Merge pull request #310 from OxygenCobalt/dev

Version 3.0.1

.github/ISSUE_TEMPLATE/bug-crash-report.yml

@@ -72,6 +72,8 @@ body:
             - `./adb -d logcat AndroidRuntime:E *:S` in the case of a crash
         5. Copy and paste the output to this area of the issue.
       render: shell
+    validations:
+      required: true
   - type: checkboxes
     id: terms
     attributes:

.github/workflows/android.yml

@@ -0,0 +1,38 @@
+name: Android CI
+
+on:
+  push:
+    branches: [ "dev" ]
+  pull_request:
+    branches: [ "dev" ]
+    
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up JDK 11
+      uses: actions/setup-java@v3
+      with:
+        java-version: '11'
+        distribution: 'temurin'
+        cache: gradle
+    - name: Set up NDK r21e
+      uses: nttld/setup-ndk@v1.2.0
+      id: setup-ndk
+      with:
+        ndk-version: r21e
+        add-to-path: false
+    - run: python3 prebuild.py
+      env:
+        ANDROID_NDK_HOME: ${{ steps.setup-ndk.outputs.ndk-path }}
+    - name: Grant execute permission for gradlew
+      run: chmod +x gradlew
+    - name: Build debug APK with Gradle
+      run: ./gradlew app:packageDebug
+    - name: Upload debug APK artifact
+      uses: actions/upload-artifact@v3.1.1
+      with:
+        name: Auxio_Canary
+        path: ./app/build/outputs/apk/debug/app-debug.apk

CHANGELOG.md

@@ -1,6 +1,26 @@
 # Changelog
 
-## dev
+## 3.0.1
+
+#### What's New
+- Added support for album date ranges (ex. 2010 - 2013)
+
+#### What's Improved
+- Formalized whitespace handling
+- Value lists are now properly localized
+- Queue no longer primarily shows previous songs when opened
+- Added reset button to ReplayGain pre-amp configuration dialog 
+
+#### What's Changed
+- R128 ReplayGain tags are now only used when playing OPUS files
+
+#### What's Fixed
+- Fixed mangled multi-value ID3v2 tags when UTF-16 is used
+- Fixed crash when playing certain MP3 files
+- Detail UI will no longer crash if the music library is unavailable
+
+#### Dev/Meta
+- Add CI workflow
 
 ## 3.0.0
 
@@ -12,7 +32,7 @@
 	- Added setting to hide "collaborator" artists
 - Upgraded music ID management:
 	- Added support for MusicBrainz IDs (MBIDs)
-	- Use the more unique MD5 hash of metadata when MBIDs can't be used
+	- Use a more unique hash of metadata when MBIDs can't be used
 - Genres now display a list of artists
 - Added toggle to load non-music (Such as podcasts)
 - Music loader now caches parsed metadata for faster load times
@@ -42,7 +62,6 @@ audio focus was lost
 
 #### What's Changed
 - Ignore MediaStore tags is now Auxio's default and unchangeable behavior. The option has been removed.
-- Removed the "Play from genre" option in the library/detail playback mode settings+
 - "Use alternate notification action" is now "Custom notification action"
 - "Show covers" and "Ignore MediaStore covers" have been unified into "Album covers"
 

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/v3.0.0">
+    <a href="https://github.com/oxygencobalt/Auxio/releases/tag/v3.0.1">
-        <img alt="Latest Version" src="https://img.shields.io/static/v1?label=tag&message=v3.0.0&color=0D5AF5">
+        <img alt="Latest Version" src="https://img.shields.io/static/v1?label=tag&message=v3.0.1&color=0D5AF5">
     </a>
     <a href="https://github.com/oxygencobalt/Auxio/releases/">
         <img alt="Releases" src="https://img.shields.io/github/downloads/OxygenCobalt/Auxio/total.svg">
@@ -79,7 +79,9 @@ Auxio relies on a custom version of ExoPlayer that enables some extra features.
 
 Auxio accepts most contributions as long as they follow the [Contribution Guidelines](/.github/CONTRIBUTING.md).
 
-However, feature additions and major UI changes are less likely to be accepted. See [Accepted Additions](/info/ADDITIONS.md) for more information.
+However, feature additions and major UI changes are less likely to be accepted. See
+[Why Are These Features Missing?](https://github.com/OxygenCobalt/Auxio/wiki/Why-Are-These-Features-Missing%3F)
+for more information.
 
 ## License
 

app/build.gradle

@@ -12,8 +12,8 @@ android {
 
     defaultConfig {
         applicationId namespace
-        versionName "3.0.0"
+        versionName "3.0.1"
-        versionCode 24
+        versionCode 25
 
         minSdk 21
         targetSdk 33
@@ -121,3 +121,7 @@ spotless {
         licenseHeaderFile("NOTICE")
     }
 }
+
+afterEvaluate {
+    preDebugBuild.dependsOn spotlessApply
+}

app/proguard-rules.pro

@@ -21,5 +21,5 @@
 #-renamesourcefileattribute SourceFile
 
 # Obsfucation is what proprietary software does to keep the user unaware of it's abuses.
-# Also it's easier to debug if the class names remain unmangled.
+# Also it's easier to fix issues if the stack trace symbols remain unmangled.
 -dontobfuscate

app/src/main/AndroidManifest.xml

@@ -116,7 +116,7 @@
 <!--            </intent-filter>-->
 <!--        </receiver>-->
 
-        <!-- "Now Playing" widget.. -->
+        <!-- "Now Playing" widget. -->
         <receiver
             android:name=".widgets.WidgetProvider"
             android:exported="false"

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

@@ -42,20 +42,12 @@ import org.oxycblt.auxio.util.systemBarInsetsCompat
  *
  * TODO: Custom language support
  *
- * TODO: Add multi-select
- *
  * TODO: Use proper material attributes (Not the weird dimen attributes I currently have)
  *
  * TODO: Migrate to material animation system
  *
  * TODO: Unit testing
  *
- * TODO: Standardize from/new usage
- *
- * TODO: Standardize companion object usage
- *
- * TODO: Standardize callback/listener naming.
- *
  * @author Alexander Capehart (OxygenCobalt)
  */
 class MainActivity : AppCompatActivity() {
@@ -146,7 +138,7 @@ class MainActivity : AppCompatActivity() {
         return true
     }
 
-    companion object {
+    private companion object {
-        private const val KEY_INTENT_USED = BuildConfig.APPLICATION_ID + ".key.FILE_INTENT_USED"
+        const val KEY_INTENT_USED = BuildConfig.APPLICATION_ID + ".key.FILE_INTENT_USED"
     }
 }

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

@@ -37,7 +37,6 @@ import kotlin.math.max
 import kotlin.math.min
 import org.oxycblt.auxio.databinding.FragmentMainBinding
 import org.oxycblt.auxio.list.selection.SelectionViewModel
-import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.PlaybackBottomSheetBehavior
@@ -62,10 +61,8 @@ class MainFragment :
     private val selectionModel: SelectionViewModel by activityViewModels()
     private val callback = DynamicBackPressedCallback()
     private var lastInsets: WindowInsets? = null
+    private var elevationNormal = 0f
     private var initialNavDestinationChange = true
-    private val elevationNormal: Float by lifecycleObject { binding ->
-        binding.context.getDimen(R.dimen.elevation_normal)
-    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -78,6 +75,8 @@ class MainFragment :
     override fun onBindingCreated(binding: FragmentMainBinding, savedInstanceState: Bundle?) {
         super.onBindingCreated(binding, savedInstanceState)
 
+        elevationNormal = binding.context.getDimen(R.dimen.elevation_normal)
+
         // --- UI SETUP ---
         val context = requireActivity()
         // Override the back pressed listener so we can map back navigation to collapsing
@@ -217,7 +216,7 @@ class MainFragment :
             lastInsets?.let { translationY = it.systemBarInsetsCompat.top * halfOutRatio }
         }
 
-        // Prevent interactions when the playback panell fully fades out.
+        // Prevent interactions when the playback panel fully fades out.
         binding.playbackPanelFragment.isInvisible = binding.playbackPanelFragment.alpha == 0f
 
         binding.queueSheet.apply {

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

@@ -20,7 +20,7 @@ package org.oxycblt.auxio.detail
 import androidx.annotation.StringRes
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.storage.MimeType
+import org.oxycblt.auxio.music.filesystem.MimeType
 
 /**
  * A header variation that displays a button to open a sort menu.
@@ -35,21 +35,13 @@ data class SortHeader(@StringRes val titleRes: Int) : Item
 data class DiscHeader(val disc: Int) : Item
 
 /**
- * A [Song] extension that adds information about it's file properties.
+ * The properties of a [Song]'s file.
- * @param song The internal song
+ * @param bitrateKbps The bit rate, in kilobytes-per-second. Null if it could not be parsed.
- * @param properties The properties of the song file. Null if parsing is ongoing.
+ * @param sampleRateHz The sample rate, in hertz.
+ * @param resolvedMimeType The known mime type of the [Song] after it's file format was determined.
  */
-data class DetailSong(val song: Song, val properties: Properties?) {
+data class SongProperties(
-    /**
+    val bitrateKbps: Int?,
-     * The properties of a [Song]'s file.
+    val sampleRateHz: Int?,
-     * @param bitrateKbps The bit rate, in kilobytes-per-second. Null if it could not be parsed.
+    val resolvedMimeType: MimeType
-     * @param sampleRateHz The sample rate, in hertz.
+)
-     * @param resolvedMimeType The known mime type of the [Song] after it's file format was
-     * determined.
-     */
-    data class Properties(
-        val bitrateKbps: Int?,
-        val sampleRateHz: Int?,
-        val resolvedMimeType: MimeType
-    )
-}

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

@@ -31,13 +31,13 @@ import androidx.recyclerview.widget.RecyclerView
 import com.google.android.material.appbar.AppBarLayout
 import java.lang.reflect.Field
 import org.oxycblt.auxio.R
-import org.oxycblt.auxio.ui.AuxioAppBarLayout
+import org.oxycblt.auxio.ui.CoordinatorAppBarLayout
 import org.oxycblt.auxio.util.getInteger
 import org.oxycblt.auxio.util.lazyReflectedField
 
 /**
- * An [AuxioAppBarLayout] that displays the title of a hidden [Toolbar] when the scrolling view goes
+ * An [CoordinatorAppBarLayout] that displays the title of a hidden [Toolbar] when the scrolling
- * beyond it's first item.
+ * view goes beyond it's first item.
  *
  * This is intended for the detail views, in which the first item is the album/artist/genre header,
  * and thus scrolling past them should make the toolbar show the name in order to give context on
@@ -51,7 +51,7 @@ import org.oxycblt.auxio.util.lazyReflectedField
 class DetailAppBarLayout
 @JvmOverloads
 constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
-    AuxioAppBarLayout(context, attrs, defStyleAttr) {
+    CoordinatorAppBarLayout(context, attrs, defStyleAttr) {
     private var titleView: TextView? = null
     private var recycler: RecyclerView? = null
 
@@ -166,8 +166,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         }
     }
 
-    companion object {
+    private companion object {
-        private val TOOLBAR_TITLE_TEXT_FIELD: Field by
+        val TOOLBAR_TITLE_TEXT_FIELD: Field by lazyReflectedField(Toolbar::class, "mTitleTextView")
-            lazyReflectedField(Toolbar::class, "mTitleTextView")
     }
 }

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

@@ -39,7 +39,7 @@ import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.music.Sort
-import org.oxycblt.auxio.music.storage.MimeType
+import org.oxycblt.auxio.music.filesystem.MimeType
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.util.*
 
@@ -51,7 +51,7 @@ import org.oxycblt.auxio.util.*
  * @author Alexander Capehart (OxygenCobalt)
  */
 class DetailViewModel(application: Application) :
-    AndroidViewModel(application), MusicStore.Callback {
+    AndroidViewModel(application), MusicStore.Listener {
     private val musicStore = MusicStore.getInstance()
     private val settings = Settings(application)
 
@@ -59,15 +59,15 @@ class DetailViewModel(application: Application) :
 
     // --- SONG ---
 
-    private val _currentSong = MutableStateFlow<DetailSong?>(null)
+    private val _currentSong = MutableStateFlow<Song?>(null)
-    /**
+    /** The current [Song] to display. Null if there is nothing to show. */
-     * The current [DetailSong] to display. Null if there is nothing to show.
+    val currentSong: StateFlow<Song?>
-     *
-     * TODO: De-couple Song and Properties?
-     */
-    val currentSong: StateFlow<DetailSong?>
         get() = _currentSong
 
+    private val _songProperties = MutableStateFlow<SongProperties?>(null)
+    /** The [SongProperties] of the currently shown [Song]. Null if not loaded yet. */
+    val songProperties: StateFlow<SongProperties?> = _songProperties
+
     // --- ALBUM ---
 
     private val _currentAlbum = MutableStateFlow<Album?>(null)
@@ -130,11 +130,11 @@ class DetailViewModel(application: Application) :
         }
 
     init {
-        musicStore.addCallback(this)
+        musicStore.addListener(this)
     }
 
     override fun onCleared() {
-        musicStore.removeCallback(this)
+        musicStore.removeListener(this)
     }
 
     override fun onLibraryChanged(library: MusicStore.Library?) {
@@ -149,13 +149,8 @@ class DetailViewModel(application: Application) :
 
         val song = currentSong.value
         if (song != null) {
-            val newSong = library.sanitize(song.song)
+            _currentSong.value = library.sanitize(song)?.also(::loadProperties)
-            if (newSong != null) {
+            logD("Updated song to ${currentSong.value}")
-                loadDetailSong(newSong)
-            } else {
-                _currentSong.value = null
-            }
-            logD("Updated song to $newSong")
         }
 
         val album = currentAlbum.value
@@ -178,17 +173,17 @@ class DetailViewModel(application: Application) :
     }
 
     /**
-     * Set a new [currentSong] from it's [Music.UID]. If the [Music.UID] differs, a new loading
+     * Set a new [currentSong] from it's [Music.UID]. If the [Music.UID] differs, [currentSong]
-     * process will begin and the newly-loaded [DetailSong] will be set to [currentSong].
+     * and [songProperties] will 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) {
-        if (_currentSong.value?.run { song.uid } == uid) {
+        if (_currentSong.value?.uid == uid) {
             // Nothing to do.
             return
         }
         logD("Opening Song [uid: $uid]")
-        loadDetailSong(requireMusic(uid))
+        _currentSong.value = requireMusic<Song>(uid)?.also(::loadProperties)
     }
 
     /**
@@ -202,7 +197,7 @@ class DetailViewModel(application: Application) :
             return
         }
         logD("Opening Album [uid: $uid]")
-        _currentAlbum.value = requireMusic<Album>(uid).also { refreshAlbumList(it) }
+        _currentAlbum.value = requireMusic<Album>(uid)?.also(::refreshAlbumList)
     }
 
     /**
@@ -216,7 +211,7 @@ class DetailViewModel(application: Application) :
             return
         }
         logD("Opening Artist [uid: $uid]")
-        _currentArtist.value = requireMusic<Artist>(uid).also { refreshArtistList(it) }
+        _currentArtist.value = requireMusic<Artist>(uid)?.also(::refreshArtistList)
     }
 
     /**
@@ -230,29 +225,29 @@ class DetailViewModel(application: Application) :
             return
         }
         logD("Opening Genre [uid: $uid]")
-        _currentGenre.value = requireMusic<Genre>(uid).also { refreshGenreList(it) }
+        _currentGenre.value = requireMusic<Genre>(uid)?.also(::refreshGenreList)
     }
 
-    private fun <T : Music> requireMusic(uid: Music.UID): T =
+    private fun <T : Music> requireMusic(uid: Music.UID) = musicStore.library?.find<T>(uid)
-        requireNotNull(unlikelyToBeNull(musicStore.library).find(uid)) { "Invalid id provided" }
 
     /**
-     * Start a new job to load a [DetailSong] based on the properties of the given [Song]'s file.
+     * Start a new job to load a given [Song]'s [SongProperties]. Result is pushed to
+     * [songProperties].
      * @param song The song to load.
      */
-    private fun loadDetailSong(song: Song) {
+    private fun loadProperties(song: Song) {
         // Clear any previous job in order to avoid stale data from appearing in the UI.
         currentSongJob?.cancel()
-        _currentSong.value = DetailSong(song, null)
+        _songProperties.value = null
         currentSongJob =
             viewModelScope.launch(Dispatchers.IO) {
-                val info = loadProperties(song)
+                val properties = this@DetailViewModel.loadPropertiesImpl(song)
                 yield()
-                _currentSong.value = DetailSong(song, info)
+                _songProperties.value = properties
             }
     }
 
-    private fun loadProperties(song: Song): DetailSong.Properties {
+    private fun loadPropertiesImpl(song: Song): SongProperties {
         // 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.
@@ -266,7 +261,7 @@ class DetailViewModel(application: Application) :
             // that we can show.
             logW("Unable to extract song attributes.")
             logW(e.stackTraceToString())
-            return DetailSong.Properties(null, null, song.mimeType)
+            return SongProperties(null, null, song.mimeType)
         }
 
         // Get the first track from the extractor (This is basically always the only
@@ -310,7 +305,7 @@ class DetailViewModel(application: Application) :
                 MimeType(song.mimeType.fromExtension, formatMimeType)
             }
 
-        return DetailSong.Properties(bitrate, sampleRate, resolvedMimeType)
+        return SongProperties(bitrate, sampleRate, resolvedMimeType)
     }
 
     private fun refreshAlbumList(album: Album) {

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

@@ -26,6 +26,7 @@ import androidx.navigation.fragment.findNavController
 import androidx.navigation.fragment.navArgs
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogSongDetailBinding
+import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
 import org.oxycblt.auxio.util.androidActivityViewModels
@@ -53,10 +54,10 @@ class SongDetailDialog : ViewBindingDialogFragment<DialogSongDetailBinding>() {
         super.onBindingCreated(binding, savedInstanceState)
         // DetailViewModel handles most initialization from the navigation argument.
         detailModel.setSongUid(args.itemUid)
-        collectImmediately(detailModel.currentSong, ::updateSong)
+        collectImmediately(detailModel.currentSong, detailModel.songProperties, ::updateSong)
     }
 
-    private fun updateSong(song: DetailSong?) {
+    private fun updateSong(song: Song?, properties: SongProperties?) {
         if (song == null) {
             // Song we were showing no longer exists.
             findNavController().navigateUp()
@@ -64,28 +65,28 @@ class SongDetailDialog : ViewBindingDialogFragment<DialogSongDetailBinding>() {
         }
 
         val binding = requireBinding()
-        if (song.properties != null) {
+        if (properties != null) {
             // Finished loading Song properties, populate and show the list of Song information.
             binding.detailLoading.isInvisible = true
             binding.detailContainer.isInvisible = false
 
             val context = requireContext()
-            binding.detailFileName.setText(song.song.path.name)
+            binding.detailFileName.setText(song.path.name)
-            binding.detailRelativeDir.setText(song.song.path.parent.resolveName(context))
+            binding.detailRelativeDir.setText(song.path.parent.resolveName(context))
-            binding.detailFormat.setText(song.properties.resolvedMimeType.resolveName(context))
+            binding.detailFormat.setText(properties.resolvedMimeType.resolveName(context))
-            binding.detailSize.setText(Formatter.formatFileSize(context, song.song.size))
+            binding.detailSize.setText(Formatter.formatFileSize(context, song.size))
-            binding.detailDuration.setText(song.song.durationMs.formatDurationMs(true))
+            binding.detailDuration.setText(song.durationMs.formatDurationMs(true))
 
-            if (song.properties.bitrateKbps != null) {
+            if (properties.bitrateKbps != null) {
                 binding.detailBitrate.setText(
-                    getString(R.string.fmt_bitrate, song.properties.bitrateKbps))
+                    getString(R.string.fmt_bitrate, properties.bitrateKbps))
             } else {
                 binding.detailBitrate.setText(R.string.def_bitrate)
             }
 
-            if (song.properties.sampleRateHz != null) {
+            if (properties.sampleRateHz != null) {
                 binding.detailSampleRate.setText(
-                    getString(R.string.fmt_sample_rate, song.properties.sampleRateHz))
+                    getString(R.string.fmt_sample_rate, properties.sampleRateHz))
             } else {
                 binding.detailSampleRate.setText(R.string.def_sample_rate)
             }

app/src/main/java/org/oxycblt/auxio/detail/recycler/AlbumDetailAdapter.kt

@@ -67,9 +67,9 @@ class AlbumDetailAdapter(private val listener: Listener) : DetailAdapter(listene
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
         when (viewType) {
-            AlbumDetailViewHolder.VIEW_TYPE -> AlbumDetailViewHolder.new(parent)
+            AlbumDetailViewHolder.VIEW_TYPE -> AlbumDetailViewHolder.from(parent)
-            DiscHeaderViewHolder.VIEW_TYPE -> DiscHeaderViewHolder.new(parent)
+            DiscHeaderViewHolder.VIEW_TYPE -> DiscHeaderViewHolder.from(parent)
-            AlbumSongViewHolder.VIEW_TYPE -> AlbumSongViewHolder.new(parent)
+            AlbumSongViewHolder.VIEW_TYPE -> AlbumSongViewHolder.from(parent)
             else -> super.onCreateViewHolder(parent, viewType)
         }
 
@@ -88,9 +88,9 @@ class AlbumDetailAdapter(private val listener: Listener) : DetailAdapter(listene
         return super.isItemFullWidth(position) || item is Album || item is DiscHeader
     }
 
-    companion object {
+    private companion object {
         /** A comparator that can be used with DiffUtil. */
-        private val DIFF_CALLBACK =
+        val DIFF_CALLBACK =
             object : SimpleItemCallback<Item>() {
                 override fun areContentsTheSame(oldItem: Item, newItem: Item): Boolean {
                     return when {
@@ -110,7 +110,7 @@ class AlbumDetailAdapter(private val listener: Listener) : DetailAdapter(listene
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays the [Album] header in the detail view. Use [new] to
+ * A [RecyclerView.ViewHolder] that displays the [Album] header in the detail view. Use [from] to
  * create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -142,7 +142,7 @@ private class AlbumDetailViewHolder private constructor(private val binding: Ite
         // Date, song count, and duration map to the info text
         binding.detailInfo.apply {
             // Fall back to a friendlier "No date" text if the album doesn't have date information
-            val date = album.date?.resolveDate(context) ?: context.getString(R.string.def_date)
+            val date = album.dates?.resolveDate(context) ?: context.getString(R.string.def_date)
             val songCount = context.getPlural(R.plurals.fmt_song_count, album.songs.size)
             val duration = album.durationMs.formatDurationMs(true)
             text = context.getString(R.string.fmt_three, date, songCount, duration)
@@ -161,7 +161,7 @@ private class AlbumDetailViewHolder private constructor(private val binding: Ite
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             AlbumDetailViewHolder(ItemDetailBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
@@ -170,7 +170,7 @@ private class AlbumDetailViewHolder private constructor(private val binding: Ite
                 override fun areContentsTheSame(oldItem: Album, newItem: Album) =
                     oldItem.rawName == newItem.rawName &&
                         oldItem.areArtistContentsTheSame(newItem) &&
-                        oldItem.date == newItem.date &&
+                        oldItem.dates == newItem.dates &&
                         oldItem.songs.size == newItem.songs.size &&
                         oldItem.durationMs == newItem.durationMs &&
                         oldItem.type == newItem.type
@@ -180,7 +180,7 @@ private class AlbumDetailViewHolder private constructor(private val binding: Ite
 
 /**
  * A [RecyclerView.ViewHolder] that displays a [DiscHeader] to delimit different disc groups. Use
- * [new] to create an instance.
+ * [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 private class DiscHeaderViewHolder(private val binding: ItemDiscHeaderBinding) :
@@ -202,7 +202,7 @@ private class DiscHeaderViewHolder(private val binding: ItemDiscHeaderBinding) :
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             DiscHeaderViewHolder(ItemDiscHeaderBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
@@ -215,7 +215,7 @@ private class DiscHeaderViewHolder(private val binding: ItemDiscHeaderBinding) :
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Song] in the context of an [Album]. Use [new] to
+ * A [RecyclerView.ViewHolder] that displays a [Song] in the context of an [Album]. Use [from] to
  * create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -227,7 +227,7 @@ private class AlbumSongViewHolder private constructor(private val binding: ItemA
      * @param listener A [SelectableListListener] to bind interactions to.
      */
     fun bind(song: Song, listener: SelectableListListener) {
-        listener.bind(this, song, binding.songMenu)
+        listener.bind(song, this, menuButton = binding.songMenu)
 
         binding.songTrack.apply {
             if (song.track != null) {
@@ -269,7 +269,7 @@ private class AlbumSongViewHolder private constructor(private val binding: ItemA
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             AlbumSongViewHolder(ItemAlbumSongBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */

app/src/main/java/org/oxycblt/auxio/detail/recycler/ArtistDetailAdapter.kt

@@ -54,9 +54,9 @@ class ArtistDetailAdapter(private val listener: Listener) : DetailAdapter(listen
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
         when (viewType) {
-            ArtistDetailViewHolder.VIEW_TYPE -> ArtistDetailViewHolder.new(parent)
+            ArtistDetailViewHolder.VIEW_TYPE -> ArtistDetailViewHolder.from(parent)
-            ArtistAlbumViewHolder.VIEW_TYPE -> ArtistAlbumViewHolder.new(parent)
+            ArtistAlbumViewHolder.VIEW_TYPE -> ArtistAlbumViewHolder.from(parent)
-            ArtistSongViewHolder.VIEW_TYPE -> ArtistSongViewHolder.new(parent)
+            ArtistSongViewHolder.VIEW_TYPE -> ArtistSongViewHolder.from(parent)
             else -> super.onCreateViewHolder(parent, viewType)
         }
 
@@ -76,9 +76,9 @@ class ArtistDetailAdapter(private val listener: Listener) : DetailAdapter(listen
         return super.isItemFullWidth(position) || item is Artist
     }
 
-    companion object {
+    private companion object {
         /** A comparator that can be used with DiffUtil. */
-        private val DIFF_CALLBACK =
+        val DIFF_CALLBACK =
             object : SimpleItemCallback<Item>() {
                 override fun areContentsTheSame(oldItem: Item, newItem: Item): Boolean {
                     return when {
@@ -97,7 +97,7 @@ class ArtistDetailAdapter(private val listener: Listener) : DetailAdapter(listen
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays the [Artist] header in the detail view. Use [new] to
+ * A [RecyclerView.ViewHolder] that displays the [Artist] header in the detail view. Use [from] to
  * create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -156,7 +156,7 @@ private class ArtistDetailViewHolder private constructor(private val binding: It
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             ArtistDetailViewHolder(ItemDetailBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
@@ -172,7 +172,7 @@ private class ArtistDetailViewHolder private constructor(private val binding: It
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays an [Album] in the context of an [Artist]. Use [new] to
+ * A [RecyclerView.ViewHolder] that displays an [Album] in the context of an [Artist]. Use [from] to
  * create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -184,12 +184,13 @@ private class ArtistAlbumViewHolder private constructor(private val binding: Ite
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     fun bind(album: Album, listener: SelectableListListener) {
-        listener.bind(this, album, binding.parentMenu)
+        listener.bind(album, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(album)
         binding.parentName.text = album.resolveName(binding.context)
         binding.parentInfo.text =
             // Fall back to a friendlier "No date" text if the album doesn't have date information
-            album.date?.resolveDate(binding.context) ?: binding.context.getString(R.string.def_date)
+            album.dates?.resolveDate(binding.context)
+                ?: binding.context.getString(R.string.def_date)
     }
 
     override fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean) {
@@ -210,20 +211,20 @@ private class ArtistAlbumViewHolder private constructor(private val binding: Ite
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             ArtistAlbumViewHolder(ItemParentBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
             object : SimpleItemCallback<Album>() {
                 override fun areContentsTheSame(oldItem: Album, newItem: Album) =
-                    oldItem.rawName == newItem.rawName && oldItem.date == newItem.date
+                    oldItem.rawName == newItem.rawName && oldItem.dates == newItem.dates
             }
     }
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Song] in the context of an [Artist]. Use [new] to
+ * A [RecyclerView.ViewHolder] that displays a [Song] in the context of an [Artist]. Use [from] to
  * create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -235,7 +236,7 @@ private class ArtistSongViewHolder private constructor(private val binding: Item
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     fun bind(song: Song, listener: SelectableListListener) {
-        listener.bind(this, song, binding.songMenu)
+        listener.bind(song, this, menuButton = binding.songMenu)
         binding.songAlbumCover.bind(song)
         binding.songName.text = song.resolveName(binding.context)
         binding.songInfo.text = song.album.resolveName(binding.context)
@@ -259,7 +260,7 @@ private class ArtistSongViewHolder private constructor(private val binding: Item
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             ArtistSongViewHolder(ItemSongBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */

app/src/main/java/org/oxycblt/auxio/detail/recycler/DetailAdapter.kt

@@ -57,8 +57,8 @@ abstract class DetailAdapter(
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
         when (viewType) {
-            HeaderViewHolder.VIEW_TYPE -> HeaderViewHolder.new(parent)
+            HeaderViewHolder.VIEW_TYPE -> HeaderViewHolder.from(parent)
-            SortHeaderViewHolder.VIEW_TYPE -> SortHeaderViewHolder.new(parent)
+            SortHeaderViewHolder.VIEW_TYPE -> SortHeaderViewHolder.from(parent)
             else -> error("Invalid item type $viewType")
         }
 
