered as "Song", "Album", "Artist", "Genre", and "Playlists
          */
-        const val SEQUENCE_DEFAULT = 0b1000_1001_1010_1011_0100
+        const val SEQUENCE_DEFAULT = 0b1000_1001_1010_1011_1100
 
         /** Maps between the integer code in the tab sequence and it's [MusicMode]. */
         private val MODE_TABLE =
-            arrayOf(MusicMode.SONGS, MusicMode.ALBUMS, MusicMode.ARTISTS, MusicMode.GENRES)
+            arrayOf(
+                MusicMode.SONGS,
+                MusicMode.ALBUMS,
+                MusicMode.ARTISTS,
+                MusicMode.GENRES,
+                MusicMode.PLAYLISTS)
 
         /**
          * Convert an array of [Tab]s into it's integer representation.
@@ -80,8 +85,8 @@ sealed class Tab(open val mode: MusicMode) {
             // Like when deserializing, make sure there are no duplicate tabs for whatever reason.
             val distinct = tabs.distinctBy { it.mode }
 
-            var sequence = 0b0100
+            var sequence = 0
-            var shift = SEQUENCE_LEN * 4
+            var shift = MAX_SEQUENCE_IDX * 4
             for (tab in distinct) {
                 val bin =
                     when (tab) {
@@ -107,9 +112,8 @@ sealed class Tab(open val mode: MusicMode) {
 
             // Try to parse a mode for each chunk in the sequence.
             // If we can't parse one, just skip it.
-            for (shift in (0..4 * SEQUENCE_LEN).reversed() step 4) {
+            for (shift in (0..MAX_SEQUENCE_IDX * 4).reversed() step 4) {
                 val chunk = intCode.shr(shift) and 0b1111
-
                 val mode = MODE_TABLE.getOrNull(chunk and 7) ?: continue
 
                 // Figure out the visibility
@@ -125,7 +129,7 @@ sealed class Tab(open val mode: MusicMode) {
             val distinct = tabs.distinctBy { it.mode }
 
             // For safety, return null if we have an empty or larger-than-expected tab array.
-            if (distinct.isEmpty() || distinct.size < SEQUENCE_LEN) {
+            if (distinct.isEmpty() || distinct.size < MAX_SEQUENCE_IDX) {
                 logE("Sequence size was ${distinct.size}, which is invalid")
                 return null
             }

app/src/main/java/org/oxycblt/auxio/home/tabs/TabAdapter.kt

@@ -24,7 +24,7 @@ import android.view.ViewGroup
 import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.ItemTabBinding
-import org.oxycblt.auxio.list.EditableListListener
+import org.oxycblt.auxio.list.EditClickListListener
 import org.oxycblt.auxio.list.recycler.DialogRecyclerView
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.util.inflater
@@ -32,9 +32,9 @@ import org.oxycblt.auxio.util.inflater
 /**
  * A [RecyclerView.Adapter] that displays an array of [Tab]s open for configuration.
  *
- * @param listener A [EditableListListener] for tab interactions.
+ * @param listener A [EditClickListListener] for tab interactions.
  */
-class TabAdapter(private val listener: EditableListListener<Tab>) :
+class TabAdapter(private val listener: EditClickListListener<Tab>) :
     RecyclerView.Adapter<TabViewHolder>() {
     /** The current array of [Tab]s. */
     var tabs = arrayOf<Tab>()
@@ -97,10 +97,10 @@ class TabViewHolder private constructor(private val binding: ItemTabBinding) :
      * Bind new data to this instance.
      *
      * @param tab The new [Tab] to bind.
-     * @param listener A [EditableListListener] to bind interactions to.
+     * @param listener A [EditClickListListener] to bind interactions to.
      */
     @SuppressLint("ClickableViewAccessibility")
-    fun bind(tab: Tab, listener: EditableListListener<Tab>) {
+    fun bind(tab: Tab, listener: EditClickListListener<Tab>) {
         listener.bind(tab, this, dragHandle = binding.tabDragHandle)
         binding.tabCheckBox.apply {
             // Update the CheckBox name to align with the mode
@@ -110,6 +110,7 @@ class TabViewHolder private constructor(private val binding: ItemTabBinding) :
                     MusicMode.ALBUMS -> R.string.lbl_albums
                     MusicMode.ARTISTS -> R.string.lbl_artists
                     MusicMode.GENRES -> R.string.lbl_genres
+                    MusicMode.PLAYLISTS -> R.string.lbl_playlists
                 })
 
             // Unlike in other adapters, we update the checked state alongside

app/src/main/java/org/oxycblt/auxio/home/tabs/TabCustomizeDialog.kt

@@ -29,7 +29,7 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogTabsBinding
 import org.oxycblt.auxio.home.HomeSettings
-import org.oxycblt.auxio.list.EditableListListener
+import org.oxycblt.auxio.list.EditClickListListener
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
 import org.oxycblt.auxio.util.logD
 
@@ -40,7 +40,7 @@ import org.oxycblt.auxio.util.logD
  */
 @AndroidEntryPoint
 class TabCustomizeDialog :
-    ViewBindingDialogFragment<DialogTabsBinding>(), EditableListListener<Tab> {
+    ViewBindingDialogFragment<DialogTabsBinding>(), EditClickListListener<Tab> {
     private val tabAdapter = TabAdapter(this)
     private var touchHelper: ItemTouchHelper? = null
     @Inject lateinit var homeSettings: HomeSettings

app/src/main/java/org/oxycblt/auxio/image/BitmapProvider.kt

@@ -95,7 +95,7 @@ constructor(
             target
                 .onConfigRequest(
                     ImageRequest.Builder(context)
-                        .data(song)
+                        .data(listOf(song))
                         // Use ORIGINAL sizing, as we are not loading into any View-like component.
                         .size(Size.ORIGINAL)
                         .transformations(SquareFrameTransform.INSTANCE))

app/src/main/java/org/oxycblt/auxio/image/ImageGroup.kt

@@ -30,10 +30,7 @@ import androidx.annotation.AttrRes
 import androidx.core.view.updateMarginsRelative
 import com.google.android.material.shape.MaterialShapeDrawable
 import org.oxycblt.auxio.R
-import org.oxycblt.auxio.music.Album
+import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.Artist
-import org.oxycblt.auxio.music.Genre
-import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.util.getAttrColorCompat
 import org.oxycblt.auxio.util.getColorCompat
 import org.oxycblt.auxio.util.getDimenPixels
@@ -52,6 +49,9 @@ import org.oxycblt.auxio.util.getInteger
  * @author Alexander Capehart (OxygenCobalt)
  *
  * TODO: Rework content descriptions here
+ * TODO: Attempt unification with StyledImageView with some kind of dynamic configuration to avoid
+ *   superfluous elements
+ * TODO: Handle non-square covers by gracefully placing them in the layout
  */
 class ImageGroup
 @JvmOverloads
@@ -177,6 +177,14 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      */
     fun bind(genre: Genre) = innerImageView.bind(genre)
 
+    /**
+     * Bind a [Playlist]'s image to the internal [StyledImageView].
+     *
+     * @param playlist the [Playlist] to bind.
+     * @see StyledImageView.bind
+     */
+    fun bind(playlist: Playlist) = innerImageView.bind(playlist)
+
     /**
      * Whether this view should be indicated to have ongoing playback or not. See
      * PlaybackIndicatorView for more information on what occurs here. Note: It's expected for this

app/src/main/java/org/oxycblt/auxio/image/ImageModule.kt

@@ -18,16 +18,10 @@
  
 package org.oxycblt.auxio.image
 
-import android.content.Context
-import coil.ImageLoader
-import coil.request.CachePolicy
 import dagger.Binds
 import dagger.Module
-import dagger.Provides
 import dagger.hilt.InstallIn
-import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
-import javax.inject.Singleton
 import org.oxycblt.auxio.image.extractor.*
 
 @Module
@@ -35,31 +29,3 @@ import org.oxycblt.auxio.image.extractor.*
 interface ImageModule {
     @Binds fun settings(imageSettings: ImageSettingsImpl): ImageSettings
 }
-
-@Module
-@InstallIn(SingletonComponent::class)
-class CoilModule {
-    @Singleton
-    @Provides
-    fun imageLoader(
-        @ApplicationContext context: Context,
-        songFactory: AlbumCoverFetcher.SongFactory,
-        albumFactory: AlbumCoverFetcher.AlbumFactory,
-        artistFactory: ArtistImageFetcher.Factory,
-        genreFactory: GenreImageFetcher.Factory
-    ) =
-        ImageLoader.Builder(context)
-            .components {
-                // Add fetchers for Music components to make them usable with ImageRequest
-                add(MusicKeyer())
-                add(songFactory)
-                add(albumFactory)
-                add(artistFactory)
-                add(genreFactory)
-            }
-            // Use our own crossfade with error drawable support
-            .transitionFactory(ErrorCrossfadeTransitionFactory())
-            // Not downloading anything, so no disk-caching
-            .diskCachePolicy(CachePolicy.DISABLED)
-            .build()
-}

app/src/main/java/org/oxycblt/auxio/image/StyledImageView.kt

@@ -38,11 +38,7 @@ import dagger.hilt.android.AndroidEntryPoint
 import javax.inject.Inject
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.image.extractor.SquareFrameTransform
-import org.oxycblt.auxio.music.Album
+import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.Artist
-import org.oxycblt.auxio.music.Genre
-import org.oxycblt.auxio.music.Music
-import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.ui.UISettings
 import org.oxycblt.auxio.util.getColorCompat
 import org.oxycblt.auxio.util.getDrawableCompat
@@ -100,41 +96,54 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      *
      * @param song The [Song] to bind.
      */
-    fun bind(song: Song) = bindImpl(song, R.drawable.ic_song_24, R.string.desc_album_cover)
+    fun bind(song: Song) = bind(song.album)
 
     /**
      * Bind an [Album]'s cover to this view, also updating the content description.
      *
      * @param album the [Album] to bind.
      */
-    fun bind(album: Album) = bindImpl(album, R.drawable.ic_album_24, R.string.desc_album_cover)
+    fun bind(album: Album) = bind(album, R.drawable.ic_album_24, R.string.desc_album_cover)
 
     /**
      * Bind an [Artist]'s image to this view, also updating the content description.
      *
      * @param artist the [Artist] to bind.
      */
-    fun bind(artist: Artist) = bindImpl(artist, R.drawable.ic_artist_24, R.string.desc_artist_image)
+    fun bind(artist: Artist) = bind(artist, R.drawable.ic_artist_24, R.string.desc_artist_image)
 
     /**
      * Bind an [Genre]'s image to this view, also updating the content description.
      *
      * @param genre the [Genre] to bind.
      */
-    fun bind(genre: Genre) = bindImpl(genre, R.drawable.ic_genre_24, R.string.desc_genre_image)
+    fun bind(genre: Genre) = bind(genre, R.drawable.ic_genre_24, R.string.desc_genre_image)
 
     /**
-     * Internally bind a [Music]'s image to this view.
+     * Bind a [Playlist]'s image to this view, also updating the content description.
      *
-     * @param music The music to find.
+     * @param playlist The [Playlist] to bind.
-     * @param errorRes The error drawable resource to use if the music cannot be loaded.
+     * @param songs [Song]s that can override the playlist image if it needs to differ for any
-     * @param descRes The content description string resource to use. The resource must have one
+     *   reason.
-     *   field for the name of the [Music].
      */
-    private fun bindImpl(music: Music, @DrawableRes errorRes: Int, @StringRes descRes: Int) {
+    fun bind(playlist: Playlist, songs: List<Song>? = null) =
+        if (songs != null) {
+            bind(
+                songs,
+                context.getString(R.string.desc_playlist_image, playlist.name.resolve(context)),
+                R.drawable.ic_playlist_24)
+        } else {
+            bind(playlist, R.drawable.ic_playlist_24, R.string.desc_playlist_image)
+        }
+
+    private fun bind(parent: MusicParent, @DrawableRes errorRes: Int, @StringRes descRes: Int) {
+        bind(parent.songs, context.getString(descRes, parent.name.resolve(context)), errorRes)
+    }
+
+    private fun bind(songs: List<Song>, desc: String, @DrawableRes errorRes: Int) {
         val request =
             ImageRequest.Builder(context)
-                .data(music)
+                .data(songs)
                 .error(StyledDrawable(context, context.getDrawableCompat(errorRes)))
                 .transformations(SquareFrameTransform.INSTANCE)
                 .target(this)
@@ -142,8 +151,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         // Dispose of any previous image request and load a new image.
         CoilUtils.dispose(this)
         imageLoader.enqueue(request)
-        // Update the content description to the specified resource.
+        contentDescription = desc
-        contentDescription = context.getString(descRes, music.resolveName(context))
     }
 
     /**

app/src/main/java/org/oxycblt/auxio/image/extractor/Components.kt

@@ -18,153 +18,31 @@
  
 package org.oxycblt.auxio.image.extractor
 
-import android.content.Context
 import coil.ImageLoader
-import coil.decode.DataSource
-import coil.decode.ImageSource
-import coil.fetch.FetchResult
 import coil.fetch.Fetcher
-import coil.fetch.SourceResult
 import coil.key.Keyer
 import coil.request.Options
 import coil.size.Size
 import javax.inject.Inject
-import kotlin.math.min
+import org.oxycblt.auxio.music.*
-import okio.buffer
-import okio.source
-import org.oxycblt.auxio.list.Sort
-import org.oxycblt.auxio.music.Album
-import org.oxycblt.auxio.music.Artist
-import org.oxycblt.auxio.music.Genre
-import org.oxycblt.auxio.music.Music
-import org.oxycblt.auxio.music.Song
 
-/**
+class SongKeyer @Inject constructor(private val coverExtractor: CoverExtractor) :
- * A [Keyer] implementation for [Music] data.
+    Keyer<List<Song>> {
- *
+    override fun key(data: List<Song>, options: Options) =
- * @author Alexander Capehart (OxygenCobalt)
+        "${coverExtractor.computeAlbumOrdering(data).hashCode()}"
- */
-class MusicKeyer : Keyer<Music> {
-    override fun key(data: Music, options: Options) =
-        if (data is Song) {
-            // Group up song covers with album covers for better caching
-            data.album.uid.toString()
-        } else {
-            data.uid.toString()
-        }
 }
 
-/**
+class SongCoverFetcher
- * Generic [Fetcher] for [Album] covers. Works with both [Album] and [Song]. Use [SongFactory] or
- * [AlbumFactory] for instantiation.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class AlbumCoverFetcher
 private constructor(
-    private val context: Context,
+    private val songs: List<Song>,
-    private val extractor: CoverExtractor,
-    private val album: Album
-) : Fetcher {
-    override suspend fun fetch(): FetchResult? =
-        extractor.extract(album)?.run {
-            SourceResult(
-                source = ImageSource(source().buffer(), context),
-                mimeType = null,
-                dataSource = DataSource.DISK)
-        }
-
-    /** A [Fetcher.Factory] implementation that works with [Song]s. */
-    class SongFactory @Inject constructor(private val coverExtractor: CoverExtractor) :
-        Fetcher.Factory<Song> {
-        override fun create(data: Song, options: Options, imageLoader: ImageLoader) =
-            AlbumCoverFetcher(options.context, coverExtractor, data.album)
-    }
-
-    /** A [Fetcher.Factory] implementation that works with [Album]s. */
-    class AlbumFactory @Inject constructor(private val coverExtractor: CoverExtractor) :
-        Fetcher.Factory<Album> {
-        override fun create(data: Album, options: Options, imageLoader: ImageLoader) =
-            AlbumCoverFetcher(options.context, coverExtractor, data)
-    }
-}
-
-/**
- * [Fetcher] for [Artist] images. Use [Factory] for instantiation.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class ArtistImageFetcher
-private constructor(
-    private val context: Context,
-    private val extractor: CoverExtractor,
     private val size: Size,
-    private val artist: Artist
+    private val coverExtractor: CoverExtractor,
 ) : Fetcher {
-    override suspend fun fetch(): FetchResult? {
+    override suspend fun fetch() = coverExtractor.extract(songs, size)
-        // Pick the "most prominent" albums (i.e albums with the most songs) to show in the image.
-        val albums = Sort(Sort.Mode.ByCount, Sort.Direction.DESCENDING).albums(artist.albums)
-        val results = albums.mapAtMostNotNull(4) { album -> extractor.extract(album) }
-        return Images.createMosaic(context, results, size)
-    }
 
-    /** [Fetcher.Factory] implementation. */
+    class Factory @Inject constructor(private val coverExtractor: CoverExtractor) :
-    class Factory @Inject constructor(private val extractor: CoverExtractor) :
+        Fetcher.Factory<List<Song>> {
-        Fetcher.Factory<Artist> {
+        override fun create(data: List<Song>, options: Options, imageLoader: ImageLoader) =
-        override fun create(data: Artist, options: Options, imageLoader: ImageLoader) =
+            SongCoverFetcher(data, options.size, coverExtractor)
-            ArtistImageFetcher(options.context, extractor, options.size, data)
     }
 }
-
-/**
- * [Fetcher] for [Genre] images. Use [Factory] for instantiation.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class GenreImageFetcher
-private constructor(
-    private val context: Context,
-    private val extractor: CoverExtractor,
-    private val size: Size,
-    private val genre: Genre
-) : Fetcher {
-    override suspend fun fetch(): FetchResult? {
-        val results = genre.albums.mapAtMostNotNull(4) { album -> extractor.extract(album) }
-        return Images.createMosaic(context, results, size)
-    }
-
-    /** [Fetcher.Factory] implementation. */
-    class Factory @Inject constructor(private val extractor: CoverExtractor) :
-        Fetcher.Factory<Genre> {
-        override fun create(data: Genre, options: Options, imageLoader: ImageLoader) =
-            GenreImageFetcher(options.context, extractor, options.size, data)
-    }
-}
-
-/**
- * Map at most N [T] items a collection into a collection of [R], ignoring [T] that cannot be
- * transformed into [R].
- *
- * @param n The maximum amount of items to map.
- * @param transform The function that transforms data [T] from the original list into data [R] in
- *   the new list. Can return null if the [T] cannot be transformed into an [R].
- * @return A new list of at most N non-null [R] items.
- */
-private inline fun <T : Any, R : Any> Collection<T>.mapAtMostNotNull(
-    n: Int,
-    transform: (T) -> R?
-): List<R> {
-    val until = min(size, n)
-    val out = mutableListOf<R>()
-
-    for (item in this) {
-        if (out.size >= until) {
-            break
-        }
-
-        // Still have more data we can transform.
-        transform(item)?.let(out::add)
-    }
-
-    return out
-}

app/src/main/java/org/oxycblt/auxio/image/extractor/CoverExtractor.kt

@@ -19,13 +19,26 @@
 package org.oxycblt.auxio.image.extractor
 
 import android.content.Context
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Canvas
 import android.media.MediaMetadataRetriever
-import com.google.android.exoplayer2.MediaItem
+import android.util.Size as AndroidSize
-import com.google.android.exoplayer2.MediaMetadata
+import androidx.core.graphics.drawable.toDrawable
-import com.google.android.exoplayer2.MetadataRetriever
+import androidx.media3.common.MediaItem
-import com.google.android.exoplayer2.metadata.flac.PictureFrame
+import androidx.media3.common.MediaMetadata
-import com.google.android.exoplayer2.metadata.id3.ApicFrame
+import androidx.media3.exoplayer.MetadataRetriever
-import com.google.android.exoplayer2.source.MediaSource
+import androidx.media3.exoplayer.source.MediaSource
+import androidx.media3.extractor.metadata.flac.PictureFrame
+import androidx.media3.extractor.metadata.id3.ApicFrame
+import coil.decode.DataSource
+import coil.decode.ImageSource
+import coil.fetch.DrawableResult
+import coil.fetch.FetchResult
+import coil.fetch.SourceResult
+import coil.size.Dimension
+import coil.size.Size
+import coil.size.pxOrElse
 import dagger.hilt.android.qualifiers.ApplicationContext
 import java.io.ByteArrayInputStream
 import java.io.InputStream
@@ -33,9 +46,12 @@ import javax.inject.Inject
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.guava.asDeferred
 import kotlinx.coroutines.withContext
+import okio.buffer
+import okio.source
 import org.oxycblt.auxio.image.CoverMode
 import org.oxycblt.auxio.image.ImageSettings
 import org.oxycblt.auxio.music.Album
+import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logW
 
@@ -46,8 +62,28 @@ constructor(
     private val imageSettings: ImageSettings,
     private val mediaSourceFactory: MediaSource.Factory
 ) {
+    suspend fun extract(songs: List<Song>, size: Size): FetchResult? {
+        val albums = computeAlbumOrdering(songs)
+        val streams = mutableListOf<InputStream>()
+        for (album in albums) {
+            openInputStream(album)?.let(streams::add)
+            if (streams.size == 4) {
+                return createMosaic(streams, size)
+            }
+        }
 
-    suspend fun extract(album: Album): InputStream? =
+        return streams.firstOrNull()?.let { stream ->
+            SourceResult(
+                source = ImageSource(stream.source().buffer(), context),
+                mimeType = null,
+                dataSource = DataSource.DISK)
+        }
+    }
+
+    fun computeAlbumOrdering(songs: List<Song>) =
+        songs.groupBy { it.album }.entries.sortedByDescending { it.value.size }.map { it.key }
+
+    private suspend fun openInputStream(album: Album): InputStream? =
         try {
             when (imageSettings.coverMode) {
                 CoverMode.OFF -> null
@@ -123,8 +159,61 @@ constructor(
         return stream
     }
 
-    @Suppress("BlockingMethodInNonBlockingContext")
     private suspend fun extractMediaStoreCover(album: Album) =
         // Eliminate any chance that this blocking call might mess up the loading process
         withContext(Dispatchers.IO) { context.contentResolver.openInputStream(album.coverUri) }
+
+    /** Derived from phonograph: https://github.com/kabouzeid/Phonograph */
+    private suspend fun createMosaic(streams: List<InputStream>, size: Size): FetchResult {
+        // Use whatever size coil gives us to create the mosaic.
+        val mosaicSize = AndroidSize(size.width.mosaicSize(), size.height.mosaicSize())
+        val mosaicFrameSize =
+            Size(Dimension(mosaicSize.width / 2), Dimension(mosaicSize.height / 2))
+
+        val mosaicBitmap =
+            Bitmap.createBitmap(mosaicSize.width, mosaicSize.height, Bitmap.Config.ARGB_8888)
+        val canvas = Canvas(mosaicBitmap)
+
+        var x = 0
+        var y = 0
+
+        // For each stream, create a bitmap scaled to 1/4th of the mosaics combined size
+        // and place it on a corner of the canvas.
+        for (stream in streams) {
+            if (y == mosaicSize.height) {
+                break
+            }
+
+            // Run the bitmap through a transform to reflect the configuration of other images.
+            val bitmap =
+                SquareFrameTransform.INSTANCE.transform(
+                    BitmapFactory.decodeStream(stream), mosaicFrameSize)
+            canvas.drawBitmap(bitmap, x.toFloat(), y.toFloat(), null)
+
+            x += bitmap.width
+            if (x == mosaicSize.width) {
+                x = 0
+                y += bitmap.height
+            }
+        }
+
+        // It's way easier to map this into a drawable then try to serialize it into an
+        // BufferedSource. Just make sure we mark it as "sampled" so Coil doesn't try to
+        // load low-res mosaics into high-res ImageViews.
+        return DrawableResult(
+            drawable = mosaicBitmap.toDrawable(context.resources),
+            isSampled = true,
+            dataSource = DataSource.DISK)
+    }
+
+    /**
+     * Get an image dimension suitable to create a mosaic with.
+     *
+     * @return A pixel dimension derived from the given [Dimension] that will always be even,
+     *   allowing it to be sub-divided.
+     */
+    private fun Dimension.mosaicSize(): Int {
+        val size = pxOrElse { 512 }
+        return if (size.mod(2) > 0) size + 1 else size
+    }
 }

app/src/main/java/org/oxycblt/auxio/image/extractor/ExtractorModule.kt

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * ExtractorModule.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.image.extractor
+
+import android.content.Context
+import coil.ImageLoader
+import coil.request.CachePolicy
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+class ExtractorModule {
+    @Singleton
+    @Provides
+    fun imageLoader(
+        @ApplicationContext context: Context,
+        songKeyer: SongKeyer,
+        songFactory: SongCoverFetcher.Factory
+    ) =
+        ImageLoader.Builder(context)
+            .components {
+                // Add fetchers for Music components to make them usable with ImageRequest
+                add(songKeyer)
+                add(songFactory)
+            }
+            // Use our own crossfade with error drawable support
+            .transitionFactory(ErrorCrossfadeTransitionFactory())
+            // Not downloading anything, so no disk-caching
+            .diskCachePolicy(CachePolicy.DISABLED)
+            .build()
+}

app/src/main/java/org/oxycblt/auxio/image/extractor/Images.kt

@@ -1,118 +0,0 @@
-/*
- * Copyright (c) 2022 Auxio Project
- * Images.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.auxio.image.extractor
-
-import android.content.Context
-import android.graphics.Bitmap
-import android.graphics.BitmapFactory
-import android.graphics.Canvas
-import android.util.Size as AndroidSize
-import androidx.core.graphics.drawable.toDrawable
-import coil.decode.DataSource
-import coil.decode.ImageSource
-import coil.fetch.DrawableResult
-import coil.fetch.FetchResult
-import coil.fetch.SourceResult
-import coil.size.Dimension
-import coil.size.Size
-import coil.size.pxOrElse
-import java.io.InputStream
-import okio.buffer
-import okio.source
-
-/**
- * Utilities for constructing Artist and Genre images.
- *
- * @author Alexander Capehart (OxygenCobalt), Karim Abou Zeid
- */
-object Images {
-    /**
-     * Create a mosaic image from the given image [InputStream]s. Derived from phonograph:
-     * https://github.com/kabouzeid/Phonograph
-     *
-     * @param context [Context] required to generate the mosaic.
-     * @param streams [InputStream]s of image data to create the mosaic out of.
-     * @param size [Size] of the Mosaic to generate.
-     */
-    suspend fun createMosaic(
-        context: Context,
-        streams: List<InputStream>,
-        size: Size
-    ): FetchResult? {
-        if (streams.size < 4) {
-            return streams.firstOrNull()?.let { stream ->
-                SourceResult(
-                    source = ImageSource(stream.source().buffer(), context),
-                    mimeType = null,
-                    dataSource = DataSource.DISK)
-            }
-        }
-
-        // Use whatever size coil gives us to create the mosaic.
-        val mosaicSize = AndroidSize(size.width.mosaicSize(), size.height.mosaicSize())
-        val mosaicFrameSize =
-            Size(Dimension(mosaicSize.width / 2), Dimension(mosaicSize.height / 2))
-
-        val mosaicBitmap =
-            Bitmap.createBitmap(mosaicSize.width, mosaicSize.height, Bitmap.Config.ARGB_8888)
-        val canvas = Canvas(mosaicBitmap)
-
-        var x = 0
-        var y = 0
-
-        // For each stream, create a bitmap scaled to 1/4th of the mosaics combined size
-        // and place it on a corner of the canvas.
-        for (stream in streams) {
-            if (y == mosaicSize.height) {
-                break
-            }
-
-            // Run the bitmap through a transform to reflect the configuration of other images.
-            val bitmap =
-                SquareFrameTransform.INSTANCE.transform(
-                    BitmapFactory.decodeStream(stream), mosaicFrameSize)
-            canvas.drawBitmap(bitmap, x.toFloat(), y.toFloat(), null)
-
-            x += bitmap.width
-            if (x == mosaicSize.width) {
-                x = 0
-                y += bitmap.height
-            }
-        }
-
-        // It's way easier to map this into a drawable then try to serialize it into an
-        // BufferedSource. Just make sure we mark it as "sampled" so Coil doesn't try to
-        // load low-res mosaics into high-res ImageViews.
-        return DrawableResult(
-            drawable = mosaicBitmap.toDrawable(context.resources),
-            isSampled = true,
-            dataSource = DataSource.DISK)
-    }
-
-    /**
-     * Get an image dimension suitable to create a mosaic with.
-     *
-     * @return A pixel dimension derived from the given [Dimension] that will always be even,
-     *   allowing it to be sub-divided.
-     */
-    private fun Dimension.mosaicSize(): Int {
-        val size = pxOrElse { 512 }
-        return if (size.mod(2) > 0) size + 1 else size
-    }
-}

app/src/main/java/org/oxycblt/auxio/list/Data.kt

@@ -40,3 +40,11 @@ interface Header : Item {
  * @author Alexander Capehart (OxygenCobalt)
  */
 data class BasicHeader(@StringRes override val titleRes: Int) : Header
+
+/**
+ * A divider decoration used to delimit groups of data.
+ *
+ * @param anchor The [Header] this divider should be next to in a list. Used as a way to preserve
+ *   divider continuity during list updates.
+ */
+data class Divider(val anchor: Header?) : Item

app/src/main/java/org/oxycblt/auxio/list/ListFragment.kt

@@ -22,7 +22,6 @@ import android.view.MenuItem
 import android.view.View
 import androidx.annotation.MenuRes
 import androidx.appcompat.widget.PopupMenu
-import androidx.core.internal.view.SupportMenu
 import androidx.core.view.MenuCompat
 import androidx.recyclerview.widget.RecyclerView
 import androidx.viewbinding.ViewBinding
@@ -30,8 +29,8 @@ import org.oxycblt.auxio.MainFragmentDirections
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.selection.SelectionFragment
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.ui.MainNavigationAction
+import org.oxycblt.auxio.navigation.MainNavigationAction
-import org.oxycblt.auxio.ui.NavigationViewModel
+import org.oxycblt.auxio.navigation.NavigationViewModel
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.showToast
 
@@ -59,7 +58,7 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
      */
     abstract fun onRealClick(item: T)
 
-    override fun onClick(item: T, viewHolder: RecyclerView.ViewHolder) {
+    final override fun onClick(item: T, viewHolder: RecyclerView.ViewHolder) {
         if (selectionModel.selected.value.isNotEmpty()) {
             // Map clicking an item to selecting an item when items are already selected.
             selectionModel.select(item)
@@ -69,7 +68,7 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
         }
     }
 
-    override fun onSelect(item: T) {
+    final override fun onSelect(item: T) {
         selectionModel.select(item)
     }
 
@@ -82,7 +81,7 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
      * @param song The [Song] to create the menu for.
      */
     protected fun openMusicMenu(anchor: View, @MenuRes menuRes: Int, song: Song) {
-        logD("Launching new song menu: ${song.rawName}")
+        logD("Launching new song menu: ${song.name}")
 
         openMusicMenuImpl(anchor, menuRes) {
             when (it.itemId) {
@@ -100,6 +99,9 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
                 R.id.action_go_album -> {
                     navModel.exploreNavigateTo(song.album)
                 }
+                R.id.action_playlist_add -> {
+                    musicModel.addToPlaylist(song)
+                }
                 R.id.action_song_detail -> {
                     navModel.mainNavigateTo(
                         MainNavigationAction.Directions(
@@ -121,7 +123,7 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
      * @param album The [Album] to create the menu for.
      */
     protected fun openMusicMenu(anchor: View, @MenuRes menuRes: Int, album: Album) {
-        logD("Launching new album menu: ${album.rawName}")
+        logD("Launching new album menu: ${album.name}")
 
         openMusicMenuImpl(anchor, menuRes) {
             when (it.itemId) {
@@ -142,6 +144,9 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
                 R.id.action_go_artist -> {
                     navModel.exploreNavigateToParentArtist(album)
                 }
+                R.id.action_playlist_add -> {
+                    musicModel.addToPlaylist(album)
+                }
                 else -> {
                     error("Unexpected menu item selected")
                 }
@@ -158,7 +163,7 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
      * @param artist The [Artist] to create the menu for.
      */
     protected fun openMusicMenu(anchor: View, @MenuRes menuRes: Int, artist: Artist) {
-        logD("Launching new artist menu: ${artist.rawName}")
+        logD("Launching new artist menu: ${artist.name}")
 
         openMusicMenuImpl(anchor, menuRes) {
             when (it.itemId) {
@@ -176,6 +181,9 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
                     playbackModel.addToQueue(artist)
                     requireContext().showToast(R.string.lng_queue_added)
                 }
+                R.id.action_playlist_add -> {
+                    musicModel.addToPlaylist(artist)
+                }
                 else -> {
                     error("Unexpected menu item selected")
                 }
@@ -192,7 +200,7 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
      * @param genre The [Genre] to create the menu for.
      */
     protected fun openMusicMenu(anchor: View, @MenuRes menuRes: Int, genre: Genre) {
-        logD("Launching new genre menu: ${genre.rawName}")
+        logD("Launching new genre menu: ${genre.name}")
 
         openMusicMenuImpl(anchor, menuRes) {
             when (it.itemId) {
@@ -210,6 +218,49 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
                     playbackModel.addToQueue(genre)
                     requireContext().showToast(R.string.lng_queue_added)
                 }
+                R.id.action_playlist_add -> {
+                    musicModel.addToPlaylist(genre)
+                }
+                else -> {
+                    error("Unexpected menu item selected")
+                }
+            }
+        }
+    }
+
+    /**
+     * Opens a menu in the context of a [Playlist]. This menu will be managed by the Fragment and
+     * closed when the view is destroyed. If a menu is already opened, this call is ignored.
+     *
+     * @param anchor The [View] to anchor the menu to.
+     * @param menuRes The resource of the menu to load.
+     * @param playlist The [Playlist] to create the menu for.
+     */
+    protected fun openMusicMenu(anchor: View, @MenuRes menuRes: Int, playlist: Playlist) {
+        logD("Launching new playlist menu: ${playlist.name}")
+
+        openMusicMenuImpl(anchor, menuRes) {
+            when (it.itemId) {
+                R.id.action_play -> {
+                    playbackModel.play(playlist)
+                }
+                R.id.action_shuffle -> {
+                    playbackModel.shuffle(playlist)
+                }
+                R.id.action_play_next -> {
+                    playbackModel.playNext(playlist)
+                    requireContext().showToast(R.string.lng_queue_added)
+                }
+                R.id.action_queue_add -> {
+                    playbackModel.addToQueue(playlist)
+                    requireContext().showToast(R.string.lng_queue_added)
+                }
+                R.id.action_rename -> {
+                    musicModel.renamePlaylist(playlist)
+                }
+                R.id.action_delete -> {
+                    musicModel.deletePlaylist(playlist)
+                }
                 else -> {
                     error("Unexpected menu item selected")
                 }
@@ -247,7 +298,6 @@ abstract class ListFragment<in T : Music, VB : ViewBinding> :
         currentMenu =
             PopupMenu(requireContext(), anchor).apply {
                 inflate(menuRes)
-                logD(menu is SupportMenu)
                 MenuCompat.setGroupDividerEnabled(menu, true)
                 block()
                 setOnDismissListener { currentMenu = null }

app/src/main/java/org/oxycblt/auxio/list/Listeners.kt

@@ -50,11 +50,11 @@ interface ClickableListListener<in T> {
 }
 
 /**
- * An extension of [ClickableListListener] that enables list editing functionality.
+ * A listener for lists that can be edited.
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-interface EditableListListener<in T> : ClickableListListener<T> {
+interface EditableListListener {
     /**
      * Called when a [RecyclerView.ViewHolder] requests that it should be dragged.
      *
@@ -62,6 +62,29 @@ interface EditableListListener<in T> : ClickableListListener<T> {
      */
     fun onPickUp(viewHolder: RecyclerView.ViewHolder)
 
+    /**
+     * Binds this instance to a list item.
+     *
+     * @param viewHolder The [RecyclerView.ViewHolder] to bind.
+     * @param dragHandle A touchable [View]. Any drag on this view will start a drag event.
+     */
+    fun bind(viewHolder: RecyclerView.ViewHolder, dragHandle: View) {
+        dragHandle.setOnTouchListener { _, motionEvent ->
+            dragHandle.performClick()
+            if (motionEvent.actionMasked == MotionEvent.ACTION_DOWN) {
+                onPickUp(viewHolder)
+                true
+            } else false
+        }
+    }
+}
+
+/**
+ * A listener for lists that can be clicked and edited at the same time.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+interface EditClickListListener<in T> : ClickableListListener<T>, EditableListListener {
     /**
      * Binds this instance to a list item.
      *
@@ -78,13 +101,7 @@ interface EditableListListener<in T> : ClickableListListener<T> {
         dragHandle: View
     ) {
         bind(item, viewHolder, bodyView)
-        dragHandle.setOnTouchListener { _, motionEvent ->
+        bind(viewHolder, dragHandle)
-            dragHandle.performClick()
-            if (motionEvent.actionMasked == MotionEvent.ACTION_DOWN) {
-                onPickUp(viewHolder)
-                true
-            } else false
-        }
     }
 }
 

app/src/main/java/org/oxycblt/auxio/list/Sort.kt

@@ -24,8 +24,8 @@ import org.oxycblt.auxio.IntegerTable
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.Sort.Mode
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.metadata.Date
+import org.oxycblt.auxio.music.info.Date
-import org.oxycblt.auxio.music.metadata.Disc
+import org.oxycblt.auxio.music.info.Disc
 
 /**
  * A sorting method.
@@ -102,39 +102,40 @@ data class Sort(val mode: Mode, val direction: Direction) {
     }
 
     /**
-     * Sort a *mutable* list of [Song]s in-place using this [Sort]'s configuration.
+     * Sort a list of [Playlist]s.
      *
-     * @param songs The [Song]s to sort.
+     * @param playlists The list of [Playlist]s.
+     * @return A new list of [Playlist]s sorted by this [Sort]'s configuration
      */
+    fun <T : Playlist> playlists(playlists: Collection<T>): List<T> {
+        val mutable = playlists.toMutableList()
+        playlistsInPlace(mutable)
+        return mutable
+    }
+
     private fun songsInPlace(songs: MutableList<out Song>) {
-        songs.sortWith(mode.getSongComparator(direction))
+        val comparator = mode.getSongComparator(direction) ?: return
+        songs.sortWith(comparator)
     }
 
-    /**
-     * Sort a *mutable* list of [Album]s in-place using this [Sort]'s configuration.
-     *
-     * @param albums The [Album]s to sort.
-     */
     private fun albumsInPlace(albums: MutableList<out Album>) {
-        albums.sortWith(mode.getAlbumComparator(direction))
+        val comparator = mode.getAlbumComparator(direction) ?: return
+        albums.sortWith(comparator)
     }
 
-    /**
-     * Sort a *mutable* list of [Artist]s in-place using this [Sort]'s configuration.
-     *
-     * @param artists The [Album]s to sort.
-     */
     private fun artistsInPlace(artists: MutableList<out Artist>) {
-        artists.sortWith(mode.getArtistComparator(direction))
+        val comparator = mode.getArtistComparator(direction) ?: return
+        artists.sortWith(comparator)
     }
 
-    /**
-     * Sort a *mutable* list of [Genre]s in-place using this [Sort]'s configuration.
-     *
-     * @param genres The [Genre]s to sort.
-     */
     private fun genresInPlace(genres: MutableList<out Genre>) {
-        genres.sortWith(mode.getGenreComparator(direction))
+        val comparator = mode.getGenreComparator(direction) ?: return
+        genres.sortWith(comparator)
+    }
+
+    private fun playlistsInPlace(playlists: MutableList<out Playlist>) {
+        val comparator = mode.getPlaylistComparator(direction) ?: return
+        playlists.sortWith(comparator)
     }
 
     /**
@@ -154,58 +155,63 @@ data class Sort(val mode: Mode, val direction: Direction) {
                 }
 
     /** Describes the type of data to sort with. */
-    sealed class Mode {
+    sealed interface Mode {
         /** The integer representation of this sort mode. */
-        abstract val intCode: Int
+        val intCode: Int
         /** The item ID of this sort mode in menu resources. */
-        abstract val itemId: Int
+        val itemId: Int
 
         /**
          * Get a [Comparator] that sorts [Song]s according to this [Mode].
          *
          * @param direction The direction to sort in.
-         * @return A [Comparator] that can be used to sort a [Song] list according to this [Mode].
+         * @return A [Comparator] that can be used to sort a [Song] list according to this [Mode],
+         *   or null to not sort at all.
          */
-        open fun getSongComparator(direction: Direction): Comparator<Song> {
+        fun getSongComparator(direction: Direction): Comparator<Song>? = null
-            throw UnsupportedOperationException()
-        }
 
         /**
          * Get a [Comparator] that sorts [Album]s according to this [Mode].
          *
          * @param direction The direction to sort in.
-         * @return A [Comparator] that can be used to sort a [Album] list according to this [Mode].
+         * @return A [Comparator] that can be used to sort a [Album] list according to this [Mode],
+         *   or null to not sort at all.
          */
-        open fun getAlbumComparator(direction: Direction): Comparator<Album> {
+        fun getAlbumComparator(direction: Direction): Comparator<Album>? = null
-            throw UnsupportedOperationException()
-        }
 
         /**
          * Return a [Comparator] that sorts [Artist]s according to this [Mode].
          *
          * @param direction The direction to sort in.
          * @return A [Comparator] that can be used to sort a [Artist] list according to this [Mode].
+         *   or null to not sort at all.
          */
-        open fun getArtistComparator(direction: Direction): Comparator<Artist> {
+        fun getArtistComparator(direction: Direction): Comparator<Artist>? = null
-            throw UnsupportedOperationException()
-        }
 
         /**
          * Return a [Comparator] that sorts [Genre]s according to this [Mode].
          *
          * @param direction The direction to sort in.
          * @return A [Comparator] that can be used to sort a [Genre] list according to this [Mode].
+         *   or null to not sort at all.
          */
-        open fun getGenreComparator(direction: Direction): Comparator<Genre> {
+        fun getGenreComparator(direction: Direction): Comparator<Genre>? = null
-            throw UnsupportedOperationException()
+
-        }
+        /**
+         * Return a [Comparator] that sorts [Playlist]s according to this [Mode].
+         *
+         * @param direction The direction to sort in.
+         * @return A [Comparator] that can be used to sort a [Genre] list according to this [Mode].
+         *   or null to not sort at all.
+         */
+        fun getPlaylistComparator(direction: Direction): Comparator<Playlist>? = null
 
         /**
          * Sort by the item's name.
          *
-         * @see Music.sortName
+         * @see Music.name
          */
-        object ByName : Mode() {
+        object ByName : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_NAME
 
@@ -223,14 +229,17 @@ data class Sort(val mode: Mode, val direction: Direction) {
 
             override fun getGenreComparator(direction: Direction) =
                 compareByDynamic(direction, BasicComparator.GENRE)
+
+            override fun getPlaylistComparator(direction: Direction) =
+                compareByDynamic(direction, BasicComparator.PLAYLIST)
         }
 
         /**
          * Sort by the [Album] of an item. Only available for [Song]s.
          *
-         * @see Album.collationKey
+         * @see Album.name
          */
-        object ByAlbum : Mode() {
+        object ByAlbum : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_ALBUM
 
@@ -248,9 +257,9 @@ data class Sort(val mode: Mode, val direction: Direction) {
         /**
          * Sort by the [Artist] name of an item. Only available for [Song] and [Album].
          *
-         * @see Artist.sortName
+         * @see Artist.name
          */
-        object ByArtist : Mode() {
+        object ByArtist : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_ARTIST
 
@@ -279,7 +288,7 @@ data class Sort(val mode: Mode, val direction: Direction) {
          * @see Song.date
          * @see Album.dates
          */
-        object ByDate : Mode() {
+        object ByDate : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_YEAR
 
@@ -301,7 +310,7 @@ data class Sort(val mode: Mode, val direction: Direction) {
         }
 
         /** Sort by the duration of an item. */
-        object ByDuration : Mode() {
+        object ByDuration : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_DURATION
 
@@ -324,6 +333,11 @@ data class Sort(val mode: Mode, val direction: Direction) {
             override fun getGenreComparator(direction: Direction): Comparator<Genre> =
                 MultiComparator(
                     compareByDynamic(direction) { it.durationMs }, compareBy(BasicComparator.GENRE))
+
+            override fun getPlaylistComparator(direction: Direction): Comparator<Playlist> =
+                MultiComparator(
+                    compareByDynamic(direction) { it.durationMs },
+                    compareBy(BasicComparator.PLAYLIST))
         }
 
         /**
@@ -331,7 +345,7 @@ data class Sort(val mode: Mode, val direction: Direction) {
          *
          * @see MusicParent.songs
          */
-        object ByCount : Mode() {
+        object ByCount : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_COUNT
 
@@ -350,6 +364,11 @@ data class Sort(val mode: Mode, val direction: Direction) {
             override fun getGenreComparator(direction: Direction): Comparator<Genre> =
                 MultiComparator(
                     compareByDynamic(direction) { it.songs.size }, compareBy(BasicComparator.GENRE))
+
+            override fun getPlaylistComparator(direction: Direction): Comparator<Playlist> =
+                MultiComparator(
+                    compareByDynamic(direction) { it.songs.size },
+                    compareBy(BasicComparator.PLAYLIST))
         }
 
         /**
@@ -357,7 +376,7 @@ data class Sort(val mode: Mode, val direction: Direction) {
          *
          * @see Song.disc
          */
-        object ByDisc : Mode() {
+        object ByDisc : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_DISC
 
@@ -376,7 +395,7 @@ data class Sort(val mode: Mode, val direction: Direction) {
          *
          * @see Song.track
          */
-        object ByTrack : Mode() {
+        object ByTrack : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_TRACK
 
@@ -396,7 +415,7 @@ data class Sort(val mode: Mode, val direction: Direction) {
          * @see Song.dateAdded
          * @see Album.dates
          */
-        object ByDateAdded : Mode() {
+        object ByDateAdded : Mode {
             override val intCode: Int
                 get() = IntegerTable.SORT_BY_DATE_ADDED
 
@@ -413,176 +432,6 @@ data class Sort(val mode: Mode, val direction: Direction) {
                     compareBy(BasicComparator.ALBUM))
         }
 