@@ -109,7 +109,7 @@ abstract class DetailAdapter(
         fun onOpenSortMenu(anchor: View)
     }
 
-    companion object {
+    protected companion object {
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
             object : SimpleItemCallback<Item>() {
@@ -128,7 +128,7 @@ abstract class DetailAdapter(
 
 /**
  * A [RecyclerView.ViewHolder] that displays a [SortHeader], a variation on [Header] that adds a
- * button opening a menu for sorting. Use [new] to create an instance.
+ * button opening a menu for sorting. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 private class SortHeaderViewHolder(private val binding: ItemSortHeaderBinding) :
@@ -157,7 +157,7 @@ private class SortHeaderViewHolder(private val binding: ItemSortHeaderBinding) :
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             SortHeaderViewHolder(ItemSortHeaderBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */

app/src/main/java/org/oxycblt/auxio/detail/recycler/GenreDetailAdapter.kt

@@ -54,9 +54,9 @@ class GenreDetailAdapter(private val listener: Listener) : DetailAdapter(listene
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
         when (viewType) {
-            GenreDetailViewHolder.VIEW_TYPE -> GenreDetailViewHolder.new(parent)
+            GenreDetailViewHolder.VIEW_TYPE -> GenreDetailViewHolder.from(parent)
-            ArtistViewHolder.VIEW_TYPE -> ArtistViewHolder.new(parent)
+            ArtistViewHolder.VIEW_TYPE -> ArtistViewHolder.from(parent)
-            SongViewHolder.VIEW_TYPE -> SongViewHolder.new(parent)
+            SongViewHolder.VIEW_TYPE -> SongViewHolder.from(parent)
             else -> super.onCreateViewHolder(parent, viewType)
         }
 
@@ -75,7 +75,7 @@ class GenreDetailAdapter(private val listener: Listener) : DetailAdapter(listene
         return super.isItemFullWidth(position) || item is Genre
     }
 
-    companion object {
+    private companion object {
         val DIFF_CALLBACK =
             object : SimpleItemCallback<Item>() {
                 override fun areContentsTheSame(oldItem: Item, newItem: Item): Boolean {
@@ -94,7 +94,7 @@ class GenreDetailAdapter(private val listener: Listener) : DetailAdapter(listene
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays the [Genre] header in the detail view. Use [new] to
+ * A [RecyclerView.ViewHolder] that displays the [Genre] header in the detail view. Use [from] to
  * create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -130,7 +130,7 @@ private class GenreDetailViewHolder private constructor(private val binding: Ite
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             GenreDetailViewHolder(ItemDetailBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */

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

@@ -49,14 +49,7 @@ 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.selection.SelectionFragment
-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.MusicMode
-import org.oxycblt.auxio.music.MusicViewModel
-import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.Sort
 import org.oxycblt.auxio.music.system.Indexer
 import org.oxycblt.auxio.ui.MainNavigationAction
 import org.oxycblt.auxio.ui.NavigationViewModel
@@ -72,17 +65,7 @@ class HomeFragment :
     private val homeModel: HomeViewModel by androidActivityViewModels()
     private val musicModel: MusicViewModel by activityViewModels()
     private val navModel: NavigationViewModel by activityViewModels()
-
+    private var storagePermissionLauncher: ActivityResultLauncher<String>? = null
-    // lifecycleObject builds this in the creation step, so doing this is okay.
-    private val storagePermissionLauncher: ActivityResultLauncher<String> by lifecycleObject {
-        registerForActivityResult(ActivityResultContracts.RequestPermission()) {
-            musicModel.refresh()
-        }
-    }
-
-    private val sortItem: MenuItem by lifecycleObject { binding ->
-        binding.homeToolbar.menu.findItem(R.id.submenu_sorting)
-    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -105,6 +88,12 @@ class HomeFragment :
     override fun onBindingCreated(binding: FragmentHomeBinding, savedInstanceState: Bundle?) {
         super.onBindingCreated(binding, savedInstanceState)
 
+        // Have to set up the permission launcher before the view is shown
+        storagePermissionLauncher =
+            registerForActivityResult(ActivityResultContracts.RequestPermission()) {
+                musicModel.refresh()
+            }
+
         // --- UI SETUP ---
         binding.homeAppbar.addOnOffsetChangedListener(this)
         binding.homeToolbar.setOnMenuItemClickListener(this)
@@ -171,6 +160,7 @@ class HomeFragment :
 
     override fun onDestroyBinding(binding: FragmentHomeBinding) {
         super.onDestroyBinding(binding)
+        storagePermissionLauncher = null
         binding.homeAppbar.removeOnOffsetChangedListener(this)
         binding.homeToolbar.setOnMenuItemClickListener(null)
     }
@@ -285,14 +275,16 @@ class HomeFragment :
                     }
             }
 
-        val sortMenu = requireNotNull(sortItem.subMenu)
+        val sortMenu =
+            unlikelyToBeNull(
+                requireBinding().homeToolbar.menu.findItem(R.id.submenu_sorting).subMenu)
         val toHighlight = homeModel.getSortForTab(tabMode)
 
         for (option in sortMenu) {
             // Check the ascending option and corresponding sort option to align with
             // the current sort of the tab.
             if (option.itemId == toHighlight.mode.itemId ||
-                    (option.itemId == R.id.option_sort_asc && toHighlight.isAscending)) {
+                (option.itemId == R.id.option_sort_asc && toHighlight.isAscending)) {
                 option.isChecked = true
             }
 
@@ -303,7 +295,13 @@ 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 = getTabRecyclerId(tabMode)
+        requireBinding().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
+            }
     }
 
     private fun handleRecreate(recreate: Boolean) {
@@ -321,9 +319,12 @@ class HomeFragment :
     }
 
     private fun updateIndexerState(state: Indexer.State?) {
+        // 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.response)
+            is Indexer.State.Complete -> setupCompleteState(binding, state.result)
             is Indexer.State.Indexing -> setupIndexingState(binding, state.indexing)
             null -> {
                 logD("Indexer is in indeterminate state")
@@ -332,53 +333,56 @@ class HomeFragment :
         }
     }
 
-    private fun setupCompleteState(binding: FragmentHomeBinding, response: Indexer.Response) {
+    private fun setupCompleteState(
-        if (response is Indexer.Response.Ok) {
+        binding: FragmentHomeBinding,
+        result: Result<MusicStore.Library>
+    ) {
+        if (result.isSuccess) {
             logD("Received ok response")
             binding.homeFab.show()
             binding.homeIndexingContainer.visibility = View.INVISIBLE
         } else {
             logD("Received non-ok response")
             val context = requireContext()
+            val throwable = unlikelyToBeNull(result.exceptionOrNull())
             binding.homeIndexingContainer.visibility = View.VISIBLE
             binding.homeIndexingProgress.visibility = View.INVISIBLE
-            when (response) {
+            when (throwable) {
-                is Indexer.Response.Err -> {
+                is Indexer.NoPermissionException -> {
-                    logD("Updating UI to Response.Err state")
+                    logD("Updating UI to permission request state")
-                    binding.homeIndexingStatus.text = context.getString(R.string.err_index_failed)
-
-                    // Configure the action to act as a reload trigger.
-                    binding.homeIndexingAction.apply {
-                        visibility = View.VISIBLE
-                        text = context.getString(R.string.lbl_retry)
-                        setOnClickListener { musicModel.refresh() }
-                    }
-                }
-                is Indexer.Response.NoMusic -> {
-                    logD("Updating UI to Response.NoMusic state")
-                    binding.homeIndexingStatus.text = context.getString(R.string.err_no_music)
-
-                    // Configure the action to act as a reload trigger.
-                    binding.homeIndexingAction.apply {
-                        visibility = View.VISIBLE
-                        text = context.getString(R.string.lbl_retry)
-                        setOnClickListener { musicModel.refresh() }
-                    }
-                }
-                is Indexer.Response.NoPerms -> {
-                    logD("Updating UI to Response.NoPerms state")
                     binding.homeIndexingStatus.text = context.getString(R.string.err_no_perms)
-
                     // Configure the action to act as a permission launcher.
                     binding.homeIndexingAction.apply {
                         visibility = View.VISIBLE
                         text = context.getString(R.string.lbl_grant)
                         setOnClickListener {
-                            storagePermissionLauncher.launch(Indexer.PERMISSION_READ_AUDIO)
+                            requireNotNull(storagePermissionLauncher) {
+                                    "Permission launcher was not available"
+                                }
+                                .launch(Indexer.PERMISSION_READ_AUDIO)
                         }
                     }
                 }
-                else -> {}
+                is Indexer.NoMusicException -> {
+                    logD("Updating UI to no music state")
+                    binding.homeIndexingStatus.text = context.getString(R.string.err_no_music)
+                    // Configure the action to act as a reload trigger.
+                    binding.homeIndexingAction.apply {
+                        visibility = View.VISIBLE
+                        text = context.getString(R.string.lbl_retry)
+                        setOnClickListener { musicModel.refresh() }
+                    }
+                }
+                else -> {
+                    logD("Updating UI to error state")
+                    binding.homeIndexingStatus.text = context.getString(R.string.err_index_failed)
+                    // Configure the action to act as a reload trigger.
+                    binding.homeIndexingAction.apply {
+                        visibility = View.VISIBLE
+                        text = context.getString(R.string.lbl_retry)
+                        setOnClickListener { musicModel.rescan() }
+                    }
+                }
             }
         }
     }
@@ -438,10 +442,9 @@ class HomeFragment :
         val binding = requireBinding()
         if (binding.homeSelectionToolbar.updateSelectionAmount(selected.size) &&
             selected.isNotEmpty()) {
+            // New selection started, show the AppBarLayout to indicate the new state.
             logD("Significant selection occurred, expanding AppBar")
-            // Significant enough change where we want to expand the RecyclerView
+            binding.homeAppbar.expandWithScrollingRecycler()
-            binding.homeAppbar.expandWithRecycler(
-                binding.homePager.findViewById(getTabRecyclerId(homeModel.currentTabMode.value)))
         }
     }
 
@@ -457,20 +460,6 @@ class HomeFragment :
         reenterTransition = MaterialSharedAxis(axis, false)
     }
 
-    /**
-     * Get the ID of the RecyclerView contained by [ViewPager2] tab represented with the given
-     * [MusicMode].
-     * @param tabMode The [MusicMode] of the tab.
-     * @return The ID of the RecyclerView contained by the given tab.
-     */
-    private fun getTabRecyclerId(tabMode: MusicMode) =
-        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
-        }
-
     /**
      * [FragmentStateAdapter] implementation for the [HomeFragment]'s [ViewPager2] instance.
      * @param tabs The current tab configuration. This will define the [Fragment]s created.
@@ -493,12 +482,10 @@ class HomeFragment :
             }
     }
 
-    companion object {
+    private companion object {
-        private val VP_RECYCLER_FIELD: Field by
+        val VP_RECYCLER_FIELD: Field by lazyReflectedField(ViewPager2::class, "mRecyclerView")
-            lazyReflectedField(ViewPager2::class, "mRecyclerView")
+        val RV_TOUCH_SLOP_FIELD: Field by lazyReflectedField(RecyclerView::class, "mTouchSlop")
-        private val RV_TOUCH_SLOP_FIELD: Field by
+        const val KEY_LAST_TRANSITION_AXIS =
-            lazyReflectedField(RecyclerView::class, "mTouchSlop")
-        private const val KEY_LAST_TRANSITION_AXIS =
             BuildConfig.APPLICATION_ID + ".key.LAST_TRANSITION_AXIS"
     }
 }

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

@@ -18,6 +18,7 @@
 package org.oxycblt.auxio.home
 
 import android.app.Application
+import android.content.SharedPreferences
 import androidx.lifecycle.AndroidViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -39,9 +40,11 @@ import org.oxycblt.auxio.util.logD
  * @author Alexander Capehart (OxygenCobalt)
  */
 class HomeViewModel(application: Application) :
-    AndroidViewModel(application), Settings.Callback, MusicStore.Callback {
+    AndroidViewModel(application),
+    MusicStore.Listener,
+    SharedPreferences.OnSharedPreferenceChangeListener {
     private val musicStore = MusicStore.getInstance()
-    private val settings = Settings(application, this)
+    private val settings = Settings(application)
 
     private val _songsList = MutableStateFlow(listOf<Song>())
     /** A list of [Song]s, sorted by the preferred [Sort], to be shown in the home view. */
@@ -91,13 +94,14 @@ class HomeViewModel(application: Application) :
     val isFastScrolling: StateFlow<Boolean> = _isFastScrolling
 
     init {
-        musicStore.addCallback(this)
+        musicStore.addListener(this)
+        settings.addListener(this)
     }
 
     override fun onCleared() {
         super.onCleared()
-        musicStore.removeCallback(this)
+        musicStore.removeListener(this)
-        settings.release()
+        settings.removeListener(this)
     }
 
     override fun onLibraryChanged(library: MusicStore.Library?) {
@@ -119,7 +123,7 @@ class HomeViewModel(application: Application) :
         }
     }
 
-    override fun onSettingChanged(key: String) {
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
         when (key) {
             context.getString(R.string.set_key_lib_tabs) -> {
                 // Tabs changed, update  the current tabs and set up a re-create event.

app/src/main/java/org/oxycblt/auxio/home/fastscroll/FastScrollPopupView.kt

@@ -169,8 +169,8 @@ constructor(context: Context, attrs: AttributeSet? = null, defStyleRes: Int = 0)
         }
     }
 
-    companion object {
+    private companion object {
         // Pre-calculate sqrt(2)
-        private const val SQRT2 = 1.4142135f
+        const val SQRT2 = 1.4142135f
     }
 }

app/src/main/java/org/oxycblt/auxio/home/fastscroll/FastScrollRecyclerView.kt

@@ -71,26 +71,6 @@ class FastScrollRecyclerView
 @JvmOverloads
 constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
     AuxioRecyclerView(context, attrs, defStyleAttr) {
-    /** An interface to provide text to use in the popup when fast-scrolling. */
-    interface PopupProvider {
-        /**
-         * Get text to use in the popup at the specified position.
-         * @param pos The position in the list.
-         * @return A [String] to use in the popup. Null if there is no applicable text for the popup
-         * at [pos].
-         */
-        fun getPopup(pos: Int): String?
-    }
-
-    /** A listener for fast scroller interactions. */
-    interface Listener {
-        /**
-         * Called when the fast scrolling state changes.
-         * @param isFastScrolling true if the user is currently fast scrolling, false otherwise.
-         */
-        fun onFastScrollingChanged(isFastScrolling: Boolean)
-    }
-
     // Thumb
     private val thumbView =
         View(context).apply {
@@ -524,7 +504,27 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
                 else -> 0
             }
 
-    companion object {
+    /** An interface to provide text to use in the popup when fast-scrolling. */
-        private const val AUTO_HIDE_SCROLLBAR_DELAY_MILLIS = 1500
+    interface PopupProvider {
+        /**
+         * Get text to use in the popup at the specified position.
+         * @param pos The position in the list.
+         * @return A [String] to use in the popup. Null if there is no applicable text for the popup
+         * at [pos].
+         */
+        fun getPopup(pos: Int): String?
+    }
+
+    /** A listener for fast scroller interactions. */
+    interface Listener {
+        /**
+         * Called when the fast scrolling state changes.
+         * @param isFastScrolling true if the user is currently fast scrolling, false otherwise.
+         */
+        fun onFastScrollingChanged(isFastScrolling: Boolean)
+    }
+
+    private companion object {
+        const val AUTO_HIDE_SCROLLBAR_DELAY_MILLIS = 1500
     }
 }

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

@@ -94,8 +94,8 @@ class AlbumListFragment :
             is Sort.Mode.ByArtist ->
                 album.artists[0].collationKey?.run { sourceString.first().uppercase() }
 
-            // Year -> Use Full Year
+            // Date -> Use minimum date (Maximum dates are not sorted by, so showing them is odd)
-            is Sort.Mode.ByDate -> album.date?.resolveDate(requireContext())
+            is Sort.Mode.ByDate -> album.dates?.run { min.resolveDate(requireContext()) }
 
             // Duration -> Use formatted duration
             is Sort.Mode.ByDuration -> album.durationMs.formatDurationMs(false)
@@ -152,7 +152,7 @@ class AlbumListFragment :
             get() = differ.currentList
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-            AlbumViewHolder.new(parent)
+            AlbumViewHolder.from(parent)
 
         override fun onBindViewHolder(holder: AlbumViewHolder, position: Int) {
             holder.bind(differ.currentList[position], listener)

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

@@ -127,7 +127,7 @@ class ArtistListFragment :
             get() = differ.currentList
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-            ArtistViewHolder.new(parent)
+            ArtistViewHolder.from(parent)
 
         override fun onBindViewHolder(holder: ArtistViewHolder, position: Int) {
             holder.bind(differ.currentList[position], listener)

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

@@ -126,7 +126,7 @@ class GenreListFragment :
             get() = differ.currentList
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-            GenreViewHolder.new(parent)
+            GenreViewHolder.from(parent)
 
         override fun onBindViewHolder(holder: GenreViewHolder, position: Int) {
             holder.bind(differ.currentList[position], listener)

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

@@ -103,7 +103,7 @@ class SongListFragment :
                 song.album.collationKey?.run { sourceString.first().uppercase() }
 
             // Year -> Use Full Year
-            is Sort.Mode.ByDate -> song.album.date?.resolveDate(requireContext())
+            is Sort.Mode.ByDate -> song.album.dates?.resolveDate(requireContext())
 
             // Duration -> Use formatted duration
             is Sort.Mode.ByDuration -> song.durationMs.formatDurationMs(false)
@@ -166,7 +166,7 @@ class SongListFragment :
             get() = differ.currentList
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-            SongViewHolder.new(parent)
+            SongViewHolder.from(parent)
 
         override fun onBindViewHolder(holder: SongViewHolder, position: Int) {
             holder.bind(differ.currentList[position], listener)

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

@@ -17,6 +17,7 @@
  
 package org.oxycblt.auxio.home.tabs
 
+import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.util.logE
 
@@ -25,7 +26,7 @@ import org.oxycblt.auxio.util.logE
  * @param mode The type of list in the home view this instance corresponds to.
  * @author Alexander Capehart (OxygenCobalt)
  */
-sealed class Tab(open val mode: MusicMode) {
+sealed class Tab(open val mode: MusicMode) : Item {
     /**
      * A visible tab. This will be visible in the home and tab configuration views.
      * @param mode The type of list in the home view this instance corresponds to.

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

@@ -18,27 +18,28 @@
 package org.oxycblt.auxio.home.tabs
 
 import android.annotation.SuppressLint
-import android.view.MotionEvent
 import android.view.View
 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.recycler.DialogRecyclerView
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.util.inflater
 
 /**
  * A [RecyclerView.Adapter] that displays an array of [Tab]s open for configuration.
- * @param listener A [Listener] for tab interactions.
+ * @param listener A [EditableListListener] for tab interactions.
  */
-class TabAdapter(private val listener: Listener) : RecyclerView.Adapter<TabViewHolder>() {
+class TabAdapter(private val listener: EditableListListener) :
+    RecyclerView.Adapter<TabViewHolder>() {
     /** The current array of [Tab]s. */
     var tabs = arrayOf<Tab>()
         private set
 
     override fun getItemCount() = tabs.size
-    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = TabViewHolder.new(parent)
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = TabViewHolder.from(parent)
     override fun onBindViewHolder(holder: TabViewHolder, position: Int) {
         holder.bind(tabs[position], listener)
     }
@@ -75,30 +76,13 @@ class TabAdapter(private val listener: Listener) : RecyclerView.Adapter<TabViewH
         notifyItemMoved(a, b)
     }
 
-    /** A listener for interactions specific to tab configuration. */
+    private companion object {
-    interface Listener {
+        val PAYLOAD_TAB_CHANGED = Any()
-        /**
-         * Called when a tab is clicked, requesting that the visibility should be inverted (i.e
-         * Visible -> Invisible and vice versa).
-         * @param tabMode The [MusicMode] of the tab clicked.
-         */
-        fun onToggleVisibility(tabMode: MusicMode)
-
-        /**
-         * Called when the drag handle on a [RecyclerView.ViewHolder] is clicked, requesting that a
-         * drag should be started.
-         * @param viewHolder The [RecyclerView.ViewHolder] to start dragging.
-         */
-        fun onPickUp(viewHolder: RecyclerView.ViewHolder)
-    }
-
-    companion object {
-        private val PAYLOAD_TAB_CHANGED = Any()
     }
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Tab]. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays a [Tab]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class TabViewHolder private constructor(private val binding: ItemTabBinding) :
@@ -106,12 +90,11 @@ class TabViewHolder private constructor(private val binding: ItemTabBinding) :
     /**
      * Bind new data to this instance.
      * @param tab The new [Tab] to bind.
-     * @param listener A [TabAdapter.Listener] to bind interactions to.
+     * @param listener A [EditableListListener] to bind interactions to.
      */
     @SuppressLint("ClickableViewAccessibility")
-    fun bind(tab: Tab, listener: TabAdapter.Listener) {
+    fun bind(tab: Tab, listener: EditableListListener) {
-        binding.root.setOnClickListener { listener.onToggleVisibility(tab.mode) }
+        listener.bind(tab, this, dragHandle = binding.tabDragHandle)
-
         binding.tabCheckBox.apply {
             // Update the CheckBox name to align with the mode
             setText(
@@ -126,15 +109,6 @@ class TabViewHolder private constructor(private val binding: ItemTabBinding) :
             // the tab data since they are in the same data structure (Tab)
             isChecked = tab is Tab.Visible
         }
-
-        // Set up the drag handle to start a drag whenever it is touched.
-        binding.tabDragHandle.setOnTouchListener { _, motionEvent ->
-            binding.tabDragHandle.performClick()
-            if (motionEvent.actionMasked == MotionEvent.ACTION_DOWN) {
-                listener.onPickUp(this)
-                true
-            } else false
-        }
     }
 
     companion object {
@@ -143,6 +117,6 @@ class TabViewHolder private constructor(private val binding: ItemTabBinding) :
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = TabViewHolder(ItemTabBinding.inflate(parent.context.inflater))
+        fun from(parent: View) = TabViewHolder(ItemTabBinding.inflate(parent.context.inflater))
     }
 }

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

@@ -25,23 +25,19 @@ import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogTabsBinding
-import org.oxycblt.auxio.music.MusicMode
+import org.oxycblt.auxio.list.EditableListListener
+import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
-import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.logD
 
 /**
  * A [ViewBindingDialogFragment] that allows the user to modify the home [Tab] configuration.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAdapter.Listener {
+class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), EditableListListener {
-    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
-
     private val tabAdapter = TabAdapter(this)
-    private val touchHelper: ItemTouchHelper by lifecycleObject {
+    private var touchHelper: ItemTouchHelper? = null
-        ItemTouchHelper(TabDragCallback(tabAdapter))
-    }
 
     override fun onCreateBinding(inflater: LayoutInflater) = DialogTabsBinding.inflate(inflater)
 
@@ -50,13 +46,13 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
             .setTitle(R.string.set_lib_tabs)
             .setPositiveButton(R.string.lbl_ok) { _, _ ->
                 logD("Committing tab changes")
-                settings.libTabs = tabAdapter.tabs
+                Settings(requireContext()).libTabs = tabAdapter.tabs
             }
             .setNegativeButton(R.string.lbl_cancel, null)
     }
 
     override fun onBindingCreated(binding: DialogTabsBinding, savedInstanceState: Bundle?) {
-        var tabs = settings.libTabs
+        var tabs = Settings(requireContext()).libTabs
         // Try to restore a pending tab configuration that was saved prior.
         if (savedInstanceState != null) {
             val savedTabs = Tab.fromIntCode(savedInstanceState.getInt(KEY_TABS))
@@ -69,7 +65,8 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
         tabAdapter.submitTabs(tabs)
         binding.tabRecycler.apply {
             adapter = tabAdapter
-            touchHelper.attachToRecyclerView(this)
+            touchHelper =
+                ItemTouchHelper(TabDragCallback(tabAdapter)).also { it.attachToRecyclerView(this) }
         }
     }
 
@@ -84,12 +81,11 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
         binding.tabRecycler.adapter = null
     }
 
-    override fun onToggleVisibility(tabMode: MusicMode) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
-        logD("Toggling tab $tabMode")
+        check(item is Tab) { "Unexpected datatype: ${item::class.java}" }
-
         // We will need the exact index of the tab to update on in order to
         // notify the adapter of the change.
-        val index = tabAdapter.tabs.indexOfFirst { it.mode == tabMode }
+        val index = tabAdapter.tabs.indexOfFirst { it.mode == item.mode }
         val tab = tabAdapter.tabs[index]
         tabAdapter.setTab(
             index,
@@ -105,10 +101,10 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
     }
 
     override fun onPickUp(viewHolder: RecyclerView.ViewHolder) {
-        touchHelper.startDrag(viewHolder)
+        requireNotNull(touchHelper) { "ItemTouchHelper was not available" }.startDrag(viewHolder)
     }
 
-    companion object {
+    private companion object {
-        private const val KEY_TABS = BuildConfig.APPLICATION_ID + ".key.PENDING_TABS"
+        const val KEY_TABS = BuildConfig.APPLICATION_ID + ".key.PENDING_TABS"
     }
 }

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

@@ -65,7 +65,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     private val cornerRadius: Float
 
     init {
-        // Obtain some StyledImageView attributes to use later when theming the cusotm view.
+        // Obtain some StyledImageView attributes to use later when theming the custom view.
         @SuppressLint("CustomViewStyleable")
         val styledAttrs = context.obtainStyledAttributes(attrs, R.styleable.StyledImageView)
         // Keep track of our corner radius so that we can apply the same attributes to the custom
@@ -107,7 +107,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
 
         // Playback indicator should sit above the inner StyledImageView and custom view/
         addView(playbackIndicatorView)
-        // Selction indicator should never be obscured, so place it at the top.
+        // Selection indicator should never be obscured, so place it at the top.
         addView(
             selectionIndicatorView,
             LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT).apply {

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

@@ -177,6 +177,8 @@ object Covers {
     @Suppress("BlockingMethodInNonBlockingContext")
     private suspend fun fetchMediaStoreCovers(context: Context, album: Album): InputStream? {
         // Eliminate any chance that this blocking call might mess up the loading process
-        return withContext(Dispatchers.IO) { context.contentResolver.openInputStream(album.coverUri) }
+        return withContext(Dispatchers.IO) {
+            context.contentResolver.openInputStream(album.coverUri)
+        }
     }
 }

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

@@ -22,6 +22,7 @@ import android.view.View
 import androidx.annotation.MenuRes
 import androidx.appcompat.widget.PopupMenu
 import androidx.fragment.app.activityViewModels
+import androidx.recyclerview.widget.RecyclerView
 import androidx.viewbinding.ViewBinding
 import org.oxycblt.auxio.MainFragmentDirections
 import org.oxycblt.auxio.R
@@ -53,7 +54,7 @@ abstract class ListFragment<VB : ViewBinding> : SelectionFragment<VB>(), Selecta
      */
     abstract fun onRealClick(music: Music)
 
-    override fun onClick(item: Item) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
         check(item is Music) { "Unexpected datatype: ${item::class.simpleName}" }
         if (selectionModel.selected.value.isNotEmpty()) {
             // Map clicking an item to selecting an item when items are already selected.