-        /**
-         * Utility function to create a [Comparator] in a dynamic way determined by [direction].
-         *
-         * @param direction The [Direction] to sort in.
-         * @see compareBy
-         * @see compareByDescending
-         */
-        protected inline fun <T : Music, K : Comparable<K>> compareByDynamic(
-            direction: Direction,
-            crossinline selector: (T) -> K
-        ) =
-            when (direction) {
-                Direction.ASCENDING -> compareBy(selector)
-                Direction.DESCENDING -> compareByDescending(selector)
-            }
-
-        /**
-         * Utility function to create a [Comparator] in a dynamic way determined by [direction]
-         *
-         * @param direction The [Direction] to sort in.
-         * @param comparator A [Comparator] to wrap.
-         * @return A new [Comparator] with the specified configuration.
-         * @see compareBy
-         * @see compareByDescending
-         */
-        protected fun <T : Music> compareByDynamic(
-            direction: Direction,
-            comparator: Comparator<in T>
-        ): Comparator<T> = compareByDynamic(direction, comparator) { it }
-
-        /**
-         * Utility function to create a [Comparator] a dynamic way determined by [direction]
-         *
-         * @param direction The [Direction] to sort in.
-         * @param comparator A [Comparator] to wrap.
-         * @param selector Called to obtain a specific attribute to sort by.
-         * @return A new [Comparator] with the specified configuration.
-         * @see compareBy
-         * @see compareByDescending
-         */
-        protected inline fun <T : Music, K> compareByDynamic(
-            direction: Direction,
-            comparator: Comparator<in K>,
-            crossinline selector: (T) -> K
-        ) =
-            when (direction) {
-                Direction.ASCENDING -> compareBy(comparator, selector)
-                Direction.DESCENDING -> compareByDescending(comparator, selector)
-            }
-
-        /**
-         * Utility function to create a [Comparator] that sorts in ascending order based on the
-         * given [Comparator], with a selector based on the item itself.
-         *
-         * @param comparator The [Comparator] to wrap.
-         * @return A new [Comparator] with the specified configuration.
-         * @see compareBy
-         */
-        protected fun <T : Music> compareBy(comparator: Comparator<T>): Comparator<T> =
-            compareBy(comparator) { it }
-
-        /**
-         * A [Comparator] that chains several other [Comparator]s together to form one comparison.
-         *
-         * @param comparators The [Comparator]s to chain. These will be iterated through in order
-         *   during a comparison, with the first non-equal result becoming the result.
-         */
-        private class MultiComparator<T>(vararg comparators: Comparator<T>) : Comparator<T> {
-            private val _comparators = comparators
-
-            override fun compare(a: T?, b: T?): Int {
-                for (comparator in _comparators) {
-                    val result = comparator.compare(a, b)
-                    if (result != 0) {
-                        return result
-                    }
-                }
-
-                return 0
-            }
-        }
-
-        /**
-         * Wraps a [Comparator], extending it to compare two lists.
-         *
-         * @param inner The [Comparator] to use.
-         */
-        private class ListComparator<T>(private val inner: Comparator<T>) : Comparator<List<T>> {
-            override fun compare(a: List<T>, b: List<T>): Int {
-                for (i in 0 until max(a.size, b.size)) {
-                    val ai = a.getOrNull(i)
-                    val bi = b.getOrNull(i)
-                    when {
-                        ai != null && bi != null -> {
-                            val result = inner.compare(ai, bi)
-                            if (result != 0) {
-                                return result
-                            }
-                        }
-                        ai == null && bi != null -> return -1 // a < b
-                        ai == null && bi == null -> return 0 // a = b
-                        else -> return 1 // a < b
-                    }
-                }
-
-                return 0
-            }
-
-            companion object {
-                /** A re-usable configured for [Artist]s.. */
-                val ARTISTS: Comparator<List<Artist>> = ListComparator(BasicComparator.ARTIST)
-            }
-        }
-
-        /**
-         * A [Comparator] that compares abstract [Music] values. Internally, this is similar to
-         * [NullableComparator], however comparing [Music.collationKey] instead of [Comparable].
-         *
-         * @see NullableComparator
-         * @see Music.collationKey
-         */
-        private class BasicComparator<T : Music> private constructor() : Comparator<T> {
-            override fun compare(a: T, b: T): Int {
-                val aKey = a.sortName
-                val bKey = b.sortName
-                return when {
-                    aKey != null && bKey != null -> aKey.compareTo(bKey)
-                    aKey == null && bKey != null -> -1 // a < b
-                    aKey == null && bKey == null -> 0 // a = b
-                    else -> 1 // a < b
-                }
-            }
-
-            companion object {
-                /** A re-usable instance configured for [Song]s. */
-                val SONG: Comparator<Song> = BasicComparator()
-                /** A re-usable instance configured for [Album]s. */
-                val ALBUM: Comparator<Album> = BasicComparator()
-                /** A re-usable instance configured for [Artist]s. */
-                val ARTIST: Comparator<Artist> = BasicComparator()
-                /** A re-usable instance configured for [Genre]s. */
-                val GENRE: Comparator<Genre> = BasicComparator()
-            }
-        }
-
-        /**
-         * A [Comparator] that compares two possibly null values. Values will be considered lesser
-         * if they are null, and greater if they are non-null.
-         */
-        private class NullableComparator<T : Comparable<T>> private constructor() : Comparator<T?> {
-            override fun compare(a: T?, b: T?) =
-                when {
-                    a != null && b != null -> a.compareTo(b)
-                    a == null && b != null -> -1 // a < b
-                    a == null && b == null -> 0 // a = b
-                    else -> 1 // a < b
-                }
-
-            companion object {
-                /** A re-usable instance configured for [Int]s. */
-                val INT = NullableComparator<Int>()
-                /** A re-usable instance configured for [Long]s. */
-                val LONG = NullableComparator<Long>()
-                /** A re-usable instance configured for [Disc]s */
-                val DISC = NullableComparator<Disc>()
-                /** A re-usable instance configured for [Date.Range]s. */
-                val DATE_RANGE = NullableComparator<Date.Range>()
-            }
-        }
-
         companion object {
             /**
              * Convert a [Mode] integer representation into an instance.
@@ -652,3 +501,166 @@ data class Sort(val mode: Mode, val direction: Direction) {
         }
     }
 }
+
+/**
+ * Utility function to create a [Comparator] in a dynamic way determined by [direction].
+ *
+ * @param direction The [Sort.Direction] to sort in.
+ * @see compareBy
+ * @see compareByDescending
+ */
+private inline fun <T : Music, K : Comparable<K>> compareByDynamic(
+    direction: Sort.Direction,
+    crossinline selector: (T) -> K
+) =
+    when (direction) {
+        Sort.Direction.ASCENDING -> compareBy(selector)
+        Sort.Direction.DESCENDING -> compareByDescending(selector)
+    }
+
+/**
+ * Utility function to create a [Comparator] in a dynamic way determined by [direction]
+ *
+ * @param direction The [Sort.Direction] to sort in.
+ * @param comparator A [Comparator] to wrap.
+ * @return A new [Comparator] with the specified configuration.
+ * @see compareBy
+ * @see compareByDescending
+ */
+private fun <T : Music> compareByDynamic(
+    direction: Sort.Direction,
+    comparator: Comparator<in T>
+): Comparator<T> = compareByDynamic(direction, comparator) { it }
+
+/**
+ * Utility function to create a [Comparator] a dynamic way determined by [direction]
+ *
+ * @param direction The [Sort.Direction] to sort in.
+ * @param comparator A [Comparator] to wrap.
+ * @param selector Called to obtain a specific attribute to sort by.
+ * @return A new [Comparator] with the specified configuration.
+ * @see compareBy
+ * @see compareByDescending
+ */
+private inline fun <T : Music, K> compareByDynamic(
+    direction: Sort.Direction,
+    comparator: Comparator<in K>,
+    crossinline selector: (T) -> K
+) =
+    when (direction) {
+        Sort.Direction.ASCENDING -> compareBy(comparator, selector)
+        Sort.Direction.DESCENDING -> compareByDescending(comparator, selector)
+    }
+
+/**
+ * Utility function to create a [Comparator] that sorts in ascending order based on the given
+ * [Comparator], with a selector based on the item itself.
+ *
+ * @param comparator The [Comparator] to wrap.
+ * @return A new [Comparator] with the specified configuration.
+ * @see compareBy
+ */
+private fun <T : Music> compareBy(comparator: Comparator<T>): Comparator<T> =
+    compareBy(comparator) { it }
+
+/**
+ * A [Comparator] that chains several other [Comparator]s together to form one comparison.
+ *
+ * @param comparators The [Comparator]s to chain. These will be iterated through in order during a
+ *   comparison, with the first non-equal result becoming the result.
+ */
+private class MultiComparator<T>(vararg comparators: Comparator<T>) : Comparator<T> {
+    private val _comparators = comparators
+
+    override fun compare(a: T?, b: T?): Int {
+        for (comparator in _comparators) {
+            val result = comparator.compare(a, b)
+            if (result != 0) {
+                return result
+            }
+        }
+
+        return 0
+    }
+}
+
+/**
+ * Wraps a [Comparator], extending it to compare two lists.
+ *
+ * @param inner The [Comparator] to use.
+ */
+private class ListComparator<T>(private val inner: Comparator<T>) : Comparator<List<T>> {
+    override fun compare(a: List<T>, b: List<T>): Int {
+        for (i in 0 until max(a.size, b.size)) {
+            val ai = a.getOrNull(i)
+            val bi = b.getOrNull(i)
+            when {
+                ai != null && bi != null -> {
+                    val result = inner.compare(ai, bi)
+                    if (result != 0) {
+                        return result
+                    }
+                }
+                ai == null && bi != null -> return -1 // a < b
+                ai == null && bi == null -> return 0 // a = b
+                else -> return 1 // a < b
+            }
+        }
+
+        return 0
+    }
+
+    companion object {
+        /** A re-usable configured for [Artist]s.. */
+        val ARTISTS: Comparator<List<Artist>> = ListComparator(BasicComparator.ARTIST)
+    }
+}
+
+/**
+ * A [Comparator] that compares abstract [Music] values. Internally, this is similar to
+ * [NullableComparator], however comparing [Music.name] instead of [Comparable].
+ *
+ * @see NullableComparator
+ * @see Music.name
+ */
+private class BasicComparator<T : Music> private constructor() : Comparator<T> {
+    override fun compare(a: T, b: T) = a.name.compareTo(b.name)
+
+    companion object {
+        /** A re-usable instance configured for [Song]s. */
+        val SONG: Comparator<Song> = BasicComparator()
+        /** A re-usable instance configured for [Album]s. */
+        val ALBUM: Comparator<Album> = BasicComparator()
+        /** A re-usable instance configured for [Artist]s. */
+        val ARTIST: Comparator<Artist> = BasicComparator()
+        /** A re-usable instance configured for [Genre]s. */
+        val GENRE: Comparator<Genre> = BasicComparator()
+        /** A re-usable instance configured for [Playlist]s. */
+        val PLAYLIST: Comparator<Playlist> = BasicComparator()
+    }
+}
+
+/**
+ * A [Comparator] that compares two possibly null values. Values will be considered lesser if they
+ * are null, and greater if they are non-null.
+ */
+private class NullableComparator<T : Comparable<T>> private constructor() : Comparator<T?> {
+    override fun compare(a: T?, b: T?) =
+        when {
+            a != null && b != null -> a.compareTo(b)
+            a == null && b != null -> -1 // a < b
+            a == null && b == null -> 0 // a = b
+            else -> 1 // a < b
+        }
+
+    companion object {
+        /** A re-usable instance configured for [Int]s. */
+        val INT = NullableComparator<Int>()
+        /** A re-usable instance configured for [Long]s. */
+        val LONG = NullableComparator<Long>()
+        /** A re-usable instance configured for [Disc]s */
+        val DISC = NullableComparator<Disc>()
+        /** A re-usable instance configured for [Date.Range]s. */
+        val DATE_RANGE = NullableComparator<Date.Range>()
+    }
+}

app/src/main/java/org/oxycblt/auxio/list/adapter/FlexibleListAdapter.kt

@@ -62,16 +62,16 @@ abstract class FlexibleListAdapter<T, VH : RecyclerView.ViewHolder>(
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-sealed class UpdateInstructions {
+sealed interface UpdateInstructions {
     /** Use an asynchronous diff. Useful for unpredictable updates, but looks chaotic and janky. */
-    object Diff : UpdateInstructions()
+    object Diff : UpdateInstructions
 
     /**
      * Visually replace all items from a given point. More visually coherent than [Diff].
      *
      * @param from The index at which to start replacing items (inclusive)
      */
-    data class Replace(val from: Int) : UpdateInstructions()
+    data class Replace(val from: Int) : UpdateInstructions
 
     /**
      * Add a new set of items.
@@ -79,7 +79,7 @@ sealed class UpdateInstructions {
      * @param at The position at which to add.
      * @param size The amount of items to add.
      */
-    data class Add(val at: Int, val size: Int) : UpdateInstructions()
+    data class Add(val at: Int, val size: Int) : UpdateInstructions
 
     /**
      * Move one item to another location.
@@ -87,14 +87,15 @@ sealed class UpdateInstructions {
      * @param from The index of the item to move.
      * @param to The index to move the item to.
      */
-    data class Move(val from: Int, val to: Int) : UpdateInstructions()
+    data class Move(val from: Int, val to: Int) : UpdateInstructions
 
     /**
      * Remove an item.
      *
      * @param at The location that the item should be removed from.
+     * @param size The amount of items to add.
      */
-    data class Remove(val at: Int) : UpdateInstructions()
+    data class Remove(val at: Int, val size: Int) : UpdateInstructions
 }
 
 /**
@@ -147,7 +148,7 @@ private class FlexibleListDiffer<T>(
             }
             is UpdateInstructions.Remove -> {
                 currentList = newList
-                updateCallback.onRemoved(instructions.at, 1)
+                updateCallback.onRemoved(instructions.at, instructions.size)
                 callback?.invoke()
             }
             is UpdateInstructions.Diff,

app/src/main/java/org/oxycblt/auxio/list/recycler/AuxioRecyclerView.kt

@@ -23,14 +23,12 @@ import android.util.AttributeSet
 import android.view.WindowInsets
 import androidx.annotation.AttrRes
 import androidx.core.view.updatePadding
-import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.util.systemBarInsetsCompat
 
 /**
  * A [RecyclerView] with a few QoL extensions, such as:
  * - Automatic edge-to-edge support
- * - Adapter-based [SpanSizeLookup] implementation
  * - Automatic [setHasFixedSize] setup
  *
  * @author Alexander Capehart (OxygenCobalt)
@@ -47,7 +45,6 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         // Auxio's non-dialog RecyclerViews never change their size based on adapter contents,
         // so we can enable fixed-size optimizations.
         setHasFixedSize(true)
-        addItemDecoration(HeaderItemDecoration(context))
     }
 
     final override fun setHasFixedSize(hasFixedSize: Boolean) {
@@ -65,36 +62,4 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         updatePadding(bottom = initialPaddingBottom + insets.systemBarInsetsCompat.bottom)
         return insets
     }
-
-    override fun setAdapter(adapter: Adapter<*>?) {
-        super.setAdapter(adapter)
-
-        if (adapter is SpanSizeLookup) {
-            // This adapter has support for special span sizes, hook it up to the
-            // GridLayoutManager.
-            val glm = (layoutManager as GridLayoutManager)
-            val fullWidthSpanCount = glm.spanCount
-            glm.spanSizeLookup =
-                object : GridLayoutManager.SpanSizeLookup() {
-                    // Using the adapter implementation, if the adapter specifies that
-                    // an item is full width, it will take up all of the spans, using a
-                    // single span otherwise.
-                    override fun getSpanSize(position: Int) =
-                        if (adapter.isItemFullWidth(position)) fullWidthSpanCount else 1
-                }
-        }
-    }
-
-    /** A [RecyclerView.Adapter]-specific hook to control divider decoration visibility. */
-
-    /** An [RecyclerView.Adapter]-specific hook to [GridLayoutManager.SpanSizeLookup]. */
-    interface SpanSizeLookup {
-        /**
-         * Get if the item at a position takes up the whole width of the [RecyclerView] or not.
-         *
-         * @param position The position of the item.
-         * @return true if the item is full-width, false otherwise.
-         */
-        fun isItemFullWidth(position: Int): Boolean
-    }
 }

app/src/main/java/org/oxycblt/auxio/list/recycler/HeaderItemDecoration.kt

@@ -1,70 +0,0 @@
-/*
- * Copyright (c) 2023 Auxio Project
- * HeaderItemDecoration.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.auxio.list.recycler
-
-import android.content.Context
-import android.util.AttributeSet
-import androidx.recyclerview.widget.ConcatAdapter
-import androidx.recyclerview.widget.LinearLayoutManager
-import androidx.recyclerview.widget.RecyclerView
-import com.google.android.material.divider.BackportMaterialDividerItemDecoration
-import org.oxycblt.auxio.R
-import org.oxycblt.auxio.list.Header
-import org.oxycblt.auxio.list.adapter.FlexibleListAdapter
-
-/**
- * A [BackportMaterialDividerItemDecoration] that sets up the divider configuration to correctly
- * separate content with headers.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class HeaderItemDecoration
-@JvmOverloads
-constructor(
-    context: Context,
-    attributeSet: AttributeSet? = null,
-    defStyleAttr: Int = R.attr.materialDividerStyle,
-    orientation: Int = LinearLayoutManager.VERTICAL
-) : BackportMaterialDividerItemDecoration(context, attributeSet, defStyleAttr, orientation) {
-    override fun shouldDrawDivider(position: Int, adapter: RecyclerView.Adapter<*>?): Boolean {
-        if (adapter is ConcatAdapter) {
-            val adapterAndPosition =
-                try {
-                    adapter.getWrappedAdapterAndPosition(position + 1)
-                } catch (e: IllegalArgumentException) {
-                    return false
-                }
-            return hasHeaderAtPosition(adapterAndPosition.second, adapterAndPosition.first)
-        } else {
-            return hasHeaderAtPosition(position + 1, adapter)
-        }
-    }
-
-    private fun hasHeaderAtPosition(position: Int, adapter: RecyclerView.Adapter<*>?) =
-        try {
-            // Add a divider if the next item is a header. This organizes the divider to separate
-            // the ends of content rather than the beginning of content, alongside an added benefit
-            // of preventing top headers from having a divider applied.
-            (adapter as FlexibleListAdapter<*, *>).getItem(position) is Header
-        } catch (e: ClassCastException) {
-            false
-        } catch (e: IndexOutOfBoundsException) {
-            false
-        }
-}

app/src/main/java/org/oxycblt/auxio/list/recycler/MaterialDragCallback.kt

@@ -0,0 +1,152 @@
+/*
+ * Copyright (c) 2021 Auxio Project
+ * MaterialDragCallback.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.list.recycler
+
+import android.graphics.Canvas
+import android.graphics.drawable.Drawable
+import android.view.View
+import android.view.animation.AccelerateDecelerateInterpolator
+import androidx.core.view.isInvisible
+import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.RecyclerView
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.util.getDimen
+import org.oxycblt.auxio.util.getInteger
+import org.oxycblt.auxio.util.logD
+
+/**
+ * A highly customized [ItemTouchHelper.Callback] that enables some extra eye candy in editable UIs,
+ * such as an animation when lifting items. Note that this requires a [ViewHolder] implementation in
+ * order to function.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+abstract class MaterialDragCallback : ItemTouchHelper.Callback() {
+    private var shouldLift = true
+
+    final override fun getMovementFlags(
+        recyclerView: RecyclerView,
+        viewHolder: RecyclerView.ViewHolder
+    ) =
+        if (viewHolder is ViewHolder && viewHolder.enabled) {
+            makeFlag(
+                ItemTouchHelper.ACTION_STATE_DRAG, ItemTouchHelper.UP or ItemTouchHelper.DOWN) or
+                makeFlag(ItemTouchHelper.ACTION_STATE_SWIPE, ItemTouchHelper.START)
+        } else {
+            0
+        }
+
+    final override fun onChildDraw(
+        c: Canvas,
+        recyclerView: RecyclerView,
+        viewHolder: RecyclerView.ViewHolder,
+        dX: Float,
+        dY: Float,
+        actionState: Int,
+        isCurrentlyActive: Boolean
+    ) {
+        val holder = viewHolder as ViewHolder
+
+        // Hook drag events to "lifting" the item (i.e raising it's elevation). Make sure
+        // this is only done once when the item is initially picked up.
+        // TODO: I think this is possible to improve with a raw ValueAnimator.
+        if (shouldLift && isCurrentlyActive && actionState == ItemTouchHelper.ACTION_STATE_DRAG) {
+            logD("Lifting item")
+
+            val bg = holder.background
+            val elevation = recyclerView.context.getDimen(R.dimen.elevation_normal)
+            holder.root
+                .animate()
+                .translationZ(elevation)
+                .setDuration(
+                    recyclerView.context.getInteger(R.integer.anim_fade_exit_duration).toLong())
+                .setUpdateListener {
+                    bg.alpha = ((holder.root.translationZ / elevation) * 255).toInt()
+                }
+                .setInterpolator(AccelerateDecelerateInterpolator())
+                .start()
+
+            shouldLift = false
+        }
+
+        // We show a background with a delete icon behind the item each time one is swiped
+        // away. To avoid working with canvas, this is simply placed behind the body.
+        // That comes with a couple of problems, however. For one, the background view will always
+        // lag behind the body view, resulting in a noticeable pixel offset when dragging. To fix
+        // this, we make this a separate view and make this view invisible whenever the item is
+        // not being swiped. This issue is also the reason why the background is not merged with
+        // the FrameLayout within the item.
+        if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
+            holder.delete.isInvisible = dX == 0f
+        }
+
+        // Update other translations. We do not call the default implementation, so we must do
+        // this ourselves.
+        holder.body.translationX = dX
+        holder.root.translationY = dY
+    }
+
+    final override fun clearView(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder) {
+        // When an elevated item is cleared, we reset the elevation using another animation.
+        val holder = viewHolder as ViewHolder
+
+        // This function can be called multiple times, so only start the animation when the view's
+        // translationZ is already non-zero.
+        if (holder.root.translationZ != 0f) {
+            logD("Dropping item")
+
+            val bg = holder.background
+            val elevation = recyclerView.context.getDimen(R.dimen.elevation_normal)
+            holder.root
+                .animate()
+                .translationZ(0f)
+                .setDuration(
+                    recyclerView.context.getInteger(R.integer.anim_fade_exit_duration).toLong())
+                .setUpdateListener {
+                    bg.alpha = ((holder.root.translationZ / elevation) * 255).toInt()
+                }
+                .setInterpolator(AccelerateDecelerateInterpolator())
+                .start()
+        }
+
+        shouldLift = true
+
+        // Reset translations. We do not call the default implementation, so we must do
+        // this ourselves.
+        holder.body.translationX = 0f
+        holder.root.translationY = 0f
+    }
+
+    // Long-press events are too buggy, only allow dragging with the handle.
+    final override fun isLongPressDragEnabled() = false
+
+    /** Required [RecyclerView.ViewHolder] implementation that exposes the following. */
+    interface ViewHolder {
+        /** Whether this [ViewHolder] can be moved right now. */
+        val enabled: Boolean
+        /** The root view containing the delete scrim and information. */
+        val root: View
+        /** The body view containing music information. */
+        val body: View
+        /** The scrim view showing the delete icon. Should be behind [body]. */
+        val delete: View
+        /** The drawable of the [body] background that can be elevated. */
+        val background: Drawable
+    }
+}

app/src/main/java/org/oxycblt/auxio/list/recycler/ViewHolders.kt

@@ -20,12 +20,14 @@ package org.oxycblt.auxio.list.recycler
 
 import android.view.View
 import androidx.recyclerview.widget.RecyclerView
+import com.google.android.material.divider.MaterialDivider
 import org.oxycblt.auxio.IntegerTable
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.ItemHeaderBinding
 import org.oxycblt.auxio.databinding.ItemParentBinding
 import org.oxycblt.auxio.databinding.ItemSongBinding
 import org.oxycblt.auxio.list.BasicHeader
+import org.oxycblt.auxio.list.Divider
 import org.oxycblt.auxio.list.SelectableListListener
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.adapter.SimpleDiffCallback
@@ -51,7 +53,7 @@ class SongViewHolder private constructor(private val binding: ItemSongBinding) :
     fun bind(song: Song, listener: SelectableListListener<Song>) {
         listener.bind(song, this, menuButton = binding.songMenu)
         binding.songAlbumCover.bind(song)
-        binding.songName.text = song.resolveName(binding.context)
+        binding.songName.text = song.name.resolve(binding.context)
         binding.songInfo.text = song.artists.resolveNames(binding.context)
     }
 
@@ -80,8 +82,7 @@ class SongViewHolder private constructor(private val binding: ItemSongBinding) :
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Song>() {
                 override fun areContentsTheSame(oldItem: Song, newItem: Song) =
-                    oldItem.rawName == newItem.rawName &&
+                    oldItem.name == newItem.name && oldItem.artists.areNamesTheSame(newItem.artists)
-                        oldItem.artists.areRawNamesTheSame(newItem.artists)
             }
     }
 }
@@ -102,7 +103,7 @@ class AlbumViewHolder private constructor(private val binding: ItemParentBinding
     fun bind(album: Album, listener: SelectableListListener<Album>) {
         listener.bind(album, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(album)
-        binding.parentName.text = album.resolveName(binding.context)
+        binding.parentName.text = album.name.resolve(binding.context)
         binding.parentInfo.text = album.artists.resolveNames(binding.context)
     }
 
@@ -131,8 +132,8 @@ class AlbumViewHolder private constructor(private val binding: ItemParentBinding
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Album>() {
                 override fun areContentsTheSame(oldItem: Album, newItem: Album) =
-                    oldItem.rawName == newItem.rawName &&
+                    oldItem.name == newItem.name &&
-                        oldItem.artists.areRawNamesTheSame(newItem.artists) &&
+                        oldItem.artists.areNamesTheSame(newItem.artists) &&
                         oldItem.releaseType == newItem.releaseType
             }
     }
@@ -154,17 +155,16 @@ class ArtistViewHolder private constructor(private val binding: ItemParentBindin
     fun bind(artist: Artist, listener: SelectableListListener<Artist>) {
         listener.bind(artist, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(artist)
-        binding.parentName.text = artist.resolveName(binding.context)
+        binding.parentName.text = artist.name.resolve(binding.context)
         binding.parentInfo.text =
-            if (artist.songs.isNotEmpty()) {
+            binding.context.getString(
-                binding.context.getString(
+                R.string.fmt_two,
-                    R.string.fmt_two,
+                binding.context.getPlural(R.plurals.fmt_album_count, artist.albums.size),
-                    binding.context.getPlural(R.plurals.fmt_album_count, artist.albums.size),
+                if (artist.songs.isNotEmpty()) {
-                    binding.context.getPlural(R.plurals.fmt_song_count, artist.songs.size))
+                    binding.context.getPlural(R.plurals.fmt_song_count, artist.songs.size)
-            } else {
+                } else {
-                // Artist has no songs, only display an album count.
+                    binding.context.getString(R.string.def_song_count)
-                binding.context.getPlural(R.plurals.fmt_album_count, artist.albums.size)
+                })
-            }
     }
 
     override fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean) {
@@ -193,7 +193,7 @@ class ArtistViewHolder private constructor(private val binding: ItemParentBindin
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Artist>() {
                 override fun areContentsTheSame(oldItem: Artist, newItem: Artist) =
-                    oldItem.rawName == newItem.rawName &&
+                    oldItem.name == newItem.name &&
                         oldItem.albums.size == newItem.albums.size &&
                         oldItem.songs.size == newItem.songs.size
             }
@@ -216,7 +216,7 @@ class GenreViewHolder private constructor(private val binding: ItemParentBinding
     fun bind(genre: Genre, listener: SelectableListListener<Genre>) {
         listener.bind(genre, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(genre)
-        binding.parentName.text = genre.resolveName(binding.context)
+        binding.parentName.text = genre.name.resolve(binding.context)
         binding.parentInfo.text =
             binding.context.getString(
                 R.string.fmt_two,
@@ -248,8 +248,66 @@ class GenreViewHolder private constructor(private val binding: ItemParentBinding
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<Genre>() {
-                override fun areContentsTheSame(oldItem: Genre, newItem: Genre): Boolean =
+                override fun areContentsTheSame(oldItem: Genre, newItem: Genre) =
-                    oldItem.rawName == newItem.rawName && oldItem.songs.size == newItem.songs.size
+                    oldItem.name == newItem.name &&
+                        oldItem.artists.size == newItem.artists.size &&
+                        oldItem.songs.size == newItem.songs.size
+            }
+    }
+}
+
+/**
+ * A [RecyclerView.ViewHolder] that displays a [Playlist]. Use [from] to create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class PlaylistViewHolder private constructor(private val binding: ItemParentBinding) :
+    SelectionIndicatorAdapter.ViewHolder(binding.root) {
+    /**
+     * Bind new data to this instance.
+     *
+     * @param playlist The new [Playlist] to bind.
+     * @param listener An [SelectableListListener] to bind interactions to.
+     */
+    fun bind(playlist: Playlist, listener: SelectableListListener<Playlist>) {
+        listener.bind(playlist, this, menuButton = binding.parentMenu)
+        binding.parentImage.bind(playlist)
+        binding.parentName.text = playlist.name.resolve(binding.context)
+        binding.parentInfo.text =
+            if (playlist.songs.isNotEmpty()) {
+                binding.context.getPlural(R.plurals.fmt_song_count, playlist.songs.size)
+            } else {
+                binding.context.getString(R.string.def_song_count)
+            }
+    }
+
+    override fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean) {
+        binding.root.isSelected = isActive
+        binding.parentImage.isPlaying = isPlaying
+    }
+
+    override fun updateSelectionIndicator(isSelected: Boolean) {
+        binding.root.isActivated = isSelected
+    }
+
+    companion object {
+        /** Unique ID for this ViewHolder type. */
+        const val VIEW_TYPE = IntegerTable.VIEW_TYPE_PLAYLIST
+
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) =
+            PlaylistViewHolder(ItemParentBinding.inflate(parent.context.inflater))
+
+        /** A comparator that can be used with DiffUtil. */
+        val DIFF_CALLBACK =
+            object : SimpleDiffCallback<Playlist>() {
+                override fun areContentsTheSame(oldItem: Playlist, newItem: Playlist) =
+                    oldItem.name == newItem.name && oldItem.songs.size == newItem.songs.size
             }
     }
 }
@@ -287,10 +345,37 @@ class BasicHeaderViewHolder private constructor(private val binding: ItemHeaderB
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
             object : SimpleDiffCallback<BasicHeader>() {
-                override fun areContentsTheSame(
+                override fun areContentsTheSame(oldItem: BasicHeader, newItem: BasicHeader) =
-                    oldItem: BasicHeader,
+                    oldItem.titleRes == newItem.titleRes
-                    newItem: BasicHeader
+            }
-                ): Boolean = oldItem.titleRes == newItem.titleRes
+    }
+}
+
+/**
+ * A [RecyclerView.ViewHolder] that displays a [Divider]. Use [from] to create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class DividerViewHolder private constructor(divider: MaterialDivider) :
+    RecyclerView.ViewHolder(divider) {
+
+    companion object {
+        /** Unique ID for this ViewHolder type. */
+        const val VIEW_TYPE = IntegerTable.VIEW_TYPE_DIVIDER
+
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) = DividerViewHolder(MaterialDivider(parent.context))
+
+        /** A comparator that can be used with DiffUtil. */
+        val DIFF_CALLBACK =
+            object : SimpleDiffCallback<Divider>() {
+                override fun areContentsTheSame(oldItem: Divider, newItem: Divider) =
+                    oldItem.anchor == newItem.anchor
             }
     }
 }

app/src/main/java/org/oxycblt/auxio/list/selection/SelectionFragment.kt

@@ -23,6 +23,7 @@ import android.view.MenuItem
 import androidx.appcompat.widget.Toolbar
 import androidx.viewbinding.ViewBinding
 import org.oxycblt.auxio.R
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.ViewBindingFragment
 import org.oxycblt.auxio.util.showToast
@@ -35,22 +36,16 @@ import org.oxycblt.auxio.util.showToast
 abstract class SelectionFragment<VB : ViewBinding> :
     ViewBindingFragment<VB>(), Toolbar.OnMenuItemClickListener {
     protected abstract val selectionModel: SelectionViewModel
+    protected abstract val musicModel: MusicViewModel
     protected abstract val playbackModel: PlaybackViewModel
 