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

@@ -17,8 +17,8 @@
  
 package org.oxycblt.auxio.list
 
+import android.view.MotionEvent
 import android.view.View
-import android.widget.Button
 import androidx.recyclerview.widget.RecyclerView
 
 /**
@@ -26,13 +26,63 @@ import androidx.recyclerview.widget.RecyclerView
  * @author Alexander Capehart (OxygenCobalt)
  */
 interface ClickableListListener {
-    // TODO: Supply a ViewHolder on clicks
-    //  (allows editable lists to be standardized into a listener.)
     /**
      * Called when an [Item] in the list is clicked.
      * @param item The [Item] that was clicked.
+     * @param viewHolder The [RecyclerView.ViewHolder] of the item that was clicked.
      */
-    fun onClick(item: Item)
+    fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder)
+
+    /**
+     * Binds this instance to a list item.
+     * @param item The [Item] that this list entry is bound to.
+     * @param viewHolder The [RecyclerView.ViewHolder] of the item that was clicked.
+     * @param bodyView The [View] containing the main body of the list item. Any click events on
+     * this [View] are routed to the listener. Defaults to the root view.
+     */
+    fun bind(
+        item: Item,
+        viewHolder: RecyclerView.ViewHolder,
+        bodyView: View = viewHolder.itemView
+    ) {
+        bodyView.setOnClickListener { onClick(item, viewHolder) }
+    }
+}
+
+/**
+ * An extension of [ClickableListListener] that enables list editing functionality.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+interface EditableListListener : ClickableListListener {
+    /**
+     * Called when a [RecyclerView.ViewHolder] requests that it should be dragged.
+     * @param viewHolder The [RecyclerView.ViewHolder] that should start being dragged.
+     */
+    fun onPickUp(viewHolder: RecyclerView.ViewHolder)
+
+    /**
+     * Binds this instance to a list item.
+     * @param item The [Item] that this list entry is bound to.
+     * @param viewHolder The [RecyclerView.ViewHolder] to bind.
+     * @param bodyView The [View] containing the main body of the list item. Any click events on
+     * this [View] are routed to the listener. Defaults to the root view.
+     * @param dragHandle A touchable [View]. Any drag on this view will start a drag event.
+     */
+    fun bind(
+        item: Item,
+        viewHolder: RecyclerView.ViewHolder,
+        bodyView: View = viewHolder.itemView,
+        dragHandle: View
+    ) {
+        bind(item, viewHolder, bodyView)
+        dragHandle.setOnTouchListener { _, motionEvent ->
+            dragHandle.performClick()
+            if (motionEvent.actionMasked == MotionEvent.ACTION_DOWN) {
+                onPickUp(viewHolder)
+                true
+            } else false
+        }
+    }
 }
 
 /**
@@ -55,19 +105,23 @@ interface SelectableListListener : ClickableListListener {
 
     /**
      * Binds this instance to a list item.
-     * @param viewHolder The [RecyclerView.ViewHolder] to bind.
      * @param item The [Item] that this list entry is bound to.
-     * @param menuButton A [Button] that opens a menu.
+     * @param viewHolder The [RecyclerView.ViewHolder] to bind.
+     * @param bodyView The [View] containing the main body of the list item. Any click events on
+     * this [View] are routed to the listener. Defaults to the root view.
+     * @param menuButton A clickable [View]. Any click events on this [View] will open a menu.
      */
-    fun bind(viewHolder: RecyclerView.ViewHolder, item: Item, menuButton: Button) {
+    fun bind(
-        viewHolder.itemView.apply {
+        item: Item,
-            // Map clicks to the click listener.
+        viewHolder: RecyclerView.ViewHolder,
-            setOnClickListener { onClick(item) }
+        bodyView: View = viewHolder.itemView,
-            // Map long clicks to the selection listener.
+        menuButton: View
-            setOnLongClickListener {
+    ) {
-                onSelect(item)
+        bind(item, viewHolder, bodyView)
-                true
+        // Map long clicks to the selection listener.
-            }
+        bodyView.setOnLongClickListener {
+            onSelect(item)
+            true
         }
         // Map the menu button to the menu opening listener.
         menuButton.setOnClickListener { onOpenMenu(item, it) }

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

@@ -115,7 +115,7 @@ abstract class PlayingIndicatorAdapter<VH : RecyclerView.ViewHolder> : RecyclerV
         abstract fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean)
     }
 
-    companion object {
+    private companion object {
-        private val PAYLOAD_PLAYING_INDICATOR_CHANGED = Any()
+        val PAYLOAD_PLAYING_INDICATOR_CHANGED = Any()
     }
 }

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

@@ -77,7 +77,7 @@ abstract class SelectionIndicatorAdapter<VH : RecyclerView.ViewHolder> :
         abstract fun updateSelectionIndicator(isSelected: Boolean)
     }
 
-    companion object {
+    private companion object {
-        private val PAYLOAD_SELECTION_INDICATOR_CHANGED = Any()
+        val PAYLOAD_SELECTION_INDICATOR_CHANGED = Any()
     }
 }

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

@@ -35,7 +35,7 @@ import org.oxycblt.auxio.util.getPlural
 import org.oxycblt.auxio.util.inflater
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Song]. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays a [Song]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class SongViewHolder private constructor(private val binding: ItemSongBinding) :
@@ -46,7 +46,7 @@ class SongViewHolder private constructor(private val binding: ItemSongBinding) :
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     fun bind(song: Song, listener: SelectableListListener) {
-        listener.bind(this, song, binding.songMenu)
+        listener.bind(song, this, menuButton = binding.songMenu)
         binding.songAlbumCover.bind(song)
         binding.songName.text = song.resolveName(binding.context)
         binding.songInfo.text = song.resolveArtistContents(binding.context)
@@ -70,7 +70,7 @@ class SongViewHolder private constructor(private val binding: ItemSongBinding) :
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = SongViewHolder(ItemSongBinding.inflate(parent.context.inflater))
+        fun from(parent: View) = SongViewHolder(ItemSongBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
@@ -82,7 +82,7 @@ class SongViewHolder private constructor(private val binding: ItemSongBinding) :
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Album]. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays a [Album]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class AlbumViewHolder private constructor(private val binding: ItemParentBinding) :
@@ -93,7 +93,7 @@ class AlbumViewHolder private constructor(private val binding: ItemParentBinding
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     fun bind(album: Album, listener: SelectableListListener) {
-        listener.bind(this, album, binding.parentMenu)
+        listener.bind(album, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(album)
         binding.parentName.text = album.resolveName(binding.context)
         binding.parentInfo.text = album.resolveArtistContents(binding.context)
@@ -117,7 +117,7 @@ class AlbumViewHolder private constructor(private val binding: ItemParentBinding
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = AlbumViewHolder(ItemParentBinding.inflate(parent.context.inflater))
+        fun from(parent: View) = AlbumViewHolder(ItemParentBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
@@ -131,7 +131,7 @@ class AlbumViewHolder private constructor(private val binding: ItemParentBinding
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Artist]. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays a [Artist]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class ArtistViewHolder private constructor(private val binding: ItemParentBinding) :
@@ -142,7 +142,7 @@ class ArtistViewHolder private constructor(private val binding: ItemParentBindin
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     fun bind(artist: Artist, listener: SelectableListListener) {
-        listener.bind(this, artist, binding.parentMenu)
+        listener.bind(artist, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(artist)
         binding.parentName.text = artist.resolveName(binding.context)
         binding.parentInfo.text =
@@ -175,7 +175,8 @@ class ArtistViewHolder private constructor(private val binding: ItemParentBindin
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = ArtistViewHolder(ItemParentBinding.inflate(parent.context.inflater))
+        fun from(parent: View) =
+            ArtistViewHolder(ItemParentBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
@@ -189,7 +190,7 @@ class ArtistViewHolder private constructor(private val binding: ItemParentBindin
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Genre]. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays a [Genre]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class GenreViewHolder private constructor(private val binding: ItemParentBinding) :
@@ -200,7 +201,7 @@ class GenreViewHolder private constructor(private val binding: ItemParentBinding
      * @param listener An [SelectableListListener] to bind interactions to.
      */
     fun bind(genre: Genre, listener: SelectableListListener) {
-        listener.bind(this, genre, binding.parentMenu)
+        listener.bind(genre, this, menuButton = binding.parentMenu)
         binding.parentImage.bind(genre)
         binding.parentName.text = genre.resolveName(binding.context)
         binding.parentInfo.text =
@@ -228,7 +229,7 @@ class GenreViewHolder private constructor(private val binding: ItemParentBinding
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = GenreViewHolder(ItemParentBinding.inflate(parent.context.inflater))
+        fun from(parent: View) = GenreViewHolder(ItemParentBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =
@@ -240,7 +241,7 @@ class GenreViewHolder private constructor(private val binding: ItemParentBinding
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays a [Header]. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays a [Header]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class HeaderViewHolder private constructor(private val binding: ItemHeaderBinding) :
@@ -262,7 +263,8 @@ class HeaderViewHolder private constructor(private val binding: ItemHeaderBindin
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = HeaderViewHolder(ItemHeaderBinding.inflate(parent.context.inflater))
+        fun from(parent: View) =
+            HeaderViewHolder(ItemHeaderBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */
         val DIFF_CALLBACK =

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

@@ -26,7 +26,7 @@ import org.oxycblt.auxio.music.*
  * A [ViewModel] that manages the current selection.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class SelectionViewModel : ViewModel(), MusicStore.Callback {
+class SelectionViewModel : ViewModel(), MusicStore.Listener {
     private val musicStore = MusicStore.getInstance()
 
     private val _selected = MutableStateFlow(listOf<Music>())
@@ -35,7 +35,7 @@ class SelectionViewModel : ViewModel(), MusicStore.Callback {
         get() = _selected
 
     init {
-        musicStore.addCallback(this)
+        musicStore.addListener(this)
     }
 
     override fun onLibraryChanged(library: MusicStore.Library?) {
@@ -58,7 +58,7 @@ class SelectionViewModel : ViewModel(), MusicStore.Callback {
 
     override fun onCleared() {
         super.onCleared()
-        musicStore.removeCallback(this)
+        musicStore.removeListener(this)
     }
 
     /**

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

@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 2022 Auxio Project
+ *
+ * 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.content.Context
+import java.text.ParseException
+import java.text.SimpleDateFormat
+import kotlin.math.max
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.util.inRangeOrNull
+import org.oxycblt.auxio.util.nonZeroOrNull
+
+/**
+ * An ISO-8601/RFC 3339 Date.
+ *
+ * This class only encodes the timestamp spec and it's conversion to a human-readable date, without
+ * any other time management or validation. In general, this should only be used for display. Use
+ * [from] to create an instance.
+ *
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class Date private constructor(private val tokens: List<Int>) : Comparable<Date> {
+    private val year = tokens[0]
+    private val month = tokens.getOrNull(1)
+    private val day = tokens.getOrNull(2)
+    private val hour = tokens.getOrNull(3)
+    private val minute = tokens.getOrNull(4)
+    private val second = tokens.getOrNull(5)
+
+    /**
+     * Resolve this instance into a human-readable date.
+     * @param context [Context] required to get human-readable names.
+     * @return If the [Date] has a valid month and year value, a more fine-grained date (ex. "Jan
+     * 2020") will be returned. Otherwise, a plain year value (ex. "2020") is returned. Dates will
+     * be properly localized.
+     */
+    fun resolveDate(context: Context): String {
+        if (month != null) {
+            // Parse a date format from an ISO-ish format
+            val format = (SimpleDateFormat.getDateInstance() as SimpleDateFormat)
+            format.applyPattern("yyyy-MM")
+            val date =
+                try {
+                    format.parse("$year-$month")
+                } catch (e: ParseException) {
+                    null
+                }
+
+            if (date != null) {
+                // Reformat as a readable month and year
+                format.applyPattern("MMM yyyy")
+                return format.format(date)
+            }
+        }
+
+        // Unable to create fine-grained date, just format as a year.
+        return context.getString(R.string.fmt_number, year)
+    }
+
+    override fun hashCode() = tokens.hashCode()
+
+    override fun equals(other: Any?) = other is Date && tokens == other.tokens
+
+    override fun compareTo(other: Date): Int {
+        for (i in 0 until max(tokens.size, other.tokens.size)) {
+            val ai = tokens.getOrNull(i)
+            val bi = other.tokens.getOrNull(i)
+            when {
+                ai != null && bi != null -> {
+                    val result = ai.compareTo(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
+    }
+
+    override fun toString() = StringBuilder().appendDate().toString()
+
+    private fun StringBuilder.appendDate(): StringBuilder {
+        // Construct an ISO-8601 date, dropping precision that doesn't exist.
+        append(year.toStringFixed(4))
+        append("-${(month ?: return this).toStringFixed(2)}")
+        append("-${(day ?: return this).toStringFixed(2)}")
+        append("T${(hour ?: return this).toStringFixed(2)}")
+        append(":${(minute ?: return this.append('Z')).toStringFixed(2)}")
+        append(":${(second ?: return this.append('Z')).toStringFixed(2)}")
+        return this.append('Z')
+    }
+
+    private fun Int.toStringFixed(len: Int) = toString().padStart(len, '0').substring(0 until len)
+
+    /**
+     * A range of [Date]s. This is used in contexts where the [Date] of an item is derived from
+     * several sub-items and thus can have a "range" of release dates. Use [from] to create an
+     * instance.
+     * @author Alexander Capehart
+     */
+    class Range
+    private constructor(
+        /** The earliest [Date] in the range. */
+        val min: Date,
+        /** the latest [Date] in the range. May be the same as [min]. ] */
+        val max: Date
+    ) : Comparable<Range> {
+
+        /**
+         * Resolve this instance into a human-readable date range.
+         * @param context [Context] required to get human-readable names.
+         * @return If the date has a maximum value, then a `min - max` formatted string will be
+         * returned with the formatted [Date]s of the minimum and maximum dates respectively.
+         * Otherwise, the formatted name of the minimum [Date] will be returned.
+         */
+        fun resolveDate(context: Context) =
+            if (min != max) {
+                context.getString(
+                    R.string.fmt_date_range, min.resolveDate(context), max.resolveDate(context))
+            } else {
+                min.resolveDate(context)
+            }
+
+        override fun equals(other: Any?) =
+            other is Range && min == other.min && max == other.max
+
+        override fun hashCode() = 31 * max.hashCode() + min.hashCode()
+
+        override fun compareTo(other: Range) = min.compareTo(other.min)
+
+        companion object {
+            /**
+             * Create a [Range] from the given list of [Date]s.
+             * @param dates The [Date]s to use.
+             * @return A [Range] based on the minimum and maximum [Date]s. If there are no [Date]s,
+             * null is returned.
+             */
+            fun from(dates: List<Date>): Range? {
+                if (dates.isEmpty()) {
+                    // Nothing to do.
+                    return null
+                }
+                // Simultaneously find the minimum and maximum values in the given range.
+                // If this list has only one item, then that one date is the minimum and maximum.
+                var min = dates.first()
+                var max = min
+                for (i in 1..dates.lastIndex) {
+                    if (dates[i] < min) {
+                        min = dates[i]
+                    }
+                    if (dates[i] > max) {
+                        max = dates[i]
+                    }
+                }
+                return Range(min, max)
+            }
+        }
+    }
+
+    companion object {
+        /**
+         * A [Regex] that can parse a variable-precision ISO-8601 timestamp. Derived from
+         * https://github.com/quodlibet/mutagen
+         */
+        private val ISO8601_REGEX =
+            Regex(
+                """^(\d{4,})([-.](\d{2})([-.](\d{2})([T ](\d{2})([:.](\d{2})([:.](\d{2})(Z)?)?)?)?)?)?$""")
+
+        /**
+         * Create a [Date] from a year component.
+         * @param year The year component.
+         * @return A new [Date] of the given component, or null if the component is invalid.
+         */
+        fun from(year: Int) = fromTokens(listOf(year))
+
+        /**
+         * Create a [Date] from a date component.
+         * @param year The year component.
+         * @param month The month component.
+         * @param day The day component.
+         * @return A new [Date] consisting of the given components. May have reduced precision if
+         * the components were partially invalid, and will be null if all components are invalid.
+         */
+        fun from(year: Int, month: Int, day: Int) = fromTokens(listOf(year, month, day))
+
+        /**
+         * Create [Date] from a datetime component.
+         * @param year The year component.
+         * @param month The month component.
+         * @param day The day component.
+         * @param hour The hour component
+         * @return A new [Date] consisting of the given components. May have reduced precision if
+         * the components were partially invalid, and will be null if all components are invalid.
+         */
+        fun from(year: Int, month: Int, day: Int, hour: Int, minute: Int) =
+            fromTokens(listOf(year, month, day, hour, minute))
+
+        /**
+         * Create a [Date] from a [String] timestamp.
+         * @param timestamp The ISO-8601 timestamp to parse. Can have reduced precision.
+         * @return A new [Date] consisting of the given components. May have reduced precision if
+         * the components were partially invalid, and will be null if all components are invalid or
+         * if the timestamp is invalid.
+         */
+        fun from(timestamp: String): Date? {
+            val tokens =
+            // Match the input with the timestamp regex
+            (ISO8601_REGEX.matchEntire(timestamp) ?: return null)
+                    .groupValues
+                    // Filter to the specific tokens we want and convert them to integer tokens.
+                    .mapIndexedNotNull { index, s -> if (index % 2 != 0) s.toIntOrNull() else null }
+            return fromTokens(tokens)
+        }
+
+        /**
+         * Create a [Date] from the given non-validated tokens.
+         * @param tokens The tokens to use for each date component, in order of precision.
+         * @return A new [Date] consisting of the given components. May have reduced precision if
+         * the components were partially invalid, and will be null if all components are invalid.
+         */
+        private fun fromTokens(tokens: List<Int>): Date? {
+            val validated = mutableListOf<Int>()
+            validateTokens(tokens, validated)
+            if (validated.isEmpty()) {
+                // No token was valid, return null.
+                return null
+            }
+            return Date(validated)
+        }
+
+        /**
+         * Validate a list of tokens provided by [src], and add the valid ones to [dst]. Will stop
+         * as soon as an invalid token is found.
+         * @param src The input tokens to validate.
+         * @param dst The destination list to add valid tokens to.
+         */
+        private fun validateTokens(src: List<Int>, dst: MutableList<Int>) {
+            dst.add(src.getOrNull(0)?.nonZeroOrNull() ?: return)
+            dst.add(src.getOrNull(1)?.inRangeOrNull(1..12) ?: return)
+            dst.add(src.getOrNull(2)?.inRangeOrNull(1..31) ?: return)
+            dst.add(src.getOrNull(3)?.inRangeOrNull(0..23) ?: return)
+            dst.add(src.getOrNull(4)?.inRangeOrNull(0..59) ?: return)
+            dst.add(src.getOrNull(5)?.inRangeOrNull(0..59) ?: return)
+        }
+    }
+}

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

@@ -24,20 +24,16 @@ import android.os.Parcelable
 import java.security.MessageDigest
 import java.text.CollationKey
 import java.text.Collator
-import java.text.ParseException
-import java.text.SimpleDateFormat
 import java.util.UUID
 import kotlin.math.max
 import kotlinx.parcelize.IgnoredOnParcel
 import kotlinx.parcelize.Parcelize
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.Item
-import org.oxycblt.auxio.music.extractor.parseId3GenreNames
+import org.oxycblt.auxio.music.filesystem.*
-import org.oxycblt.auxio.music.extractor.parseMultiValue
+import org.oxycblt.auxio.music.parsing.parseId3GenreNames
-import org.oxycblt.auxio.music.extractor.toUuidOrNull
+import org.oxycblt.auxio.music.parsing.parseMultiValue
-import org.oxycblt.auxio.music.storage.*
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.util.inRangeOrNull
 import org.oxycblt.auxio.util.nonZeroOrNull
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
@@ -114,6 +110,27 @@ sealed class Music : Item {
         return COLLATOR.getCollationKey(sortName)
     }
 
+    /**
+     * Join a list of [Music]'s resolved names into a string in a localized manner, using
+     * [R.string.fmt_list].
+     * @param context [Context] required to obtain localized formatting.
+     * @param values The list of [Music] to format.
+     * @return A single string consisting of the values delimited by a localized separator.
+     */
+    protected fun resolveNames(context: Context, values: List<Music>): String {
+        if (values.isEmpty()) {
+            // Nothing to do.
+            return ""
+        }
+
+        var joined = values.first().resolveName(context)
+        for (i in 1..values.lastIndex) {
+            // Chain all previous values with the next value in the list with another delimiter.
+            joined = context.getString(R.string.fmt_list, joined, values[i].resolveName(context))
+        }
+        return joined
+    }
+
     // Note: We solely use the UID in comparisons so that certain items that differ in all
     // but UID are treated differently.
 
@@ -262,9 +279,9 @@ sealed class Music : Item {
         }
     }
 
-    companion object {
+    private companion object {
         /** Cached collator instance re-used with [makeCollationKeyImpl]. */
-        private val COLLATOR = Collator.getInstance().apply { strength = Collator.PRIMARY }
+        val COLLATOR: Collator = Collator.getInstance().apply { strength = Collator.PRIMARY }
     }
 }
 
@@ -399,9 +416,7 @@ class Song constructor(raw: Raw, settings: Settings) : Music() {
      * Resolves one or more [Artist]s into a single piece of human-readable names.
      * @param context [Context] required for [resolveName]. formatter.
      */
-    fun resolveArtistContents(context: Context) =
+    fun resolveArtistContents(context: Context) = resolveNames(context, artists)
-        // TODO Internationalize the list
-        artists.joinToString { it.resolveName(context) }
 
     /**
      * Checks if the [Artist] *display* of this [Song] and another [Song] are equal. This will only
@@ -433,7 +448,7 @@ class Song constructor(raw: Raw, settings: Settings) : Music() {
      * Resolves one or more [Genre]s into a single piece human-readable names.
      * @param context [Context] required for [resolveName].
      */
-    fun resolveGenreContents(context: Context) = genres.joinToString { it.resolveName(context) }
+    fun resolveGenreContents(context: Context) = resolveNames(context, genres)
 
     // --- INTERNAL FIELDS ---
 
@@ -504,7 +519,6 @@ class Song constructor(raw: Raw, settings: Settings) : Music() {
         for (i in _artists.indices) {
             // Non-destructively reorder the linked artists so that they align with
             // the artist ordering within the song metadata.
-            // TODO: Make sure this works for artists only derived from album artists.
             val newIdx = _artists[i]._getOriginalPositionIn(_rawArtists)
             val other = _artists[newIdx]
             _artists[newIdx] = _artists[i]
@@ -610,11 +624,8 @@ class Album constructor(raw: Raw, override val songs: List<Song>) : MusicParent(
     override val collationKey = makeCollationKeyImpl()
     override fun resolveName(context: Context) = rawName
 
-    /**
+    /** The [Date.Range] that [Song]s in the [Album] were released. */
-     * The earliest [Date] this album was released. Will be null if no valid date was present in the
+    val dates = Date.Range.from(songs.mapNotNull { it.date })
-     * metadata of any [Song]
-     */
-    val date: Date? // TODO: Date ranges?
 
     /**
      * The [Type] of this album, signifying the type of release it actually is. Defaults to
@@ -634,31 +645,18 @@ class Album constructor(raw: Raw, override val songs: List<Song>) : MusicParent(
     val dateAdded: Long
 
     init {
-        var earliestDate: Date? = null
         var totalDuration: Long = 0
         var earliestDateAdded: Long = Long.MAX_VALUE
 
         // Do linking and value generation in the same loop for efficiency.
         for (song in songs) {
             song._link(this)
-
-            if (song.date != null) {
-                // Since we can't really assign a maximum value for dates, we instead
-                // just check if the current earliest date doesn't exist and fill it
-                // in with the current song if that's the case.
-                if (earliestDate == null || song.date < earliestDate) {
-                    earliestDate = song.date
-                }
-            }
-
             if (song.dateAdded < earliestDateAdded) {
                 earliestDateAdded = song.dateAdded
             }
-
             totalDuration += song.durationMs
         }
 
-        date = earliestDate
         durationMs = totalDuration
         dateAdded = earliestDateAdded
     }
@@ -676,7 +674,7 @@ class Album constructor(raw: Raw, override val songs: List<Song>) : MusicParent(
      * Resolves one or more [Artist]s into a single piece of human-readable names.
      * @param context [Context] required for [resolveName].
      */
-    fun resolveArtistContents(context: Context) = artists.joinToString { it.resolveName(context) }
+    fun resolveArtistContents(context: Context) = resolveNames(context, artists)
 
     /**
      * Checks if the [Artist] *display* of this [Album] and another [Album] are equal. This will
@@ -1043,7 +1041,7 @@ class Artist constructor(private val raw: Raw, songAlbums: List<Music>) : MusicP
      * Resolves one or more [Genre]s into a single piece of human-readable names.
      * @param context [Context] required for [resolveName].
      */
-    fun resolveGenreContents(context: Context) = genres.joinToString { it.resolveName(context) }
+    fun resolveGenreContents(context: Context) = resolveNames(context, genres)
 
     /**
      * Checks if the [Genre] *display* of this [Artist] and another [Artist] are equal. This will
@@ -1212,181 +1210,20 @@ class Genre constructor(private val raw: Raw, override val songs: List<Song>) :
     }
 }
 
-/**
- * An ISO-8601/RFC 3339 Date.
- *
- * This class only encodes the timestamp spec and it's conversion to a human-readable date, without
- * any other time management or validation. In general, this should only be used for display.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class Date private constructor(private val tokens: List<Int>) : Comparable<Date> {
-    private val year = tokens[0]
-    private val month = tokens.getOrNull(1)
-    private val day = tokens.getOrNull(2)
-    private val hour = tokens.getOrNull(3)
-    private val minute = tokens.getOrNull(4)
-    private val second = tokens.getOrNull(5)
-
-    /**
-     * Resolve this instance into a human-readable date.
-     * @param context [Context] required to get human-readable names.
-     * @return If the [Date] has a valid month and year value, a more fine-grained date (ex. "Jan
-     * 2020") will be returned. Otherwise, a plain year value (ex. "2020") is returned. Dates will
-     * be properly localized.
-     */
-    fun resolveDate(context: Context): String {
-        if (month != null) {
-            // Parse a date format from an ISO-ish format
-            val format = (SimpleDateFormat.getDateInstance() as SimpleDateFormat)
-            format.applyPattern("yyyy-MM")
-            val date =
-                try {
-                    format.parse("$year-$month")
-                } catch (e: ParseException) {
-                    null
-                }
-
-            if (date != null) {
-                // Reformat as a readable month and year
-                format.applyPattern("MMM yyyy")
-                return format.format(date)
-            }
-        }
-
-        // Unable to create fine-grained date, just format as a year.
-        return context.getString(R.string.fmt_number, year)
-    }
-
-    override fun hashCode() = tokens.hashCode()
-
-    override fun equals(other: Any?) = other is Date && tokens == other.tokens
-
-    override fun compareTo(other: Date): Int {
-        for (i in 0 until max(tokens.size, other.tokens.size)) {
-            val ai = tokens.getOrNull(i)
-            val bi = other.tokens.getOrNull(i)
-            when {
-                ai != null && bi != null -> {
-                    val result = ai.compareTo(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
-    }
-
-    override fun toString() = StringBuilder().appendDate().toString()
-
-    private fun StringBuilder.appendDate(): StringBuilder {
-        // Construct an ISO-8601 date, dropping precision that doesn't exist.
-        append(year.toStringFixed(4))
-        append("-${(month ?: return this).toStringFixed(2)}")
-        append("-${(day ?: return this).toStringFixed(2)}")
-        append("T${(hour ?: return this).toStringFixed(2)}")
-        append(":${(minute ?: return this.append('Z')).toStringFixed(2)}")
-        append(":${(second ?: return this.append('Z')).toStringFixed(2)}")
-        return this.append('Z')
-    }
-
-    private fun Int.toStringFixed(len: Int) = toString().padStart(len, '0').substring(0 until len)
-
-    companion object {
-        /**
-         * A [Regex] that can parse a variable-precision ISO-8601 timestamp. Derived from
-         * https://github.com/quodlibet/mutagen
-         */
-        private val ISO8601_REGEX =
-            Regex(
-                """^(\d{4,})([-.](\d{2})([-.](\d{2})([T ](\d{2})([:.](\d{2})([:.](\d{2})(Z)?)?)?)?)?)?$""")
-
-        /**
-         * Create a [Date] from a year component.
-         * @param year The year component.
-         * @return A new [Date] of the given component, or null if the component is invalid.
-         */
-        fun from(year: Int) = fromTokens(listOf(year))
-
-        /**
-         * Create a [Date] from a date component.
-         * @param year The year component.
-         * @param month The month component.
-         * @param day The day component.
-         * @return A new [Date] consisting of the given components. May have reduced precision if
-         * the components were partially invalid, and will be null if all components are invalid.
-         */
-        fun from(year: Int, month: Int, day: Int) = fromTokens(listOf(year, month, day))
-
-        /**
-         * Create [Date] from a datetime component.
-         * @param year The year component.
-         * @param month The month component.
-         * @param day The day component.
-         * @param hour The hour component
-         * @return A new [Date] consisting of the given components. May have reduced precision if
-         * the components were partially invalid, and will be null if all components are invalid.
-         */
-        fun from(year: Int, month: Int, day: Int, hour: Int, minute: Int) =
-            fromTokens(listOf(year, month, day, hour, minute))
-
-        /**
-         * Create a [Date] from a [String] timestamp.
-         * @param timestamp The ISO-8601 timestamp to parse. Can have reduced precision.
-         * @return A new [Date] consisting of the given components. May have reduced precision if
-         * the components were partially invalid, and will be null if all components are invalid or
-         * if the timestamp is invalid.
-         */
-        fun from(timestamp: String): Date? {
-            val tokens =
-            // Match the input with the timestamp regex
-            (ISO8601_REGEX.matchEntire(timestamp) ?: return null)
-                    .groupValues
-                    // Filter to the specific tokens we want and convert them to integer tokens.
-                    .mapIndexedNotNull { index, s -> if (index % 2 != 0) s.toIntOrNull() else null }
-            return fromTokens(tokens)
-        }
-
-        /**
-         * Create a [Date] from the given non-validated tokens.
-         * @param tokens The tokens to use for each date component, in order of precision.
-         * @return A new [Date] consisting of the given components. May have reduced precision if
-         * the components were partially invalid, and will be null if all components are invalid.
-         */
-        private fun fromTokens(tokens: List<Int>): Date? {
-            val validated = mutableListOf<Int>()
-            validateTokens(tokens, validated)
-            if (validated.isEmpty()) {
-                // No token was valid, return null.
-                return null
-            }
-            return Date(validated)
-        }
-
-        /**
-         * Validate a list of tokens provided by [src], and add the valid ones to [dst]. Will stop
-         * as soon as an invalid token is found.
-         * @param src The input tokens to validate.
-         * @param dst The destination list to add valid tokens to.
-         */
-        private fun validateTokens(src: List<Int>, dst: MutableList<Int>) {
-            dst.add(src.getOrNull(0)?.nonZeroOrNull() ?: return)
-            dst.add(src.getOrNull(1)?.inRangeOrNull(1..12) ?: return)
-            dst.add(src.getOrNull(2)?.inRangeOrNull(1..31) ?: return)
-            dst.add(src.getOrNull(3)?.inRangeOrNull(0..23) ?: return)
-            dst.add(src.getOrNull(4)?.inRangeOrNull(0..59) ?: return)
-            dst.add(src.getOrNull(5)?.inRangeOrNull(0..59) ?: return)
-        }
-    }
-}
-
 // --- MUSIC UID CREATION UTILITIES ---
 
+/**
+ * Convert a [String] to a [UUID].
+ * @return A [UUID] converted from the [String] value, or null if the value was not valid.
+ * @see UUID.fromString
+ */
+fun String.toUuidOrNull(): UUID? =
+    try {
+        UUID.fromString(this)
+    } catch (e: IllegalArgumentException) {
+        null
+    }
+
 /**
  * Update a [MessageDigest] with a lowercase [String].
  * @param string The [String] to hash. If null, it will not be hashed.

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

@@ -20,8 +20,8 @@ package org.oxycblt.auxio.music
 import android.content.Context
 import android.net.Uri
 import android.provider.OpenableColumns
-import org.oxycblt.auxio.music.storage.contentResolverSafe
+import org.oxycblt.auxio.music.filesystem.contentResolverSafe
-import org.oxycblt.auxio.music.storage.useQuery
+import org.oxycblt.auxio.music.filesystem.useQuery
 
 /**
  * A repository granting access to the music library..
@@ -33,42 +33,43 @@ import org.oxycblt.auxio.music.storage.useQuery
  * @author Alexander Capehart (OxygenCobalt)
  */
 class MusicStore private constructor() {
-    private val callbacks = mutableListOf<Callback>()
+    private val listeners = mutableListOf<Listener>()
 
     /**
      * The current [Library]. May be null if a [Library] has not been successfully loaded yet. This
      * can change, so it's highly recommended to not access this directly and instead rely on
-     * [Callback].
+     * [Listener].
      */
+    @Volatile
     var library: Library? = null
         set(value) {
             field = value
-            for (callback in callbacks) {
+            for (callback in listeners) {
                 callback.onLibraryChanged(library)
             }
         }
 
     /**
-     * Add a [Callback] to this instance. This can be used to receive changes in the music library.
+     * Add a [Listener] to this instance. This can be used to receive changes in the music library.
-     * Will invoke all [Callback] methods to initialize the instance with the current state.
+     * Will invoke all [Listener] methods to initialize the instance with the current state.
-     * @param callback The [Callback] to add.
+     * @param listener The [Listener] to add.
-     * @see Callback
+     * @see Listener
      */
     @Synchronized
-    fun addCallback(callback: Callback) {
+    fun addListener(listener: Listener) {
-        callback.onLibraryChanged(library)
+        listener.onLibraryChanged(library)
-        callbacks.add(callback)
+        listeners.add(listener)
     }
 
     /**
-     * Remove a [Callback] from this instance, preventing it from recieving any further updates.
+     * Remove a [Listener] from this instance, preventing it from recieving any further updates.
-     * @param callback The [Callback] to remove. Does nothing if the [Callback] was never added in
+     * @param listener The [Listener] to remove. Does nothing if the [Listener] was never added in
      * the first place.
-     * @see Callback
+     * @see Listener
      */
     @Synchronized
-    fun removeCallback(callback: Callback) {
+    fun removeListener(listener: Listener) {
-        callbacks.remove(callback)
+        listeners.remove(listener)
     }
 
     /**
@@ -167,7 +168,7 @@ class MusicStore private constructor() {
     }
 
     /** A listener for changes in the music library. */
-    interface Callback {
+    interface Listener {
         /**
          * Called when the current [Library] has changed.
          * @param library The new [Library], or null if no [Library] has been loaded yet.

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

@@ -26,7 +26,7 @@ import org.oxycblt.auxio.music.system.Indexer
  * A [ViewModel] providing data specific to the music loading process.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class MusicViewModel : ViewModel(), Indexer.Callback {
+class MusicViewModel : ViewModel(), Indexer.Listener {
     private val indexer = Indexer.getInstance()
 
     private val _indexerState = MutableStateFlow<Indexer.State?>(null)
@@ -39,18 +39,18 @@ class MusicViewModel : ViewModel(), Indexer.Callback {
         get() = _statistics
 
     init {
-        indexer.registerCallback(this)
+        indexer.registerListener(this)
     }
 
     override fun onCleared() {
-        indexer.unregisterCallback(this)
+        indexer.unregisterListener(this)
     }
 
     override fun onIndexerStateChanged(state: Indexer.State?) {
         _indexerState.value = state
-        if (state is Indexer.State.Complete && state.response is Indexer.Response.Ok) {
+        if (state is Indexer.State.Complete) {
             // New state is a completed library, update the statistics values.
-            val library = state.response.library
+            val library = state.result.getOrNull() ?: return
             _statistics.value =
                 Statistics(
                     library.songs.size,

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

@@ -232,7 +232,7 @@ data class Sort(val mode: Mode, val isAscending: Boolean) {
             override fun getSongComparator(isAscending: Boolean): Comparator<Song> =
                 MultiComparator(
                     compareByDynamic(isAscending, ListComparator.ARTISTS) { it.artists },
-                    compareByDescending(NullableComparator.DATE) { it.album.date },
+                    compareByDescending(NullableComparator.DATE_RANGE) { it.album.dates },
                     compareByDescending(BasicComparator.ALBUM) { it.album },
                     compareBy(NullableComparator.INT) { it.disc },
                     compareBy(NullableComparator.INT) { it.track },
@@ -241,14 +241,14 @@ data class Sort(val mode: Mode, val isAscending: Boolean) {
             override fun getAlbumComparator(isAscending: Boolean): Comparator<Album> =
                 MultiComparator(
                     compareByDynamic(isAscending, ListComparator.ARTISTS) { it.artists },
-                    compareByDescending(NullableComparator.DATE) { it.date },
+                    compareByDescending(NullableComparator.DATE_RANGE) { it.dates },
                     compareBy(BasicComparator.ALBUM))
         }
 
         /**
          * Sort by the [Date] of an item. Only available for [Song] and [Album].
          * @see Song.date
-         * @see Album.date
+         * @see Album.dates
          */
         object ByDate : Mode() {
             override val intCode: Int
@@ -259,7 +259,7 @@ data class Sort(val mode: Mode, val isAscending: Boolean) {
 
             override fun getSongComparator(isAscending: Boolean): Comparator<Song> =
                 MultiComparator(
-                    compareByDynamic(isAscending, NullableComparator.DATE) { it.album.date },
+                    compareByDynamic(isAscending, NullableComparator.DATE_RANGE) { it.album.dates },
                     compareByDescending(BasicComparator.ALBUM) { it.album },
                     compareBy(NullableComparator.INT) { it.disc },
                     compareBy(NullableComparator.INT) { it.track },
@@ -267,7 +267,7 @@ data class Sort(val mode: Mode, val isAscending: Boolean) {
 
             override fun getAlbumComparator(isAscending: Boolean): Comparator<Album> =
                 MultiComparator(
-                    compareByDynamic(isAscending, NullableComparator.DATE) { it.date },
+                    compareByDynamic(isAscending, NullableComparator.DATE_RANGE) { it.dates },
                     compareBy(BasicComparator.ALBUM))
         }
 
@@ -366,7 +366,7 @@ data class Sort(val mode: Mode, val isAscending: Boolean) {
         /**
          * Sort by the date an item was added. Only supported by [Song]s and [Album]s.
          * @see Song.dateAdded
-         * @see Album.date
+         * @see Album.dates
          */
         object ByDateAdded : Mode() {
             override val intCode: Int
@@ -543,8 +543,8 @@ data class Sort(val mode: Mode, val isAscending: Boolean) {
                 val INT = NullableComparator<Int>()
                 /** A re-usable instance configured for [Long]s. */
                 val LONG = NullableComparator<Long>()
-                /** A re-usable instance configured for [Date]s. */
+                /** A re-usable instance configured for [Date.Range]s. */
-                val DATE = NullableComparator<Date>()
+                val DATE_RANGE = NullableComparator<Date.Range>()
             }
         }
 

app/src/main/java/org/oxycblt/auxio/music/extractor/CacheExtractor.kt

@@ -23,7 +23,10 @@ import android.database.sqlite.SQLiteDatabase
 import android.database.sqlite.SQLiteOpenHelper
 import androidx.core.database.getIntOrNull
 import androidx.core.database.getStringOrNull
+import org.oxycblt.auxio.music.Date
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.music.parsing.correctWhitespace
+import org.oxycblt.auxio.music.parsing.splitEscaped
 import org.oxycblt.auxio.util.*
 
 /**
@@ -278,7 +281,7 @@ private class CacheDatabase(context: Context) :
 
                 raw.track = cursor.getIntOrNull(trackIndex)
                 raw.disc = cursor.getIntOrNull(discIndex)
-                raw.date = cursor.getStringOrNull(dateIndex)?.parseTimestamp()
+                raw.date = cursor.getStringOrNull(dateIndex)?.let(Date::from)
 
                 raw.albumMusicBrainzId = cursor.getStringOrNull(albumMusicBrainzIdIndex)
                 raw.albumName = cursor.getString(albumNameIndex)
@@ -387,8 +390,7 @@ private class CacheDatabase(context: Context) :
      * @return A list of strings corresponding to the delimited values present within the original
      * string. Escaped delimiters are converted back into their normal forms.
      */
-    private fun String.parseSQLMultiValue() =
+    private fun String.parseSQLMultiValue() = splitEscaped { it == ';' }.correctWhitespace()
-        splitEscaped { it == ';' }
 
     /** Defines the columns used in this database. */
     private object Columns {

app/src/main/java/org/oxycblt/auxio/music/extractor/ExtractionResult.kt

@@ -24,10 +24,8 @@ package org.oxycblt.auxio.music.extractor
 enum class ExtractionResult {
     /** A raw song was successfully extracted from the cache. */
     CACHED,
-
     /** A raw song was successfully extracted from parsing it's file. */
     PARSED,
-
     /** A raw song could not be parsed. */
     NONE
 }

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

@@ -27,17 +27,20 @@ import androidx.annotation.RequiresApi
 import androidx.core.database.getIntOrNull
 import androidx.core.database.getStringOrNull
 import java.io.File
+import org.oxycblt.auxio.music.Date
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.storage.Directory
+import org.oxycblt.auxio.music.filesystem.Directory
-import org.oxycblt.auxio.music.storage.contentResolverSafe
+import org.oxycblt.auxio.music.filesystem.contentResolverSafe
-import org.oxycblt.auxio.music.storage.directoryCompat
+import org.oxycblt.auxio.music.filesystem.directoryCompat
-import org.oxycblt.auxio.music.storage.mediaStoreVolumeNameCompat
+import org.oxycblt.auxio.music.filesystem.mediaStoreVolumeNameCompat
-import org.oxycblt.auxio.music.storage.safeQuery
+import org.oxycblt.auxio.music.filesystem.safeQuery
-import org.oxycblt.auxio.music.storage.storageVolumesCompat
+import org.oxycblt.auxio.music.filesystem.storageVolumesCompat
-import org.oxycblt.auxio.music.storage.useQuery
+import org.oxycblt.auxio.music.filesystem.useQuery
+import org.oxycblt.auxio.music.parsing.parseId3v2Position
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.util.getSystemServiceCompat
 import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.nonZeroOrNull
 
 /**
  * The layer that loads music from the [MediaStore] database. This is an intermediate step in the
@@ -302,7 +305,7 @@ abstract class MediaStoreExtractor(
         // MediaStore only exposes the year value of a file. This is actually worse than it
         // seems, as it means that it will not read ID3v2 TDRC tags or Vorbis DATE comments.
         // This is one of the major weaknesses of using MediaStore, hence the redundancy layers.
-        raw.date = cursor.getIntOrNull(yearIndex)?.toDate()
+        raw.date = cursor.getIntOrNull(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
         // file is not actually in the root internal storage directory. We can't do anything to
@@ -322,12 +325,12 @@ abstract class MediaStoreExtractor(
         genreNamesMap[raw.mediaStoreId]?.let { raw.genreNames = listOf(it) }
     }
 
-    companion object {
+    private companion object {
         /**
          * The base selector that works across all versions of android. Does not exclude
          * directories.
          */
-        private const val BASE_SELECTOR = "NOT ${MediaStore.Audio.Media.SIZE}=0"
+        const val BASE_SELECTOR = "NOT ${MediaStore.Audio.Media.SIZE}=0"
 
         /**
          * The album artist of a song. This column has existed since at least API 21, but until API
@@ -335,13 +338,13 @@ abstract class MediaStoreExtractor(
          * versions that Auxio supports.
          */
         @Suppress("InlinedApi")
-        private const val AUDIO_COLUMN_ALBUM_ARTIST = MediaStore.Audio.AudioColumns.ALBUM_ARTIST
+        const val AUDIO_COLUMN_ALBUM_ARTIST = MediaStore.Audio.AudioColumns.ALBUM_ARTIST
 
         /**
          * The external volume. This naming has existed since API 21, but no constant existed for it
          * until API 29. This will work on all versions that Auxio supports.
          */
-        @Suppress("InlinedApi") private const val VOLUME_EXTERNAL = MediaStore.VOLUME_EXTERNAL
+        @Suppress("InlinedApi") const val VOLUME_EXTERNAL = MediaStore.VOLUME_EXTERNAL
     }
 }
 
@@ -561,7 +564,24 @@ class Api30MediaStoreExtractor(context: Context, cacheExtractor: CacheExtractor)
         // the tag itself, which is to say that it is formatted as NN/TT tracks, where
         // N is the number and T is the total. Parse the number while ignoring the
         // total, as we have no use for it.
-        cursor.getStringOrNull(trackIndex)?.parsePositionNum()?.let { raw.track = it }
+        cursor.getStringOrNull(trackIndex)?.parseId3v2Position()?.let { raw.track = it }
-        cursor.getStringOrNull(discIndex)?.parsePositionNum()?.let { raw.disc = it }
+        cursor.getStringOrNull(discIndex)?.parseId3v2Position()?.let { raw.disc = it }
     }
 }
+
+/**
+ * Unpack the track number from a combined track + disc [Int] field. These fields appear within
+ * MediaStore's TRACK column, and combine the track and disc value into a single field where the
+ * disc number is the 4th+ digit.
+ * @return The track number extracted from the combined integer value, or null if the value was
+ * zero.
+ */
+private fun Int.unpackTrackNo() = mod(1000).nonZeroOrNull()
+
+/**
+ * Unpack the disc number from a combined track + disc [Int] field. These fields appear within
+ * MediaStore's TRACK column, and combine the track and disc value into a single field where the
+ * disc number is the 4th+ digit.
+ * @return The disc number extracted from the combined integer field, or null if the value was zero.
+ */
+private fun Int.unpackDiscNo() = div(1000).nonZeroOrNull()

app/src/main/java/org/oxycblt/auxio/music/extractor/MetadataExtractor.kt

@@ -21,12 +21,10 @@ import android.content.Context
 import androidx.core.text.isDigitsOnly
 import com.google.android.exoplayer2.MediaItem
 import com.google.android.exoplayer2.MetadataRetriever
-import com.google.android.exoplayer2.metadata.Metadata
-import com.google.android.exoplayer2.metadata.id3.TextInformationFrame
-import com.google.android.exoplayer2.metadata.vorbis.VorbisComment
 import org.oxycblt.auxio.music.Date
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.music.storage.toAudioUri
+import org.oxycblt.auxio.music.filesystem.toAudioUri
+import org.oxycblt.auxio.music.parsing.parseId3v2Position
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logW
 
@@ -116,8 +114,8 @@ class MetadataExtractor(
         }
     }
 
-    companion object {
+    private companion object {
-        private const val TASK_CAPACITY = 8
+        const val TASK_CAPACITY = 8
     }
 }
 
@@ -128,7 +126,6 @@ class MetadataExtractor(
  * @author Alexander Capehart (OxygenCobalt)
  */
 class Task(context: Context, private val raw: Song.Raw) {
-    // TODO: Unify with MetadataExtractor
     // 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.
@@ -144,6 +141,7 @@ class Task(context: Context, private val raw: Song.Raw) {
      */
     fun get(): Song.Raw? {
         if (!future.isDone) {
+            // Not done yet, nothing to do.
             return null
         }
 
@@ -162,7 +160,9 @@ class Task(context: Context, private val raw: Song.Raw) {
 
         val metadata = format.metadata
         if (metadata != null) {
-            populateWithMetadata(metadata)
+            val tags = Tags(metadata)
+            populateWithId3v2(tags.id3v2)
+            populateWithVorbis(tags.vorbis)
         } else {
             logD("No metadata could be extracted for ${raw.name}")
         }
@@ -170,51 +170,6 @@ class Task(context: Context, private val raw: Song.Raw) {
         return raw
     }
 
-    /**
-     * Complete this instance's [Song.Raw] with the newly extracted [Metadata].
-     * @param metadata The [Metadata] to complete the [Song.Raw] with.
-     */
-    private fun populateWithMetadata(metadata: Metadata) {
-        val id3v2Tags = mutableMapOf<String, List<String>>()
-        val vorbisTags = mutableMapOf<String, MutableList<String>>()
-
-        // ExoPlayer only exposes ID3v2 and Vorbis metadata, which constitutes the vast majority
-        // of audio formats. Load both of these types of tags into separate maps, letting the
-        // "source of truth" be the last of a particular tag in a file.
-        for (i in 0 until metadata.length()) {
-            when (val tag = metadata[i]) {
-                is TextInformationFrame -> {
-                    // Map TXXX frames differently so we can specifically index by their
-                    // descriptions.
-                    val id = tag.description?.let { "TXXX:${it.sanitize()}" } ?: tag.id.sanitize()
-                    val values = tag.values.map { it.sanitize() }.filter { it.isNotEmpty() }
-                    if (values.isNotEmpty()) {
-                        id3v2Tags[id] = values
-                    }
-                }
-                is VorbisComment -> {
-                    // Vorbis comment keys can be in any case, make them uppercase for simplicity.
-                    val id = tag.key.sanitize().uppercase()
-                    val value = tag.value.sanitize()
-                    if (value.isNotEmpty()) {
-                        vorbisTags.getOrPut(id) { mutableListOf() }.add(value)
-                    }
-                }
-            }
-        }
-
-        when {
-            vorbisTags.isEmpty() -> populateWithId3v2(id3v2Tags)
-            id3v2Tags.isEmpty() -> populateWithVorbis(vorbisTags)
-            else -> {
-                // Some formats (like FLAC) can contain both ID3v2 and Vorbis, so we apply
-                // them both with priority given to vorbis.
-                populateWithId3v2(id3v2Tags)
-                populateWithVorbis(vorbisTags)
-            }
-        }
-    }
-
     /**
      * Complete this instance's [Song.Raw] with ID3v2 Text Identification Frames.
      * @param textFrames A mapping between ID3v2 Text Identification Frame IDs and one or more
@@ -222,15 +177,15 @@ class Task(context: Context, private val raw: Song.Raw) {
      */
     private fun populateWithId3v2(textFrames: Map<String, List<String>>) {
         // Song
-        textFrames["TXXX:MusicBrainz Release Track Id"]?.let { raw.musicBrainzId = it[0] }
+        textFrames["TXXX:musicbrainz release track id"]?.let { raw.musicBrainzId = it[0] }
         textFrames["TIT2"]?.let { raw.name = it[0] }
         textFrames["TSOT"]?.let { raw.sortName = it[0] }
 
         // Track. Only parse out the track number and ignore the total tracks value.
-        textFrames["TRCK"]?.run { get(0).parsePositionNum() }?.let { raw.track = it }
+        textFrames["TRCK"]?.run { first().parseId3v2Position() }?.let { raw.track = it }
 
         // Disc. Only parse out the disc number and ignore the total discs value.
-        textFrames["TPOS"]?.run { get(0).parsePositionNum() }?.let { raw.disc = it }
+        textFrames["TPOS"]?.run { first().parseId3v2Position() }?.let { raw.disc = it }
 
         // Dates are somewhat complicated, as not only did their semantics change from a flat year
         // value in ID3v2.3 to a full ISO-8601 date in ID3v2.4, but there are also a variety of
@@ -241,27 +196,27 @@ class Task(context: Context, private val raw: Song.Raw) {
         // 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
-        (textFrames["TDOR"]?.run { get(0).parseTimestamp() }
+        (textFrames["TDOR"]?.run { Date.from(first()) }
-                ?: textFrames["TDRC"]?.run { get(0).parseTimestamp() }
+                ?: textFrames["TDRC"]?.run { Date.from(first()) }
-                    ?: textFrames["TDRL"]?.run { get(0).parseTimestamp() }
+                    ?: textFrames["TDRL"]?.run { Date.from(first()) }
                     ?: parseId3v23Date(textFrames))
             ?.let { raw.date = it }
 
         // Album
-        textFrames["TXXX:MusicBrainz Album Id"]?.let { raw.albumMusicBrainzId = it[0] }
+        textFrames["TXXX:musicbrainz album id"]?.let { raw.albumMusicBrainzId = it[0] }
         textFrames["TALB"]?.let { raw.albumName = it[0] }
         textFrames["TSOA"]?.let { raw.albumSortName = it[0] }
-        (textFrames["TXXX:MusicBrainz Album Type"] ?: textFrames["GRP1"])?.let {
+        (textFrames["TXXX:musicbrainz album type"] ?: textFrames["GRP1"])?.let {
             raw.albumTypes = it
         }
 
         // Artist
-        textFrames["TXXX:MusicBrainz Artist Id"]?.let { raw.artistMusicBrainzIds = it }
+        textFrames["TXXX:musicbrainz artist id"]?.let { raw.artistMusicBrainzIds = it }
         textFrames["TPE1"]?.let { raw.artistNames = it }
         textFrames["TSOP"]?.let { raw.artistSortNames = it }
 
         // Album artist
-        textFrames["TXXX:MusicBrainz Album Artist Id"]?.let { raw.albumArtistMusicBrainzIds = it }
+        textFrames["TXXX:musicbrainz album artist id"]?.let { raw.albumArtistMusicBrainzIds = it }
         textFrames["TPE2"]?.let { raw.albumArtistNames = it }
         textFrames["TSO2"]?.let { raw.albumArtistSortNames = it }
 
@@ -282,8 +237,8 @@ class Task(context: Context, private val raw: Song.Raw) {
         // Assume that TDAT/TIME can refer to TYER or TORY depending on if TORY
         // is present.
         val year =
-            textFrames["TORY"]?.run { get(0).toIntOrNull() }
+            textFrames["TORY"]?.run { first().toIntOrNull() }
-                ?: textFrames["TYER"]?.run { get(0).toIntOrNull() } ?: return null
+                ?: textFrames["TYER"]?.run { first().toIntOrNull() } ?: return null
 
         val tdat = textFrames["TDAT"]
         return if (tdat != null && tdat[0].length == 4 && tdat[0].isDigitsOnly()) {
@@ -317,17 +272,17 @@ class Task(context: Context, private val raw: Song.Raw) {
      */
     private fun populateWithVorbis(comments: Map<String, List<String>>) {
         // Song
-        comments["MUSICBRAINZ_RELEASETRACKID"]?.let { raw.musicBrainzId = it[0] }
+        comments["musicbrainz_releasetrackid"]?.let { raw.musicBrainzId = it[0] }
-        comments["TITLE"]?.let { raw.name = it[0] }
+        comments["title"]?.let { raw.name = it[0] }
-        comments["TITLESORT"]?.let { raw.sortName = it[0] }
+        comments["titlesort"]?.let { raw.sortName = it[0] }
 
         // Track. The total tracks value is in a different comment, so we can just
         // convert the entirety of this comment into a number.
-        comments["TRACKNUMBER"]?.run { get(0).toIntOrNull() }?.let { raw.track = it }
+        comments["tracknumber"]?.run { first().toIntOrNull() }?.let { raw.track = it }
 
         // Disc. The total discs value is in a different comment, so we can just
         // convert the entirety of this comment into a number.
-        comments["DISCNUMBER"]?.run { get(0).toIntOrNull() }?.let { raw.disc = it }
+        comments["discnumber"]?.run { first().toIntOrNull() }?.let { raw.disc = it }
 
         // Vorbis dates are less complicated, but there are still several types
         // Our hierarchy for dates is as such:
@@ -335,35 +290,28 @@ class Task(context: Context, private val raw: Song.Raw) {
         // 2. Date, as it is the most common date type
         // 3. Year, as old vorbis tags tended to use this (I know this because it's the only
         // date tag that android supports, so it must be 15 years old or more!)
-        (comments["ORIGINALDATE"]?.run { get(0).parseTimestamp() }
+        (comments["originaldate"]?.run { Date.from(first()) }
-                ?: comments["DATE"]?.run { get(0).parseTimestamp() }
+                ?: comments["date"]?.run { Date.from(first()) }
-                    ?: comments["YEAR"]?.run { get(0).parseYear() })
+                    ?: comments["year"]?.run { first().toIntOrNull()?.let(Date::from) })
             ?.let { raw.date = it }
 
         // Album
-        comments["MUSICBRAINZ_ALBUMID"]?.let { raw.albumMusicBrainzId = it[0] }
+        comments["musicbrainz_albumid"]?.let { raw.albumMusicBrainzId = it[0] }
-        comments["ALBUM"]?.let { raw.albumName = it[0] }
+        comments["album"]?.let { raw.albumName = it[0] }
-        comments["ALBUMSORT"]?.let { raw.albumSortName = it[0] }
+        comments["albumsort"]?.let { raw.albumSortName = it[0] }
-        comments["RELEASETYPE"]?.let { raw.albumTypes = it }
+        comments["releasetype"]?.let { raw.albumTypes = it }
 