-    /**
+    open fun getSelectionToolbar(binding: VB): Toolbar? = null
-     * Get the [SelectionToolbarOverlay] of the concrete Fragment to be automatically managed by
-     * [SelectionFragment].
-     *
-     * @return The [SelectionToolbarOverlay] of the concrete [SelectionFragment]'s [VB], or null if
-     *   there is not one.
-     */
-    open fun getSelectionToolbar(binding: VB): SelectionToolbarOverlay? = null
 
     override fun onBindingCreated(binding: VB, savedInstanceState: Bundle?) {
         super.onBindingCreated(binding, savedInstanceState)
         getSelectionToolbar(binding)?.apply {
             // Add cancel and menu item listeners to manage what occurs with the selection.
-            setOnSelectionCancelListener { selectionModel.consume() }
+            setNavigationOnClickListener { selectionModel.drop() }
             setOnMenuItemClickListener(this@SelectionFragment)
         }
     }
@@ -63,21 +58,25 @@ abstract class SelectionFragment<VB : ViewBinding> :
     override fun onMenuItemClick(item: MenuItem) =
         when (item.itemId) {
             R.id.action_selection_play_next -> {
-                playbackModel.playNext(selectionModel.consume())
+                playbackModel.playNext(selectionModel.take())
                 requireContext().showToast(R.string.lng_queue_added)
                 true
             }
             R.id.action_selection_queue_add -> {
-                playbackModel.addToQueue(selectionModel.consume())
+                playbackModel.addToQueue(selectionModel.take())
                 requireContext().showToast(R.string.lng_queue_added)
                 true
             }
+            R.id.action_selection_playlist_add -> {
+                musicModel.addToPlaylist(selectionModel.take())
+                true
+            }
             R.id.action_selection_play -> {
-                playbackModel.play(selectionModel.consume())
+                playbackModel.play(selectionModel.take())
                 true
             }
             R.id.action_selection_shuffle -> {
-                playbackModel.shuffle(selectionModel.consume())
+                playbackModel.shuffle(selectionModel.take())
                 true
             }
             else -> false

app/src/main/java/org/oxycblt/auxio/list/selection/SelectionToolbarOverlay.kt

@@ -1,176 +0,0 @@
-/*
- * Copyright (c) 2022 Auxio Project
- * SelectionToolbarOverlay.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.auxio.list.selection
-
-import android.animation.ValueAnimator
-import android.content.Context
-import android.util.AttributeSet
-import android.widget.FrameLayout
-import androidx.annotation.AttrRes
-import androidx.appcompat.widget.Toolbar.OnMenuItemClickListener
-import androidx.core.view.isInvisible
-import com.google.android.material.appbar.MaterialToolbar
-import org.oxycblt.auxio.R
-import org.oxycblt.auxio.util.getInteger
-import org.oxycblt.auxio.util.logD
-
-/**
- * A wrapper around a [MaterialToolbar] that adds an additional [MaterialToolbar] showing the
- * current selection state.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class SelectionToolbarOverlay
-@JvmOverloads
-constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
-    FrameLayout(context, attrs, defStyleAttr) {
-    private lateinit var innerToolbar: MaterialToolbar
-    private val selectionToolbar =
-        MaterialToolbar(context).apply {
-            setNavigationIcon(R.drawable.ic_close_24)
-            inflateMenu(R.menu.menu_selection_actions)
-
-            if (isInEditMode) {
-                isInvisible = true
-            }
-        }
-    private var fadeThroughAnimator: ValueAnimator? = null
-
-    override fun onFinishInflate() {
-        super.onFinishInflate()
-        // Sanity check: Avoid incorrect views from being included in this layout.
-        check(childCount == 1 && getChildAt(0) is MaterialToolbar) {
-            "SelectionToolbarOverlay Must have only one MaterialToolbar child"
-        }
-        // The inner toolbar should be the first child.
-        innerToolbar = getChildAt(0) as MaterialToolbar
-        // Selection toolbar should appear on top of the inner toolbar.
-        addView(selectionToolbar)
-    }
-
-    /**
-     * Set an OnClickListener for when the "cancel" button in the selection [MaterialToolbar] is
-     * pressed.
-     *
-     * @param listener The OnClickListener to respond to this interaction.
-     * @see MaterialToolbar.setNavigationOnClickListener
-     */
-    fun setOnSelectionCancelListener(listener: OnClickListener) {
-        selectionToolbar.setNavigationOnClickListener(listener)
-    }
-
-    /**
-     * Set an [OnMenuItemClickListener] for when a MenuItem is selected from the selection
-     * [MaterialToolbar].
-     *
-     * @param listener The [OnMenuItemClickListener] to respond to this interaction.
-     * @see MaterialToolbar.setOnMenuItemClickListener
-     */
-    fun setOnMenuItemClickListener(listener: OnMenuItemClickListener?) {
-        selectionToolbar.setOnMenuItemClickListener(listener)
-    }
-
-    /**
-     * Update the selection [MaterialToolbar] to reflect the current selection amount.
-     *
-     * @param amount The amount of items that are currently selected.
-     * @return true if the selection [MaterialToolbar] changes, false otherwise.
-     */
-    fun updateSelectionAmount(amount: Int): Boolean {
-        logD("Updating selection amount to $amount")
-        return if (amount > 0) {
-            // Only update the selected amount when it's non-zero to prevent a strange
-            // title text.
-            selectionToolbar.title = context.getString(R.string.fmt_selected, amount)
-            animateToolbarsVisibility(true)
-        } else {
-            animateToolbarsVisibility(false)
-        }
-    }
-
-    /**
-     * Animate the visibility of the inner and selection [MaterialToolbar]s to the given state.
-     *
-     * @param selectionVisible Whether the selection [MaterialToolbar] should be visible or not.
-     * @return true if the toolbars have changed, false otherwise.
-     */
-    private fun animateToolbarsVisibility(selectionVisible: Boolean): Boolean {
-        // TODO: Animate nicer Material Fade transitions using animators (Normal transitions
-        //  don't work due to translation)
-        // Set up the target transitions for both the inner and selection toolbars.
-        val targetInnerAlpha: Float
-        val targetSelectionAlpha: Float
-        val targetDuration: Long
-
-        if (selectionVisible) {
-            targetInnerAlpha = 0f
-            targetSelectionAlpha = 1f
-            targetDuration = context.getInteger(R.integer.anim_fade_enter_duration).toLong()
-        } else {
-            targetInnerAlpha = 1f
-            targetSelectionAlpha = 0f
-            targetDuration = context.getInteger(R.integer.anim_fade_exit_duration).toLong()
-        }
-
-        if (innerToolbar.alpha == targetInnerAlpha &&
-            selectionToolbar.alpha == targetSelectionAlpha) {
-            // Nothing to do.
-            return false
-        }
-
-        if (!isLaidOut) {
-            // Not laid out, just change it immediately while are not shown to the user.
-            // This is an initialization, so we return false despite changing.
-            setToolbarsAlpha(targetInnerAlpha)
-            return false
-        }
-
-        if (fadeThroughAnimator != null) {
-            fadeThroughAnimator?.cancel()
-            fadeThroughAnimator = null
-        }
-
-        fadeThroughAnimator =
-            ValueAnimator.ofFloat(innerToolbar.alpha, targetInnerAlpha).apply {
-                duration = targetDuration
-                addUpdateListener { setToolbarsAlpha(it.animatedValue as Float) }
-                start()
-            }
-
-        return true
-    }
-
-    /**
-     * Update the alpha of the inner and selection [MaterialToolbar]s.
-     *
-     * @param innerAlpha The opacity of the inner [MaterialToolbar]. This will map to the inverse
-     *   opacity of the selection [MaterialToolbar].
-     */
-    private fun setToolbarsAlpha(innerAlpha: Float) {
-        innerToolbar.apply {
-            alpha = innerAlpha
-            isInvisible = innerAlpha == 0f
-        }
-
-        selectionToolbar.apply {
-            alpha = 1 - innerAlpha
-            isInvisible = innerAlpha == 1f
-        }
-    }
-}

app/src/main/java/org/oxycblt/auxio/list/selection/SelectionViewModel.kt

@@ -24,7 +24,6 @@ import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.model.Library
 
 /**
  * A [ViewModel] that manages the current selection.
@@ -32,38 +31,42 @@ import org.oxycblt.auxio.music.model.Library
  * @author Alexander Capehart (OxygenCobalt)
  */
 @HiltViewModel
-class SelectionViewModel @Inject constructor(private val musicRepository: MusicRepository) :
+class SelectionViewModel
-    ViewModel(), MusicRepository.Listener {
+@Inject
+constructor(
+    private val musicRepository: MusicRepository,
+    private val musicSettings: MusicSettings
+) : ViewModel(), MusicRepository.UpdateListener {
     private val _selected = MutableStateFlow(listOf<Music>())
     /** the currently selected items. These are ordered in earliest selected and latest selected. */
     val selected: StateFlow<List<Music>>
         get() = _selected
 
     init {
-        musicRepository.addListener(this)
+        musicRepository.addUpdateListener(this)
     }
 
-    override fun onLibraryChanged(library: Library?) {
+    override fun onMusicChanges(changes: MusicRepository.Changes) {
-        if (library == null) {
+        if (!changes.deviceLibrary) return
-            return
+        val deviceLibrary = musicRepository.deviceLibrary ?: return
-        }
+        val userLibrary = musicRepository.userLibrary ?: return
-
         // Sanitize the selection to remove items that no longer exist and thus
         // won't appear in any list.
         _selected.value =
             _selected.value.mapNotNull {
                 when (it) {
-                    is Song -> library.sanitize(it)
+                    is Song -> deviceLibrary.findSong(it.uid)
-                    is Album -> library.sanitize(it)
+                    is Album -> deviceLibrary.findAlbum(it.uid)
-                    is Artist -> library.sanitize(it)
+                    is Artist -> deviceLibrary.findArtist(it.uid)
-                    is Genre -> library.sanitize(it)
+                    is Genre -> deviceLibrary.findGenre(it.uid)
+                    is Playlist -> userLibrary.findPlaylist(it.uid)
                 }
             }
     }
 
     override fun onCleared() {
         super.onCleared()
-        musicRepository.removeListener(this)
+        musicRepository.removeUpdateListener(this)
     }
 
     /**
@@ -81,9 +84,27 @@ class SelectionViewModel @Inject constructor(private val musicRepository: MusicR
     }
 
     /**
-     * Consume the current selection. This will clear any items that were selected prior.
+     * Clear the current selection and return it.
      *
-     * @return The list of selected items before it was cleared.
+     * @return A list of [Song]s collated from each item selected.
      */
-    fun consume() = _selected.value.also { _selected.value = listOf() }
+    fun take() =
+        _selected.value
+            .flatMap {
+                when (it) {
+                    is Song -> listOf(it)
+                    is Album -> musicSettings.albumSongSort.songs(it.songs)
+                    is Artist -> musicSettings.artistSongSort.songs(it.songs)
+                    is Genre -> musicSettings.genreSongSort.songs(it.songs)
+                    is Playlist -> it.songs
+                }
+            }
+            .also { drop() }
+
+    /**
+     * Clear the current selection.
+     *
+     * @return true if the prior selection was non-empty, false otherwise.
+     */
+    fun drop() = _selected.value.isNotEmpty().also { _selected.value = listOf() }
 }

app/src/main/java/org/oxycblt/auxio/music/Indexing.kt

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * Indexing.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music
+
+import android.os.Build
+
+/** Version-aware permission identifier for reading audio files. */
+val PERMISSION_READ_AUDIO =
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+        android.Manifest.permission.READ_MEDIA_AUDIO
+    } else {
+        android.Manifest.permission.READ_EXTERNAL_STORAGE
+    }
+
+/**
+ * Represents the current state of the music loader.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+sealed interface IndexingState {
+    /**
+     * Music loading is on-going.
+     *
+     * @param progress The current progress of the music loading.
+     */
+    data class Indexing(val progress: IndexingProgress) : IndexingState
+
+    /**
+     * Music loading has completed.
+     *
+     * @param error If music loading has failed, the error that occurred will be here. Otherwise, it
+     *   will be null.
+     */
+    data class Completed(val error: Throwable?) : IndexingState
+}
+
+/**
+ * Represents the current progress of music loading.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+sealed interface IndexingProgress {
+    /** Other work is being done that does not have a defined progress. */
+    object Indeterminate : IndexingProgress
+
+    /**
+     * Songs are currently being loaded.
+     *
+     * @param current The current amount of songs loaded.
+     * @param total The projected total amount of songs.
+     */
+    data class Songs(val current: Int, val total: Int) : IndexingProgress
+}
+
+/**
+ * Thrown by the music loader when [PERMISSION_READ_AUDIO] was not granted.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class NoAudioPermissionException : Exception() {
+    override val message = "Storage permissions are required to load music"
+}
+
+/**
+ * Thrown when no music was found.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class NoMusicException : Exception() {
+    override val message = "No music was found on the device"
+}

app/src/main/java/org/oxycblt/auxio/music/Music.kt

@@ -21,19 +21,19 @@ package org.oxycblt.auxio.music
 import android.content.Context
 import android.net.Uri
 import android.os.Parcelable
+import androidx.room.TypeConverter
 import java.security.MessageDigest
-import java.text.CollationKey
-import java.text.Collator
 import java.util.UUID
 import kotlin.math.max
 import kotlinx.parcelize.IgnoredOnParcel
 import kotlinx.parcelize.Parcelize
 import org.oxycblt.auxio.list.Item
-import org.oxycblt.auxio.music.metadata.Date
+import org.oxycblt.auxio.music.fs.MimeType
-import org.oxycblt.auxio.music.metadata.Disc
+import org.oxycblt.auxio.music.fs.Path
-import org.oxycblt.auxio.music.metadata.ReleaseType
+import org.oxycblt.auxio.music.info.Date
-import org.oxycblt.auxio.music.storage.MimeType
+import org.oxycblt.auxio.music.info.Disc
-import org.oxycblt.auxio.music.storage.Path
+import org.oxycblt.auxio.music.info.Name
+import org.oxycblt.auxio.music.info.ReleaseType
 import org.oxycblt.auxio.util.concatLocalized
 import org.oxycblt.auxio.util.toUuidOrNull
 
@@ -51,35 +51,8 @@ sealed interface Music : Item {
      */
     val uid: UID
 
-    /**
+    /** The [Name] of the music item. */
-     * The raw name of this item as it was extracted from the file-system. Will be null if the
+    val name: Name
-     * item's name is unknown. When showing this item in a UI, avoid this in favor of [resolveName].
-     */
-    val rawName: String?
-
-    /**
-     * Returns a name suitable for use in the app UI. This should be favored over [rawName] in
-     * nearly all cases.
-     *
-     * @param context [Context] required to obtain placeholder text or formatting information.
-     * @return A human-readable string representing the name of this music. In the case that the
-     *   item does not have a name, an analogous "Unknown X" name is returned.
-     */
-    fun resolveName(context: Context): String
-
-    /**
-     * The raw sort name of this item as it was extracted from the file-system. This can be used not
-     * only when sorting music, but also trying to locate music based on a fuzzy search by the user.
-     * Will be null if the item has no known sort name.
-     */
-    val rawSortName: String?
-
-    /**
-     * A black-box value derived from [rawSortName] and [rawName] that can be used for user-friendly
-     * sorting in the context of music. This should be preferred over [rawSortName] in most cases.
-     * Null if there are no [rawName] or [rawSortName] values to build on.
-     */
-    val sortName: SortName?
 
     /**
      * A unique identifier for a piece of music.
@@ -136,7 +109,25 @@ sealed interface Music : Item {
             MUSICBRAINZ("org.musicbrainz")
         }
 
+        object TypeConverters {
+            /** @see [Music.UID.toString] */
+            @TypeConverter fun fromMusicUID(uid: UID?) = uid?.toString()
+
+            /** @see [Music.UID.fromString] */
+            @TypeConverter fun toMusicUid(string: String?) = string?.let(UID::fromString)
+        }
+
         companion object {
+            /**
+             * Creates an Auxio-style [UID] of random composition. Used if there is no
+             * non-subjective, unlikely-to-change metadata of the music.
+             *
+             * @param mode The analogous [MusicMode] of the item that created this [UID].
+             */
+            fun auxio(mode: MusicMode): UID {
+                return UID(Format.AUXIO, mode, UUID.randomUUID())
+            }
+
             /**
              * Creates an Auxio-style [UID] with a [UUID] composed of a hash of the non-subjective,
              * unlikely-to-change metadata of the music.
@@ -189,7 +180,7 @@ sealed interface Music : Item {
              *   file.
              * @return A new MusicBrainz-style [UID].
              */
-            fun musicBrainz(mode: MusicMode, mbid: UUID): UID = UID(Format.MUSICBRAINZ, mode, mbid)
+            fun musicBrainz(mode: MusicMode, mbid: UUID) = UID(Format.MUSICBRAINZ, mode, mbid)
 
             /**
              * Convert a [UID]'s string representation back into a concrete [UID] instance.
@@ -357,83 +348,39 @@ interface Genre : MusicParent {
 }
 
 /**
- * A black-box datatype for a variation of music names that is suitable for music-oriented sorting.
+ * A playlist.
- * It will automatically handle articles like "The" and numeric components like "An".
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class SortName(name: String, musicSettings: MusicSettings) : Comparable<SortName> {
+interface Playlist : MusicParent {
-    private val collationKey: CollationKey
+    /** The albums indirectly linked to by the [Song]s of this [Playlist]. */
-    val thumbString: String?
+    val albums: List<Album>
-
+    /** The total duration of the songs in this genre, in milliseconds. */
-    init {
+    val durationMs: Long
-        var sortName = name
-        if (musicSettings.intelligentSorting) {
-            sortName = sortName.replace(LEADING_PUNCTUATION_REGEX, "")
-
-            sortName =
-                sortName.run {
-                    when {
-                        length > 5 && startsWith("the ", ignoreCase = true) -> substring(4)
-                        length > 4 && startsWith("an ", ignoreCase = true) -> substring(3)
-                        length > 3 && startsWith("a ", ignoreCase = true) -> substring(2)
-                        else -> this
-                    }
-                }
-
-            // Zero pad all numbers to six digits for better sorting
-            sortName = sortName.replace(CONSECUTIVE_DIGITS_REGEX) { it.value.padStart(6, '0') }
-        }
-
-        collationKey = COLLATOR.getCollationKey(sortName)
-
-        // Keep track of a string to use in the thumb view.
-        // Simply show '#' for everything before 'A'
-        // TODO: This needs to be moved elsewhere.
-        thumbString =
-            collationKey?.run {
-                val thumbChar = sourceString.firstOrNull()
-                if (thumbChar?.isLetter() == true) thumbChar.uppercase() else "#"
-            }
-    }
-
-    override fun toString(): String = collationKey.sourceString
-
-    override fun compareTo(other: SortName) = collationKey.compareTo(other.collationKey)
-
-    override fun equals(other: Any?) = other is SortName && collationKey == other.collationKey
-
-    override fun hashCode(): Int = collationKey.hashCode()
-
-    private companion object {
-        val COLLATOR: Collator = Collator.getInstance().apply { strength = Collator.PRIMARY }
-        val LEADING_PUNCTUATION_REGEX = Regex("[\\p{Punct}+]")
-        val CONSECUTIVE_DIGITS_REGEX = Regex("\\d+")
-    }
 }
 
 /**
- * Run [Music.resolveName] on each instance in the given list and concatenate them into a [String]
+ * Run [Name.resolve] on each instance in the given list and concatenate them into a [String] in a
- * in a localized manner.
+ * localized manner.
  *
  * @param context [Context] required
  * @return A concatenated string.
  */
 fun <T : Music> List<T>.resolveNames(context: Context) =
-    concatLocalized(context) { it.resolveName(context) }
+    concatLocalized(context) { it.name.resolve(context) }
 
 /**
- * Returns if [Music.rawName] matches for each item in a list. Useful for scenarios where the
+ * Returns if [Music.name] matches for each item in a list. Useful for scenarios where the display
- * display information of an item must be compared without a context.
+ * information of an item must be compared without a context.
  *
  * @param other The list of items to compare to.
- * @return True if they are the same (by [Music.rawName]), false otherwise.
+ * @return True if they are the same (by [Music.name]), false otherwise.
  */
-fun <T : Music> List<T>.areRawNamesTheSame(other: List<T>): Boolean {
+fun <T : Music> List<T>.areNamesTheSame(other: List<T>): Boolean {
     for (i in 0 until max(size, other.size)) {
         val a = getOrNull(i) ?: return false
         val b = other.getOrNull(i) ?: return false
-        if (a.rawName != b.rawName) {
+        if (a.name != b.name) {
             return false
         }
     }

app/src/main/java/org/oxycblt/auxio/music/MusicMode.kt

@@ -33,7 +33,9 @@ enum class MusicMode {
     /** Configure with respect to [Artist] instances. */
     ARTISTS,
     /** Configure with respect to [Genre] instances. */
-    GENRES;
+    GENRES,
+    /** Configure with respect to [Playlist] instances. */
+    PLAYLISTS;
 
     /**
      * The integer representation of this instance.
@@ -47,6 +49,7 @@ enum class MusicMode {
                 ALBUMS -> IntegerTable.MUSIC_MODE_ALBUMS
                 ARTISTS -> IntegerTable.MUSIC_MODE_ARTISTS
                 GENRES -> IntegerTable.MUSIC_MODE_GENRES
+                PLAYLISTS -> IntegerTable.MUSIC_MODE_PLAYLISTS
             }
 
     companion object {
@@ -63,6 +66,7 @@ enum class MusicMode {
                 IntegerTable.MUSIC_MODE_ALBUMS -> ALBUMS
                 IntegerTable.MUSIC_MODE_ARTISTS -> ARTISTS
                 IntegerTable.MUSIC_MODE_GENRES -> GENRES
+                IntegerTable.MUSIC_MODE_PLAYLISTS -> PLAYLISTS
                 else -> null
             }
     }

app/src/main/java/org/oxycblt/auxio/music/MusicModule.kt

@@ -23,13 +23,10 @@ import dagger.Module
 import dagger.hilt.InstallIn
 import dagger.hilt.components.SingletonComponent
 import javax.inject.Singleton
-import org.oxycblt.auxio.music.system.Indexer
-import org.oxycblt.auxio.music.system.IndexerImpl
 
 @Module
 @InstallIn(SingletonComponent::class)
 interface MusicModule {
     @Singleton @Binds fun repository(musicRepository: MusicRepositoryImpl): MusicRepository
-    @Singleton @Binds fun indexer(indexer: IndexerImpl): Indexer
     @Binds fun settings(musicSettingsImpl: MusicSettingsImpl): MusicSettings
 }

app/src/main/java/org/oxycblt/auxio/music/MusicRepository.kt

@@ -18,75 +18,452 @@
  
 package org.oxycblt.auxio.music
 
+import android.content.Context
+import android.content.pm.PackageManager
+import androidx.core.content.ContextCompat
+import java.util.*
 import javax.inject.Inject
-import org.oxycblt.auxio.music.model.Library
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+import kotlinx.coroutines.*
+import kotlinx.coroutines.channels.Channel
+import org.oxycblt.auxio.music.cache.CacheRepository
+import org.oxycblt.auxio.music.device.DeviceLibrary
+import org.oxycblt.auxio.music.device.RawSong
+import org.oxycblt.auxio.music.fs.MediaStoreExtractor
+import org.oxycblt.auxio.music.metadata.TagExtractor
+import org.oxycblt.auxio.music.user.MutableUserLibrary
+import org.oxycblt.auxio.music.user.UserLibrary
+import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.logE
+import org.oxycblt.auxio.util.logW
 
 /**
- * A repository granting access to the music library.
+ * Primary manager of music information and loading.
  *
- * This can be used to obtain certain music items, or await changes to the music library. It is
+ * Music information is loaded in-memory by this repository using an [IndexingWorker]. Changes in
- * generally recommended to use this over Indexer to keep track of the library state, as the
+ * music (loading) can be reacted to with [UpdateListener] and [IndexingListener].
- * interface will be less volatile.
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
 interface MusicRepository {
-    /**
+    /** The current music information found on the device. */
-     * The current [Library]. May be null if a [Library] has not been successfully loaded yet. This
+    val deviceLibrary: DeviceLibrary?
-     * can change, so it's highly recommended to not access this directly and instead rely on
+    /** The current user-defined music information. */
-     * [Listener].
+    val userLibrary: UserLibrary?
-     */
+    /** The current state of music loading. Null if no load has occurred yet. */
-    var library: Library?
+    val indexingState: IndexingState?
 