         // Artist
-        comments["MUSICBRAINZ_ARTISTID"]?.let { raw.artistMusicBrainzIds = it }
+        comments["musicbrainz_artistid"]?.let { raw.artistMusicBrainzIds = it }
-        comments["ARTIST"]?.let { raw.artistNames = it }
+        comments["artist"]?.let { raw.artistNames = it }
-        comments["ARTISTSORT"]?.let { raw.artistSortNames = it }
+        comments["artistsort"]?.let { raw.artistSortNames = it }
 
         // Album artist
-        comments["MUSICBRAINZ_ALBUMARTISTID"]?.let { raw.albumArtistMusicBrainzIds = it }
+        comments["musicbrainz_albumartistid"]?.let { raw.albumArtistMusicBrainzIds = it }
-        comments["ALBUMARTIST"]?.let { raw.albumArtistNames = it }
+        comments["albumartist"]?.let { raw.albumArtistNames = it }
-        comments["ALBUMARTISTSORT"]?.let { raw.albumArtistSortNames = it }
+        comments["albumartistsort"]?.let { raw.albumArtistSortNames = it }
 
         // Genre
         comments["GENRE"]?.let { raw.genreNames = it }
     }
-
-    /**
-     * Copies and sanitizes a possibly native/non-UTF-8 string.
-     * @return A new string allocated in a memory-safe manner with any UTF-8 errors replaced with
-     * the Unicode replacement byte sequence.
-     */
-    private fun String.sanitize() = String(encodeToByteArray())
 }

app/src/main/java/org/oxycblt/auxio/music/extractor/Tags.kt

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ *
+ * 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.extractor
+
+import com.google.android.exoplayer2.metadata.Metadata
+import com.google.android.exoplayer2.metadata.id3.InternalFrame
+import com.google.android.exoplayer2.metadata.id3.TextInformationFrame
+import com.google.android.exoplayer2.metadata.vorbis.VorbisComment
+import org.oxycblt.auxio.music.parsing.correctWhitespace
+
+/**
+ * Processing wrapper for [Metadata] that allows access to more organized music tags.
+ * @param metadata The [Metadata] to wrap.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+class Tags(metadata: Metadata) {
+    private val _id3v2 = mutableMapOf<String, List<String>>()
+    /** The ID3v2 text identification frames found in the file. Can have more than one value. */
+    val id3v2: Map<String, List<String>>
+        get() = _id3v2
+
+    private val _vorbis = mutableMapOf<String, MutableList<String>>()
+    /** The vorbis comments found in the file. Can have more than one value. */
+    val vorbis: Map<String, List<String>>
+        get() = _vorbis
+
+    init {
+        for (i in 0 until metadata.length()) {
+            when (val tag = metadata[i]) {
+                is TextInformationFrame -> {
+                    // Map TXXX frames differently so we can specifically index by their
+                    // descriptions.
+                    val id =
+                        tag.description?.let { "TXXX:${it.sanitize().lowercase()}" }
+                            ?: tag.id.sanitize()
+                    val values = tag.values.map { it.sanitize() }.correctWhitespace()
+                    if (values.isNotEmpty()) {
+                        _id3v2[id] = values
+                    }
+                }
+                is InternalFrame -> {
+                    // Most MP4 metadata atoms map to ID3v2 text frames, except for the ---- atom,
+                    // which has it's own frame. Map this to TXXX, it's rough ID3v2 equivalent.
+                    val id = "TXXX:${tag.description.sanitize().lowercase()}"
+                    val value = tag.text
+                    if (value.isNotEmpty()) {
+                        _id3v2[id] = listOf(value)
+                    }
+                }
+                is VorbisComment -> {
+                    // Vorbis comment keys can be in any case, make them uppercase for simplicity.
+                    val id = tag.key.sanitize().lowercase()
+                    val value = tag.value.sanitize().correctWhitespace()
+                    if (value != null) {
+                        _vorbis.getOrPut(id) { mutableListOf() }.add(value)
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Copies and sanitizes a possibly invalid string outputted from ExoPlayer.
+     * @return A new string allocated in a memory-safe manner with any UTF-8 errors replaced with
+     * the Unicode replacement byte sequence.
+     */
+    private fun String.sanitize() = String(encodeToByteArray())
+}

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

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.filesystem
 
 import android.view.View
 import android.view.ViewGroup
@@ -41,7 +41,7 @@ class DirectoryAdapter(private val listener: Listener) :
     override fun getItemCount() = dirs.size
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-        MusicDirViewHolder.new(parent)
+        MusicDirViewHolder.from(parent)
 
     override fun onBindViewHolder(holder: MusicDirViewHolder, position: Int) =
         holder.bind(dirs[position], listener)
@@ -86,7 +86,7 @@ class DirectoryAdapter(private val listener: Listener) :
 }
 
 /**
- * A [RecyclerView.Recycler] that displays a [Directory]. Use [new] to create an instance.
+ * A [RecyclerView.Recycler] that displays a [Directory]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class MusicDirViewHolder private constructor(private val binding: ItemMusicDirBinding) :
@@ -107,7 +107,7 @@ class MusicDirViewHolder private constructor(private val binding: ItemMusicDirBi
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             MusicDirViewHolder(ItemMusicDirBinding.inflate(parent.context.inflater))
     }
 }

app/src/main/java/org/oxycblt/auxio/music/filesystem/Filesystem.kt

@@ -15,15 +15,13 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.filesystem
 
 import android.content.Context
-import android.media.MediaExtractor
 import android.media.MediaFormat
 import android.os.storage.StorageManager
 import android.os.storage.StorageVolume
 import android.webkit.MimeTypeMap
-import com.google.android.exoplayer2.util.MimeTypes
 import java.io.File
 import org.oxycblt.auxio.R
 

app/src/main/java/org/oxycblt/auxio/music/filesystem/FilesystemUtil.kt

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.filesystem
 
 import android.annotation.SuppressLint
 import android.content.ContentResolver

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

@@ -15,13 +15,14 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.storage
+package org.oxycblt.auxio.music.filesystem
 
 import android.net.Uri
 import android.os.Bundle
 import android.os.storage.StorageManager
 import android.provider.DocumentsContract
 import android.view.LayoutInflater
+import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AlertDialog
 import androidx.core.view.isVisible
@@ -30,7 +31,6 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogMusicDirsBinding
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
-import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.getSystemServiceCompat
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.showToast
@@ -42,10 +42,8 @@ import org.oxycblt.auxio.util.showToast
 class MusicDirsDialog :
     ViewBindingDialogFragment<DialogMusicDirsBinding>(), DirectoryAdapter.Listener {
     private val dirAdapter = DirectoryAdapter(this)
-    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
+    private var openDocumentTreeLauncher: ActivityResultLauncher<Uri?>? = null
-    private val storageManager: StorageManager by lifecycleObject { binding ->
+    private var storageManager: StorageManager? = null
-        binding.context.getSystemServiceCompat(StorageManager::class)
-    }
 
     override fun onCreateBinding(inflater: LayoutInflater) =
         DialogMusicDirsBinding.inflate(inflater)
@@ -57,7 +55,10 @@ class MusicDirsDialog :
             .setNeutralButton(R.string.lbl_add, null)
             .setNegativeButton(R.string.lbl_cancel, null)
             .setPositiveButton(R.string.lbl_save) { _, _ ->
-                val dirs = settings.getMusicDirs(storageManager)
+                val settings = Settings(requireContext())
+                val dirs =
+                    settings.getMusicDirs(
+                        requireNotNull(storageManager) { "StorageManager was not available" })
                 val newDirs = MusicDirectories(dirAdapter.dirs, isUiModeInclude(requireBinding()))
                 if (dirs != newDirs) {
                     logD("Committing changes")
@@ -67,7 +68,11 @@ class MusicDirsDialog :
     }
 
     override fun onBindingCreated(binding: DialogMusicDirsBinding, savedInstanceState: Bundle?) {
-        val launcher =
+        val context = requireContext()
+        val storageManager =
+            context.getSystemServiceCompat(StorageManager::class).also { storageManager = it }
+
+        openDocumentTreeLauncher =
             registerForActivityResult(
                 ActivityResultContracts.OpenDocumentTree(), ::addDocumentTreeUriToDirs)
 
@@ -79,7 +84,10 @@ class MusicDirsDialog :
             val dialog = it as AlertDialog
             dialog.getButton(AlertDialog.BUTTON_NEUTRAL)?.setOnClickListener {
                 logD("Opening launcher")
-                launcher.launch(null)
+                requireNotNull(openDocumentTreeLauncher) {
+                        "Document tree launcher was not available"
+                    }
+                    .launch(null)
             }
         }
 
@@ -88,7 +96,7 @@ class MusicDirsDialog :
             itemAnimator = null
         }
 
-        var dirs = settings.getMusicDirs(storageManager)
+        var dirs = Settings(context).getMusicDirs(storageManager)
 
         if (savedInstanceState != null) {
             val pendingDirs = savedInstanceState.getStringArrayList(KEY_PENDING_DIRS)
@@ -127,6 +135,8 @@ class MusicDirsDialog :
 
     override fun onDestroyBinding(binding: DialogMusicDirsBinding) {
         super.onDestroyBinding(binding)
+        storageManager = null
+        openDocumentTreeLauncher = null
         binding.dirsRecycler.adapter = null
     }
 
@@ -153,7 +163,9 @@ class MusicDirsDialog :
             DocumentsContract.buildDocumentUriUsingTree(
                 uri, DocumentsContract.getTreeDocumentId(uri))
         val treeUri = DocumentsContract.getTreeDocumentId(docUri)
-        val dir = Directory.fromDocumentTreeUri(storageManager, treeUri)
+        val dir =
+            Directory.fromDocumentTreeUri(
+                requireNotNull(storageManager) { "StorageManager was not available" }, treeUri)
 
         if (dir != null) {
             dirAdapter.add(dir)
@@ -176,7 +188,7 @@ class MusicDirsDialog :
     private fun isUiModeInclude(binding: DialogMusicDirsBinding) =
         binding.folderModeGroup.checkedButtonId == R.id.dirs_mode_include
 
-    companion object {
+    private companion object {
         const val KEY_PENDING_DIRS = BuildConfig.APPLICATION_ID + ".key.PENDING_DIRS"
         const val KEY_PENDING_MODE = BuildConfig.APPLICATION_ID + ".key.SHOULD_INCLUDE"
     }

app/src/main/java/org/oxycblt/auxio/music/parsing/ParsingUtil.kt

@@ -15,61 +15,27 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.extractor
+package org.oxycblt.auxio.music.parsing
 
-import androidx.core.text.isDigitsOnly
-import java.util.UUID
-import org.oxycblt.auxio.music.Date
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.nonZeroOrNull
 
-/**
+/// --- GENERIC PARSING ---
- * Unpack the track number from a combined track + disc [Int] field. These fields appear within
- * MediaStore's TRACK column, and combine the track and disc value into a single field where the
- * disc number is the 4th+ digit.
- * @return The track number extracted from the combined integer value, or null if the value was
- * zero.
- */
-fun Int.unpackTrackNo() = mod(1000).nonZeroOrNull()
 
 /**
- * Unpack the disc number from a combined track + disc [Int] field. These fields appear within
+ * Parse a multi-value tag based on the user configuration. If the value is already composed of more
- * MediaStore's TRACK column, and combine the track and disc value into a single field where the
+ * than one value, nothing is done. Otherwise, this function will attempt to split it based on the
- * disc number is the 4th+ digit.
+ * user's separator preferences.
- * @return The disc number extracted from the combined integer field, or null if the value was zero.
+ * @param settings [Settings] required to obtain user separator configuration.
+ * @return A new list of one or more [String]s.
  */
-fun Int.unpackDiscNo() = div(1000).nonZeroOrNull()
+fun List<String>.parseMultiValue(settings: Settings) =
-
+    if (size == 1) {
-/**
+        first().maybeParseBySeparators(settings)
- * Parse the number out of a combined number + total position [String] field. These fields often
+    } else {
- * appear in ID3v2 files, and consist of a number and an (optional) total value delimited by a /.
+        // Nothing to do.
- * @return The number value extracted from the string field, or null if the value could not be
+        this
- * parsed or if the value was zero.
+    }
- */
-fun String.parsePositionNum() = split('/', limit = 2)[0].toIntOrNull()?.nonZeroOrNull()
-
-/**
- * Transform an [Int] year field into a [Date].
- * @return A [Date] consisting of the year value, or null if the value was zero.
- * @see Date.from
- */
-fun Int.toDate() = Date.from(this)
-
-/**
- * Parse an integer year field from a [String] and transform it into a [Date].
- * @return A [Date] consisting of the year value, or null if the value could not be parsed or if the
- * value was zero.
- * @see Date.from
- */
-fun String.parseYear() = toIntOrNull()?.toDate()
-
-/**
- * Parse an ISO-8601 timestamp [String] into a [Date].
- * @return A [Date] consisting of the year value plus one or more refinement values (ex. month,
- * day), or null if the timestamp was not valid.
- */
-fun String.parseTimestamp() = Date.from(this)
 
 /**
  * Split a [String] by the given selector, automatically handling escaped characters that satisfy
@@ -116,42 +82,38 @@ inline fun String.splitEscaped(selector: (Char) -> Boolean): List<String> {
 }
 
 /**
- * Parse a multi-value tag based on the user configuration. If the value is already composed of more
+ * Fix trailing whitespace or blank contents in a [String].
- * than one value, nothing is done. Otherwise, this function will attempt to split it based on the
+ * @return A string with trailing whitespace remove,d or null if the [String] was all whitespace or
- * user's separator preferences.
+ * empty.
- * @param settings [Settings] required to obtain user separator configuration.
- * @return A new list of one or more [String]s.
  */
-fun List<String>.parseMultiValue(settings: Settings) =
+fun String.correctWhitespace() = trim().ifBlank { null }
-    if (size == 1) {
+
-        get(0).maybeParseSeparators(settings)
+/**
-    } else {
+ * Fix trailing whitespace or blank contents within a list of [String]s.
-        // Nothing to do.
+ * @return A list of non-blank strings with trailing whitespace removed.
-        this.map { it.trim() }
+ */
-    }
+fun List<String>.correctWhitespace() = mapNotNull { it.correctWhitespace() }
 
 /**
  * Attempt to parse a string by the user's separator preferences.
  * @param settings [Settings] required to obtain user separator configuration.
  * @return A list of one or more [String]s that were split up by the user-defined separators.
  */
-fun String.maybeParseSeparators(settings: Settings): List<String> {
+private fun String.maybeParseBySeparators(settings: Settings): List<String> {
     // Get the separators the user desires. If null, there's nothing to do.
     val separators = settings.musicSeparators ?: return listOf(this)
-    return splitEscaped { separators.contains(it) }.map { it.trim() }
+    return splitEscaped { separators.contains(it) }.correctWhitespace()
 }
 
+/// --- ID3v2 PARSING ---
+
 /**
- * Convert a [String] to a [UUID].
+ * Parse the number out of a ID3v2-style number + total position [String] field. These fields
- * @return A [UUID] converted from the [String] value, or null if the value was not valid.
+ * consist of a number and an (optional) total value delimited by a /.
- * @see UUID.fromString
+ * @return The number value extracted from the string field, or null if the value could not be
+ * parsed or if the value was zero.
  */
-fun String.toUuidOrNull(): UUID? =
+fun String.parseId3v2Position() = split('/', limit = 2)[0].toIntOrNull()?.nonZeroOrNull()
-    try {
-        UUID.fromString(this)
-    } catch (e: IllegalArgumentException) {
-        null
-    }
 
 /**
  * Parse a multi-value genre name using ID3 rules. This will convert any ID3v1 integer
@@ -162,7 +124,7 @@ fun String.toUuidOrNull(): UUID? =
  */
 fun List<String>.parseId3GenreNames(settings: Settings) =
     if (size == 1) {
-        get(0).parseId3GenreNames(settings)
+        first().parseId3MultiValueGenre(settings)
     } else {
         // Nothing to split, just map any ID3v1 genres to their name counterparts.
         map { it.parseId3v1Genre() ?: it }
@@ -172,8 +134,8 @@ fun List<String>.parseId3GenreNames(settings: Settings) =
  * Parse a single ID3v1/ID3v2 integer genre field into their named representations.
  * @return A list of one or more genre names.
  */
-fun String.parseId3GenreNames(settings: Settings) =
+private fun String.parseId3MultiValueGenre(settings: Settings) =
-    parseId3v1Genre()?.let { listOf(it) } ?: parseId3v2Genre() ?: maybeParseSeparators(settings)
+    parseId3v1Genre()?.let { listOf(it) } ?: parseId3v2Genre() ?: maybeParseBySeparators(settings)
 
 /**
  * Parse an ID3v1 integer genre field.
@@ -182,15 +144,17 @@ fun String.parseId3GenreNames(settings: Settings) =
  */
 private fun String.parseId3v1Genre(): String? {
     // ID3v1 genres are a plain integer value without formatting, so in that case
-    // try to index the genre table with such. If this fails, then try to compare it
+    // try to index the genre table with such.
-    // to some other hard-coded values.
+    val numeric =
-    val numeric = toIntOrNull() ?: return when (this) {
+        toIntOrNull()
-        // CR and RX are not technically ID3v1, but are formatted similarly to a plain number.
+        // Not a numeric value, try some other fixed values.
-        "CR" -> "Cover"
+        ?: return when (this) {
-        "RX" -> "Remix"
+                // CR and RX are not technically ID3v1, but are formatted similarly to a plain
-        else -> null
+                // number.
-    }
+                "CR" -> "Cover"
-
+                "RX" -> "Remix"
+                else -> null
+            }
     return GENRE_TABLE.getOrNull(numeric)
 }
 

app/src/main/java/org/oxycblt/auxio/music/parsing/Separators.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2023 Auxio Project
+ *
+ * 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.parsing
+
+/**
+ * Defines the allowed separator characters that can be used to delimit multi-value tags.
+ * @author Alexander Capehart (OxygenCobalt)
+ */
+object Separators {
+    const val COMMA = ','
+    const val SEMICOLON = ';'
+    const val SLASH = '/'
+    const val PLUS = '+'
+    const val AND = '&'
+}

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

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.music.extractor
+package org.oxycblt.auxio.music.parsing
 
 import android.os.Bundle
 import android.view.LayoutInflater
@@ -27,7 +27,6 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogSeparatorsBinding
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
-import org.oxycblt.auxio.util.context
 
 /**
  * A [ViewBindingDialogFragment] that allows the user to configure the separator characters used to
@@ -35,8 +34,6 @@ import org.oxycblt.auxio.util.context
  * @author Alexander Capehart (OxygenCobalt)
  */
 class SeparatorsDialog : ViewBindingDialogFragment<DialogSeparatorsBinding>() {
-    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
-
     override fun onCreateBinding(inflater: LayoutInflater) =
         DialogSeparatorsBinding.inflate(inflater)
 
@@ -45,7 +42,7 @@ class SeparatorsDialog : ViewBindingDialogFragment<DialogSeparatorsBinding>() {
             .setTitle(R.string.set_separators)
             .setNegativeButton(R.string.lbl_cancel, null)
             .setPositiveButton(R.string.lbl_save) { _, _ ->
-                settings.musicSeparators = getCurrentSeparators()
+                Settings(requireContext()).musicSeparators = getCurrentSeparators()
             }
     }
 
@@ -61,16 +58,18 @@ class SeparatorsDialog : ViewBindingDialogFragment<DialogSeparatorsBinding>() {
         // More efficient to do one iteration through the separator list and initialize
         // the corresponding CheckBox for each character instead of doing an iteration
         // through the separator list for each CheckBox.
-        (savedInstanceState?.getString(KEY_PENDING_SEPARATORS) ?: settings.musicSeparators)?.forEach {
+        (savedInstanceState?.getString(KEY_PENDING_SEPARATORS)
-            when (it) {
+                ?: Settings(requireContext()).musicSeparators)
-                SEPARATOR_COMMA -> binding.separatorComma.isChecked = true
+            ?.forEach {
-                SEPARATOR_SEMICOLON -> binding.separatorSemicolon.isChecked = true
+                when (it) {
-                SEPARATOR_SLASH -> binding.separatorSlash.isChecked = true
+                    Separators.COMMA -> binding.separatorComma.isChecked = true
-                SEPARATOR_PLUS -> binding.separatorPlus.isChecked = true
+                    Separators.SEMICOLON -> binding.separatorSemicolon.isChecked = true
-                SEPARATOR_AND -> binding.separatorAnd.isChecked = true
+                    Separators.SLASH -> binding.separatorSlash.isChecked = true
-                else -> error("Unexpected separator in settings data")
+                    Separators.PLUS -> binding.separatorPlus.isChecked = true
+                    Separators.AND -> binding.separatorAnd.isChecked = true
+                    else -> error("Unexpected separator in settings data")
+                }
             }
-        }
     }
 
     override fun onSaveInstanceState(outState: Bundle) {
@@ -85,21 +84,15 @@ class SeparatorsDialog : ViewBindingDialogFragment<DialogSeparatorsBinding>() {
         // of use a mapping that could feasibly drift from the actual layout.
         var separators = ""
         val binding = requireBinding()
-        if (binding.separatorComma.isChecked) separators += SEPARATOR_COMMA
+        if (binding.separatorComma.isChecked) separators += Separators.COMMA
-        if (binding.separatorSemicolon.isChecked) separators += SEPARATOR_SEMICOLON
+        if (binding.separatorSemicolon.isChecked) separators += Separators.SEMICOLON
-        if (binding.separatorSlash.isChecked) separators += SEPARATOR_SLASH
+        if (binding.separatorSlash.isChecked) separators += Separators.SLASH
-        if (binding.separatorPlus.isChecked) separators += SEPARATOR_PLUS
+        if (binding.separatorPlus.isChecked) separators += Separators.PLUS
-        if (binding.separatorAnd.isChecked) separators += SEPARATOR_AND
+        if (binding.separatorAnd.isChecked) separators += Separators.AND
         return separators
     }
 
-    companion object {
+    private companion object {
-        private val KEY_PENDING_SEPARATORS = BuildConfig.APPLICATION_ID + ".key.PENDING_SEPARATORS"
+        const val KEY_PENDING_SEPARATORS = BuildConfig.APPLICATION_ID + ".key.PENDING_SEPARATORS"
-        // TODO: Move these to a more "Correct" location?
-        private const val SEPARATOR_COMMA = ','
-        private const val SEPARATOR_SEMICOLON = ';'
-        private const val SEPARATOR_SLASH = '/'
-        private const val SEPARATOR_PLUS = '+'
-        private const val SEPARATOR_AND = '&'
     }
 }

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

@@ -39,7 +39,7 @@ class ArtistChoiceAdapter(private val listener: ClickableListListener) :
     override fun getItemCount() = artists.size
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-        ArtistChoiceViewHolder.new(parent)
+        ArtistChoiceViewHolder.from(parent)
 
     override fun onBindViewHolder(holder: ArtistChoiceViewHolder, position: Int) =
         holder.bind(artists[position], listener)
@@ -58,7 +58,7 @@ class ArtistChoiceAdapter(private val listener: ClickableListListener) :
 
 /**
  * A [DialogRecyclerView.ViewHolder] that displays a smaller variant of a typical [Artist] item, for
- * use with [ArtistChoiceAdapter]. Use [new] to create an instance.
+ * use with [ArtistChoiceAdapter]. Use [from] to create an instance.
  */
 class ArtistChoiceViewHolder(private val binding: ItemPickerChoiceBinding) :
     DialogRecyclerView.ViewHolder(binding.root) {
@@ -68,7 +68,7 @@ class ArtistChoiceViewHolder(private val binding: ItemPickerChoiceBinding) :
      * @param listener A [ClickableListListener] to bind interactions to.
      */
     fun bind(artist: Artist, listener: ClickableListListener) {
-        binding.root.setOnClickListener { listener.onClick(artist) }
+        listener.bind(artist, this)
         binding.pickerImage.bind(artist)
         binding.pickerName.text = artist.resolveName(binding.context)
     }
@@ -79,7 +79,7 @@ class ArtistChoiceViewHolder(private val binding: ItemPickerChoiceBinding) :
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             ArtistChoiceViewHolder(ItemPickerChoiceBinding.inflate(parent.context.inflater))
     }
 }

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

@@ -20,6 +20,7 @@ package org.oxycblt.auxio.music.picker
 import android.os.Bundle
 import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.navArgs
+import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.databinding.DialogMusicPickerBinding
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.music.Artist
@@ -40,8 +41,8 @@ class ArtistNavigationPickerDialog : ArtistPickerDialog() {
         super.onBindingCreated(binding, savedInstanceState)
     }
 
-    override fun onClick(item: Item) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
-        super.onClick(item)
+        super.onClick(item, viewHolder)
         check(item is Artist) { "Unexpected datatype: ${item::class.simpleName}" }
         // User made a choice, navigate to it.
         navModel.exploreNavigateTo(item)

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

@@ -22,6 +22,7 @@ import android.view.LayoutInflater
 import androidx.appcompat.app.AlertDialog
 import androidx.fragment.app.viewModels
 import androidx.navigation.fragment.findNavController
+import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogMusicPickerBinding
 import org.oxycblt.auxio.list.ClickableListListener
@@ -67,7 +68,7 @@ abstract class ArtistPickerDialog :
         binding.pickerRecycler.adapter = null
     }
 
-    override fun onClick(item: Item) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
         findNavController().navigateUp()
     }
 }

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

@@ -19,6 +19,7 @@ package org.oxycblt.auxio.music.picker
 
 import android.os.Bundle
 import androidx.navigation.fragment.navArgs
+import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.databinding.DialogMusicPickerBinding
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.music.Artist
@@ -41,8 +42,8 @@ class ArtistPlaybackPickerDialog : ArtistPickerDialog() {
         super.onBindingCreated(binding, savedInstanceState)
     }
 
-    override fun onClick(item: Item) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
-        super.onClick(item)
+        super.onClick(item, viewHolder)
         // User made a choice, play the given song from that artist.
         check(item is Artist) { "Unexpected datatype: ${item::class.simpleName}" }
         val song = pickerModel.currentItem.value

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

@@ -1,3 +1,20 @@
+/*
+ * Copyright (c) 2022 Auxio Project
+ *
+ * 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
@@ -22,7 +39,7 @@ class GenreChoiceAdapter(private val listener: ClickableListListener) :
     override fun getItemCount() = genres.size
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-        GenreChoiceViewHolder.new(parent)
+        GenreChoiceViewHolder.from(parent)
 
     override fun onBindViewHolder(holder: GenreChoiceViewHolder, position: Int) =
         holder.bind(genres[position], listener)
@@ -41,7 +58,7 @@ class GenreChoiceAdapter(private val listener: ClickableListListener) :
 
 /**
  * A [DialogRecyclerView.ViewHolder] that displays a smaller variant of a typical [Genre] item, for
- * use with [GenreChoiceAdapter]. Use [new] to create an instance.
+ * use with [GenreChoiceAdapter]. Use [from] to create an instance.
  */
 class GenreChoiceViewHolder(private val binding: ItemPickerChoiceBinding) :
     DialogRecyclerView.ViewHolder(binding.root) {
@@ -51,7 +68,7 @@ class GenreChoiceViewHolder(private val binding: ItemPickerChoiceBinding) :
      * @param listener A [ClickableListListener] to bind interactions to.
      */
     fun bind(genre: Genre, listener: ClickableListListener) {
-        binding.root.setOnClickListener { listener.onClick(genre) }
+        listener.bind(genre, this)
         binding.pickerImage.bind(genre)
         binding.pickerName.text = genre.resolveName(binding.context)
     }
@@ -62,7 +79,7 @@ class GenreChoiceViewHolder(private val binding: ItemPickerChoiceBinding) :
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             GenreChoiceViewHolder(ItemPickerChoiceBinding.inflate(parent.context.inflater))
     }
 }

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

@@ -1,3 +1,20 @@
+/*
+ * Copyright (c) 2022 Auxio Project
+ *
+ * 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
@@ -6,6 +23,7 @@ import androidx.appcompat.app.AlertDialog
 import androidx.fragment.app.viewModels
 import androidx.navigation.fragment.findNavController
 import androidx.navigation.fragment.navArgs
+import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogMusicPickerBinding
 import org.oxycblt.auxio.list.ClickableListListener
@@ -21,7 +39,8 @@ import org.oxycblt.auxio.util.collectImmediately
  * A picker [ViewBindingDialogFragment] intended for when [Genre] playback is ambiguous.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class GenrePlaybackPickerDialog : ViewBindingDialogFragment<DialogMusicPickerBinding>(), ClickableListListener {
+class GenrePlaybackPickerDialog :
+    ViewBindingDialogFragment<DialogMusicPickerBinding>(), ClickableListListener {
     private val pickerModel: PickerViewModel by viewModels()
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
     // Information about what Song to show choices for is initially within the navigation arguments
@@ -56,7 +75,7 @@ class GenrePlaybackPickerDialog : ViewBindingDialogFragment<DialogMusicPickerBin
         binding.pickerRecycler.adapter = null
     }
 