     /**
-     * Add a [Listener] to this instance. This can be used to receive changes in the music library.
+     * Add an [UpdateListener] to receive updates from this instance.
-     * Will invoke all [Listener] methods to initialize the instance with the current state.
      *
-     * @param listener The [Listener] to add.
+     * @param listener The [UpdateListener] to add.
-     * @see Listener
      */
-    fun addListener(listener: Listener)
+    fun addUpdateListener(listener: UpdateListener)
 
     /**
-     * Remove a [Listener] from this instance, preventing it from receiving any further updates.
+     * Remove an [UpdateListener] such that it does not receive any further updates from this
+     * instance.
      *
-     * @param listener The [Listener] to remove. Does nothing if the [Listener] was never added in
+     * @param listener The [UpdateListener] to remove.
-     *   the first place.
-     * @see Listener
      */
-    fun removeListener(listener: Listener)
+    fun removeUpdateListener(listener: UpdateListener)
 
-    /** A listener for changes in [MusicRepository] */
+    /**
-    interface Listener {
+     * Add an [IndexingListener] to receive updates from this instance.
+     *
+     * @param listener The [UpdateListener] to add.
+     */
+    fun addIndexingListener(listener: IndexingListener)
+
+    /**
+     * Remove an [IndexingListener] such that it does not receive any further updates from this
+     * instance.
+     *
+     * @param listener The [IndexingListener] to remove.
+     */
+    fun removeIndexingListener(listener: IndexingListener)
+
+    /**
+     * Register an [IndexingWorker] to handle loading operations. Will do nothing if one is already
+     * registered.
+     *
+     * @param worker The [IndexingWorker] to register.
+     */
+    fun registerWorker(worker: IndexingWorker)
+
+    /**
+     * Unregister an [IndexingWorker] and drop any work currently being done by it. Does nothing if
+     * given [IndexingWorker] is not the currently registered instance.
+     *
+     * @param worker The [IndexingWorker] to unregister.
+     */
+    fun unregisterWorker(worker: IndexingWorker)
+
+    /**
+     * Generically search for the [Music] associated with the given [Music.UID]. Note that this
+     * method is much slower that type-specific find implementations, so this should only be used if
+     * the type of music being searched for is entirely unknown.
+     *
+     * @param uid The [Music.UID] to search for.
+     * @return The expected [Music] information, or null if it could not be found.
+     */
+    fun find(uid: Music.UID): Music?
+
+    /**
+     * Create a new [Playlist] of the given [Song]s.
+     *
+     * @param name The name of the new [Playlist].
+     * @param songs The songs to populate the new [Playlist] with.
+     */
+    suspend fun createPlaylist(name: String, songs: List<Song>)
+
+    /**
+     * Rename a [Playlist].
+     *
+     * @param playlist The [Playlist] to rename.
+     * @param name The name of the new [Playlist].
+     */
+    suspend fun renamePlaylist(playlist: Playlist, name: String)
+
+    /**
+     * Delete a [Playlist].
+     *
+     * @param playlist The playlist to delete.
+     */
+    suspend fun deletePlaylist(playlist: Playlist)
+
+    /**
+     * Add the given [Song]s to a [Playlist].
+     *
+     * @param songs The [Song]s to add to the [Playlist].
+     * @param playlist The [Playlist] to add to.
+     */
+    suspend fun addToPlaylist(songs: List<Song>, playlist: Playlist)
+
+    /**
+     * Update the [Song]s of a [Playlist].
+     *
+     * @param playlist The [Playlist] to update.
+     * @param songs The new [Song]s to be contained in the [Playlist].
+     */
+    suspend fun rewritePlaylist(playlist: Playlist, songs: List<Song>)
+
+    /**
+     * Request that a music loading operation is started by the current [IndexingWorker]. Does
+     * nothing if one is not available.
+     *
+     * @param withCache Whether to load with the music cache or not.
+     */
+    fun requestIndex(withCache: Boolean)
+
+    /**
+     * Load the music library. Any prior loads will be canceled.
+     *
+     * @param worker The [IndexingWorker] to perform the work with.
+     * @param withCache Whether to load with the music cache or not.
+     * @return The top-level music loading [Job] started.
+     */
+    fun index(worker: IndexingWorker, withCache: Boolean): Job
+
+    /** A listener for changes to the stored music information. */
+    interface UpdateListener {
         /**
-         * Called when the current [Library] has changed.
+         * Called when a change to the stored music information occurs.
          *
-         * @param library The new [Library], or null if no [Library] has been loaded yet.
+         * @param changes The [Changes] that have occurred.
          */
-        fun onLibraryChanged(library: Library?)
+        fun onMusicChanges(changes: Changes)
+    }
+
+    /**
+     * Flags indicating which kinds of music information changed.
+     *
+     * @param deviceLibrary Whether the current [DeviceLibrary] has changed.
+     * @param userLibrary Whether the current [Playlist]s have changed.
+     */
+    data class Changes(val deviceLibrary: Boolean, val userLibrary: Boolean)
+
+    /** A listener for events in the music loading process. */
+    interface IndexingListener {
+        /** Called when the music loading state changed. */
+        fun onIndexingStateChanged()
+    }
+
+    /** A persistent worker that can load music in the background. */
+    interface IndexingWorker {
+        /** A [Context] required to read device storage */
+        val context: Context
+
+        /** The [CoroutineScope] to perform coroutine music loading work on. */
+        val scope: CoroutineScope
+
+        /**
+         * Request that the music loading process ([index]) should be started. Any prior loads
+         * should be canceled.
+         *
+         * @param withCache Whether to use the music cache when loading.
+         */
+        fun requestIndex(withCache: Boolean)
     }
 }
 
-class MusicRepositoryImpl @Inject constructor() : MusicRepository {
+class MusicRepositoryImpl
-    private val listeners = mutableListOf<MusicRepository.Listener>()
+@Inject
+constructor(
+    private val cacheRepository: CacheRepository,
+    private val mediaStoreExtractor: MediaStoreExtractor,
+    private val tagExtractor: TagExtractor,
+    private val deviceLibraryFactory: DeviceLibrary.Factory,
+    private val userLibraryFactory: UserLibrary.Factory
+) : MusicRepository {
+    private val updateListeners = mutableListOf<MusicRepository.UpdateListener>()
+    private val indexingListeners = mutableListOf<MusicRepository.IndexingListener>()
+    @Volatile private var indexingWorker: MusicRepository.IndexingWorker? = null
 
-    @Volatile
+    @Volatile override var deviceLibrary: DeviceLibrary? = null
-    override var library: Library? = null
+    @Volatile override var userLibrary: MutableUserLibrary? = null
-        set(value) {
+    @Volatile private var previousCompletedState: IndexingState.Completed? = null
-            field = value
+    @Volatile private var currentIndexingState: IndexingState? = null
-            for (callback in listeners) {
+    override val indexingState: IndexingState?
-                callback.onLibraryChanged(library)
+        get() = currentIndexingState ?: previousCompletedState
+
+    @Synchronized
+    override fun addUpdateListener(listener: MusicRepository.UpdateListener) {
+        updateListeners.add(listener)
+        listener.onMusicChanges(MusicRepository.Changes(deviceLibrary = true, userLibrary = true))
+    }
+
+    @Synchronized
+    override fun removeUpdateListener(listener: MusicRepository.UpdateListener) {
+        updateListeners.remove(listener)
+    }
+
+    @Synchronized
+    override fun addIndexingListener(listener: MusicRepository.IndexingListener) {
+        indexingListeners.add(listener)
+        listener.onIndexingStateChanged()
+    }
+
+    @Synchronized
+    override fun removeIndexingListener(listener: MusicRepository.IndexingListener) {
+        indexingListeners.remove(listener)
+    }
+
+    @Synchronized
+    override fun registerWorker(worker: MusicRepository.IndexingWorker) {
+        if (indexingWorker != null) {
+            logW("Worker is already registered")
+            return
+        }
+        indexingWorker = worker
+        if (indexingState == null) {
+            worker.requestIndex(true)
+        }
+    }
+
+    @Synchronized
+    override fun unregisterWorker(worker: MusicRepository.IndexingWorker) {
+        if (indexingWorker !== worker) {
+            logW("Given worker did not match current worker")
+            return
+        }
+        indexingWorker = null
+        currentIndexingState = null
+    }
+
+    @Synchronized
+    override fun find(uid: Music.UID) =
+        (deviceLibrary?.run { findSong(uid) ?: findAlbum(uid) ?: findArtist(uid) ?: findGenre(uid) }
+            ?: userLibrary?.findPlaylist(uid))
+
+    override suspend fun createPlaylist(name: String, songs: List<Song>) {
+        val userLibrary = synchronized(this) { userLibrary ?: return }
+        userLibrary.createPlaylist(name, songs)
+        notifyUserLibraryChange()
+    }
+
+    override suspend fun renamePlaylist(playlist: Playlist, name: String) {
+        val userLibrary = synchronized(this) { userLibrary ?: return }
+        userLibrary.renamePlaylist(playlist, name)
+        notifyUserLibraryChange()
+    }
+
+    override suspend fun deletePlaylist(playlist: Playlist) {
+        val userLibrary = synchronized(this) { userLibrary ?: return }
+        userLibrary.deletePlaylist(playlist)
+        notifyUserLibraryChange()
+    }
+
+    override suspend fun addToPlaylist(songs: List<Song>, playlist: Playlist) {
+        val userLibrary = synchronized(this) { userLibrary ?: return }
+        userLibrary.addToPlaylist(playlist, songs)
+        notifyUserLibraryChange()
+    }
+
+    override suspend fun rewritePlaylist(playlist: Playlist, songs: List<Song>) {
+        val userLibrary = synchronized(this) { userLibrary ?: return }
+        userLibrary.rewritePlaylist(playlist, songs)
+        notifyUserLibraryChange()
+    }
+
+    @Synchronized
+    private fun notifyUserLibraryChange() {
+        for (listener in updateListeners) {
+            listener.onMusicChanges(
+                MusicRepository.Changes(deviceLibrary = false, userLibrary = true))
+        }
+    }
+
+    @Synchronized
+    override fun requestIndex(withCache: Boolean) {
+        indexingWorker?.requestIndex(withCache)
+    }
+
+    override fun index(worker: MusicRepository.IndexingWorker, withCache: Boolean) =
+        worker.scope.launch {
+            try {
+                val start = System.currentTimeMillis()
+                indexImpl(worker, withCache)
+                logD(
+                    "Music indexing completed successfully in " +
+                        "${System.currentTimeMillis() - start}ms")
+            } catch (e: CancellationException) {
+                // Got cancelled, propagate upwards to top-level co-routine.
+                logD("Loading routine was cancelled")
+                throw e
+            } catch (e: Exception) {
+                // Music loading process failed due to something we have not handled.
+                logE("Music indexing failed")
+                logE(e.stackTraceToString())
+                emitComplete(e)
             }
         }
 
-    @Synchronized
+    private suspend fun indexImpl(worker: MusicRepository.IndexingWorker, withCache: Boolean) {
-    override fun addListener(listener: MusicRepository.Listener) {
+        if (ContextCompat.checkSelfPermission(worker.context, PERMISSION_READ_AUDIO) ==
-        listener.onLibraryChanged(library)
+            PackageManager.PERMISSION_DENIED) {
-        listeners.add(listener)
+            logE("Permission check failed")
+            // No permissions, signal that we can't do anything.
+            throw NoAudioPermissionException()
+        }
+
+        // Start initializing the extractors. Use an indeterminate state, as there is no ETA on
+        // how long a media database query will take.
+        emitLoading(IndexingProgress.Indeterminate)
+
+        // Do the initial query of the cache and media databases in parallel.
+        logD("Starting queries")
+        val mediaStoreQueryJob = worker.scope.tryAsync { mediaStoreExtractor.query() }
+        val cache =
+            if (withCache) {
+                cacheRepository.readCache()
+            } else {
+                null
+            }
+        val query = mediaStoreQueryJob.await().getOrThrow()
+
+        // Now start processing the queried song information in parallel. Songs that can't be
+        // received from the cache are consisted incomplete and pushed to a separate channel
+        // that will eventually be processed into completed raw songs.
+        logD("Starting song discovery")
+        val completeSongs = Channel<RawSong>(Channel.UNLIMITED)
+        val incompleteSongs = Channel<RawSong>(Channel.UNLIMITED)
+        val mediaStoreJob =
+            worker.scope.tryAsync {
+                mediaStoreExtractor.consume(query, cache, incompleteSongs, completeSongs)
+                incompleteSongs.close()
+            }
+        val metadataJob =
+            worker.scope.tryAsync {
+                tagExtractor.consume(incompleteSongs, completeSongs)
+                completeSongs.close()
+            }
+
+        // Await completed raw songs as they are processed.
+        val rawSongs = LinkedList<RawSong>()
+        for (rawSong in completeSongs) {
+            rawSongs.add(rawSong)
+            emitLoading(IndexingProgress.Songs(rawSongs.size, query.projectedTotal))
+        }
+        // These should be no-ops
+        mediaStoreJob.await().getOrThrow()
+        metadataJob.await().getOrThrow()
+
+        if (rawSongs.isEmpty()) {
+            logE("Music library was empty")
+            throw NoMusicException()
+        }
+
+        // Successfully loaded the library, now save the cache, create the library, and
+        // read playlist information in parallel.
+        logD("Discovered ${rawSongs.size} songs, starting finalization")
+        // TODO: Indicate playlist state in loading process?
+        emitLoading(IndexingProgress.Indeterminate)
+        val deviceLibraryChannel = Channel<DeviceLibrary>()
+        val deviceLibraryJob =
+            worker.scope.tryAsync(Dispatchers.Main) {
+                deviceLibraryFactory.create(rawSongs).also { deviceLibraryChannel.send(it) }
+            }
+        val userLibraryJob =
+            worker.scope.tryAsync {
+                userLibraryFactory.read(deviceLibraryChannel).also { deviceLibraryChannel.close() }
+            }
+        if (cache == null || cache.invalidated) {
+            cacheRepository.writeCache(rawSongs)
+        }
+        val deviceLibrary = deviceLibraryJob.await().getOrThrow()
+        val userLibrary = userLibraryJob.await().getOrThrow()
+        withContext(Dispatchers.Main) {
+            emitComplete(null)
+            emitData(deviceLibrary, userLibrary)
+        }
+    }
+
+    private inline fun <R> CoroutineScope.tryAsync(
+        context: CoroutineContext = EmptyCoroutineContext,
+        crossinline block: suspend () -> R
+    ) =
+        async(context) {
+            try {
+                Result.success(block())
+            } catch (e: Exception) {
+                Result.failure(e)
+            }
+        }
+
+    private suspend fun emitLoading(progress: IndexingProgress) {
+        yield()
+        synchronized(this) {
+            currentIndexingState = IndexingState.Indexing(progress)
+            for (listener in indexingListeners) {
+                listener.onIndexingStateChanged()
+            }
+        }
+    }
+
+    private suspend fun emitComplete(error: Exception?) {
+        yield()
+        synchronized(this) {
+            previousCompletedState = IndexingState.Completed(error)
+            currentIndexingState = null
+            for (listener in indexingListeners) {
+                listener.onIndexingStateChanged()
+            }
+        }
     }
 
     @Synchronized
-    override fun removeListener(listener: MusicRepository.Listener) {
+    private fun emitData(deviceLibrary: DeviceLibrary, userLibrary: MutableUserLibrary) {
-        listeners.remove(listener)
+        val deviceLibraryChanged = this.deviceLibrary != deviceLibrary
+        val userLibraryChanged = this.userLibrary != userLibrary
+        if (!deviceLibraryChanged && !userLibraryChanged) return
+
+        this.deviceLibrary = deviceLibrary
+        this.userLibrary = userLibrary
+        val changes = MusicRepository.Changes(deviceLibraryChanged, userLibraryChanged)
+        for (listener in updateListeners) {
+            listener.onMusicChanges(changes)
+        }
     }
 }

app/src/main/java/org/oxycblt/auxio/music/MusicSettings.kt

@@ -25,8 +25,8 @@ import dagger.hilt.android.qualifiers.ApplicationContext
 import javax.inject.Inject
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.Sort
-import org.oxycblt.auxio.music.storage.Directory
+import org.oxycblt.auxio.music.fs.Directory
-import org.oxycblt.auxio.music.storage.MusicDirectories
+import org.oxycblt.auxio.music.fs.MusicDirectories
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.util.getSystemServiceCompat
 
@@ -55,11 +55,13 @@ interface MusicSettings : Settings<MusicSettings.Listener> {
     var artistSort: Sort
     /** The [Sort] mode used in [Genre] lists. */
     var genreSort: Sort
+    /** The [Sort] mode used in [Playlist] lists. */
+    var playlistSort: Sort
     /** The [Sort] mode used in an [Album]'s [Song] list. */
     var albumSongSort: Sort
     /** The [Sort] mode used in an [Artist]'s [Song] list. */
     var artistSongSort: Sort
-    /** The [Sort] mode used in an [Genre]'s [Song] list. */
+    /** The [Sort] mode used in a [Genre]'s [Song] list. */
     var genreSongSort: Sort
 
     interface Listener {
@@ -162,6 +164,17 @@ class MusicSettingsImpl @Inject constructor(@ApplicationContext context: Context
             }
         }
 
+    override var playlistSort: Sort
+        get() =
+            Sort.fromIntCode(
+                sharedPreferences.getInt(getString(R.string.set_key_playlists_sort), Int.MIN_VALUE))
+                ?: Sort(Sort.Mode.ByName, Sort.Direction.ASCENDING)
+        set(value) {
+            sharedPreferences.edit {
+                putInt(getString(R.string.set_key_playlists_sort), value.intCode)
+                apply()
+            }
+        }
     override var albumSongSort: Sort
         get() {
             var sort =

app/src/main/java/org/oxycblt/auxio/music/MusicViewModel.kt

@@ -19,11 +19,15 @@
 package org.oxycblt.auxio.music
 
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
-import org.oxycblt.auxio.music.system.Indexer
+import kotlinx.coroutines.launch
+import org.oxycblt.auxio.util.Event
+import org.oxycblt.auxio.util.MutableEvent
 
 /**
  * A [ViewModel] providing data specific to the music loading process.
@@ -31,49 +35,171 @@ import org.oxycblt.auxio.music.system.Indexer
  * @author Alexander Capehart (OxygenCobalt)
  */
 @HiltViewModel
-class MusicViewModel @Inject constructor(private val indexer: Indexer) :
+class MusicViewModel
-    ViewModel(), Indexer.Listener {
+@Inject
+constructor(
+    private val musicRepository: MusicRepository,
+    private val musicSettings: MusicSettings
+) : ViewModel(), MusicRepository.UpdateListener, MusicRepository.IndexingListener {
 
-    private val _indexerState = MutableStateFlow<Indexer.State?>(null)
+    private val _indexingState = MutableStateFlow<IndexingState?>(null)
     /** The current music loading state, or null if no loading is going on. */
-    val indexerState: StateFlow<Indexer.State?> = _indexerState
+    val indexingState: StateFlow<IndexingState?> = _indexingState
 
     private val _statistics = MutableStateFlow<Statistics?>(null)
     /** [Statistics] about the last completed music load. */
     val statistics: StateFlow<Statistics?>
         get() = _statistics
 
+    private val _newPlaylistSongs = MutableEvent<List<Song>>()
+    /** Flag for opening a dialog to create a playlist of the given [Song]s. */
+    val newPlaylistSongs: Event<List<Song>> = _newPlaylistSongs
+
+    private val _playlistToRename = MutableEvent<Playlist?>()
+    /** Flag for opening a dialog to rename the given [Playlist]. */
+    val playlistToRename: Event<Playlist?>
+        get() = _playlistToRename
+
+    private val _playlistToDelete = MutableEvent<Playlist>()
+    /** Flag for opening a dialog to confirm deletion of the given [Playlist]. */
+    val playlistToDelete: Event<Playlist>
+        get() = _playlistToDelete
+
+    private val _songsToAdd = MutableEvent<List<Song>>()
+    /** Flag for opening a dialog to add the given [Song]s to a playlist. */
+    val songsToAdd: Event<List<Song>> = _songsToAdd
+
     init {
-        indexer.registerListener(this)
+        musicRepository.addUpdateListener(this)
+        musicRepository.addIndexingListener(this)
     }
 
     override fun onCleared() {
-        indexer.unregisterListener(this)
+        musicRepository.removeUpdateListener(this)
+        musicRepository.removeIndexingListener(this)
     }
 
-    override fun onIndexerStateChanged(state: Indexer.State?) {
+    override fun onMusicChanges(changes: MusicRepository.Changes) {
-        _indexerState.value = state
+        if (!changes.deviceLibrary) return
-        if (state is Indexer.State.Complete) {
+        val deviceLibrary = musicRepository.deviceLibrary ?: return
-            // New state is a completed library, update the statistics values.
+        _statistics.value =
-            val library = state.result.getOrNull() ?: return
+            Statistics(
-            _statistics.value =
+                deviceLibrary.songs.size,
-                Statistics(
+                deviceLibrary.albums.size,
-                    library.songs.size,
+                deviceLibrary.artists.size,
-                    library.albums.size,
+                deviceLibrary.genres.size,
-                    library.artists.size,
+                deviceLibrary.songs.sumOf { it.durationMs })
-                    library.genres.size,
+    }
-                    library.songs.sumOf { it.durationMs })
+
-        }
+    override fun onIndexingStateChanged() {
+        _indexingState.value = musicRepository.indexingState
     }
 
     /** Requests that the music library should be re-loaded while leveraging the cache. */
     fun refresh() {
-        indexer.requestReindex(true)
+        musicRepository.requestIndex(true)
     }
 
     /** Requests that the music library be re-loaded without the cache. */
     fun rescan() {
-        indexer.requestReindex(false)
+        musicRepository.requestIndex(false)
+    }
+
+    /**
+     * Create a new generic [Playlist].
+     *
+     * @param name The name of the new [Playlist]. If null, the user will be prompted for one.
+     * @param songs The [Song]s to be contained in the new playlist.
+     */
+    fun createPlaylist(name: String? = null, songs: List<Song> = listOf()) {
+        if (name != null) {
+            viewModelScope.launch(Dispatchers.IO) { musicRepository.createPlaylist(name, songs) }
+        } else {
+            _newPlaylistSongs.put(songs)
+        }
+    }
+
+    /**
+     * Rename the given playlist.
+     *
+     * @param playlist The [Playlist] to rename,
+     * @param name The new name of the [Playlist]. If null, the user will be prompted for a name.
+     */
+    fun renamePlaylist(playlist: Playlist, name: String? = null) {
+        if (name != null) {
+            viewModelScope.launch(Dispatchers.IO) { musicRepository.renamePlaylist(playlist, name) }
+        } else {
+            _playlistToRename.put(playlist)
+        }
+    }
+
+    /**
+     * Delete a [Playlist].
+     *
+     * @param playlist The playlist to delete.
+     * @param rude Whether to immediately delete the playlist or prompt the user first. This should
+     *   be false at almost all times.
+     */
+    fun deletePlaylist(playlist: Playlist, rude: Boolean = false) {
+        if (rude) {
+            viewModelScope.launch(Dispatchers.IO) { musicRepository.deletePlaylist(playlist) }
+        } else {
+            _playlistToDelete.put(playlist)
+        }
+    }
+
+    /**
+     * Add a [Song] to a [Playlist].
+     *
+     * @param song The [Song] to add to the [Playlist].
+     * @param playlist The [Playlist] to add to. If null, the user will be prompted for one.
+     */
+    fun addToPlaylist(song: Song, playlist: Playlist? = null) {
+        addToPlaylist(listOf(song), playlist)
+    }
+
+    /**
+     * Add an [Album] to a [Playlist].
+     *
+     * @param album The [Album] to add to the [Playlist].
+     * @param playlist The [Playlist] to add to. If null, the user will be prompted for one.
+     */
+    fun addToPlaylist(album: Album, playlist: Playlist? = null) {
+        addToPlaylist(musicSettings.albumSongSort.songs(album.songs), playlist)
+    }
+
+    /**
+     * Add an [Artist] to a [Playlist].
+     *
+     * @param artist The [Artist] to add to the [Playlist].
+     * @param playlist The [Playlist] to add to. If null, the user will be prompted for one.
+     */
+    fun addToPlaylist(artist: Artist, playlist: Playlist? = null) {
+        addToPlaylist(musicSettings.artistSongSort.songs(artist.songs), playlist)
+    }
+
+    /**
+     * Add a [Genre] to a [Playlist].
+     *
+     * @param genre The [Genre] to add to the [Playlist].
+     * @param playlist The [Playlist] to add to. If null, the user will be prompted for one.
+     */
+    fun addToPlaylist(genre: Genre, playlist: Playlist? = null) {
+        addToPlaylist(musicSettings.genreSongSort.songs(genre.songs), playlist)
+    }
+
+    /**
+     * Add [Song]s to a [Playlist].
+     *
+     * @param songs The [Song]s to add to the [Playlist].
+     * @param playlist The [Playlist] to add to. If null, the user will be prompted for one.
+     */
+    fun addToPlaylist(songs: List<Song>, playlist: Playlist? = null) {
+        if (playlist != null) {
+            viewModelScope.launch(Dispatchers.IO) { musicRepository.addToPlaylist(songs, playlist) }
+        } else {
+            _songsToAdd.put(songs)
+        }
     }
 
     /**

app/src/main/java/org/oxycblt/auxio/music/cache/CacheDatabase.kt

@@ -27,10 +27,10 @@ import androidx.room.Query
 import androidx.room.RoomDatabase
 import androidx.room.TypeConverter
 import androidx.room.TypeConverters
-import org.oxycblt.auxio.music.metadata.Date
+import org.oxycblt.auxio.music.device.RawSong
+import org.oxycblt.auxio.music.info.Date
 import org.oxycblt.auxio.music.metadata.correctWhitespace
 import org.oxycblt.auxio.music.metadata.splitEscaped
-import org.oxycblt.auxio.music.model.RawSong
 
 @Database(entities = [CachedSong::class], version = 27, exportSchema = false)
 abstract class CacheDatabase : RoomDatabase() {

app/src/main/java/org/oxycblt/auxio/music/cache/CacheRepository.kt

@@ -19,7 +19,7 @@
 package org.oxycblt.auxio.music.cache
 
 import javax.inject.Inject
-import org.oxycblt.auxio.music.model.RawSong
+import org.oxycblt.auxio.music.device.RawSong
 import org.oxycblt.auxio.util.*
 
 /**

app/src/main/java/org/oxycblt/auxio/music/device/DeviceLibrary.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2023 Auxio Project
- * Library.kt is part of Auxio.
+ * DeviceLibrary.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,60 +16,44 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.model
+package org.oxycblt.auxio.music.device
 
 import android.content.Context
 import android.net.Uri
 import android.provider.OpenableColumns
+import javax.inject.Inject
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.storage.contentResolverSafe
+import org.oxycblt.auxio.music.fs.contentResolverSafe
-import org.oxycblt.auxio.music.storage.useQuery
+import org.oxycblt.auxio.music.fs.useQuery
 import org.oxycblt.auxio.util.logD
 
 /**
- * Organized music library information.
+ * Organized music library information obtained from device storage.
  *
  * This class allows for the creation of a well-formed music library graph from raw song
- * information. It's generally not expected to create this yourself and instead use
+ * information. Instances are immutable. It's generally not expected to create this yourself and
- * [MusicRepository].
+ * instead use [MusicRepository].
  *
  * @author Alexander Capehart
  */
-interface Library {
+interface DeviceLibrary {
-    /** All [Song]s in this [Library]. */
+    /** All [Song]s in this [DeviceLibrary]. */
     val songs: List<Song>
-    /** All [Album]s in this [Library]. */
+    /** All [Album]s in this [DeviceLibrary]. */
     val albums: List<Album>
-    /** All [Artist]s in this [Library]. */
+    /** All [Artist]s in this [DeviceLibrary]. */
     val artists: List<Artist>
-    /** All [Genre]s in this [Library]. */
+    /** All [Genre]s in this [DeviceLibrary]. */
     val genres: List<Genre>
 
     /**
-     * Finds a [Music] item [T] in the library by it's [Music.UID].
+     * Find a [Song] instance corresponding to the given [Music.UID].
      *
      * @param uid The [Music.UID] to search for.
-     * @return The [T] corresponding to the given [Music.UID], or null if nothing could be found or
+     * @return The corresponding [Song], or null if one was not found.
-     *   the [Music.UID] did not correspond to a [T].
      */
-    fun <T : Music> find(uid: Music.UID): T?
+    fun findSong(uid: Music.UID): Song?
-
-    /**
-     * Convert a [Song] from an another library into a [Song] in this [Library].
-     *
-     * @param song The [Song] to convert.
-     * @return The analogous [Song] in this [Library], or null if it does not exist.
-     */
-    fun sanitize(song: Song): Song?
-
-    /**
-     * Convert a [MusicParent] from an another library into a [MusicParent] in this [Library].
-     *
-     * @param parent The [MusicParent] to convert.
-     * @return The analogous [Album] in this [Library], or null if it does not exist.
-     */
-    fun <T : MusicParent> sanitize(parent: T): T?
 