-    override fun onClick(item: Item) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
         // User made a choice, play the given song from that genre.
         check(item is Genre) { "Unexpected datatype: ${item::class.simpleName}" }
         val song = pickerModel.currentItem.value

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

@@ -28,12 +28,13 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
  * contain the music themselves and then exit if the library changes.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class PickerViewModel : ViewModel(), MusicStore.Callback {
+class PickerViewModel : ViewModel(), MusicStore.Listener {
     private val musicStore = MusicStore.getInstance()
 
     private val _currentItem = MutableStateFlow<Music?>(null)
     /** The current item whose artists should be shown in the picker. Null if there is no item. */
-    val currentItem: StateFlow<Music?> get() = _currentItem
+    val currentItem: StateFlow<Music?>
+        get() = _currentItem
 
     private val _artistChoices = MutableStateFlow<List<Artist>>(listOf())
     /** The current [Artist] choices. Empty if no item is shown in the picker. */
@@ -46,7 +47,7 @@ class PickerViewModel : ViewModel(), MusicStore.Callback {
         get() = _genreChoices
 
     override fun onCleared() {
-        musicStore.removeCallback(this)
+        musicStore.removeListener(this)
     }
 
     override fun onLibraryChanged(library: MusicStore.Library?) {
@@ -75,5 +76,4 @@ class PickerViewModel : ViewModel(), MusicStore.Callback {
             else -> {}
         }
     }
-
 }

app/src/main/java/org/oxycblt/auxio/music/system/Indexer.kt

@@ -51,10 +51,10 @@ import org.oxycblt.auxio.util.logW
  * @author Alexander Capehart (OxygenCobalt)
  */
 class Indexer private constructor() {
-    private var lastResponse: Response? = null
+    @Volatile private var lastResponse: Result<MusicStore.Library>? = null
-    private var indexingState: Indexing? = null
+    @Volatile private var indexingState: Indexing? = null
-    private var controller: Controller? = null
+    @Volatile private var controller: Controller? = null
-    private var callback: Callback? = null
+    @Volatile private var listener: Listener? = null
 
     /** Whether music loading is occurring or not. */
     val isIndexing: Boolean
@@ -71,7 +71,7 @@ class Indexer private constructor() {
     /**
      * Register a [Controller] for this instance. This instance will handle any commands to start
      * the music loading process. There can be only one [Controller] at a time. Will invoke all
-     * [Callback] methods to initialize the instance with the current state.
+     * [Listener] methods to initialize the instance with the current state.
      * @param controller The [Controller] to register. Will do nothing if already registered.
      */
     @Synchronized
@@ -105,14 +105,14 @@ class Indexer private constructor() {
     }
 
     /**
-     * Register the [Callback] for this instance. This can be used to receive rapid-fire updates to
+     * Register the [Listener] for this instance. This can be used to receive rapid-fire updates to
-     * the current music loading state. There can be only one [Callback] at a time. Will invoke all
+     * the current music loading state. There can be only one [Listener] at a time. Will invoke all
-     * [Callback] methods to initialize the instance with the current state.
+     * [Listener] methods to initialize the instance with the current state.
-     * @param callback The [Callback] to add.
+     * @param listener The [Listener] to add.
      */
     @Synchronized
-    fun registerCallback(callback: Callback) {
+    fun registerListener(listener: Listener) {
-        if (BuildConfig.DEBUG && this.callback != null) {
+        if (BuildConfig.DEBUG && this.listener != null) {
             logW("Listener is already registered")
             return
         }
@@ -120,24 +120,24 @@ class Indexer private constructor() {
         // Initialize the listener with the current state.
         val currentState =
             indexingState?.let { State.Indexing(it) } ?: lastResponse?.let { State.Complete(it) }
-        callback.onIndexerStateChanged(currentState)
+        listener.onIndexerStateChanged(currentState)
-        this.callback = callback
+        this.listener = listener
     }
 
     /**
-     * Unregister a [Callback] from this instance, preventing it from recieving any further updates.
+     * Unregister a [Listener] from this instance, preventing it from recieving any further updates.
-     * @param callback The [Callback] to unregister. Must be the current [Callback]. Does nothing if
+     * @param listener The [Listener] to unregister. Must be the current [Listener]. Does nothing if
-     * invoked by another [Callback] implementation.
+     * invoked by another [Listener] implementation.
-     * @see Callback
+     * @see Listener
      */
     @Synchronized
-    fun unregisterCallback(callback: Callback) {
+    fun unregisterListener(listener: Listener) {
-        if (BuildConfig.DEBUG && this.callback !== callback) {
+        if (BuildConfig.DEBUG && this.listener !== listener) {
             logW("Given controller did not match current controller")
             return
         }
 
-        this.callback = null
+        this.listener = null
     }
 
     /**
@@ -148,28 +148,14 @@ class Indexer private constructor() {
      * be written, but no cache entries will be loaded into the new library.
      */
     suspend fun index(context: Context, withCache: Boolean) {
-        if (ContextCompat.checkSelfPermission(context, PERMISSION_READ_AUDIO) ==
+        val result =
-            PackageManager.PERMISSION_DENIED) {
-            // No permissions, signal that we can't do anything.
-            emitCompletion(Response.NoPerms)
-            return
-        }
-
-        val response =
             try {
                 val start = System.currentTimeMillis()
                 val library = indexImpl(context, withCache)
-                if (library != null) {
+                logD(
-                    // Successfully loaded a library.
+                    "Music indexing completed successfully in " +
-                    logD(
+                        "${System.currentTimeMillis() - start}ms")
-                        "Music indexing completed successfully in " +
+                Result.success(library)
-                            "${System.currentTimeMillis() - start}ms")
-                    Response.Ok(library)
-                } else {
-                    // Loaded a library, but it contained no music.
-                    logE("No music found")
-                    Response.NoMusic
-                }
             } catch (e: CancellationException) {
                 // Got cancelled, propagate upwards to top-level co-routine.
                 logD("Loading routine was cancelled")
@@ -178,10 +164,9 @@ class Indexer private constructor() {
                 // Music loading process failed due to something we have not handled.
                 logE("Music indexing failed")
                 logE(e.stackTraceToString())
-                Response.Err(e)
+                Result.failure(e)
             }
-
+        emitCompletion(result)
-        emitCompletion(response)
     }
 
     /**
@@ -212,9 +197,17 @@ class Indexer private constructor() {
      * @param context [Context] required to load music.
      * @param withCache Whether to use the cache or not when loading. If false, the cache will still
      * be written, but no cache entries will be loaded into the new library.
-     * @return A newly-loaded [MusicStore.Library], or null if nothing was loaded.
+     * @return A newly-loaded [MusicStore.Library].
+     * @throws NoPermissionException If [PERMISSION_READ_AUDIO] was not granted.
+     * @throws NoMusicException If no music was found on the device.
      */
-    private suspend fun indexImpl(context: Context, withCache: Boolean): MusicStore.Library? {
+    private suspend fun indexImpl(context: Context, withCache: Boolean): MusicStore.Library {
+        if (ContextCompat.checkSelfPermission(context, PERMISSION_READ_AUDIO) ==
+            PackageManager.PERMISSION_DENIED) {
+            // No permissions, signal that we can't do anything.
+            throw NoPermissionException()
+        }
+
         // Create the chain of extractors. Each extractor builds on the previous and
         // enables version-specific features in order to create the best possible music
         // experience.
@@ -236,12 +229,8 @@ class Indexer private constructor() {
 
         val metadataExtractor = MetadataExtractor(context, mediaStoreExtractor)
 
-        val songs = buildSongs(metadataExtractor, Settings(context))
+        val songs =
-        if (songs.isEmpty()) {
+            buildSongs(metadataExtractor, Settings(context)).ifEmpty { throw NoMusicException() }
-            // No songs, nothing else to do.
-            return null
-        }
-
         // Build the rest of the music library from the song list. This is much more powerful
         // and reliable compared to using MediaStore to obtain grouping information.
         val buildStart = System.currentTimeMillis()
@@ -249,7 +238,6 @@ class Indexer private constructor() {
         val artists = buildArtists(songs, albums)
         val genres = buildGenres(songs)
         logD("Successfully built library in ${System.currentTimeMillis() - buildStart}ms")
-
         return MusicStore.Library(songs, albums, artists, genres)
     }
 
@@ -388,17 +376,17 @@ class Indexer private constructor() {
         val state =
             indexingState?.let { State.Indexing(it) } ?: lastResponse?.let { State.Complete(it) }
         controller?.onIndexerStateChanged(state)
-        callback?.onIndexerStateChanged(state)
+        listener?.onIndexerStateChanged(state)
     }
 
     /**
      * Emit a new [State.Complete] state. This can be used to signal the completion of the music
      * loading process to external code. Will check if the callee has not been canceled and thus has
      * the ability to emit a new state
-     * @param response The new [Response] to emit, representing the outcome of the music loading
+     * @param result The new [Result] to emit, representing the outcome of the music loading
      * process.
      */
-    private suspend fun emitCompletion(response: Response) {
+    private suspend fun emitCompletion(result: Result<MusicStore.Library>) {
         yield()
         // Swap to the Main thread so that downstream callbacks don't crash from being on
         // a background thread. Does not occur in emitIndexing due to efficiency reasons.
@@ -406,12 +394,12 @@ class Indexer private constructor() {
             synchronized(this) {
                 // Do not check for redundancy here, as we actually need to notify a switch
                 // from Indexing -> Complete and not Indexing -> Indexing or Complete -> Complete.
-                lastResponse = response
+                lastResponse = result
                 indexingState = null
                 // Signal that the music loading process has been completed.
-                val state = State.Complete(response)
+                val state = State.Complete(result)
                 controller?.onIndexerStateChanged(state)
-                callback?.onIndexerStateChanged(state)
+                listener?.onIndexerStateChanged(state)
             }
         }
     }
@@ -427,10 +415,9 @@ class Indexer private constructor() {
 
         /**
          * Music loading has completed.
-         * @param response The outcome of the music loading process.
+         * @param result The outcome of the music loading process.
-         * @see Response
          */
-        data class Complete(val response: Response) : State()
+        data class Complete(val result: Result<MusicStore.Library>) : State()
     }
 
     /**
@@ -451,35 +438,26 @@ class Indexer private constructor() {
         class Songs(val current: Int, val total: Int) : Indexing()
     }
 
-    /** Represents the possible outcomes of the music loading process. */
+    /** Thrown when the required permissions to load the music library have not been granted yet. */
-    sealed class Response {
+    class NoPermissionException : Exception() {
-        /**
+        override val message: String
-         * Music load was successful and produced a [MusicStore.Library].
+            get() = "Not granted permissions to load music library"
-         * @param library The loaded [MusicStore.Library].
+    }
-         */
-        data class Ok(val library: MusicStore.Library) : Response()
 
-        /**
+    /** Thrown when no music was found on the device. */
-         * Music loading encountered an unexpected error.
+    class NoMusicException : Exception() {
-         * @param throwable The error thrown.
+        override val message: String
-         */
+            get() = "Unable to find any music"
-        data class Err(val throwable: Throwable) : Response()
-
-        /** Music loading occurred, but resulted in no music. */
-        object NoMusic : Response()
-
-        /** Music loading could not occur due to a lack of storage permissions. */
-        object NoPerms : Response()
     }
 
     /**
      * A listener for rapid-fire changes in the music loading state.
      *
      * This is only useful for code that absolutely must show the current loading process.
-     * Otherwise, [MusicStore.Callback] is highly recommended due to it's updates only consisting of
+     * Otherwise, [MusicStore.Listener] is highly recommended due to it's updates only consisting of
      * the [MusicStore.Library].
      */
-    interface Callback {
+    interface Listener {
         /**
          * Called when the current state of the Indexer changed.
          *
@@ -495,7 +473,7 @@ class Indexer private constructor() {
      * Context that runs the music loading process. Implementations should be capable of running the
      * background for long periods of time without android killing the process.
      */
-    interface Controller : Callback {
+    interface Controller : Listener {
         /**
          * Called when a new music loading process was requested. Implementations should forward
          * this to [index].
@@ -514,8 +492,7 @@ class Indexer private constructor() {
          * system to load audio.
          */
         val PERMISSION_READ_AUDIO =
-        // TODO: Move elsewhere.
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                 // READ_EXTERNAL_STORAGE was superseded by READ_MEDIA_AUDIO in Android 13
                 Manifest.permission.READ_MEDIA_AUDIO
             } else {

app/src/main/java/org/oxycblt/auxio/music/system/IndexerNotifications.kt

@@ -72,7 +72,6 @@ class IndexingNotification(private val context: Context) :
                 // Determinate state, show an active progress meter. Since these updates arrive
                 // highly rapidly, only update every 1.5 seconds to prevent notification rate
                 // limiting.
-                // TODO: Can I port this to the playback notification somehow?
                 val now = SystemClock.elapsedRealtime()
                 if (lastUpdateTime > -1 && (now - lastUpdateTime) < 1500) {
                     return false

app/src/main/java/org/oxycblt/auxio/music/system/IndexerService.kt

@@ -19,6 +19,7 @@ package org.oxycblt.auxio.music.system
 
 import android.app.Service
 import android.content.Intent
+import android.content.SharedPreferences
 import android.database.ContentObserver
 import android.os.Handler
 import android.os.IBinder
@@ -33,7 +34,7 @@ import kotlinx.coroutines.launch
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.music.MusicStore
-import org.oxycblt.auxio.music.storage.contentResolverSafe
+import org.oxycblt.auxio.music.filesystem.contentResolverSafe
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 import org.oxycblt.auxio.service.ForegroundManager
 import org.oxycblt.auxio.settings.Settings
@@ -54,7 +55,8 @@ import org.oxycblt.auxio.util.logD
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class IndexerService : Service(), Indexer.Controller, Settings.Callback {
+class IndexerService :
+    Service(), Indexer.Controller, SharedPreferences.OnSharedPreferenceChangeListener {
     private val indexer = Indexer.getInstance()
     private val musicStore = MusicStore.getInstance()
     private val playbackManager = PlaybackStateManager.getInstance()
@@ -81,7 +83,8 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
         // Initialize any listener-dependent components last as we wouldn't want a listener race
         // condition to cause us to load music before we were fully initialize.
         indexerContentObserver = SystemContentObserver()
-        settings = Settings(this, this)
+        settings = Settings(this)
+        settings.addListener(this)
         indexer.registerController(this)
         // An indeterminate indexer and a missing library implies we are extremely early
         // in app initialization so start loading music.
@@ -105,7 +108,7 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
         // Then cancel the listener-dependent components to ensure that stray reloading
         // events will not occur.
         indexerContentObserver.release()
-        settings.release()
+        settings.removeListener(this)
         indexer.unregisterController(this)
         // Then cancel any remaining music loading jobs.
         serviceJob.cancel()
@@ -126,11 +129,11 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
 
     override fun onIndexerStateChanged(state: Indexer.State?) {
         when (state) {
+            is Indexer.State.Indexing -> updateActiveSession(state.indexing)
             is Indexer.State.Complete -> {
-                if (state.response is Indexer.Response.Ok &&
+                val newLibrary = state.result.getOrNull()
-                    state.response.library != musicStore.library) {
+                if (newLibrary != null && newLibrary != musicStore.library) {
                     logD("Applying new library")
-                    val newLibrary = state.response.library
                     // We only care if the newly-loaded library is going to replace a previously
                     // loaded library.
                     if (musicStore.library != null) {
@@ -149,9 +152,6 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
                 // handled right now.
                 updateIdleSession()
             }
-            is Indexer.State.Indexing -> {
-                updateActiveSession(state.indexing)
-            }
             null -> {
                 // Null is the indeterminate state that occurs on app startup or after
                 // the cancellation of a load, so in that case we want to stop foreground
@@ -195,7 +195,7 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
             // 2. If a non-foreground service is killed, the app will probably still be alive,
             // and thus the music library will not be updated at all.
             // TODO: Assuming I unify this with PlaybackService, it's possible that I won't need
-            //  this anymore.
+            //  this anymore, or at least I only have to use it when the app task is not removed.
             if (!foregroundManager.tryStartForeground(observingNotification)) {
                 observingNotification.post()
             }
@@ -230,7 +230,7 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
 
     // --- SETTING CALLBACKS ---
 
-    override fun onSettingChanged(key: String) {
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
         when (key) {
             // Hook changes in music settings to a new music loading event.
             getString(R.string.set_key_exclude_non_music),
@@ -287,8 +287,8 @@ class IndexerService : Service(), Indexer.Controller, Settings.Callback {
         }
     }
 
-    companion object {
+    private companion object {
-        private const val WAKELOCK_TIMEOUT_MS = 60 * 1000L
+        const val WAKELOCK_TIMEOUT_MS = 60 * 1000L
-        private const val REINDEX_DELAY_MS = 500L
+        const val REINDEX_DELAY_MS = 500L
     }
 }

app/src/main/java/org/oxycblt/auxio/playback/PlaybackPanelFragment.kt

@@ -23,6 +23,7 @@ import android.media.audiofx.AudioEffect
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.MenuItem
+import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.widget.Toolbar
 import androidx.core.view.updatePadding
@@ -53,13 +54,7 @@ class PlaybackPanelFragment :
     StyledSeekBar.Listener {
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
     private val navModel: NavigationViewModel by activityViewModels()
-    // AudioEffect expects you to use startActivityForResult with the panel intent. There is no
+    private var equalizerLauncher: ActivityResultLauncher<Intent>? = null
-    // contract analogue for this intent, so the generic contract is used instead.
-    private val equalizerLauncher by lifecycleObject {
-        registerForActivityResult(ActivityResultContracts.StartActivityForResult()) {
-            // Nothing to do
-        }
-    }
 
     override fun onCreateBinding(inflater: LayoutInflater) =
         FragmentPlaybackPanelBinding.inflate(inflater)
@@ -70,6 +65,13 @@ class PlaybackPanelFragment :
     ) {
         super.onBindingCreated(binding, savedInstanceState)
 
+        // AudioEffect expects you to use startActivityForResult with the panel intent. There is no
+        // contract analogue for this intent, so the generic contract is used instead.
+        equalizerLauncher =
+            registerForActivityResult(ActivityResultContracts.StartActivityForResult()) {
+                // Nothing to do
+            }
+
         // --- UI SETUP ---
         binding.root.setOnApplyWindowInsetsListener { view, insets ->
             val bars = insets.systemBarInsetsCompat
@@ -100,6 +102,7 @@ class PlaybackPanelFragment :
         binding.playbackSeekBar.listener = this
 
         // Set up actions
+        // TODO: Add better playback button accessibility
         binding.playbackRepeat.setOnClickListener { playbackModel.toggleRepeatMode() }
         binding.playbackSkipPrev.setOnClickListener { playbackModel.prev() }
         binding.playbackPlayPause.setOnClickListener { playbackModel.toggleIsPlaying() }
@@ -116,6 +119,7 @@ class PlaybackPanelFragment :
     }
 
     override fun onDestroyBinding(binding: FragmentPlaybackPanelBinding) {
+        equalizerLauncher = null
         binding.playbackToolbar.setOnMenuItemClickListener(null)
         // Marquee elements leak if they are not disabled when the views are destroyed.
         binding.playbackSong.isSelected = false
@@ -127,10 +131,9 @@ class PlaybackPanelFragment :
         when (item.itemId) {
             R.id.action_open_equalizer -> {
                 // Launch the system equalizer app, if possible.
-                // TODO: Move this to a utility
                 val equalizerIntent =
                     Intent(AudioEffect.ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL)
-                        // Provide audio session ID so equalizer can show options for this app
+                        // Provide audio session ID so the equalizer can show options for this app
                         // in particular.
                         .putExtra(
                             AudioEffect.EXTRA_AUDIO_SESSION, playbackModel.currentAudioSessionId)
@@ -138,7 +141,10 @@ class PlaybackPanelFragment :
                         // music playback.
                         .putExtra(AudioEffect.EXTRA_CONTENT_TYPE, AudioEffect.CONTENT_TYPE_MUSIC)
                 try {
-                    equalizerLauncher.launch(equalizerIntent)
+                    requireNotNull(equalizerLauncher) {
+                            "Equalizer panel launcher was not available"
+                        }
+                        .launch(equalizerIntent)
                 } catch (e: ActivityNotFoundException) {
                     requireContext().showToast(R.string.err_no_app)
                 }

app/src/main/java/org/oxycblt/auxio/playback/PlaybackViewModel.kt

@@ -38,7 +38,7 @@ import org.oxycblt.auxio.util.context
  * @author Alexander Capehart (OxygenCobalt)
  */
 class PlaybackViewModel(application: Application) :
-    AndroidViewModel(application), PlaybackStateManager.Callback {
+    AndroidViewModel(application), PlaybackStateManager.Listener {
     private val settings = Settings(application)
     private val playbackManager = PlaybackStateManager.getInstance()
     private var lastPositionJob: Job? = null
@@ -70,8 +70,8 @@ class PlaybackViewModel(application: Application) :
 
     private val _artistPlaybackPickerSong = MutableStateFlow<Song?>(null)
     /**
-     * Flag signaling to open a picker dialog in order to resolve an ambiguous choice when
+     * Flag signaling to open a picker dialog in order to resolve an ambiguous choice when playing a
-     * playing a [Song] from one of it's [Artist]s.
+     * [Song] from one of it's [Artist]s.
      * @see playFromArtist
      */
     val artistPickerSong: StateFlow<Song?>
@@ -79,8 +79,8 @@ class PlaybackViewModel(application: Application) :
 
     private val _genrePlaybackPickerSong = MutableStateFlow<Song?>(null)
     /**
-     * Flag signaling to open a picker dialog in order to resolve an ambiguous choice when playing
+     * Flag signaling to open a picker dialog in order to resolve an ambiguous choice when playing a
-     * a [Song] from one of it's [Genre]s.
+     * [Song] from one of it's [Genre]s.
      */
     val genrePickerSong: StateFlow<Song?>
         get() = _genrePlaybackPickerSong
@@ -93,11 +93,11 @@ class PlaybackViewModel(application: Application) :
         get() = playbackManager.currentAudioSessionId
 
     init {
-        playbackManager.addCallback(this)
+        playbackManager.addListener(this)
     }
 
     override fun onCleared() {
-        playbackManager.removeCallback(this)
+        playbackManager.removeListener(this)
     }
 
     override fun onIndexMoved(index: Int) {

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueAdapter.kt

@@ -19,7 +19,6 @@ package org.oxycblt.auxio.playback.queue
 
 import android.annotation.SuppressLint
 import android.graphics.drawable.LayerDrawable
-import android.view.MotionEvent
 import android.view.View
 import android.view.ViewGroup
 import androidx.core.view.isInvisible
@@ -27,6 +26,7 @@ import androidx.recyclerview.widget.RecyclerView
 import com.google.android.material.shape.MaterialShapeDrawable
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.ItemQueueSongBinding
+import org.oxycblt.auxio.list.EditableListListener
 import org.oxycblt.auxio.list.recycler.PlayingIndicatorAdapter
 import org.oxycblt.auxio.list.recycler.SongViewHolder
 import org.oxycblt.auxio.list.recycler.SyncListDiffer
@@ -38,10 +38,11 @@ import org.oxycblt.auxio.util.inflater
 
 /**
  * A [RecyclerView.Adapter] that shows an editable list of queue items.
- * @param listener A [Listener] to bind interactions to.
+ * @param listener A [EditableListListener] to bind interactions to.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class QueueAdapter(private val listener: Listener) : RecyclerView.Adapter<QueueSongViewHolder>() {
+class QueueAdapter(private val listener: EditableListListener) :
+    RecyclerView.Adapter<QueueSongViewHolder>() {
     private var differ = SyncListDiffer(this, QueueSongViewHolder.DIFF_CALLBACK)
     // Since PlayingIndicator adapter relies on an item value, we cannot use it for this
     // adapter, as one item can appear at several points in the UI. Use a similar implementation
@@ -52,7 +53,7 @@ class QueueAdapter(private val listener: Listener) : RecyclerView.Adapter<QueueS
     override fun getItemCount() = differ.currentList.size
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
-        QueueSongViewHolder.new(parent)
+        QueueSongViewHolder.from(parent)
 
     override fun onBindViewHolder(holder: QueueSongViewHolder, position: Int) =
         throw IllegalStateException()
@@ -121,29 +122,13 @@ class QueueAdapter(private val listener: Listener) : RecyclerView.Adapter<QueueS
         }
     }
 
-    /** A listener for queue list events. */
+    private companion object {
-    interface Listener {
+        val PAYLOAD_UPDATE_POSITION = Any()
-        /**
-         * Called when a [RecyclerView.ViewHolder] in the list as clicked.
-         * @param viewHolder The [RecyclerView.ViewHolder] that was clicked.
-         */
-        fun onClick(viewHolder: RecyclerView.ViewHolder)
-
-        /**
-         * Called when the drag handle on a [RecyclerView.ViewHolder] is clicked, requesting that a
-         * drag should be started.
-         * @param viewHolder The [RecyclerView.ViewHolder] to start dragging.
-         */
-        fun onPickUp(viewHolder: RecyclerView.ViewHolder)
-    }
-
-    companion object {
-        private val PAYLOAD_UPDATE_POSITION = Any()
     }
 }
 
 /**
- * A [PlayingIndicatorAdapter.ViewHolder] that displays a queue [Song]. Use [new] to create an
+ * A [PlayingIndicatorAdapter.ViewHolder] that displays a queue [Song]. Use [from] to create an
  * instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
@@ -190,26 +175,17 @@ class QueueSongViewHolder private constructor(private val binding: ItemQueueSong
     /**
      * Bind new data to this instance.
      * @param song The new [Song] to bind.
-     * @param listener A [QueueAdapter.Listener] to bind interactions to.
+     * @param listener A [EditableListListener] to bind interactions to.
      */
     @SuppressLint("ClickableViewAccessibility")
-    fun bind(song: Song, listener: QueueAdapter.Listener) {
+    fun bind(song: Song, listener: EditableListListener) {
-        binding.body.setOnClickListener { listener.onClick(this) }
+        listener.bind(song, this, bodyView, binding.songDragHandle)
-
         binding.songAlbumCover.bind(song)
         binding.songName.text = song.resolveName(binding.context)
         binding.songInfo.text = song.resolveArtistContents(binding.context)
-        // TODO: Why is this here?
+        // Not swiping this ViewHolder if it's being re-bound, ensure that the background is
+        // not visible. See QueueDragCallback for why this is done.
         binding.background.isInvisible = true
-
-        // Set up the drag handle to start a drag whenever it is touched.
-        binding.songDragHandle.setOnTouchListener { _, motionEvent ->
-            binding.songDragHandle.performClick()
-            if (motionEvent.actionMasked == MotionEvent.ACTION_DOWN) {
-                listener.onPickUp(this)
-                true
-            } else false
-        }
     }
 
     override fun updatePlayingIndicator(isActive: Boolean, isPlaying: Boolean) {
@@ -223,7 +199,7 @@ class QueueSongViewHolder private constructor(private val binding: ItemQueueSong
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) =
+        fun from(parent: View) =
             QueueSongViewHolder(ItemQueueSongBinding.inflate(parent.context.inflater))
 
         /** A comparator that can be used with DiffUtil. */

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueFragment.kt

@@ -24,7 +24,10 @@ import androidx.fragment.app.activityViewModels
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
+import kotlin.math.min
 import org.oxycblt.auxio.databinding.FragmentQueueBinding
+import org.oxycblt.auxio.list.EditableListListener
+import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.ViewBindingFragment
@@ -36,13 +39,11 @@ import org.oxycblt.auxio.util.logD
  * A [ViewBindingFragment] that displays an editable queue.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueAdapter.Listener {
+class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), EditableListListener {
     private val queueModel: QueueViewModel by activityViewModels()
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
     private val queueAdapter = QueueAdapter(this)
-    private val touchHelper: ItemTouchHelper by lifecycleObject {
+    private var touchHelper: ItemTouchHelper? = null
-        ItemTouchHelper(QueueDragCallback(queueModel))
-    }
 
     override fun onCreateBinding(inflater: LayoutInflater) = FragmentQueueBinding.inflate(inflater)
 