     /**
      * Find a [Song] instance corresponding to the given Intent.ACTION_VIEW [Uri].
@@ -80,34 +64,72 @@ interface Library {
      */
     fun findSongForUri(context: Context, uri: Uri): Song?
 
+    /**
+     * Find a [Album] instance corresponding to the given [Music.UID].
+     *
+     * @param uid The [Music.UID] to search for.
+     * @return The corresponding [Song], or null if one was not found.
+     */
+    fun findAlbum(uid: Music.UID): Album?
+
+    /**
+     * Find a [Artist] instance corresponding to the given [Music.UID].
+     *
+     * @param uid The [Music.UID] to search for.
+     * @return The corresponding [Song], or null if one was not found.
+     */
+    fun findArtist(uid: Music.UID): Artist?
+
+    /**
+     * Find a [Genre] instance corresponding to the given [Music.UID].
+     *
+     * @param uid The [Music.UID] to search for.
+     * @return The corresponding [Song], or null if one was not found.
+     */
+    fun findGenre(uid: Music.UID): Genre?
+
+    /** Constructs a [DeviceLibrary] implementation in an asynchronous manner. */
+    interface Factory {
+        /**
+         * Create a new [DeviceLibrary].
+         *
+         * @param rawSongs [RawSong] instances to create a [DeviceLibrary] from.
+         */
+        suspend fun create(rawSongs: List<RawSong>): DeviceLibrary
+    }
+
     companion object {
         /**
-         * Create an instance of [Library].
+         * Create an instance of [DeviceLibrary].
          *
          * @param rawSongs [RawSong]s to create the library out of.
          * @param settings [MusicSettings] required.
          */
-        fun from(rawSongs: List<RawSong>, settings: MusicSettings): Library =
+        fun from(rawSongs: List<RawSong>, settings: MusicSettings): DeviceLibrary =
-            LibraryImpl(rawSongs, settings)
+            DeviceLibraryImpl(rawSongs, settings)
     }
 }
 
-private class LibraryImpl(rawSongs: List<RawSong>, settings: MusicSettings) : Library {
+class DeviceLibraryFactoryImpl @Inject constructor(private val musicSettings: MusicSettings) :
+    DeviceLibrary.Factory {
+    override suspend fun create(rawSongs: List<RawSong>): DeviceLibrary =
+        DeviceLibraryImpl(rawSongs, musicSettings)
+}
+
+private class DeviceLibraryImpl(rawSongs: List<RawSong>, settings: MusicSettings) : DeviceLibrary {
     override val songs = buildSongs(rawSongs, settings)
     override val albums = buildAlbums(songs, settings)
     override val artists = buildArtists(songs, albums, settings)
     override val genres = buildGenres(songs, settings)
 
     // Use a mapping to make finding information based on it's UID much faster.
-    private val uidMap = buildMap {
+    private val songUidMap = buildMap { songs.forEach { put(it.uid, it.finalize()) } }
-        songs.forEach { put(it.uid, it.finalize()) }
+    private val albumUidMap = buildMap { albums.forEach { put(it.uid, it.finalize()) } }
-        albums.forEach { put(it.uid, it.finalize()) }
+    private val artistUidMap = buildMap { artists.forEach { put(it.uid, it.finalize()) } }
-        artists.forEach { put(it.uid, it.finalize()) }
+    private val genreUidMap = buildMap { genres.forEach { put(it.uid, it.finalize()) } }
-        genres.forEach { put(it.uid, it.finalize()) }
-    }
 
     override fun equals(other: Any?) =
-        other is Library &&
+        other is DeviceLibrary &&
             other.songs == songs &&
             other.albums == albums &&
             other.artists == artists &&
@@ -121,18 +143,10 @@ private class LibraryImpl(rawSongs: List<RawSong>, settings: MusicSettings) : Li
         return hashCode
     }
 
-    /**
+    override fun findSong(uid: Music.UID) = songUidMap[uid]
-     * Finds a [Music] item [T] in the library by it's [Music.UID].
+    override fun findAlbum(uid: Music.UID) = albumUidMap[uid]
-     *
+    override fun findArtist(uid: Music.UID) = artistUidMap[uid]
-     * @param uid The [Music.UID] to search for.
+    override fun findGenre(uid: Music.UID) = genreUidMap[uid]
-     * @return The [T] corresponding to the given [Music.UID], or null if nothing could be found or
-     *   the [Music.UID] did not correspond to a [T].
-     */
-    @Suppress("UNCHECKED_CAST") override fun <T : Music> find(uid: Music.UID) = uidMap[uid] as? T
-
-    override fun sanitize(song: Song) = find<Song>(song.uid)
-
-    override fun <T : MusicParent> sanitize(parent: T) = find<T>(parent.uid)
 
     override fun findSongForUri(context: Context, uri: Uri) =
         context.contentResolverSafe.useQuery(
@@ -156,7 +170,7 @@ private class LibraryImpl(rawSongs: List<RawSong>, settings: MusicSettings) : Li
      */
     private fun buildSongs(rawSongs: List<RawSong>, settings: MusicSettings) =
         Sort(Sort.Mode.ByName, Sort.Direction.ASCENDING)
-            .songs(rawSongs.map { SongImpl(it, settings) }.distinct())
+            .songs(rawSongs.map { SongImpl(it, settings) }.distinctBy { it.uid })
 
     /**
      * Build a list of [Album]s from the given [Song]s.

app/src/main/java/org/oxycblt/auxio/music/device/DeviceModule.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2023 Auxio Project
- * Separators.kt is part of Auxio.
+ * DeviceModule.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,17 +16,15 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.metadata
+package org.oxycblt.auxio.music.device
 
-/**
+import dagger.Binds
- * Defines the allowed separator characters that can be used to delimit multi-value tags.
+import dagger.Module
- *
+import dagger.hilt.InstallIn
- * @author Alexander Capehart (OxygenCobalt)
+import dagger.hilt.components.SingletonComponent
- */
+
-object Separators {
+@Module
-    const val COMMA = ','
+@InstallIn(SingletonComponent::class)
-    const val SEMICOLON = ';'
+interface DeviceModule {
-    const val SLASH = '/'
+    @Binds fun deviceLibraryProvider(factory: DeviceLibraryFactoryImpl): DeviceLibrary.Factory
-    const val PLUS = '+'
-    const val AND = '&'
 }

app/src/main/java/org/oxycblt/auxio/music/device/DeviceMusicImpl.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2023 Auxio Project
- * MusicImpl.kt is part of Auxio.
+ * DeviceMusicImpl.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,26 +16,23 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.model
+package org.oxycblt.auxio.music.device
 
-import android.content.Context
-import androidx.annotation.VisibleForTesting
-import java.security.MessageDigest
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.metadata.Date
+import org.oxycblt.auxio.music.fs.MimeType
-import org.oxycblt.auxio.music.metadata.Disc
+import org.oxycblt.auxio.music.fs.Path
-import org.oxycblt.auxio.music.metadata.ReleaseType
+import org.oxycblt.auxio.music.fs.toAudioUri
+import org.oxycblt.auxio.music.fs.toCoverUri
+import org.oxycblt.auxio.music.info.*
+import org.oxycblt.auxio.music.info.Date
 import org.oxycblt.auxio.music.metadata.parseId3GenreNames
 import org.oxycblt.auxio.music.metadata.parseMultiValue
-import org.oxycblt.auxio.music.storage.MimeType
-import org.oxycblt.auxio.music.storage.Path
-import org.oxycblt.auxio.music.storage.toAudioUri
-import org.oxycblt.auxio.music.storage.toCoverUri
 import org.oxycblt.auxio.util.nonZeroOrNull
 import org.oxycblt.auxio.util.toUuidOrNull
 import org.oxycblt.auxio.util.unlikelyToBeNull
+import org.oxycblt.auxio.util.update
 
 /**
  * Library-backed implementation of [Song].
@@ -44,7 +41,7 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
  * @param musicSettings [MusicSettings] to for user parsing configuration.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class SongImpl(rawSong: RawSong, musicSettings: MusicSettings) : Song {
+class SongImpl(private val rawSong: RawSong, musicSettings: MusicSettings) : Song {
     override val uid =
         // Attempt to use a MusicBrainz ID first before falling back to a hashed UID.
         rawSong.musicBrainzId?.toUuidOrNull()?.let { Music.UID.musicBrainz(MusicMode.SONGS, it) }
@@ -62,10 +59,11 @@ class SongImpl(rawSong: RawSong, musicSettings: MusicSettings) : Song {
                 update(rawSong.artistNames)
                 update(rawSong.albumArtistNames)
             }
-    override val rawName = requireNotNull(rawSong.name) { "Invalid raw: No title" }
+    override val name =
-    override val rawSortName = rawSong.sortName
+        Name.Known.from(
-    override val sortName = SortName((rawSortName ?: rawName), musicSettings)
+            requireNotNull(rawSong.name) { "Invalid raw: No title" },
-    override fun resolveName(context: Context) = rawName
+            rawSong.sortName,
+            musicSettings)
 
     override val track = rawSong.track
     override val disc = rawSong.disc?.let { Disc(it, rawSong.subtitle) }
@@ -87,9 +85,9 @@ class SongImpl(rawSong: RawSong, musicSettings: MusicSettings) : Song {
     override val album: Album
         get() = unlikelyToBeNull(_album)
 
-    // Note: Only compare by UID so songs that differ only in MBID are treated differently.
+    override fun hashCode() = 31 * uid.hashCode() + rawSong.hashCode()
-    override fun hashCode() = uid.hashCode()
+    override fun equals(other: Any?) =
-    override fun equals(other: Any?) = other is Song && uid == other.uid
+        other is SongImpl && uid == other.uid && rawSong == other.rawSong
 
     private val artistMusicBrainzIds = rawSong.artistMusicBrainzIds.parseMultiValue(musicSettings)
     private val artistNames = rawSong.artistNames.parseMultiValue(musicSettings)
@@ -238,10 +236,7 @@ class AlbumImpl(
                 update(rawAlbum.name)
                 update(rawAlbum.rawArtists.map { it.name })
             }
-    override val rawName = rawAlbum.name
+    override val name = Name.Known.from(rawAlbum.name, rawAlbum.sortName, musicSettings)
-    override val rawSortName = rawAlbum.sortName
-    override val sortName = SortName((rawSortName ?: rawName), musicSettings)
-    override fun resolveName(context: Context) = rawName
 
     override val dates = Date.Range.from(songs.mapNotNull { it.date })
     override val releaseType = rawAlbum.releaseType ?: ReleaseType.Album(null)
@@ -249,11 +244,15 @@ class AlbumImpl(
     override val durationMs: Long
     override val dateAdded: Long
 
-    // Note: Append song contents to MusicParent equality so that Groups with
+    override fun hashCode(): Int {
-    // the same UID but different contents are not equal.
+        var hashCode = uid.hashCode()
-    override fun hashCode() = 31 * uid.hashCode() + songs.hashCode()
+        hashCode = 31 * hashCode + rawAlbum.hashCode()
+        hashCode = 31 * hashCode + songs.hashCode()
+        return hashCode
+    }
+
     override fun equals(other: Any?) =
-        other is AlbumImpl && uid == other.uid && songs == other.songs
+        other is AlbumImpl && uid == other.uid && rawAlbum == other.rawAlbum && songs == other.songs
 
     private val _artists = mutableListOf<ArtistImpl>()
     override val artists: List<Artist>
@@ -331,21 +330,29 @@ class ArtistImpl(
         // Attempt to use a MusicBrainz ID first before falling back to a hashed UID.
         rawArtist.musicBrainzId?.let { Music.UID.musicBrainz(MusicMode.ARTISTS, it) }
             ?: Music.UID.auxio(MusicMode.ARTISTS) { update(rawArtist.name) }
-    override val rawName = rawArtist.name
+    override val name =
-    override val rawSortName = rawArtist.sortName
+        rawArtist.name?.let { Name.Known.from(it, rawArtist.sortName, musicSettings) }
-    override val sortName = (rawSortName ?: rawName)?.let { SortName(it, musicSettings) }
+            ?: Name.Unknown(R.string.def_artist)
-    override fun resolveName(context: Context) = rawName ?: context.getString(R.string.def_artist)
-    override val songs: List<Song>
 
+    override val songs: List<Song>
     override val albums: List<Album>
     override val durationMs: Long?
     override val isCollaborator: Boolean
 
-    // Note: Append song contents to MusicParent equality so that Groups with
+    // Note: Append song contents to MusicParent equality so that artists with
-    // the same UID but different contents are not equal.
+    // the same UID but different songs are not equal.
-    override fun hashCode() = 31 * uid.hashCode() + songs.hashCode()
+    override fun hashCode(): Int {
+        var hashCode = uid.hashCode()
+        hashCode = 31 * hashCode + rawArtist.hashCode()
+        hashCode = 31 * hashCode + songs.hashCode()
+        return hashCode
+    }
+
     override fun equals(other: Any?) =
-        other is ArtistImpl && uid == other.uid && songs == other.songs
+        other is ArtistImpl &&
+            uid == other.uid &&
+            rawArtist == other.rawArtist &&
+            songs == other.songs
 
     override lateinit var genres: List<Genre>
 
@@ -416,20 +423,23 @@ class GenreImpl(
     override val songs: List<SongImpl>
 ) : Genre {
     override val uid = Music.UID.auxio(MusicMode.GENRES) { update(rawGenre.name) }
-    override val rawName = rawGenre.name
+    override val name =
-    override val rawSortName = rawName
+        rawGenre.name?.let { Name.Known.from(it, rawGenre.name, musicSettings) }
-    override val sortName = (rawSortName ?: rawName)?.let { SortName(it, musicSettings) }
+            ?: Name.Unknown(R.string.def_genre)
-    override fun resolveName(context: Context) = rawName ?: context.getString(R.string.def_genre)
 
     override val albums: List<Album>
     override val artists: List<Artist>
     override val durationMs: Long
 
-    // Note: Append song contents to MusicParent equality so that Groups with
+    override fun hashCode(): Int {
-    // the same UID but different contents are not equal.
+        var hashCode = uid.hashCode()
-    override fun hashCode() = 31 * uid.hashCode() + songs.hashCode()
+        hashCode = 31 * hashCode + rawGenre.hashCode()
+        hashCode = 31 * hashCode + songs.hashCode()
+        return hashCode
+    }
+
     override fun equals(other: Any?) =
-        other is GenreImpl && uid == other.uid && songs == other.songs
+        other is GenreImpl && uid == other.uid && rawGenre == other.rawGenre && songs == other.songs
 
     init {
         val distinctAlbums = mutableSetOf<Album>()
@@ -467,60 +477,8 @@ class GenreImpl(
      *
      * @return This instance upcasted to [Genre].
      */
-    fun finalize(): Music {
+    fun finalize(): Genre {
         check(songs.isNotEmpty()) { "Malformed genre: Empty" }
         return this
     }
 }
-
-/**
- * Update a [MessageDigest] with a lowercase [String].
- *
- * @param string The [String] to hash. If null, it will not be hashed.
- */
-@VisibleForTesting
-fun MessageDigest.update(string: String?) {
-    if (string != null) {
-        update(string.lowercase().toByteArray())
-    } else {
-        update(0)
-    }
-}
-
-/**
- * Update a [MessageDigest] with the string representation of a [Date].
- *
- * @param date The [Date] to hash. If null, nothing will be done.
- */
-@VisibleForTesting
-fun MessageDigest.update(date: Date?) {
-    if (date != null) {
-        update(date.toString().toByteArray())
-    } else {
-        update(0)
-    }
-}
-
-/**
- * Update a [MessageDigest] with the lowercase versions of all of the input [String]s.
- *
- * @param strings The [String]s to hash. If a [String] is null, it will not be hashed.
- */
-@VisibleForTesting
-fun MessageDigest.update(strings: List<String?>) {
-    strings.forEach(::update)
-}
-
-/**
- * Update a [MessageDigest] with the little-endian bytes of a [Int].
- *
- * @param n The [Int] to write. If null, nothing will be done.
- */
-@VisibleForTesting
-fun MessageDigest.update(n: Int?) {
-    if (n != null) {
-        update(byteArrayOf(n.toByte(), n.shr(8).toByte(), n.shr(16).toByte(), n.shr(24).toByte()))
-    } else {
-        update(0)
-    }
-}

app/src/main/java/org/oxycblt/auxio/music/device/RawMusic.kt

@@ -16,19 +16,20 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.model
+package org.oxycblt.auxio.music.device
 
 import java.util.UUID
 import org.oxycblt.auxio.music.*
-import org.oxycblt.auxio.music.metadata.*
+import org.oxycblt.auxio.music.fs.Directory
-import org.oxycblt.auxio.music.storage.Directory
+import org.oxycblt.auxio.music.info.Date
+import org.oxycblt.auxio.music.info.ReleaseType
 
 /**
  * Raw information about a [SongImpl] obtained from the filesystem/Extractor instances.
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class RawSong(
+data class RawSong(
     /**
      * The ID of the [SongImpl]'s audio file, obtained from MediaStore. Note that this ID is highly
      * unstable and should only be used for accessing the audio file.
@@ -50,15 +51,15 @@ class RawSong(
     var extensionMimeType: String? = null,
     /** @see Music.UID */
     var musicBrainzId: String? = null,
-    /** @see Music.rawName */
+    /** @see Music.name */
     var name: String? = null,
-    /** @see Music.rawSortName */
+    /** @see Music.name */
     var sortName: String? = null,
     /** @see Song.track */
     var track: Int? = null,
-    /** @see Disc.number */
+    /** @see Song.disc */
     var disc: Int? = null,
-    /** @See Disc.name */
+    /** @See Song.disc */
     var subtitle: String? = null,
     /** @see Song.date */
     var date: Date? = null,
@@ -93,7 +94,7 @@ class RawSong(
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class RawAlbum(
+data class RawAlbum(
     /**
      * The ID of the [AlbumImpl]'s grouping, obtained from MediaStore. Note that this ID is highly
      * unstable and should only be used for accessing the system-provided cover art.
@@ -101,9 +102,9 @@ class RawAlbum(
     val mediaStoreId: Long,
     /** @see Music.uid */
     val musicBrainzId: UUID?,
-    /** @see Music.rawName */
+    /** @see Music.name */
     val name: String,
-    /** @see Music.rawSortName */
+    /** @see Music.name */
     val sortName: String?,
     /** @see Album.releaseType */
     val releaseType: ReleaseType?,
@@ -140,12 +141,12 @@ class RawAlbum(
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class RawArtist(
+data class RawArtist(
     /** @see Music.UID */
     val musicBrainzId: UUID? = null,
-    /** @see Music.rawName */
+    /** @see Music.name */
     val name: String? = null,
-    /** @see Music.rawSortName */
+    /** @see Music.name */
     val sortName: String? = null
 ) {
     // Artists are grouped as follows:
@@ -182,17 +183,17 @@ class RawArtist(
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class RawGenre(
+data class RawGenre(
-    /** @see Music.rawName */
+    /** @see Music.name */
     val name: String? = null
 ) {
-    // Only group by the lowercase genre name. This allows Genre grouping to be
-    // case-insensitive, which may be helpful in some libraries with different ways of
-    // formatting genres.
 
     // Cache the hashCode for HashMap efficiency.
     private val hashCode = name?.lowercase().hashCode()
 
+    // Only group by the lowercase genre name. This allows Genre grouping to be
+    // case-insensitive, which may be helpful in some libraries with different ways of
+    // formatting genres.
     override fun hashCode() = hashCode
 
     override fun equals(other: Any?) =

app/src/main/java/org/oxycblt/auxio/music/fs/DirectoryAdapter.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.fs
 
 import android.view.View
 import android.view.ViewGroup

app/src/main/java/org/oxycblt/auxio/music/fs/Fs.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2022 Auxio Project
- * Filesystem.kt is part of Auxio.
+ * Fs.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.fs
 
 import android.content.Context
 import android.media.MediaFormat

app/src/main/java/org/oxycblt/auxio/music/fs/FsModule.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2023 Auxio Project
- * StorageModule.kt is part of Auxio.
+ * FsModule.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.fs
 
 import android.content.Context
 import dagger.Module
@@ -28,7 +28,7 @@ import org.oxycblt.auxio.music.MusicSettings
 
 @Module
 @InstallIn(SingletonComponent::class)
-class StorageModule {
+class FsModule {
     @Provides
     fun mediaStoreExtractor(@ApplicationContext context: Context, musicSettings: MusicSettings) =
         MediaStoreExtractor.from(context, musicSettings)

app/src/main/java/org/oxycblt/auxio/music/fs/MediaStoreExtractor.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.fs
 
 import android.content.Context
 import android.database.Cursor
@@ -31,10 +31,10 @@ import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.yield
 import org.oxycblt.auxio.music.MusicSettings
 import org.oxycblt.auxio.music.cache.Cache
-import org.oxycblt.auxio.music.metadata.Date
+import org.oxycblt.auxio.music.device.RawSong
+import org.oxycblt.auxio.music.info.Date
 import org.oxycblt.auxio.music.metadata.parseId3v2PositionField
 import org.oxycblt.auxio.music.metadata.transformPositionField
-import org.oxycblt.auxio.music.model.RawSong
 import org.oxycblt.auxio.util.getSystemServiceCompat
 import org.oxycblt.auxio.util.logD
 
@@ -178,8 +178,8 @@ private abstract class BaseMediaStoreExtractor(
 
                             while (cursor.moveToNext()) {
                                 // Assume that a song can't inhabit multiple genre entries, as I
-                                // doubt
+                                // doubt MediaStore is actually aware that songs can have multiple
-                                // MediaStore is actually aware that songs can have multiple genres.
+                                // genres.
                                 genreNamesMap[cursor.getLong(songIdIndex)] = name
                             }
                         }
@@ -210,7 +210,6 @@ private abstract class BaseMediaStoreExtractor(
         // Free the cursor and signal that no more incomplete songs will be produced by
         // this extractor.
         query.close()
-        incompleteSongs.close()
     }
 
     /**
@@ -311,9 +310,8 @@ private abstract class BaseMediaStoreExtractor(
             rawSong.date = cursor.getStringOrNull(yearIndex)?.let(Date::from)
             // A non-existent album name should theoretically be the name of the folder it contained
             // in, but in practice it is more often "0" (as in /storage/emulated/0), even when it
-            // the
+            // the file is not actually in the root internal storage directory. We can't do
-            // file is not actually in the root internal storage directory. We can't do anything to
+            // anything to fix this, really.
-            // fix this, really.
             rawSong.albumName = cursor.getString(albumIndex)
             // Android does not make a non-existent artist tag null, it instead fills it in
             // as <unknown>, which makes absolutely no sense given how other columns default
@@ -356,9 +354,6 @@ private abstract class BaseMediaStoreExtractor(
 // Note: The separation between version-specific backends may not be the cleanest. To preserve
 // speed, we only want to add redundancy on known issues, not with possible issues.
 