@@ -52,7 +53,10 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueAdapter.
         // --- UI SETUP ---
         binding.queueRecycler.apply {
             adapter = queueAdapter
-            touchHelper.attachToRecyclerView(this)
+            touchHelper =
+                ItemTouchHelper(QueueDragCallback(queueModel)).also {
+                    it.attachToRecyclerView(this)
+                }
         }
 
         // Sometimes the scroll can change without the listener being updated, so we also
@@ -77,13 +81,12 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueAdapter.
         binding.queueRecycler.adapter = null
     }
 
-    override fun onClick(viewHolder: RecyclerView.ViewHolder) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
-        // Clicking on a queue item should start playing it.
         queueModel.goto(viewHolder.bindingAdapterPosition)
     }
 
     override fun onPickUp(viewHolder: RecyclerView.ViewHolder) {
-        touchHelper.startDrag(viewHolder)
+        requireNotNull(touchHelper) { "ItemTouchHelper was not available" }.startDrag(viewHolder)
     }
 
     private fun updateDivider() {
@@ -108,17 +111,25 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueAdapter.
         queueModel.finishReplace()
 
         // If requested, scroll to a new item (occurs when the index moves)
-        // TODO: Scroll to center/top instead of bottom
         val scrollTo = queueModel.scrollTo
         if (scrollTo != null) {
-            // Do not scroll to indices that are in the currently visible range. As that would
-            // lead to the queue jumping around every time goto is called.
             val lmm = binding.queueRecycler.layoutManager as LinearLayoutManager
             val start = lmm.findFirstCompletelyVisibleItemPosition()
             val end = lmm.findLastCompletelyVisibleItemPosition()
-            if (scrollTo !in start..end) {
+            val notInitialized =
-                logD("Scrolling to new position")
+                start == RecyclerView.NO_POSITION || end == RecyclerView.NO_POSITION
+            // When we scroll, we want to scroll to the almost-top so the user can see
+            // future songs instead of past songs. The way we have to do this however is
+            // dependent on where we have to scroll to get to the currently playing song.
+            if (notInitialized || scrollTo < start) {
+                // We need to scroll upwards, or initialize the scroll, no need to offset
                 binding.queueRecycler.scrollToPosition(scrollTo)
+            } else if (scrollTo > end) {
+                // We need to scroll downwards, we need to offset by a screen of songs.
+                // This does have some error due to what the layout manager returns being
+                // somewhat mutable. This is considered okay.
+                binding.queueRecycler.scrollToPosition(
+                    min(queue.lastIndex, scrollTo + (end - start)))
             }
         }
         queueModel.finishScrollTo()

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueViewModel.kt

@@ -29,7 +29,7 @@ import org.oxycblt.auxio.playback.state.PlaybackStateManager
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class QueueViewModel : ViewModel(), PlaybackStateManager.Callback {
+class QueueViewModel : ViewModel(), PlaybackStateManager.Listener {
     private val playbackManager = PlaybackStateManager.getInstance()
 
     private val _queue = MutableStateFlow(listOf<Song>())
@@ -47,7 +47,7 @@ class QueueViewModel : ViewModel(), PlaybackStateManager.Callback {
     var scrollTo: Int? = null
 
     init {
-        playbackManager.addCallback(this)
+        playbackManager.addListener(this)
     }
 
     /**
@@ -135,6 +135,6 @@ class QueueViewModel : ViewModel(), PlaybackStateManager.Callback {
 
     override fun onCleared() {
         super.onCleared()
-        playbackManager.removeCallback(this)
+        playbackManager.removeListener(this)
     }
 }

app/src/main/java/org/oxycblt/auxio/playback/replaygain/PreAmpCustomizeDialog.kt

@@ -26,15 +26,12 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogPreAmpBinding
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
-import org.oxycblt.auxio.util.context
 
 /**
  * aa [ViewBindingDialogFragment] that allows user configuration of the current [ReplayGainPreAmp].
  * @author Alexander Capehart (OxygenCobalt)
  */
 class PreAmpCustomizeDialog : ViewBindingDialogFragment<DialogPreAmpBinding>() {
-    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
-
     override fun onCreateBinding(inflater: LayoutInflater) = DialogPreAmpBinding.inflate(inflater)
 
     override fun onConfigDialog(builder: AlertDialog.Builder) {
@@ -42,9 +39,12 @@ class PreAmpCustomizeDialog : ViewBindingDialogFragment<DialogPreAmpBinding>() {
             .setTitle(R.string.set_pre_amp)
             .setPositiveButton(R.string.lbl_ok) { _, _ ->
                 val binding = requireBinding()
-                settings.replayGainPreAmp =
+                Settings(requireContext()).replayGainPreAmp =
                     ReplayGainPreAmp(binding.withTagsSlider.value, binding.withoutTagsSlider.value)
             }
+            .setNeutralButton(R.string.lbl_reset) { _, _ ->
+                Settings(requireContext()).replayGainPreAmp = ReplayGainPreAmp(0f, 0f)
+            }
             .setNegativeButton(R.string.lbl_cancel, null)
     }
 
@@ -53,7 +53,7 @@ class PreAmpCustomizeDialog : ViewBindingDialogFragment<DialogPreAmpBinding>() {
             // First initialization, we need to supply the sliders with the values from
             // settings. After this, the sliders save their own state, so we do not need to
             // do any restore behavior.
-            val preAmp = settings.replayGainPreAmp
+            val preAmp = Settings(requireContext()).replayGainPreAmp
             binding.withTagsSlider.value = preAmp.with
             binding.withoutTagsSlider.value = preAmp.without
         }

app/src/main/java/org/oxycblt/auxio/playback/replaygain/ReplayGainAudioProcessor.kt

@@ -18,33 +18,38 @@
 package org.oxycblt.auxio.playback.replaygain
 
 import android.content.Context
+import android.content.SharedPreferences
 import com.google.android.exoplayer2.C
+import com.google.android.exoplayer2.Format
+import com.google.android.exoplayer2.Player
+import com.google.android.exoplayer2.Tracks
 import com.google.android.exoplayer2.audio.AudioProcessor
 import com.google.android.exoplayer2.audio.BaseAudioProcessor
-import com.google.android.exoplayer2.metadata.Metadata
+import com.google.android.exoplayer2.util.MimeTypes
-import com.google.android.exoplayer2.metadata.id3.InternalFrame
-import com.google.android.exoplayer2.metadata.id3.TextInformationFrame
-import com.google.android.exoplayer2.metadata.vorbis.VorbisComment
 import java.nio.ByteBuffer
 import kotlin.math.pow
+import org.oxycblt.auxio.R
 import org.oxycblt.auxio.music.Album
+import org.oxycblt.auxio.music.extractor.Tags
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.util.logD
-import org.oxycblt.auxio.util.unlikelyToBeNull
 
 /**
  * An [AudioProcessor] that handles ReplayGain values and their amplification of the audio stream.
  * Instead of leveraging the volume attribute like other implementations, this system manipulates
  * the bitstream itself to modify the volume, which allows the use of positive ReplayGain values.
  *
- * Note: This instance must be updated with a new [Metadata] every time the active track chamges.
+ * Note: This audio processor must be attached to a respective [Player] instance as a
+ * [Player.Listener] to function properly.
  *
  * @author Alexander Capehart (OxygenCobalt)
  */
-class ReplayGainAudioProcessor(context: Context) : BaseAudioProcessor() {
+class ReplayGainAudioProcessor(private val context: Context) :
+    BaseAudioProcessor(), Player.Listener, SharedPreferences.OnSharedPreferenceChangeListener {
     private val playbackManager = PlaybackStateManager.getInstance()
     private val settings = Settings(context)
+    private var lastFormat: Format? = null
 
     private var volume = 1f
         set(value) {
@@ -53,20 +58,69 @@ class ReplayGainAudioProcessor(context: Context) : BaseAudioProcessor() {
             flush()
         }
 
+    /**
+     * Add this instance to the components required for it to function correctly.
+     * @param player The [Player] to attach to. Should already have this instance as an audio
+     * processor.
+     */
+    fun addToListeners(player: Player) {
+        player.addListener(this)
+        settings.addListener(this)
+    }
+
+    /**
+     * Remove this instance from the components required for it to function correctly.
+     * @param player The [Player] to detach from. Should already have this instance as an audio
+     * processor.
+     */
+    fun releaseFromListeners(player: Player) {
+        player.removeListener(this)
+        settings.removeListener(this)
+    }
+
+    // --- OVERRIDES ---
+
+    override fun onTracksChanged(tracks: Tracks) {
+        super.onTracksChanged(tracks)
+        // Try to find the currently playing track so we can update the ReplayGain adjustment
+        // based on it.
+        for (group in tracks.groups) {
+            if (group.isSelected) {
+                for (i in 0 until group.length) {
+                    if (group.isTrackSelected(i)) {
+                        applyReplayGain(group.getTrackFormat(i))
+                        return
+                    }
+                }
+            }
+        }
+        // Nothing selected, apply nothing
+        applyReplayGain(null)
+    }
+
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
+        if (key == context.getString(R.string.set_key_replay_gain) ||
+            key == context.getString(R.string.set_key_pre_amp_with) ||
+            key == context.getString(R.string.set_key_pre_amp_without)) {
+            // ReplayGain changed, we need to set it up again.
+            applyReplayGain(lastFormat)
+        }
+    }
+
     // --- REPLAYGAIN PARSING ---
 
     /**
-     * Updates the volume adjustment based on the given [Metadata].
+     * Updates the volume adjustment based on the given [Format].
-     * @param metadata The [Metadata] of the currently playing track, or null if the track has no
+     * @param format The [Format] of the currently playing track, or null if nothing is playing.
-     * [Metadata].
      */
-    fun applyReplayGain(metadata: Metadata?) {
+    private fun applyReplayGain(format: Format?) {
-        // TODO: Allow this to automatically obtain it's own [Metadata].
+        lastFormat = format
-        val gain = metadata?.let(::parseReplayGain)
+        val gain = parseReplayGain(format ?: return)
         val preAmp = settings.replayGainPreAmp
 
         val adjust =
             if (gain != null) {
+                logD("Found ReplayGain adjustment $gain")
                 // ReplayGain is configurable, so determine what to do based off of the mode.
                 val useAlbumGain =
                     when (settings.replayGainMode) {
@@ -109,104 +163,58 @@ class ReplayGainAudioProcessor(context: Context) : BaseAudioProcessor() {
     }
 
     /**
-     * Parse ReplayGain information from the given [Metadata].
+     * Parse ReplayGain information from the given [Format].
-     * @param metadata The [Metadata] to parse.
+     * @param format The [Format] to parse.
-     * @return A [Gain] adjustment, or null if there was no adjustments to parse.
+     * @return A [Adjustment] adjustment, or null if there were no valid adjustments.
      */
-    private fun parseReplayGain(metadata: Metadata): Gain? {
+    private fun parseReplayGain(format: Format): Adjustment? {
-        // TODO: Unify this parser with the music parser? They both grok Metadata.
+        val tags = Tags(format.metadata ?: return null)
-
         var trackGain = 0f
         var albumGain = 0f
-        var found = false
 
-        val tags = mutableListOf<GainTag>()
+        // Most ReplayGain tags are formatted as a simple decibel adjustment in a custom
-
+        // replaygain_*_gain tag.
-        for (i in 0 until metadata.length()) {
+        if (format.sampleMimeType != MimeTypes.AUDIO_OPUS) {
-            val entry = metadata.get(i)
+            tags.id3v2["TXXX:$TAG_RG_TRACK_GAIN"]
-
+                ?.run { first().parseReplayGainAdjustment() }
-            val key: String?
+                ?.let { trackGain = it }
-            val value: String
+            tags.id3v2["TXXX:$TAG_RG_ALBUM_GAIN"]
-
+                ?.run { first().parseReplayGainAdjustment() }
-            when (entry) {
+                ?.let { albumGain = it }
-                // ID3v2 text information frame, usually these are formatted in lowercase
+            tags.vorbis[TAG_RG_ALBUM_GAIN]
-                // (like "replaygain_track_gain"), but can also be uppercase. Make sure that
+                ?.run { first().parseReplayGainAdjustment() }
-                // capitalization is consistent before continuing.
+                ?.let { trackGain = it }
-                is TextInformationFrame -> {
+            tags.vorbis[TAG_RG_TRACK_GAIN]
-                    key = entry.description
+                ?.run { first().parseReplayGainAdjustment() }
-                    value = entry.values[0]
+                ?.let { albumGain = it }
-                }
+        } else {
-                // Internal Frame. This is actually MP4's "----" atom, but mapped to an ID3v2
+            // Opus has it's own "r128_*_gain" ReplayGain specification, which requires dividing the
-                // frame by ExoPlayer (presumably to reduce duplication).
+            // adjustment by 256 to get the gain. This is used alongside the base adjustment
-                is InternalFrame -> {
+            // intrinsic to the format to create the normalized adjustment. That base adjustment
-                    key = entry.description
+            // is already handled by the media  framework, so we just need to apply the more
-                    value = entry.text
+            // specific adjustments.
-                }
+            tags.vorbis[TAG_R128_TRACK_GAIN]
-                // Vorbis comment. These are nearly always uppercase, so a check for such is
+                ?.run { first().parseReplayGainAdjustment() }
-                // skipped.
+                ?.let { trackGain = it / 256f }
-                is VorbisComment -> {
+            tags.vorbis[TAG_R128_ALBUM_GAIN]
-                    key = entry.key
+                ?.run { first().parseReplayGainAdjustment() }
-                    value = entry.value
+                ?.let { albumGain = it / 256f }
-                }
-                else -> continue
-            }
-
-            if (key in REPLAY_GAIN_TAGS) {
-                // Grok a float from a ReplayGain tag by removing everything that is not 0-9, ,
-                // or -.
-                // Derived from vanilla music: https://github.com/vanilla-music/vanilla
-                val gainValue =
-                    try {
-                        value.replace(Regex("[^\\d.-]"), "").toFloat()
-                    } catch (e: Exception) {
-                        0f
-                    }
-
-                tags.add(GainTag(unlikelyToBeNull(key), gainValue))
-            }
         }
 
-        // Case 1: Normal ReplayGain, most commonly found on MPEG files.
+        return if (trackGain != 0f || albumGain != 0f) {
-        tags
+            Adjustment(trackGain, albumGain)
-            .findLast { tag -> tag.key.equals(TAG_RG_TRACK, ignoreCase = true) }
-            ?.let { tag ->
-                trackGain = tag.value
-                found = true
-            }
-
-        tags
-            .findLast { tag -> tag.key.equals(TAG_RG_ALBUM, ignoreCase = true) }
-            ?.let { tag ->
-                albumGain = tag.value
-                found = true
-            }
-
-        // Case 2: R128 ReplayGain, most commonly found on FLAC files and other lossless
-        // encodings to increase precision in volume adjustments.
-        // While technically there is the R128 base gain in Opus files, that is automatically
-        // applied by the media framework [which ExoPlayer relies on]. The only reason we would
-        // want to read it is to zero previous ReplayGain values for being invalid, however there
-        // is no demand to fix that edge case right now.
-        tags
-            .findLast { tag -> tag.key.equals(R128_TRACK, ignoreCase = true) }
-            ?.let { tag ->
-                trackGain += tag.value / 256f
-                found = true
-            }
-
-        tags
-            .findLast { tag -> tag.key.equals(R128_ALBUM, ignoreCase = true) }
-            ?.let { tag ->
-                albumGain += tag.value / 256f
-                found = true
-            }
-
-        return if (found) {
-            Gain(trackGain, albumGain)
         } else {
             null
         }
     }
+
+    /**
+     * Parse a ReplayGain adjustment into a float value.
+     * @return A parsed adjustment float, or null if the adjustment had invalid formatting.
+     */
+    private fun String.parseReplayGainAdjustment() =
+        replace(REPLAYGAIN_ADJUSTMENT_FILTER_REGEX, "").toFloatOrNull()
+
     // --- AUDIO PROCESSOR IMPLEMENTATION ---
 
     override fun onConfigure(
@@ -271,22 +279,18 @@ class ReplayGainAudioProcessor(context: Context) : BaseAudioProcessor() {
      * @param track The track adjustment (in dB), or 0 if it is not present.
      * @param album The album adjustment (in dB), or 0 if it is not present.
      */
-    private data class Gain(val track: Float, val album: Float)
+    private data class Adjustment(val track: Float, val album: Float)
 
-    /**
+    private companion object {
-     * A raw ReplayGain adjustment.
+        const val TAG_RG_TRACK_GAIN = "replaygain_track_gain"
-     * @param key The tag's key.
+        const val TAG_RG_ALBUM_GAIN = "replaygain_album_gain"
-     * @param value The tag's adjustment, in dB.
+        const val TAG_R128_TRACK_GAIN = "r128_track_gain"
-     */
+        const val TAG_R128_ALBUM_GAIN = "r128_album_gain"
-    private data class GainTag(val key: String, val value: Float)
-    // TODO: Try to phase this out
 
-    companion object {
+        /**
-        private const val TAG_RG_TRACK = "replaygain_track_gain"
+         * Matches non-float information from ReplayGain adjustments. Derived from vanilla music:
-        private const val TAG_RG_ALBUM = "replaygain_album_gain"
+         * https://github.com/vanilla-music/vanilla
-        private const val R128_TRACK = "r128_track_gain"
+         */
-        private const val R128_ALBUM = "r128_album_gain"
+        val REPLAYGAIN_ADJUSTMENT_FILTER_REGEX = Regex("[^\\d.-]")
-
-        private val REPLAY_GAIN_TAGS = arrayOf(TAG_RG_TRACK, TAG_RG_ALBUM, R128_ALBUM, R128_TRACK)
     }
 }

app/src/main/java/org/oxycblt/auxio/playback/state/InternalPlayer.kt

@@ -85,6 +85,9 @@ interface InternalPlayer {
         data class Open(val uri: Uri) : Action()
     }
 
+    /**
+     * A representation of the current state of audio playback. Use [from] to create an instance.
+     */
     class State
     private constructor(
         /** Whether the player is actively playing audio or set to play audio in the future. */
@@ -157,7 +160,7 @@ interface InternalPlayer {
              * @param isAdvancing Whether the player is actively playing audio in this moment.
              * @param positionMs The current position of the player.
              */
-            fun new(isPlaying: Boolean, isAdvancing: Boolean, positionMs: Long) =
+            fun from(isPlaying: Boolean, isAdvancing: Boolean, positionMs: Long) =
                 State(
                     isPlaying,
                     // Minor sanity check: Make sure that advancing can't occur if already paused.

app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateManager.kt

@@ -27,7 +27,7 @@ import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.playback.state.PlaybackStateManager.Callback
+import org.oxycblt.auxio.playback.state.PlaybackStateManager.Listener
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logE
@@ -45,7 +45,7 @@ import org.oxycblt.auxio.util.logW
  * - If you want to use the playback state with the ExoPlayer instance or system-side things, use
  * [org.oxycblt.auxio.playback.system.PlaybackService].
  *
- * Internal consumers should usually use [Callback], however the component that manages the player
+ * Internal consumers should usually use [Listener], however the component that manages the player
  * itself should instead use [InternalPlayer].
  *
  * All access should be done with [PlaybackStateManager.getInstance].
@@ -54,35 +54,40 @@ import org.oxycblt.auxio.util.logW
  */
 class PlaybackStateManager private constructor() {
     private val musicStore = MusicStore.getInstance()
-    private val callbacks = mutableListOf<Callback>()
+    private val listeners = mutableListOf<Listener>()
-    private var internalPlayer: InternalPlayer? = null
+    @Volatile private var internalPlayer: InternalPlayer? = null
-    private var pendingAction: InternalPlayer.Action? = null
+    @Volatile private var pendingAction: InternalPlayer.Action? = null
-    private var isInitialized = false
+    @Volatile private var isInitialized = false
 
     /** The currently playing [Song]. Null if nothing is playing. */
     val song
         get() = queue.getOrNull(index)
     /** The [MusicParent] currently being played. Null if playback is occurring from all songs. */
+    @Volatile
     var parent: MusicParent? = null
         private set
 
-    private var _queue = mutableListOf<Song>()
+    @Volatile private var _queue = mutableListOf<Song>()
     /** The current queue. */
     val queue
         get() = _queue
     /** The position of the currently playing item in the queue. */
+    @Volatile
     var index = -1
         private set
     /** The current [InternalPlayer] state. */
-    var playerState = InternalPlayer.State.new(isPlaying = false, isAdvancing = false, 0)
+    @Volatile
+    var playerState = InternalPlayer.State.from(isPlaying = false, isAdvancing = false, 0)
         private set
     /** The current [RepeatMode] */
+    @Volatile
     var repeatMode = RepeatMode.NONE
         set(value) {
             field = value
             notifyRepeatModeChanged()
         }
     /** Whether the queue is shuffled. */
+    @Volatile
     var isShuffled = false
         private set
     /**
@@ -93,32 +98,32 @@ class PlaybackStateManager private constructor() {
         get() = internalPlayer?.audioSessionId
 
     /**
-     * Add a [Callback] to this instance. This can be used to receive changes in the playback state.
+     * Add a [Listener] to this instance. This can be used to receive changes in the playback state.
-     * Will immediately invoke [Callback] methods to initialize the instance with the current state.
+     * Will immediately invoke [Listener] methods to initialize the instance with the current state.
-     * @param callback The [Callback] to add.
+     * @param listener The [Listener] to add.
-     * @see Callback
+     * @see Listener
      */
     @Synchronized
-    fun addCallback(callback: Callback) {
+    fun addListener(listener: Listener) {
         if (isInitialized) {
-            callback.onNewPlayback(index, queue, parent)
+            listener.onNewPlayback(index, queue, parent)
-            callback.onRepeatChanged(repeatMode)
+            listener.onRepeatChanged(repeatMode)
-            callback.onShuffledChanged(isShuffled)
+            listener.onShuffledChanged(isShuffled)
-            callback.onStateChanged(playerState)
+            listener.onStateChanged(playerState)
         }
 
-        callbacks.add(callback)
+        listeners.add(listener)
     }
 
     /**
-     * Remove a [Callback] from this instance, preventing it from recieving any further updates.
+     * Remove a [Listener] from this instance, preventing it from recieving any further updates.
-     * @param callback The [Callback] to remove. Does nothing if the [Callback] was never added in
+     * @param listener The [Listener] to remove. Does nothing if the [Listener] was never added in
      * the first place.
-     * @see Callback
+     * @see Listener
      */
     @Synchronized
-    fun removeCallback(callback: Callback) {
+    fun removeListener(listener: Listener) {
-        callbacks.remove(callback)
+        listeners.remove(listener)
     }
 
     /**
@@ -521,10 +526,9 @@ class PlaybackStateManager private constructor() {
      * @param database The [PlaybackStateDatabase] to clear te state from
      * @return If the state was cleared, false otherwise.
      */
-    suspend fun wipeState(database: PlaybackStateDatabase): Boolean {
+    suspend fun wipeState(database: PlaybackStateDatabase) =
-        logD("Wiping state")
+        try {
-
+            logD("Wiping state")
-        return try {
             withContext(Dispatchers.IO) { database.write(null) }
             true
         } catch (e: Exception) {
@@ -532,7 +536,6 @@ class PlaybackStateManager private constructor() {
             logE(e.stackTraceToString())
             false
         }
-    }
 
     /**
      * Update the playback state to align with a new [MusicStore.Library].
@@ -586,52 +589,52 @@ class PlaybackStateManager private constructor() {
     // --- CALLBACKS ---
 
     private fun notifyIndexMoved() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onIndexMoved(index)
         }
     }
 
     private fun notifyQueueChanged() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onQueueChanged(queue)
         }
     }
 
     private fun notifyQueueReworked() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onQueueReworked(index, queue)
         }
     }
 
     private fun notifyNewPlayback() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onNewPlayback(index, queue, parent)
         }
     }
 
     private fun notifyStateChanged() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onStateChanged(playerState)
         }
     }
 
     private fun notifyRepeatModeChanged() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onRepeatChanged(repeatMode)
         }
     }
 
     private fun notifyShuffledChanged() {
-        for (callback in callbacks) {
+        for (callback in listeners) {
             callback.onShuffledChanged(isShuffled)
         }
     }
 
     /**
      * The interface for receiving updates from [PlaybackStateManager]. Add the listener to
-     * [PlaybackStateManager] using [addCallback], remove them on destruction with [removeCallback].
+     * [PlaybackStateManager] using [addListener], remove them on destruction with [removeListener].
      */
-    interface Callback {
+    interface Listener {
         /**
          * Called when the position of the currently playing item has changed, changing the current
          * [Song], but no other queue attribute has changed.

app/src/main/java/org/oxycblt/auxio/playback/system/MediaSessionComponent.kt

@@ -19,6 +19,7 @@ package org.oxycblt.auxio.playback.system
 
 import android.content.Context
 import android.content.Intent
+import android.content.SharedPreferences
 import android.graphics.Bitmap
 import android.net.Uri
 import android.os.Bundle
@@ -43,11 +44,13 @@ import org.oxycblt.auxio.util.logD
  * A component that mirrors the current playback state into the [MediaSessionCompat] and
  * [NotificationComponent].
  * @param context [Context] required to initialize components.
- * @param callback [Callback] to forward notification updates to.
+ * @param listener [Listener] to forward notification updates to.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class MediaSessionComponent(private val context: Context, private val callback: Callback) :
+class MediaSessionComponent(private val context: Context, private val listener: Listener) :
-    MediaSessionCompat.Callback(), PlaybackStateManager.Callback, Settings.Callback {
+    MediaSessionCompat.Callback(),
+    PlaybackStateManager.Listener,
+    SharedPreferences.OnSharedPreferenceChangeListener {
     private val mediaSession =
         MediaSessionCompat(context, context.packageName).apply {
             isActive = true
@@ -55,13 +58,13 @@ class MediaSessionComponent(private val context: Context, private val callback:
         }
 
     private val playbackManager = PlaybackStateManager.getInstance()
-    private val settings = Settings(context, this)
+    private val settings = Settings(context)
 
     private val notification = NotificationComponent(context, mediaSession.sessionToken)
     private val provider = BitmapProvider(context)
 
     init {
-        playbackManager.addCallback(this)
+        playbackManager.addListener(this)
         mediaSession.setCallback(this)
     }
 
@@ -79,15 +82,15 @@ class MediaSessionComponent(private val context: Context, private val callback:
      */
     fun release() {
         provider.release()
-        settings.release()
+        settings.removeListener(this)
-        playbackManager.removeCallback(this)
+        playbackManager.removeListener(this)
         mediaSession.apply {
             isActive = false
             release()
         }
     }
 
-    // --- PLAYBACKSTATEMANAGER CALLBACKS ---
+    // --- PLAYBACKSTATEMANAGER OVERRIDES ---
 
     override fun onIndexMoved(index: Int) {
         updateMediaMetadata(playbackManager.song, playbackManager.parent)
@@ -113,7 +116,7 @@ class MediaSessionComponent(private val context: Context, private val callback:
         invalidateSessionState()
         notification.updatePlaying(playbackManager.playerState.isPlaying)
         if (!provider.isBusy) {
-            callback.onPostNotification(notification)
+            listener.onPostNotification(notification)
         }
     }
 
@@ -139,9 +142,9 @@ class MediaSessionComponent(private val context: Context, private val callback:
         invalidateSecondaryAction()
     }
 
-    // --- SETTINGSMANAGER CALLBACKS ---
+    // --- SETTINGS OVERRIDES ---
 
-    override fun onSettingChanged(key: String) {
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
         when (key) {
             context.getString(R.string.set_key_cover_mode) ->
                 updateMediaMetadata(playbackManager.song, playbackManager.parent)
@@ -149,7 +152,7 @@ class MediaSessionComponent(private val context: Context, private val callback:
         }
     }
 
-    // --- MEDIASESSION CALLBACKS ---
+    // --- MEDIASESSION OVERRIDES ---
 
     override fun onPlayFromMediaId(mediaId: String?, extras: Bundle?) {
         super.onPlayFromMediaId(mediaId, extras)
@@ -306,7 +309,7 @@ class MediaSessionComponent(private val context: Context, private val callback:
                     val metadata = builder.build()
                     mediaSession.setMetadata(metadata)
                     notification.updateMetadata(metadata)
-                    callback.onPostNotification(notification)
+                    listener.onPostNotification(notification)
                 }
             })
     }
@@ -393,12 +396,12 @@ class MediaSessionComponent(private val context: Context, private val callback:
         }
 
         if (!provider.isBusy) {
-            callback.onPostNotification(notification)
+            listener.onPostNotification(notification)
         }
     }
 