-// Note: The separation between version-specific backends may not be the cleanest. To preserve
-// speed, we only want to add redundancy on known issues, not with possible issues.
-
 private class Api21MediaStoreExtractor(context: Context, musicSettings: MusicSettings) :
     BaseMediaStoreExtractor(context, musicSettings) {
     override val projection: Array<String>

app/src/main/java/org/oxycblt/auxio/music/fs/MusicDirsDialog.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.fs
 
 import android.content.ActivityNotFoundException
 import android.net.Uri

app/src/main/java/org/oxycblt/auxio/music/fs/StorageUtil.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.fs
 
 import android.annotation.SuppressLint
 import android.content.ContentResolver

app/src/main/java/org/oxycblt/auxio/music/info/Date.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.metadata
+package org.oxycblt.auxio.music.info
 
 import android.content.Context
 import java.text.ParseException
@@ -185,9 +185,10 @@ class Date private constructor(private val tokens: List<Int>) : Comparable<Date>
          * A [Regex] that can parse a variable-precision ISO-8601 timestamp. Derived from
          * https://github.com/quodlibet/mutagen
          */
-        private val ISO8601_REGEX =
+        private val ISO8601_REGEX by lazy {
             Regex(
                 """^(\d{4})([-.](\d{2})([-.](\d{2})([T ](\d{2})([:.](\d{2})([:.](\d{2})(Z)?)?)?)?)?)?$""")
+        }
 
         /**
          * Create a [Date] from a year component.

app/src/main/java/org/oxycblt/auxio/music/info/Disc.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.metadata
+package org.oxycblt.auxio.music.info
 
 import org.oxycblt.auxio.list.Item
 
@@ -27,7 +27,7 @@ import org.oxycblt.auxio.list.Item
  * @param name The name of the disc group, if any. Null if not present.
  */
 class Disc(val number: Int, val name: String?) : Item, Comparable<Disc> {
-    override fun hashCode() = number.hashCode()
     override fun equals(other: Any?) = other is Disc && number == other.number
+    override fun hashCode() = number.hashCode()
     override fun compareTo(other: Disc) = number.compareTo(other.number)
 }

app/src/main/java/org/oxycblt/auxio/music/info/Name.kt

@@ -0,0 +1,219 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * Name.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.info
+
+import android.content.Context
+import androidx.annotation.StringRes
+import java.text.CollationKey
+import java.text.Collator
+import org.oxycblt.auxio.music.MusicSettings
+
+/**
+ * The name of a music item.
+ *
+ * This class automatically implements
+ *
+ * @author Alexander Capehart
+ */
+sealed interface Name : Comparable<Name> {
+    /**
+     * A logical first character that can be used to collate a sorted list of music.
+     *
+     * TODO: Move this to the home package
+     */
+    val thumb: String
+
+    /**
+     * Get a human-readable string representation of this instance.
+     *
+     * @param context [Context] required.
+     */
+    fun resolve(context: Context): String
+
+    /** A name that could be obtained for the music item. */
+    sealed class Known : Name {
+        /** The raw name string obtained. Should be ignored in favor of [resolve]. */
+        abstract val raw: String
+        /** The raw sort name string obtained. */
+        abstract val sort: String?
+
+        /** A tokenized version of the name that will be compared. */
+        protected abstract val sortTokens: List<SortToken>
+
+        /** An individual part of a name string that can be compared intelligently. */
+        protected data class SortToken(val collationKey: CollationKey, val type: Type) :
+            Comparable<SortToken> {
+            override fun compareTo(other: SortToken): Int {
+                // Numeric tokens should always be lower than lexicographic tokens.
+                val modeComp = type.compareTo(other.type)
+                if (modeComp != 0) {
+                    return modeComp
+                }
+
+                // Numeric strings must be ordered by magnitude, thus immediately short-circuit
+                // the comparison if the lengths do not match.
+                if (type == Type.NUMERIC &&
+                    collationKey.sourceString.length != other.collationKey.sourceString.length) {
+                    return collationKey.sourceString.length - other.collationKey.sourceString.length
+                }
+
+                return collationKey.compareTo(other.collationKey)
+            }
+
+            /** Denotes the type of comparison to be performed with this token. */
+            enum class Type {
+                /** Compare as a digit string, like "65". */
+                NUMERIC,
+                /** Compare as a standard alphanumeric string, like "65daysofstatic" */
+                LEXICOGRAPHIC
+            }
+        }
+
+        final override val thumb: String
+            get() =
+                // TODO: Remove these safety checks once you have real unit testing
+                sortTokens
+                    .firstOrNull()
+                    ?.run { collationKey.sourceString.firstOrNull() }
+                    ?.let { if (it.isDigit()) "#" else it.uppercase() }
+                    ?: "?"
+
+        final override fun resolve(context: Context) = raw
+
+        final override fun compareTo(other: Name) =
+            when (other) {
+                is Known -> {
+                    // Progressively compare the sort tokens between each known name.
+                    sortTokens.zip(other.sortTokens).fold(0) { acc, (token, otherToken) ->
+                        acc.takeIf { it != 0 } ?: token.compareTo(otherToken)
+                    }
+                }
+                // Unknown names always come before known names.
+                is Unknown -> 1
+            }
+
+        companion object {
+            /**
+             * Create a new instance of [Name.Known]
+             *
+             * @param raw The raw name obtained from the music item
+             * @param sort The raw sort name obtained from the music item
+             * @param musicSettings [MusicSettings] required for name configuration.
+             */
+            fun from(raw: String, sort: String?, musicSettings: MusicSettings): Known =
+                if (musicSettings.intelligentSorting) {
+                    IntelligentKnownName(raw, sort)
+                } else {
+                    SimpleKnownName(raw, sort)
+                }
+        }
+    }
+
+    /**
+     * A placeholder name that is used when a [Known] name could not be obtained for the item.
+     *
+     * @author Alexander Capehart
+     */
+    data class Unknown(@StringRes val stringRes: Int) : Name {
+        override val thumb = "?"
+        override fun resolve(context: Context) = context.getString(stringRes)
+        override fun compareTo(other: Name) =
+            when (other) {
+                // Unknown names do not need any direct comparison right now.
+                is Unknown -> 0
+                // Unknown names always come before known names.
+                is Known -> -1
+            }
+    }
+}
+
+private val COLLATOR: Collator = Collator.getInstance().apply { strength = Collator.PRIMARY }
+private val PUNCT_REGEX by lazy { Regex("[\\p{Punct}+]") }
+
+/**
+ * Plain [Name.Known] implementation that is internationalization-safe.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+private data class SimpleKnownName(override val raw: String, override val sort: String?) :
+    Name.Known() {
+    override val sortTokens = listOf(parseToken(sort ?: raw))
+
+    private fun parseToken(name: String): SortToken {
+        // Remove excess punctuation from the string, as those usually aren't considered in sorting.
+        val stripped = name.replace(PUNCT_REGEX, "").ifEmpty { name }
+        val collationKey = COLLATOR.getCollationKey(stripped)
+        // Always use lexicographic mode since we aren't parsing any numeric components
+        return SortToken(collationKey, SortToken.Type.LEXICOGRAPHIC)
+    }
+}
+
+/**
+ * [Name.Known] implementation that adds advanced sorting behavior at the cost of localization.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+private data class IntelligentKnownName(override val raw: String, override val sort: String?) :
+    Name.Known() {
+    override val sortTokens = parseTokens(sort ?: raw)
+
+    private fun parseTokens(name: String): List<SortToken> {
+        val stripped =
+            name
+                // Remove excess punctuation from the string, as those u
+                .replace(PUNCT_REGEX, "")
+                .ifEmpty { name }
+                .run {
+                    // Strip any english articles like "the" or "an" from the start, as music
+                    // sorting should ignore such when possible.
+                    when {
+                        length > 4 && startsWith("the ", ignoreCase = true) -> substring(4)
+                        length > 3 && startsWith("an ", ignoreCase = true) -> substring(3)
+                        length > 2 && startsWith("a ", ignoreCase = true) -> substring(2)
+                        else -> this
+                    }
+                }
+
+        // To properly compare numeric components in names, we have to split them up into
+        // individual lexicographic and numeric tokens and then individually compare them
+        // with special logic.
+        return TOKEN_REGEX.findAll(stripped).mapTo(mutableListOf()) { match ->
+            // Remove excess whitespace where possible
+            val token = match.value.trim().ifEmpty { match.value }
+            val collationKey: CollationKey
+            val type: SortToken.Type
+            // Separate each token into their numeric and lexicographic counterparts.
+            if (token.first().isDigit()) {
+                // The digit string comparison breaks with preceding zero digits, remove those
+                val digits = token.trimStart('0').ifEmpty { token }
+                // Other languages have other types of digit strings, still use collation keys
+                collationKey = COLLATOR.getCollationKey(digits)
+                type = SortToken.Type.NUMERIC
+            } else {
+                collationKey = COLLATOR.getCollationKey(token)
+                type = SortToken.Type.LEXICOGRAPHIC
+            }
+            SortToken(collationKey, type)
+        }
+    }
+
+    companion object {
+        private val TOKEN_REGEX by lazy { Regex("(\\d+)|(\\D+)") }
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/info/ReleaseType.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.metadata
+package org.oxycblt.auxio.music.info
 
 import org.oxycblt.auxio.R
 
@@ -28,15 +28,15 @@ import org.oxycblt.auxio.R
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-sealed class ReleaseType {
+sealed interface ReleaseType {
     /**
      * A specification of what kind of performance this release is. If null, the release is
      * considered "Plain".
      */
-    abstract val refinement: Refinement?
+    val refinement: Refinement?
 
     /** The string resource corresponding to the name of this release type to show in the UI. */
-    abstract val stringRes: Int
+    val stringRes: Int
 
     /**
      * A plain album.
@@ -44,7 +44,7 @@ sealed class ReleaseType {
      * @param refinement A specification of what kind of performance this release is. If null, the
      *   release is considered "Plain".
      */
-    data class Album(override val refinement: Refinement?) : ReleaseType() {
+    data class Album(override val refinement: Refinement?) : ReleaseType {
         override val stringRes: Int
             get() =
                 when (refinement) {
@@ -61,7 +61,7 @@ sealed class ReleaseType {
      * @param refinement A specification of what kind of performance this release is. If null, the
      *   release is considered "Plain".
      */
-    data class EP(override val refinement: Refinement?) : ReleaseType() {
+    data class EP(override val refinement: Refinement?) : ReleaseType {
         override val stringRes: Int
             get() =
                 when (refinement) {
@@ -78,7 +78,7 @@ sealed class ReleaseType {
      * @param refinement A specification of what kind of performance this release is. If null, the
      *   release is considered "Plain".
      */
-    data class Single(override val refinement: Refinement?) : ReleaseType() {
+    data class Single(override val refinement: Refinement?) : ReleaseType {
         override val stringRes: Int
             get() =
                 when (refinement) {
@@ -95,7 +95,7 @@ sealed class ReleaseType {
      * @param refinement A specification of what kind of performance this release is. If null, the
      *   release is considered "Plain".
      */
-    data class Compilation(override val refinement: Refinement?) : ReleaseType() {
+    data class Compilation(override val refinement: Refinement?) : ReleaseType {
         override val stringRes: Int
             get() =
                 when (refinement) {
@@ -110,7 +110,7 @@ sealed class ReleaseType {
      * A soundtrack. Similar to a [Compilation], but created for a specific piece of (usually
      * visual) media.
      */
-    object Soundtrack : ReleaseType() {
+    object Soundtrack : ReleaseType {
         override val refinement: Refinement?
             get() = null
 
@@ -122,7 +122,7 @@ sealed class ReleaseType {
      * A (DJ) Mix. These are usually one large track consisting of the artist playing several
      * sub-tracks with smooth transitions between them.
      */
-    object Mix : ReleaseType() {
+    object Mix : ReleaseType {
         override val refinement: Refinement?
             get() = null
 
@@ -134,7 +134,7 @@ sealed class ReleaseType {
      * A Mix-tape. These are usually [EP]-sized releases of music made to promote an Artist or a
      * future release.
      */
-    object Mixtape : ReleaseType() {
+    object Mixtape : ReleaseType {
         override val refinement: Refinement?
             get() = null
 

app/src/main/java/org/oxycblt/auxio/music/metadata/AudioProperties.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2023 Auxio Project
- * AudioInfo.kt is part of Auxio.
+ * AudioProperties.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -24,7 +24,7 @@ import android.media.MediaFormat
 import dagger.hilt.android.qualifiers.ApplicationContext
 import javax.inject.Inject
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.storage.MimeType
+import org.oxycblt.auxio.music.fs.MimeType
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logE
 import org.oxycblt.auxio.util.logW
@@ -37,32 +37,33 @@ import org.oxycblt.auxio.util.logW
  * @param resolvedMimeType The known mime type of the [Song] after it's file format was determined.
  * @author Alexander Capehart (OxygenCobalt)
  */
-data class AudioInfo(
+data class AudioProperties(
     val bitrateKbps: Int?,
     val sampleRateHz: Int?,
     val resolvedMimeType: MimeType
 ) {
-    /** Implements the process of extracting [AudioInfo] from a given [Song]. */
+    /** Implements the process of extracting [AudioProperties] from a given [Song]. */
-    interface Provider {
+    interface Factory {
         /**
-         * Extract the [AudioInfo] of a given [Song].
+         * Extract the [AudioProperties] of a given [Song].
          *
          * @param song The [Song] to read.
-         * @return The [AudioInfo] of the [Song], if possible to obtain.
+         * @return The [AudioProperties] of the [Song], if possible to obtain.
          */
-        suspend fun extract(song: Song): AudioInfo
+        suspend fun extract(song: Song): AudioProperties
     }
 }
 
 /**
- * A framework-backed implementation of [AudioInfo.Provider].
+ * A framework-backed implementation of [AudioProperties.Factory].
  *
  * @param context [Context] required to read audio files.
  */
-class AudioInfoProviderImpl @Inject constructor(@ApplicationContext private val context: Context) :
+class AudioPropertiesFactoryImpl
-    AudioInfo.Provider {
+@Inject
+constructor(@ApplicationContext private val context: Context) : AudioProperties.Factory {
 
-    override suspend fun extract(song: Song): AudioInfo {
+    override suspend fun extract(song: Song): AudioProperties {
         // While we would use ExoPlayer to extract this information, it doesn't support
         // common data like bit rate in progressive data sources due to there being no
         // demand. Thus, we are stuck with the inferior OS-provided MediaExtractor.
@@ -76,7 +77,7 @@ class AudioInfoProviderImpl @Inject constructor(@ApplicationContext private val
             // that we can show.
             logW("Unable to extract song attributes.")
             logW(e.stackTraceToString())
-            return AudioInfo(null, null, song.mimeType)
+            return AudioProperties(null, null, song.mimeType)
         }
 
         // Get the first track from the extractor (This is basically always the only
@@ -122,6 +123,6 @@ class AudioInfoProviderImpl @Inject constructor(@ApplicationContext private val
 
         extractor.release()
 
-        return AudioInfo(bitrate, sampleRate, resolvedMimeType)
+        return AudioProperties(bitrate, sampleRate, resolvedMimeType)
     }
 }

app/src/main/java/org/oxycblt/auxio/music/metadata/MetadataModule.kt

@@ -26,7 +26,7 @@ import dagger.hilt.components.SingletonComponent
 @Module
 @InstallIn(SingletonComponent::class)
 interface MetadataModule {
-    @Binds fun tagExtractor(tagExtractor: TagExtractorImpl): TagExtractor
+    @Binds fun tagExtractor(extractor: TagExtractorImpl): TagExtractor
-    @Binds fun tagWorkerFactory(taskFactory: TagWorkerImpl.Factory): TagWorker.Factory
+    @Binds fun tagWorkerFactory(factory: TagWorkerFactoryImpl): TagWorker.Factory
-    @Binds fun audioInfoProvider(audioInfoProvider: AudioInfoProviderImpl): AudioInfo.Provider
+    @Binds fun audioPropertiesFactory(factory: AudioPropertiesFactoryImpl): AudioProperties.Factory
 }

app/src/main/java/org/oxycblt/auxio/music/metadata/SeparatorsDialog.kt

@@ -99,6 +99,14 @@ class SeparatorsDialog : ViewBindingDialogFragment<DialogSeparatorsBinding>() {
         return separators
     }
 
+    private object Separators {
+        const val COMMA = ','
+        const val SEMICOLON = ';'
+        const val SLASH = '/'
+        const val PLUS = '+'
+        const val AND = '&'
+    }
+
     private companion object {
         const val KEY_PENDING_SEPARATORS = BuildConfig.APPLICATION_ID + ".key.PENDING_SEPARATORS"
     }

app/src/main/java/org/oxycblt/auxio/music/metadata/TagExtractor.kt

@@ -18,11 +18,11 @@
  
 package org.oxycblt.auxio.music.metadata
 
-import com.google.android.exoplayer2.MetadataRetriever
+import androidx.media3.exoplayer.MetadataRetriever
 import javax.inject.Inject
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.yield
-import org.oxycblt.auxio.music.model.RawSong
+import org.oxycblt.auxio.music.device.RawSong
 
 /**
  * The extractor that leverages ExoPlayer's [MetadataRetriever] API to parse metadata. This is the
@@ -87,8 +87,6 @@ class TagExtractorImpl @Inject constructor(private val tagWorkerFactory: TagWork
                 }
             }
         } while (ongoingTasks)
-
-        completeSongs.close()
     }
 
     private companion object {

app/src/main/java/org/oxycblt/auxio/music/metadata/TagUtil.kt

@@ -209,7 +209,7 @@ private fun String.parseId3v1Genre(): String? {
  * A [Regex] that implements parsing for ID3v2's genre format. Derived from mutagen:
  * https://github.com/quodlibet/mutagen
  */
-private val ID3V2_GENRE_RE = Regex("((?:\\((\\d+|RX|CR)\\))*)(.+)?")
+private val ID3V2_GENRE_RE by lazy { Regex("((?:\\((\\d+|RX|CR)\\))*)(.+)?") }
 
 /**
  * Parse an ID3v2 integer genre field, which has support for multiple genre values and combined
@@ -228,7 +228,7 @@ private fun String.parseId3v2Genre(): List<String>? {
     // Case 1: Genre IDs in the format (INT|RX|CR). If these exist, parse them as
     // ID3v1 tags.
     val genreIds = groups.getOrNull(1)
-    if (genreIds != null && genreIds.isNotEmpty()) {
+    if (!genreIds.isNullOrEmpty()) {
         val ids = genreIds.substring(1, genreIds.lastIndex).split(")(")
         for (id in ids) {
             id.parseId3v1Genre()?.let(genres::add)
@@ -238,7 +238,7 @@ private fun String.parseId3v2Genre(): List<String>? {
     // Case 2: Genre names as a normal string. The only case we have to look out for are
     // escaped strings formatted as ((genre).
     val genreName = groups.getOrNull(3)
-    if (genreName != null && genreName.isNotEmpty()) {
+    if (!genreName.isNullOrEmpty()) {
         if (genreName.startsWith("((")) {
             genres.add(genreName.substring(1))
         } else {

app/src/main/java/org/oxycblt/auxio/music/metadata/TagWorker.kt

@@ -19,14 +19,15 @@
 package org.oxycblt.auxio.music.metadata
 
 import androidx.core.text.isDigitsOnly
-import com.google.android.exoplayer2.MediaItem
+import androidx.media3.common.MediaItem
-import com.google.android.exoplayer2.MetadataRetriever
+import androidx.media3.exoplayer.MetadataRetriever
-import com.google.android.exoplayer2.source.MediaSource
+import androidx.media3.exoplayer.source.MediaSource
-import com.google.android.exoplayer2.source.TrackGroupArray
+import androidx.media3.exoplayer.source.TrackGroupArray
 import java.util.concurrent.Future
 import javax.inject.Inject
-import org.oxycblt.auxio.music.model.RawSong
+import org.oxycblt.auxio.music.device.RawSong
-import org.oxycblt.auxio.music.storage.toAudioUri
+import org.oxycblt.auxio.music.fs.toAudioUri
+import org.oxycblt.auxio.music.info.Date
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logW
 
@@ -56,14 +57,26 @@ interface TagWorker {
     }
 }
 
-class TagWorkerImpl
+class TagWorkerFactoryImpl
-private constructor(private val rawSong: RawSong, private val future: Future<TrackGroupArray>) :
+@Inject
-    TagWorker {
+constructor(private val mediaSourceFactory: MediaSource.Factory) : TagWorker.Factory {
-    /**
+    override fun create(rawSong: RawSong): TagWorker =
-     * Try to get a completed song from this [TagWorker], if it has finished processing.
+        // Note that we do not leverage future callbacks. This is because errors in the
-     *
+        // (highly fallible) extraction process will not bubble up to Indexer when a
-     * @return A [RawSong] instance if processing has completed, null otherwise.
+        // listener is used, instead crashing the app entirely.
-     */
+        TagWorkerImpl(
+            rawSong,
+            MetadataRetriever.retrieveMetadata(
+                mediaSourceFactory,
+                MediaItem.fromUri(
+                    requireNotNull(rawSong.mediaStoreId) { "Invalid raw: No id" }.toAudioUri())))
+}
+
+private class TagWorkerImpl(
+    private val rawSong: RawSong,
+    private val future: Future<TrackGroupArray>
+) : TagWorker {
+
     override fun poll(): RawSong? {
         if (!future.isDone) {
             // Not done yet, nothing to do.
@@ -95,12 +108,6 @@ private constructor(private val rawSong: RawSong, private val future: Future<Tra
         return rawSong
     }
 
-    /**
-     * Complete this instance's [RawSong] with ID3v2 Text Identification Frames.
-     *
-     * @param textFrames A mapping between ID3v2 Text Identification Frame IDs and one or more
-     *   values.
-     */
     private fun populateWithId3v2(textFrames: Map<String, List<String>>) {
         // Song
         textFrames["TXXX:musicbrainz release track id"]?.let { rawSong.musicBrainzId = it.first() }
@@ -123,6 +130,9 @@ private constructor(private val rawSong: RawSong, private val future: Future<Tra
         // 3. ID3v2.4 Release Date, as it is the second most common date type
         // 4. ID3v2.3 Original Date, as it is like #1
         // 5. ID3v2.3 Release Year, as it is the most common date type
+        // TODO: Show original and normal dates side-by-side
+        // TODO: Handle dates that are in "January" because the actual specific release date
+        //  isn't known?
         (textFrames["TDOR"]?.run { Date.from(first()) }
                 ?: textFrames["TDRC"]?.run { Date.from(first()) }
                     ?: textFrames["TDRL"]?.run { Date.from(first()) }
@@ -162,23 +172,15 @@ private constructor(private val rawSong: RawSong, private val future: Future<Tra
         (textFrames["TCMP"]
                 ?: textFrames["TXXX:compilation"] ?: textFrames["TXXX:itunescompilation"])
             ?.let {
+                // Ignore invalid instances of this tag
                 if (it.size != 1 || it[0] != "1") return@let
+                // Change the metadata to be a compilation album made by "Various Artists"
                 rawSong.albumArtistNames =
                     rawSong.albumArtistNames.ifEmpty { COMPILATION_ALBUM_ARTISTS }
                 rawSong.releaseTypes = rawSong.releaseTypes.ifEmpty { COMPILATION_RELEASE_TYPES }
             }
     }
 
-    /**
-     * Parses the ID3v2.3 timestamp specification into a [Date] from the given Text Identification
-     * Frames.
-     *
-     * @param textFrames A mapping between ID3v2 Text Identification Frame IDs and one or more
-     *   values.
-     * @return A [Date] of a year value from TORY/TYER, a month and day value from TDAT, and a
-     *   hour/minute value from TIME. No second value is included. The latter two fields may not be
-     *   included in they cannot be parsed. Will be null if a year value could not be parsed.
-     */
     private fun parseId3v23Date(textFrames: Map<String, List<String>>): Date? {
         // Assume that TDAT/TIME can refer to TYER or TORY depending on if TORY
         // is present.
@@ -212,11 +214,6 @@ private constructor(private val rawSong: RawSong, private val future: Future<Tra
         }
     }
 
-    /**
-     * Complete this instance's [RawSong] with Vorbis comments.
-     *
-     * @param comments A mapping between vorbis comment names and one or more vorbis comment values.
-     */
     private fun populateWithVorbis(comments: Map<String, List<String>>) {
         // Song
         comments["musicbrainz_releasetrackid"]?.let { rawSong.musicBrainzId = it.first() }
@@ -270,28 +267,15 @@ private constructor(private val rawSong: RawSong, private val future: Future<Tra
 
         // Compilation Flag
         (comments["compilation"] ?: comments["itunescompilation"])?.let {
+            // Ignore invalid instances of this tag
             if (it.size != 1 || it[0] != "1") return@let
+            // Change the metadata to be a compilation album made by "Various Artists"
             rawSong.albumArtistNames =
                 rawSong.albumArtistNames.ifEmpty { COMPILATION_ALBUM_ARTISTS }
             rawSong.releaseTypes = rawSong.releaseTypes.ifEmpty { COMPILATION_RELEASE_TYPES }
         }
     }
 
-    class Factory @Inject constructor(private val mediaSourceFactory: MediaSource.Factory) :
-        TagWorker.Factory {
-        override fun create(rawSong: RawSong) =
-            // Note that we do not leverage future callbacks. This is because errors in the
-            // (highly fallible) extraction process will not bubble up to Indexer when a
-            // listener is used, instead crashing the app entirely.
-            TagWorkerImpl(
-                rawSong,
-                MetadataRetriever.retrieveMetadata(
-                    mediaSourceFactory,
-                    MediaItem.fromUri(
-                        requireNotNull(rawSong.mediaStoreId) { "Invalid raw: No id" }
-                            .toAudioUri())))
-    }
-
     private companion object {
         val COMPILATION_ALBUM_ARTISTS = listOf("Various Artists")
         val COMPILATION_RELEASE_TYPES = listOf("compilation")

app/src/main/java/org/oxycblt/auxio/music/metadata/TextTags.kt

@@ -18,10 +18,10 @@
  
 package org.oxycblt.auxio.music.metadata
 
-import com.google.android.exoplayer2.metadata.Metadata
+import androidx.media3.common.Metadata
-import com.google.android.exoplayer2.metadata.id3.InternalFrame
+import androidx.media3.extractor.metadata.id3.InternalFrame
-import com.google.android.exoplayer2.metadata.id3.TextInformationFrame
+import androidx.media3.extractor.metadata.id3.TextInformationFrame
-import com.google.android.exoplayer2.metadata.vorbis.VorbisComment
+import androidx.media3.extractor.metadata.vorbis.VorbisComment
 
 /**
  * Processing wrapper for [Metadata] that allows organized access to text-based audio tags.

app/src/main/java/org/oxycblt/auxio/music/picker/AddToPlaylistDialog.kt

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * AddToPlaylistDialog.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import androidx.appcompat.app.AlertDialog
+import androidx.fragment.app.activityViewModels
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import androidx.recyclerview.widget.ConcatAdapter
+import androidx.recyclerview.widget.RecyclerView
+import dagger.hilt.android.AndroidEntryPoint
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.DialogMusicChoicesBinding
+import org.oxycblt.auxio.list.ClickableListListener
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.collectImmediately
+import org.oxycblt.auxio.util.showToast
+
+/**
+ * A dialog that allows the user to pick a specific playlist to add song(s) to.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+@AndroidEntryPoint
+class AddToPlaylistDialog :
+    ViewBindingDialogFragment<DialogMusicChoicesBinding>(),
+    ClickableListListener<PlaylistChoice>,
+    NewPlaylistFooterAdapter.Listener {
+    private val musicModel: MusicViewModel by activityViewModels()
+    private val pickerModel: PlaylistPickerViewModel by viewModels()
+    // Information about what playlist to name for is initially within the navigation arguments
+    // as UIDs, as that is the only safe way to parcel playlist information.
+    private val args: AddToPlaylistDialogArgs by navArgs()
+    private val choiceAdapter = PlaylistChoiceAdapter(this)
+    private val footerAdapter = NewPlaylistFooterAdapter(this)
+
+    override fun onConfigDialog(builder: AlertDialog.Builder) {
+        builder.setTitle(R.string.lbl_playlists).setNegativeButton(R.string.lbl_cancel, null)
+    }
+
+    override fun onCreateBinding(inflater: LayoutInflater) =
+        DialogMusicChoicesBinding.inflate(inflater)
+
+    override fun onBindingCreated(binding: DialogMusicChoicesBinding, savedInstanceState: Bundle?) {
+        super.onBindingCreated(binding, savedInstanceState)
+
+        binding.choiceRecycler.apply {
+            itemAnimator = null
+            adapter = ConcatAdapter(choiceAdapter, footerAdapter)
+        }
+
+        // --- VIEWMODEL SETUP ---
+        pickerModel.setSongsToAdd(args.songUids)
+        collectImmediately(pickerModel.currentSongsToAdd, ::updatePendingSongs)
+        collectImmediately(pickerModel.playlistAddChoices, ::updatePlaylistChoices)
+    }
+
+    override fun onDestroyBinding(binding: DialogMusicChoicesBinding) {
+        super.onDestroyBinding(binding)
+        binding.choiceRecycler.adapter = null
+    }
+
+    override fun onClick(item: PlaylistChoice, viewHolder: RecyclerView.ViewHolder) {
+        musicModel.addToPlaylist(pickerModel.currentSongsToAdd.value ?: return, item.playlist)
+        requireContext().showToast(R.string.lng_playlist_added)
+        findNavController().navigateUp()
+    }
+
+    override fun onNewPlaylist() {
+        musicModel.createPlaylist(songs = pickerModel.currentSongsToAdd.value ?: return)
+    }
+
+    private fun updatePendingSongs(songs: List<Song>?) {
+        if (songs == null) {
+            // No songs to feasibly add to a playlist, leave.
+            findNavController().navigateUp()
+        }
+    }
+
+    private fun updatePlaylistChoices(choices: List<PlaylistChoice>) {
+        choiceAdapter.update(choices, null)
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/picker/DeletePlaylistDialog.kt

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * DeletePlaylistDialog.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import androidx.appcompat.app.AlertDialog
+import androidx.fragment.app.activityViewModels
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import dagger.hilt.android.AndroidEntryPoint
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.DialogDeletePlaylistBinding
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.collectImmediately
+import org.oxycblt.auxio.util.showToast
+import org.oxycblt.auxio.util.unlikelyToBeNull
+
+/**
+ * A [ViewBindingDialogFragment] that asks the user to confirm the deletion of a [Playlist].
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+@AndroidEntryPoint
+class DeletePlaylistDialog : ViewBindingDialogFragment<DialogDeletePlaylistBinding>() {
+    private val pickerModel: PlaylistPickerViewModel by viewModels()
+    private val musicModel: MusicViewModel by activityViewModels()
+    // Information about what playlist to name for is initially within the navigation arguments
+    // as UIDs, as that is the only safe way to parcel playlist information.
+    private val args: DeletePlaylistDialogArgs by navArgs()
+
+    override fun onConfigDialog(builder: AlertDialog.Builder) {
+        builder
+            .setTitle(R.string.lbl_confirm_delete_playlist)
+            .setPositiveButton(R.string.lbl_delete) { _, _ ->
+                // Now we can delete the playlist for-real this time.
+                musicModel.deletePlaylist(
+                    unlikelyToBeNull(pickerModel.currentPlaylistToDelete.value), rude = true)
+                requireContext().showToast(R.string.lng_playlist_deleted)
+            }
+            .setNegativeButton(R.string.lbl_cancel, null)
+    }
+
+    override fun onCreateBinding(inflater: LayoutInflater) =
+        DialogDeletePlaylistBinding.inflate(inflater)
+
+    override fun onBindingCreated(
+        binding: DialogDeletePlaylistBinding,
+        savedInstanceState: Bundle?
+    ) {
+        super.onBindingCreated(binding, savedInstanceState)
+
+        // --- VIEWMODEL SETUP ---
+        pickerModel.setPlaylistToDelete(args.playlistUid)
+        collectImmediately(pickerModel.currentPlaylistToDelete, ::updatePlaylistToDelete)
+    }
+
+    private fun updatePlaylistToDelete(playlist: Playlist?) {
+        if (playlist == null) {
+            // Playlist does not exist anymore, leave
+            findNavController().navigateUp()
+            return
+        }
+
+        requireBinding().deletionInfo.text =
+            getString(R.string.fmt_deletion_info, playlist.name.resolve(requireContext()))
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/picker/NewPlaylistDialog.kt

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * NewPlaylistDialog.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import androidx.appcompat.app.AlertDialog
+import androidx.core.widget.addTextChangedListener
+import androidx.fragment.app.activityViewModels
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import dagger.hilt.android.AndroidEntryPoint
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.DialogPlaylistNameBinding
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.collectImmediately
+import org.oxycblt.auxio.util.showToast
+import org.oxycblt.auxio.util.unlikelyToBeNull
+
+/**
+ * A dialog allowing the name of a new playlist to be chosen before committing it to the database.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+@AndroidEntryPoint
+class NewPlaylistDialog : ViewBindingDialogFragment<DialogPlaylistNameBinding>() {
+    private val musicModel: MusicViewModel by activityViewModels()
+    private val pickerModel: PlaylistPickerViewModel by viewModels()
+    // Information about what playlist to name for is initially within the navigation arguments
+    // as UIDs, as that is the only safe way to parcel playlist information.
+    private val args: NewPlaylistDialogArgs by navArgs()
+
+    override fun onConfigDialog(builder: AlertDialog.Builder) {
+        builder
+            .setTitle(R.string.lbl_new_playlist)
+            .setPositiveButton(R.string.lbl_ok) { _, _ ->
+                val pendingPlaylist = unlikelyToBeNull(pickerModel.currentPendingPlaylist.value)
+                val name =
+                    when (val chosenName = pickerModel.chosenName.value) {
+                        is ChosenName.Valid -> chosenName.value
+                        is ChosenName.Empty -> pendingPlaylist.preferredName
+                        else -> throw IllegalStateException()
+                    }
+                // TODO: Navigate to playlist if there are songs in it
+                musicModel.createPlaylist(name, pendingPlaylist.songs)
+                requireContext().showToast(R.string.lng_playlist_created)
+                findNavController().apply {
+                    navigateUp()
+                    // Do an additional navigation away from the playlist addition dialog, if
+                    // needed. If that dialog isn't present, this should be a no-op. Hopefully.
+                    navigateUp()
+                }
+            }
+            .setNegativeButton(R.string.lbl_cancel, null)
+    }
+
+    override fun onCreateBinding(inflater: LayoutInflater) =
+        DialogPlaylistNameBinding.inflate(inflater)
+
+    override fun onBindingCreated(binding: DialogPlaylistNameBinding, savedInstanceState: Bundle?) {
+        super.onBindingCreated(binding, savedInstanceState)
+
+        // --- UI SETUP ---
+        binding.playlistName.addTextChangedListener { pickerModel.updateChosenName(it?.toString()) }
+
+        // --- VIEWMODEL SETUP ---
+        pickerModel.setPendingPlaylist(requireContext(), args.songUids)
+        collectImmediately(pickerModel.currentPendingPlaylist, ::updatePendingPlaylist)
+        collectImmediately(pickerModel.chosenName, ::updateChosenName)
+    }
+
+    private fun updatePendingPlaylist(pendingPlaylist: PendingPlaylist?) {
+        if (pendingPlaylist == null) {
+            findNavController().navigateUp()
+            return
+        }
+
+        requireBinding().playlistName.hint = pendingPlaylist.preferredName
+    }
+
+    private fun updateChosenName(chosenName: ChosenName) {
+        (dialog as AlertDialog).getButton(AlertDialog.BUTTON_POSITIVE)?.isEnabled =
+            chosenName is ChosenName.Valid || chosenName is ChosenName.Empty
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/picker/NewPlaylistFooterAdapter.kt

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * NewPlaylistFooterAdapter.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.view.View
+import android.view.ViewGroup
+import androidx.recyclerview.widget.RecyclerView
+import org.oxycblt.auxio.databinding.ItemNewPlaylistChoiceBinding
+import org.oxycblt.auxio.list.recycler.DialogRecyclerView
+import org.oxycblt.auxio.util.inflater
+
+/**
+ * A purely-visual [RecyclerView.Adapter] that acts as a footer providing a "New Playlist" choice in
+ * [AddToPlaylistDialog].
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class NewPlaylistFooterAdapter(private val listener: Listener) :
+    RecyclerView.Adapter<NewPlaylistFooterViewHolder>() {
+    override fun getItemCount() = 1
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+        NewPlaylistFooterViewHolder.from(parent)
+
+    override fun onBindViewHolder(holder: NewPlaylistFooterViewHolder, position: Int) {
+        holder.bind(listener)
+    }
+
+    /** A listener for [NewPlaylistFooterAdapter] interactions. */
+    interface Listener {
+        /**
+         * Called when the footer has been pressed, requesting to create a new playlist to add to.
+         */
+        fun onNewPlaylist()
+    }
+}
+
+/**
+ * A [RecyclerView.ViewHolder] that displays a "New Playlist" choice in [NewPlaylistFooterAdapter].
+ * Use [from] to create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class NewPlaylistFooterViewHolder
+private constructor(private val binding: ItemNewPlaylistChoiceBinding) :
+    DialogRecyclerView.ViewHolder(binding.root) {
+    /**
+     * Bind new data to this instance.
+     *
+     * @param listener A [NewPlaylistFooterAdapter.Listener] to bind interactions to.
+     */
+    fun bind(listener: NewPlaylistFooterAdapter.Listener) {
+        binding.root.setOnClickListener { listener.onNewPlaylist() }
+    }
+
+    companion object {
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) =
+            NewPlaylistFooterViewHolder(
+                ItemNewPlaylistChoiceBinding.inflate(parent.context.inflater))
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/picker/PlaylistChoiceAdapter.kt

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistChoiceAdapter.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.view.View
+import android.view.ViewGroup
+import org.oxycblt.auxio.databinding.ItemPickerChoiceBinding
+import org.oxycblt.auxio.list.ClickableListListener
+import org.oxycblt.auxio.list.adapter.FlexibleListAdapter
+import org.oxycblt.auxio.list.adapter.SimpleDiffCallback
+import org.oxycblt.auxio.list.recycler.DialogRecyclerView
+import org.oxycblt.auxio.util.context
+import org.oxycblt.auxio.util.inflater
+
+/**
+ * A [FlexibleListAdapter] that displays a list of [PlaylistChoice] options to select from in
+ * [AddToPlaylistDialog].
+ *
+ * @param listener [ClickableListListener] to bind interactions to.
+ */
+class PlaylistChoiceAdapter(val listener: ClickableListListener<PlaylistChoice>) :
+    FlexibleListAdapter<PlaylistChoice, PlaylistChoiceViewHolder>(
+        PlaylistChoiceViewHolder.DIFF_CALLBACK) {
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+        PlaylistChoiceViewHolder.from(parent)
+
+    override fun onBindViewHolder(holder: PlaylistChoiceViewHolder, position: Int) {
+        holder.bind(getItem(position), listener)
+    }
+}
+
+/**
+ * A [DialogRecyclerView.ViewHolder] that displays an individual playlist choice. Use [from] to
+ * create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class PlaylistChoiceViewHolder private constructor(private val binding: ItemPickerChoiceBinding) :
+    DialogRecyclerView.ViewHolder(binding.root) {
+    fun bind(choice: PlaylistChoice, listener: ClickableListListener<PlaylistChoice>) {
+        listener.bind(choice, this)
+        binding.pickerImage.apply {
+            bind(choice.playlist)
+            isActivated = choice.alreadyAdded
+        }
+        binding.pickerName.text = choice.playlist.name.resolve(binding.context)
+    }
+
+    companion object {
+        /**
+         * Create a new instance.
+         *
+         * @param parent The parent to inflate this instance from.
+         * @return A new instance.
+         */
+        fun from(parent: View) =
+            PlaylistChoiceViewHolder(ItemPickerChoiceBinding.inflate(parent.context.inflater))
+
+        /** A comparator that can be used with DiffUtil. */
+        val DIFF_CALLBACK =
+            object : SimpleDiffCallback<PlaylistChoice>() {
+                override fun areContentsTheSame(oldItem: PlaylistChoice, newItem: PlaylistChoice) =
+                    oldItem.playlist.name == newItem.playlist.name &&
+                        oldItem.alreadyAdded == newItem.alreadyAdded
+            }
+    }
+}

app/src/main/java/org/oxycblt/auxio/music/picker/PlaylistPickerViewModel.kt

@@ -0,0 +1,232 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * PlaylistPickerViewModel.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.content.Context
+import androidx.lifecycle.ViewModel
+import dagger.hilt.android.lifecycle.HiltViewModel
+import javax.inject.Inject
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.list.Item
+import org.oxycblt.auxio.list.Sort
+import org.oxycblt.auxio.music.Music
+import org.oxycblt.auxio.music.MusicRepository
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.music.Song
+
+/**
+ * A [ViewModel] managing the state of the playlist picker dialogs.
+ *
+ * @author Alexander Capehart
+ */
+@HiltViewModel
+class PlaylistPickerViewModel @Inject constructor(private val musicRepository: MusicRepository) :
+    ViewModel(), MusicRepository.UpdateListener {
+    private val _currentPendingPlaylist = MutableStateFlow<PendingPlaylist?>(null)
+    /** A new [Playlist] having it's name chosen by the user. Null if none yet. */
+    val currentPendingPlaylist: StateFlow<PendingPlaylist?>
+        get() = _currentPendingPlaylist
+
+    private val _currentPlaylistToRename = MutableStateFlow<Playlist?>(null)
+    /** An existing [Playlist] that is being renamed. Null if none yet. */
+    val currentPlaylistToRename: StateFlow<Playlist?>
+        get() = _currentPlaylistToRename
+
+    private val _currentPlaylistToDelete = MutableStateFlow<Playlist?>(null)
+    /** The current [Playlist] that needs it's deletion confirmed. Null if none yet. */
+    val currentPlaylistToDelete: StateFlow<Playlist?>
+        get() = _currentPlaylistToDelete
+
+    private val _chosenName = MutableStateFlow<ChosenName>(ChosenName.Empty)
+    /** The users chosen name for [currentPendingPlaylist] or [currentPlaylistToRename]. */
+    val chosenName: StateFlow<ChosenName>
+        get() = _chosenName
+
+    private val _currentSongsToAdd = MutableStateFlow<List<Song>?>(null)
+    /** A batch of [Song]s to add to a playlist chosen by the user. Null if none yet. */
+    val currentSongsToAdd: StateFlow<List<Song>?>
+        get() = _currentSongsToAdd
+
+    private val _playlistAddChoices = MutableStateFlow<List<PlaylistChoice>>(listOf())
+    /** The [Playlist]s that [currentSongsToAdd] could be added to. */
+    val playlistAddChoices: StateFlow<List<PlaylistChoice>>
+        get() = _playlistAddChoices
+
+    init {
+        musicRepository.addUpdateListener(this)
+    }
+
+    override fun onMusicChanges(changes: MusicRepository.Changes) {
+        var refreshChoicesWith: List<Song>? = null
+        val deviceLibrary = musicRepository.deviceLibrary
+        if (changes.deviceLibrary && deviceLibrary != null) {
+            _currentPendingPlaylist.value =
+                _currentPendingPlaylist.value?.let { pendingPlaylist ->
+                    PendingPlaylist(
+                        pendingPlaylist.preferredName,
+                        pendingPlaylist.songs.mapNotNull { deviceLibrary.findSong(it.uid) })
+                }
+            _currentSongsToAdd.value =
+                _currentSongsToAdd.value?.let { pendingSongs ->
+                    pendingSongs
+                        .mapNotNull { deviceLibrary.findSong(it.uid) }
+                        .ifEmpty { null }
+                        .also { refreshChoicesWith = it }
+                }
+        }
+
+        val chosenName = _chosenName.value
+        if (changes.userLibrary) {
+            when (chosenName) {
+                is ChosenName.Valid -> updateChosenName(chosenName.value)
+                is ChosenName.AlreadyExists -> updateChosenName(chosenName.prior)
+                else -> {
+                    // Nothing to do.
+                }
+            }
+            refreshChoicesWith = refreshChoicesWith ?: _currentSongsToAdd.value
+        }
+
+        refreshChoicesWith?.let(::refreshPlaylistChoices)
+    }
+
+    override fun onCleared() {
+        musicRepository.removeUpdateListener(this)
+    }
+
+    /**
+     * Set a new [currentPendingPlaylist] from a new batch of pending [Song] [Music.UID]s.
+     *
+     * @param context [Context] required to generate a playlist name.
+     * @param songUids The [Music.UID]s of songs to be present in the playlist.
+     */
+    fun setPendingPlaylist(context: Context, songUids: Array<Music.UID>) {
+        val deviceLibrary = musicRepository.deviceLibrary ?: return
+        val songs = songUids.mapNotNull(deviceLibrary::findSong)
+
+        val userLibrary = musicRepository.userLibrary ?: return
+        var i = 1
+        while (true) {
+            val possibleName = context.getString(R.string.fmt_def_playlist, i)
+            if (userLibrary.playlists.none { it.name.resolve(context) == possibleName }) {
+                _currentPendingPlaylist.value = PendingPlaylist(possibleName, songs)
+                return
+            }
+            ++i
+        }
+    }
+
+    /**
+     * Set a new [currentPlaylistToRename] from a [Playlist] [Music.UID].
+     *
+     * @param playlistUid The [Music.UID]s of the [Playlist] to rename.
+     */
+    fun setPlaylistToRename(playlistUid: Music.UID) {
+        _currentPlaylistToRename.value = musicRepository.userLibrary?.findPlaylist(playlistUid)
+    }
+
+    /**
+     * Set a new [currentPendingPlaylist] from a new [Playlist] [Music.UID].
+     *
+     * @param playlistUid The [Music.UID] of the [Playlist] to delete.
+     */
+    fun setPlaylistToDelete(playlistUid: Music.UID) {
+        _currentPlaylistToDelete.value = musicRepository.userLibrary?.findPlaylist(playlistUid)
+    }
+
+    /**
+     * Update the current [chosenName] based on new user input.
+     *
+     * @param name The new user-inputted name, or null if not present.
+     */
+    fun updateChosenName(name: String?) {
+        _chosenName.value =
+            when {
+                name.isNullOrEmpty() -> ChosenName.Empty
+                name.isBlank() -> ChosenName.Blank
+                else -> {
+                    val trimmed = name.trim()
+                    val userLibrary = musicRepository.userLibrary
+                    if (userLibrary != null && userLibrary.findPlaylist(trimmed) == null) {
+                        ChosenName.Valid(trimmed)
+                    } else {
+                        ChosenName.AlreadyExists(trimmed)
+                    }
+                }
+            }
+    }
+
+    /**
+     * Set a new [currentSongsToAdd] from a new batch of pending [Song] [Music.UID]s.
+     *
+     * @param songUids The [Music.UID]s of songs to add to a playlist.
+     */
+    fun setSongsToAdd(songUids: Array<Music.UID>) {
+        val deviceLibrary = musicRepository.deviceLibrary ?: return
+        val songs = songUids.mapNotNull(deviceLibrary::findSong)
+        _currentSongsToAdd.value = songs
+        refreshPlaylistChoices(songs)
+    }
+
+    private fun refreshPlaylistChoices(songs: List<Song>) {
+        val userLibrary = musicRepository.userLibrary ?: return
+        _playlistAddChoices.value =
+            Sort(Sort.Mode.ByName, Sort.Direction.ASCENDING).playlists(userLibrary.playlists).map {
+                val songSet = it.songs.toSet()
+                PlaylistChoice(it, songs.all(songSet::contains))
+            }
+    }
+}
+
+/**
+ * Represents a playlist that will be created as soon as a name is chosen.
+ *
+ * @param preferredName The name to be used by default if no other name is chosen.
+ * @param songs The [Song]s to be contained in the [PendingPlaylist]
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+data class PendingPlaylist(val preferredName: String, val songs: List<Song>)
+
+/**
+ * Represents the (processed) user input from the playlist naming dialogs.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+sealed interface ChosenName {
+    /** The current name is valid. */
+    data class Valid(val value: String) : ChosenName
+    /** The current name already exists. */
+    data class AlreadyExists(val prior: String) : ChosenName
+    /** The current name is empty. */
+    object Empty : ChosenName
+    /** The current name only consists of whitespace. */
+    object Blank : ChosenName
+}
+
+/**
+ * An individual [Playlist] choice to add [Song]s to.
+ *
+ * @param playlist The [Playlist] represented.
+ * @param alreadyAdded Whether the songs currently pending addition have already been added to the
+ *   [Playlist].
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+data class PlaylistChoice(val playlist: Playlist, val alreadyAdded: Boolean) : Item

app/src/main/java/org/oxycblt/auxio/music/picker/RenamePlaylistDialog.kt

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ * RenamePlaylistDialog.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.music.picker
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import androidx.appcompat.app.AlertDialog
+import androidx.core.widget.addTextChangedListener
+import androidx.fragment.app.activityViewModels
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import dagger.hilt.android.AndroidEntryPoint
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.databinding.DialogPlaylistNameBinding
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.Playlist
+import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.collectImmediately
+import org.oxycblt.auxio.util.showToast
+import org.oxycblt.auxio.util.unlikelyToBeNull
+
+/**
+ * A dialog allowing the name of a new playlist to be chosen before committing it to the database.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+@AndroidEntryPoint
+class RenamePlaylistDialog : ViewBindingDialogFragment<DialogPlaylistNameBinding>() {
+    private val musicModel: MusicViewModel by activityViewModels()
+    private val pickerModel: PlaylistPickerViewModel by viewModels()
+    // Information about what playlist to name for is initially within the navigation arguments
+    // as UIDs, as that is the only safe way to parcel playlist information.
+    private val args: RenamePlaylistDialogArgs by navArgs()
+    private var initializedField = false
+
+    override fun onConfigDialog(builder: AlertDialog.Builder) {
+        builder
+            .setTitle(R.string.lbl_rename_playlist)
+            .setPositiveButton(R.string.lbl_ok) { _, _ ->
+                val playlist = unlikelyToBeNull(pickerModel.currentPlaylistToRename.value)
+                val chosenName = pickerModel.chosenName.value as ChosenName.Valid
+                musicModel.renamePlaylist(playlist, chosenName.value)
+                requireContext().showToast(R.string.lng_playlist_renamed)
+                findNavController().navigateUp()
+            }
+            .setNegativeButton(R.string.lbl_cancel, null)
+    }
+
+    override fun onCreateBinding(inflater: LayoutInflater) =
+        DialogPlaylistNameBinding.inflate(inflater)
+
+    override fun onBindingCreated(binding: DialogPlaylistNameBinding, savedInstanceState: Bundle?) {
+        super.onBindingCreated(binding, savedInstanceState)
+
+        // --- UI SETUP ---
+        binding.playlistName.addTextChangedListener { pickerModel.updateChosenName(it?.toString()) }
+
+        // --- VIEWMODEL SETUP ---
+        pickerModel.setPlaylistToRename(args.playlistUid)
+        collectImmediately(pickerModel.currentPlaylistToRename, ::updatePlaylistToRename)
+        collectImmediately(pickerModel.chosenName, ::updateChosenName)
+    }
+
+    private fun updatePlaylistToRename(playlist: Playlist?) {
+        if (playlist == null) {
+            // Nothing to rename anymore.
+            findNavController().navigateUp()
+            return
+        }
+
+        if (!initializedField) {
+            requireBinding().playlistName.setText(playlist.name.resolve(requireContext()))
+            initializedField = true
+        }
+    }
+
+    private fun updateChosenName(chosenName: ChosenName) {
+        (dialog as AlertDialog).getButton(AlertDialog.BUTTON_POSITIVE)?.isEnabled =
+            chosenName is ChosenName.Valid
+    }
+}