     /** An interface for handling changes in the notification configuration. */
-    interface Callback {
+    interface Listener {
         /**
          * Called when the [NotificationComponent] changes, requiring it to be re-posed.
          * @param notification The new [NotificationComponent].

app/src/main/java/org/oxycblt/auxio/playback/system/NotificationComponent.kt

@@ -148,9 +148,9 @@ class NotificationComponent(private val context: Context, sessionToken: MediaSes
                 iconRes, actionName, context.newBroadcastPendingIntent(actionName))
             .build()
 
-    companion object {
+    private companion object {
         /** Notification channel used by solely the playback notification. */
-        private val CHANNEL_INFO =
+        val CHANNEL_INFO =
             ChannelInfo(
                 id = BuildConfig.APPLICATION_ID + ".channel.PLAYBACK",
                 nameRes = R.string.lbl_playback)

app/src/main/java/org/oxycblt/auxio/playback/system/PlaybackService.kt

@@ -31,7 +31,6 @@ import com.google.android.exoplayer2.MediaItem
 import com.google.android.exoplayer2.PlaybackException
 import com.google.android.exoplayer2.Player
 import com.google.android.exoplayer2.RenderersFactory
-import com.google.android.exoplayer2.Tracks
 import com.google.android.exoplayer2.audio.AudioAttributes
 import com.google.android.exoplayer2.audio.AudioCapabilities
 import com.google.android.exoplayer2.audio.MediaCodecAudioRenderer
@@ -44,7 +43,6 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import org.oxycblt.auxio.BuildConfig
-import org.oxycblt.auxio.R
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.replaygain.ReplayGainAudioProcessor
@@ -79,9 +77,8 @@ class PlaybackService :
     Service(),
     Player.Listener,
     InternalPlayer,
-    MediaSessionComponent.Callback,
+    MediaSessionComponent.Listener,
-    Settings.Callback,
+    MusicStore.Listener {
-    MusicStore.Callback {
     // Player components
     private lateinit var player: ExoPlayer
     private lateinit var replayGainProcessor: ReplayGainAudioProcessor
@@ -143,13 +140,14 @@ class PlaybackService :
                     true)
                 .build()
                 .also { it.addListener(this) }
+        replayGainProcessor.addToListeners(player)
         // Initialize the core service components
-        settings = Settings(this, this)
+        settings = Settings(this)
         foregroundManager = ForegroundManager(this)
         // Initialize any listener-dependent components last as we wouldn't want a listener race
         // condition to cause us to load music before we were fully initialize.
         playbackManager.registerInternalPlayer(this)
-        musicStore.addCallback(this)
+        musicStore.addListener(this)
         widgetComponent = WidgetComponent(this)
         mediaSessionComponent = MediaSessionComponent(this, this)
         registerReceiver(
@@ -185,12 +183,11 @@ class PlaybackService :
         super.onDestroy()
 
         foregroundManager.release()
-        settings.release()
 
         // Pause just in case this destruction was unexpected.
         playbackManager.setPlaying(false)
         playbackManager.unregisterInternalPlayer(this)
-        musicStore.removeCallback(this)
+        musicStore.removeListener(this)
 
         unregisterReceiver(systemReceiver)
         serviceJob.cancel()
@@ -198,6 +195,7 @@ class PlaybackService :
         widgetComponent.release()
         mediaSessionComponent.release()
 
+        replayGainProcessor.releaseFromListeners(player)
         player.release()
         if (openAudioEffectSession) {
             // Make sure to close the audio session when we release the player.
@@ -217,7 +215,7 @@ class PlaybackService :
         get() = settings.rewindWithPrev && player.currentPosition > REWIND_THRESHOLD
 
     override fun getState(durationMs: Long) =
-        InternalPlayer.State.new(
+        InternalPlayer.State.from(
             player.playWhenReady,
             player.isPlaying,
             // The position value can be below zero or past the expected duration, make
@@ -302,24 +300,6 @@ class PlaybackService :
         playbackManager.next()
     }
 
-    override fun onTracksChanged(tracks: Tracks) {
-        super.onTracksChanged(tracks)
-        // Try to find the currently playing track so we can update ReplayGainAudioProcessor
-        // with it.
-        for (group in tracks.groups) {
-            if (group.isSelected) {
-                for (i in 0 until group.length) {
-                    if (group.isTrackSelected(i)) {
-                        replayGainProcessor.applyReplayGain(group.getTrackFormat(i).metadata)
-                        break
-                    }
-                }
-
-                break
-            }
-        }
-    }
-
     // --- MUSICSTORE OVERRIDES ---
 
     override fun onLibraryChanged(library: MusicStore.Library?) {
@@ -329,16 +309,6 @@ class PlaybackService :
         }
     }
 
-    // --- SETTINGSMANAGER OVERRIDES ---
-
-    override fun onSettingChanged(key: String) {
-        if (key == getString(R.string.set_key_replay_gain) ||
-            key == getString(R.string.set_key_pre_amp_with) ||
-            key == getString(R.string.set_key_pre_amp_without)) {
-            onTracksChanged(player.currentTracks)
-        }
-    }
-
     // --- OTHER FUNCTIONS ---
 
     private fun broadcastAudioEffectAction(event: String) {

app/src/main/java/org/oxycblt/auxio/search/SearchAdapter.kt

@@ -51,11 +51,11 @@ class SearchAdapter(private val listener: SelectableListListener) :
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
         when (viewType) {
-            SongViewHolder.VIEW_TYPE -> SongViewHolder.new(parent)
+            SongViewHolder.VIEW_TYPE -> SongViewHolder.from(parent)
-            AlbumViewHolder.VIEW_TYPE -> AlbumViewHolder.new(parent)
+            AlbumViewHolder.VIEW_TYPE -> AlbumViewHolder.from(parent)
-            ArtistViewHolder.VIEW_TYPE -> ArtistViewHolder.new(parent)
+            ArtistViewHolder.VIEW_TYPE -> ArtistViewHolder.from(parent)
-            GenreViewHolder.VIEW_TYPE -> GenreViewHolder.new(parent)
+            GenreViewHolder.VIEW_TYPE -> GenreViewHolder.from(parent)
-            HeaderViewHolder.VIEW_TYPE -> HeaderViewHolder.new(parent)
+            HeaderViewHolder.VIEW_TYPE -> HeaderViewHolder.from(parent)
             else -> error("Invalid item type $viewType")
         }
 
@@ -81,9 +81,9 @@ class SearchAdapter(private val listener: SelectableListListener) :
         differ.submitList(newList, callback)
     }
 
-    companion object {
+    private companion object {
         /** A comparator that can be used with DiffUtil. */
-        private val DIFF_CALLBACK =
+        val DIFF_CALLBACK =
             object : SimpleItemCallback<Item>() {
                 override fun areContentsTheSame(oldItem: Item, newItem: Item) =
                     when {

app/src/main/java/org/oxycblt/auxio/search/SearchFragment.kt

@@ -53,10 +53,8 @@ import org.oxycblt.auxio.util.*
 class SearchFragment : ListFragment<FragmentSearchBinding>() {
     private val searchModel: SearchViewModel by androidViewModels()
     private val searchAdapter = SearchAdapter(this)
+    private var imm: InputMethodManager? = null
     private var launchedKeyboard = false
-    private val imm: InputMethodManager by lifecycleObject { binding ->
-        binding.context.getSystemServiceCompat(InputMethodManager::class)
-    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -74,13 +72,15 @@ class SearchFragment : ListFragment<FragmentSearchBinding>() {
     override fun onBindingCreated(binding: FragmentSearchBinding, savedInstanceState: Bundle?) {
         super.onBindingCreated(binding, savedInstanceState)
 
+        imm = binding.context.getSystemServiceCompat(InputMethodManager::class)
+
         binding.searchToolbar.apply {
             // Initialize the current filtering mode.
             menu.findItem(searchModel.getFilterOptionId()).isChecked = true
 
             setNavigationOnClickListener {
                 // Keyboard is no longer needed.
-                imm.hide()
+                hideKeyboard()
                 findNavController().navigateUp()
             }
 
@@ -95,7 +95,7 @@ class SearchFragment : ListFragment<FragmentSearchBinding>() {
 
             if (!launchedKeyboard) {
                 // Auto-open the keyboard when this view is shown
-                imm.show(this)
+                showKeyboard(this)
                 launchedKeyboard = true
             }
         }
@@ -184,7 +184,7 @@ class SearchFragment : ListFragment<FragmentSearchBinding>() {
                 else -> return
             }
         // Keyboard is no longer needed.
-        imm.hide()
+        hideKeyboard()
         findNavController().navigate(action)
     }
 
@@ -193,7 +193,7 @@ class SearchFragment : ListFragment<FragmentSearchBinding>() {
         if (requireBinding().searchSelectionToolbar.updateSelectionAmount(selected.size) &&
             selected.isNotEmpty()) {
             // Make selection of obscured items easier by hiding the keyboard.
-            imm.hide()
+            hideKeyboard()
         }
     }
 
@@ -201,15 +201,19 @@ class SearchFragment : ListFragment<FragmentSearchBinding>() {
      * Safely focus the keyboard on a particular [View].
      * @param view The [View] to focus the keyboard on.
      */
-    private fun InputMethodManager.show(view: View) {
+    private fun showKeyboard(view: View) {
         view.apply {
             requestFocus()
-            postDelayed(200) { showSoftInput(view, InputMethodManager.SHOW_IMPLICIT) }
+            postDelayed(200) {
+                requireNotNull(imm) { "InputMethodManager was not available" }
+                    .showSoftInput(view, InputMethodManager.SHOW_IMPLICIT)
+            }
         }
     }
 
     /** Safely hide the keyboard from this view. */
-    private fun InputMethodManager.hide() {
+    private fun hideKeyboard() {
-        hideSoftInputFromWindow(requireView().windowToken, InputMethodManager.HIDE_NOT_ALWAYS)
+        requireNotNull(imm) { "InputMethodManager was not available" }
+            .hideSoftInputFromWindow(requireView().windowToken, InputMethodManager.HIDE_NOT_ALWAYS)
     }
 }

app/src/main/java/org/oxycblt/auxio/search/SearchViewModel.kt

@@ -43,7 +43,7 @@ import org.oxycblt.auxio.util.logD
  * @author Alexander Capehart (OxygenCobalt)
  */
 class SearchViewModel(application: Application) :
-    AndroidViewModel(application), MusicStore.Callback {
+    AndroidViewModel(application), MusicStore.Listener {
     private val musicStore = MusicStore.getInstance()
     private val settings = Settings(context)
     private var lastQuery: String? = null
@@ -55,12 +55,12 @@ class SearchViewModel(application: Application) :
         get() = _searchResults
 
     init {
-        musicStore.addCallback(this)
+        musicStore.addListener(this)
     }
 
     override fun onCleared() {
         super.onCleared()
-        musicStore.removeCallback(this)
+        musicStore.removeListener(this)
     }
 
     override fun onLibraryChanged(library: MusicStore.Library?) {
@@ -212,11 +212,11 @@ class SearchViewModel(application: Application) :
         search(lastQuery)
     }
 
-    companion object {
+    private companion object {
         /**
          * Converts the output of [Normalizer] to remove any junk characters added by it's
          * replacements.
          */
-        private val NORMALIZATION_SANITIZE_REGEX = Regex("\\p{InCombiningDiacriticalMarks}+")
+        val NORMALIZATION_SANITIZE_REGEX = Regex("\\p{InCombiningDiacriticalMarks}+")
     }
 }

app/src/main/java/org/oxycblt/auxio/settings/AboutFragment.kt

@@ -152,14 +152,14 @@ class AboutFragment : ViewBindingFragment<FragmentAboutBinding>() {
         startActivity(chooserIntent)
     }
 
-    companion object {
+    private companion object {
         /** The URL to the source code. */
-        private const val LINK_SOURCE = "https://github.com/OxygenCobalt/Auxio"
+        const val LINK_SOURCE = "https://github.com/OxygenCobalt/Auxio"
         /** The URL to the app wiki. */
-        private const val LINK_WIKI = "$LINK_SOURCE/wiki"
+        const val LINK_WIKI = "$LINK_SOURCE/wiki"
         /** The URL to the licenses wiki page. */
-        private const val LINK_LICENSES = "$LINK_WIKI/Licenses"
+        const val LINK_LICENSES = "$LINK_WIKI/Licenses"
         /** The URL to the app author. */
-        private const val LINK_AUTHOR = "https://github.com/OxygenCobalt"
+        const val LINK_AUTHOR = "https://github.com/OxygenCobalt"
     }
 }

app/src/main/java/org/oxycblt/auxio/settings/Settings.kt

@@ -19,6 +19,7 @@ package org.oxycblt.auxio.settings
 
 import android.content.Context
 import android.content.SharedPreferences
+import android.content.SharedPreferences.OnSharedPreferenceChangeListener
 import android.os.Build
 import android.os.storage.StorageManager
 import androidx.appcompat.app.AppCompatDelegate
@@ -30,8 +31,8 @@ import org.oxycblt.auxio.home.tabs.Tab
 import org.oxycblt.auxio.image.CoverMode
 import org.oxycblt.auxio.music.MusicMode
 import org.oxycblt.auxio.music.Sort
-import org.oxycblt.auxio.music.storage.Directory
+import org.oxycblt.auxio.music.filesystem.Directory
-import org.oxycblt.auxio.music.storage.MusicDirectories
+import org.oxycblt.auxio.music.filesystem.MusicDirectories
 import org.oxycblt.auxio.playback.ActionMode
 import org.oxycblt.auxio.playback.replaygain.ReplayGainMode
 import org.oxycblt.auxio.playback.replaygain.ReplayGainPreAmp
@@ -40,20 +41,14 @@ import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
 /**
- * A [SharedPreferences] wrapper providing type-safe interfaces to all of the app's settings. Object
+ * A [SharedPreferences] wrapper providing type-safe interfaces to all of the app's settings. Member
- * mutability
+ * mutability is dependent on how they are used in app. Immutable members are often only modified by
+ * the preferences view, while mutable members are modified elsewhere.
  * @author Alexander Capehart (OxygenCobalt)
  */
-class Settings(private val context: Context, private val callback: Callback? = null) :
+class Settings(private val context: Context) {
-    SharedPreferences.OnSharedPreferenceChangeListener {
     private val inner = PreferenceManager.getDefaultSharedPreferences(context.applicationContext)
 
-    init {
-        if (callback != null) {
-            inner.registerOnSharedPreferenceChangeListener(this)
-        }
-    }
-
     /**
      * Migrate any settings from an old version into their modern counterparts. This can cause data
      * loss depending on the feasibility of a migration.
@@ -154,27 +149,19 @@ class Settings(private val context: Context, private val callback: Callback? = n
     }
 
     /**
-     * Release this instance and any callbacks held by it. This is not needed if no [Callback] was
+     * Add a [SharedPreferences.OnSharedPreferenceChangeListener] to monitor for settings updates.
-     * originally attached.
+     * @param listener The [SharedPreferences.OnSharedPreferenceChangeListener] to add.
      */
-    fun release() {
+    fun addListener(listener: OnSharedPreferenceChangeListener) {
-        inner.unregisterOnSharedPreferenceChangeListener(this)
+        inner.registerOnSharedPreferenceChangeListener(listener)
-    }
-
-    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
-        unlikelyToBeNull(callback).onSettingChanged(key)
     }
 
     /**
-     * Simplified callback for settings changes.
+     * Unregister a [SharedPreferences.OnSharedPreferenceChangeListener], preventing any further
+     * settings updates from being sent to ti.t
      */
-    interface Callback {
+    fun removeListener(listener: OnSharedPreferenceChangeListener) {
-        // TODO: Refactor this lifecycle
+        inner.unregisterOnSharedPreferenceChangeListener(listener)
-        /**
-         * Called when a setting has changed.
-         * @param key The key of the setting that changed.
-         */
-        fun onSettingChanged(key: String)
     }
 
     // --- VALUES ---

app/src/main/java/org/oxycblt/auxio/settings/prefs/IntListPreference.kt

@@ -162,8 +162,8 @@ constructor(
         }
     }
 
-    companion object {
+    private companion object {
-        private val PREFERENCE_DEFAULT_VALUE_FIELD: Field by
+        val PREFERENCE_DEFAULT_VALUE_FIELD: Field by
             lazyReflectedField(Preference::class, "mDefaultValue")
     }
 }

app/src/main/java/org/oxycblt/auxio/settings/prefs/IntListPreferenceDialog.kt

@@ -24,7 +24,7 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 
 /**
- * The companion dialog to [IntListPreference]. Use [new] to create an instance.
+ * The companion dialog to [IntListPreference]. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class IntListPreferenceDialog : PreferenceDialogFragmentCompat() {
@@ -62,11 +62,10 @@ class IntListPreferenceDialog : PreferenceDialogFragmentCompat() {
          * @param preference The [IntListPreference] to display.
          * @return A new instance.
          */
-        fun new(preference: IntListPreference): IntListPreferenceDialog {
+        fun from(preference: IntListPreference) =
-            return IntListPreferenceDialog().apply {
+            IntListPreferenceDialog().apply {
                 // Populate the key field required by PreferenceDialogFragmentCompat.
                 arguments = Bundle().apply { putString(ARG_KEY, preference.key) }
             }
-        }
     }
 }

app/src/main/java/org/oxycblt/auxio/settings/prefs/PreferenceFragment.kt

@@ -76,7 +76,7 @@ class PreferenceFragment : PreferenceFragmentCompat() {
             is IntListPreference -> {
                 // Copy the built-in preference dialog launching code into our project so
                 // we can automatically use the provided preference class.
-                val dialog = IntListPreferenceDialog.new(preference)
+                val dialog = IntListPreferenceDialog.from(preference)
                 dialog.setTargetFragment(this, 0)
                 dialog.show(parentFragmentManager, IntListPreferenceDialog.TAG)
             }
@@ -104,46 +104,44 @@ class PreferenceFragment : PreferenceFragmentCompat() {
     }
 
     override fun onPreferenceTreeClick(preference: Preference): Boolean {
-        val context = requireContext()
-
         // Hook generic preferences to their specified preferences
         // TODO: These seem like good things to put into a side navigation view, if I choose to
         //  do one.
         when (preference.key) {
-            context.getString(R.string.set_key_save_state) -> {
+            getString(R.string.set_key_save_state) -> {
                 playbackModel.savePlaybackState { saved ->
                     // Use the nullable context, as we could try to show a toast when this
                     // fragment is no longer attached.
                     if (saved) {
-                        this.context?.showToast(R.string.lbl_state_saved)
+                        context?.showToast(R.string.lbl_state_saved)
                     } else {
-                        this.context?.showToast(R.string.err_did_not_save)
+                        context?.showToast(R.string.err_did_not_save)
                     }
                 }
             }
-            context.getString(R.string.set_key_wipe_state) -> {
+            getString(R.string.set_key_wipe_state) -> {
                 playbackModel.wipePlaybackState { wiped ->
                     if (wiped) {
                         // Use the nullable context, as we could try to show a toast when this
                         // fragment is no longer attached.
-                        this.context?.showToast(R.string.lbl_state_wiped)
+                        context?.showToast(R.string.lbl_state_wiped)
                     } else {
-                        this.context?.showToast(R.string.err_did_not_wipe)
+                        context?.showToast(R.string.err_did_not_wipe)
                     }
                 }
             }
-            context.getString(R.string.set_key_restore_state) ->
+            getString(R.string.set_key_restore_state) ->
                 playbackModel.tryRestorePlaybackState { restored ->
                     if (restored) {
                         // Use the nullable context, as we could try to show a toast when this
                         // fragment is no longer attached.
-                        this.context?.showToast(R.string.lbl_state_restored)
+                        context?.showToast(R.string.lbl_state_restored)
                     } else {
-                        this.context?.showToast(R.string.err_did_not_restore)
+                        context?.showToast(R.string.err_did_not_restore)
                     }
                 }
-            context.getString(R.string.set_key_reindex) -> musicModel.refresh()
+            getString(R.string.set_key_reindex) -> musicModel.refresh()
-            context.getString(R.string.set_key_rescan) -> musicModel.rescan()
+            getString(R.string.set_key_rescan) -> musicModel.rescan()
             else -> return super.onPreferenceTreeClick(preference)
         }
 
@@ -151,8 +149,7 @@ class PreferenceFragment : PreferenceFragmentCompat() {
     }
 
     private fun setupPreference(preference: Preference) {
-        val context = requireActivity()
+        val settings = Settings(requireContext())
-        val settings = Settings(context)
 
         if (!preference.isVisible) {
             // Nothing to do.
@@ -165,30 +162,31 @@ class PreferenceFragment : PreferenceFragmentCompat() {
         }
 
         when (preference.key) {
-            context.getString(R.string.set_key_theme) -> {
+            getString(R.string.set_key_theme) -> {
                 preference.onPreferenceChangeListener =
                     Preference.OnPreferenceChangeListener { _, value ->
                         AppCompatDelegate.setDefaultNightMode(value as Int)
                         true
                     }
             }
-            context.getString(R.string.set_key_accent) -> {
+            getString(R.string.set_key_accent) -> {
-                preference.summary = context.getString(settings.accent.name)
+                preference.summary = getString(settings.accent.name)
             }
-            context.getString(R.string.set_key_black_theme) -> {
+            getString(R.string.set_key_black_theme) -> {
                 preference.onPreferenceChangeListener =
                     Preference.OnPreferenceChangeListener { _, _ ->
-                        if (context.isNight) {
+                        val activity = requireActivity()
-                            context.recreate()
+                        if (activity.isNight) {
+                            activity.recreate()
                         }
 
                         true
                     }
             }
-            context.getString(R.string.set_key_cover_mode) -> {
+            getString(R.string.set_key_cover_mode) -> {
                 preference.onPreferenceChangeListener =
                     Preference.OnPreferenceChangeListener { _, _ ->
-                        Coil.imageLoader(context).memoryCache?.clear()
+                        Coil.imageLoader(requireContext()).memoryCache?.clear()
                         true
                     }
             }

app/src/main/java/org/oxycblt/auxio/ui/CoordinatorAppBarLayout.kt

@@ -42,7 +42,7 @@ import org.oxycblt.auxio.util.coordinatorLayoutBehavior
  *
  * @author Hai Zhang, Alexander Capehart (OxygenCobalt)
  */
-open class AuxioAppBarLayout
+open class CoordinatorAppBarLayout
 @JvmOverloads
 constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
     AppBarLayout(context, attrs, defStyleAttr) {
@@ -68,14 +68,14 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     }
 
     /**
-     * Expand this [AppBarLayout] with respect to the given [RecyclerView], preventing it from
+     * Expand this [AppBarLayout] with respect to the current [RecyclerView] at
-     * jumping around.
+     * [liftOnScrollTargetViewId], preventing it from jumping around.
-     * @param recycler [RecyclerView] to expand with, or null if one is currently unavailable.
      */
-    fun expandWithRecycler(recycler: RecyclerView?) {
+    fun expandWithScrollingRecycler() {
-        // TODO: Is it possible to use liftOnScrollTargetViewId to avoid the RecyclerView arg?
         setExpanded(true)
-        recycler?.let { addOnOffsetChangedListener(ExpansionHackListener(it)) }
+        (findScrollingChild() as? RecyclerView)?.let {
+            addOnOffsetChangedListener(ExpansionHackListener(it))
+        }
     }
 
     override fun onDetachedFromWindow() {
@@ -136,8 +136,8 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         }
     }
 
-    companion object {
+    private companion object {
         /** @see AppBarLayout.BaseBehavior.MAX_OFFSET_ANIMATION_DURATION */
-        private const val APP_BAR_LAYOUT_MAX_OFFSET_ANIMATION_DURATION = 600
+        const val APP_BAR_LAYOUT_MAX_OFFSET_ANIMATION_DURATION = 600
     }
 }

app/src/main/java/org/oxycblt/auxio/ui/NavigationViewModel.kt

@@ -92,8 +92,8 @@ class NavigationViewModel : ViewModel() {
 
     /**
      * Navigate to one of the parent [Artist]'s of the given [Song].
-     * @param song The [Song] to navigate with. If there are multiple parent [Artist]s,
+     * @param song The [Song] to navigate with. If there are multiple parent [Artist]s, a picker
-     * a picker dialog will be shown.
+     * dialog will be shown.
      */
     fun exploreNavigateToParentArtist(song: Song) {
         exploreNavigateToParentArtistImpl(song, song.artists)
@@ -101,8 +101,8 @@ class NavigationViewModel : ViewModel() {
 
     /**
      * Navigate to one of the parent [Artist]'s of the given [Album].
-     * @param album The [Album] to navigate with. If there are multiple parent [Artist]s,
+     * @param album The [Album] to navigate with. If there are multiple parent [Artist]s, a picker
-     * a picker dialog will be shown.
+     * dialog will be shown.
      */
     fun exploreNavigateToParentArtist(album: Album) {
         exploreNavigateToParentArtistImpl(album, album.artists)

app/src/main/java/org/oxycblt/auxio/ui/ViewBindingDialogFragment.kt

@@ -23,11 +23,8 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.app.AlertDialog
 import androidx.fragment.app.DialogFragment
-import androidx.fragment.app.Fragment
 import androidx.viewbinding.ViewBinding
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
-import kotlin.properties.ReadOnlyProperty
-import kotlin.reflect.KProperty
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
@@ -37,7 +34,6 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
  */
 abstract class ViewBindingDialogFragment<VB : ViewBinding> : DialogFragment() {
     private var _binding: VB? = null
-    private var lifecycleObjects = mutableListOf<LifecycleObject<VB, *>>()
 
     /**
      * Configure the [AlertDialog.Builder] during [onCreateDialog].
@@ -85,25 +81,6 @@ abstract class ViewBindingDialogFragment<VB : ViewBinding> : DialogFragment() {
         }
     }
 
-    /**
-     * Delegate to automatically create and destroy an object derived from the [ViewBinding].
-     * @param create Block to create the object from the [ViewBinding].
-     */
-    fun <T> lifecycleObject(create: (VB) -> T): ReadOnlyProperty<Fragment, T> {
-        lifecycleObjects.add(LifecycleObject(null, create))
-
-        return object : ReadOnlyProperty<Fragment, T> {
-            private val objIdx = lifecycleObjects.lastIndex
-
-            @Suppress("UNCHECKED_CAST")
-            override fun getValue(thisRef: Fragment, property: KProperty<*>) =
-                requireNotNull(lifecycleObjects[objIdx].data) {
-                    "Cannot access lifecycle object when view does not exist"
-                }
-                    as T
-        }
-    }
-
     final override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -119,9 +96,6 @@ abstract class ViewBindingDialogFragment<VB : ViewBinding> : DialogFragment() {
 
     final override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        val binding = unlikelyToBeNull(_binding)
-        // Populate lifecycle-dependent objects
-        lifecycleObjects.forEach { it.populate(binding) }
         // Configure binding
         onBindingCreated(requireBinding(), savedInstanceState)
         // Apply the newly-configured view to the dialog.
@@ -132,21 +106,8 @@ abstract class ViewBindingDialogFragment<VB : ViewBinding> : DialogFragment() {
     final override fun onDestroyView() {
         super.onDestroyView()
         onDestroyBinding(unlikelyToBeNull(_binding))
-        // Clear the lifecycle-dependent objects
-        lifecycleObjects.forEach { it.clear() }
         // Clear binding
         _binding = null
         logD("Fragment destroyed")
     }
-
-    /** Internal implementation of [lifecycleObject]. */
-    private data class LifecycleObject<VB, T>(var data: T?, val create: (VB) -> T) {
-        fun populate(binding: VB) {
-            data = create(binding)
-        }
-
-        fun clear() {
-            data = null
-        }
-    }
 }

app/src/main/java/org/oxycblt/auxio/ui/ViewBindingFragment.kt

@@ -23,8 +23,6 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.viewbinding.ViewBinding
-import kotlin.properties.ReadOnlyProperty
-import kotlin.reflect.KProperty
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
@@ -34,7 +32,6 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
  */
 abstract class ViewBindingFragment<VB : ViewBinding> : Fragment() {
     private var _binding: VB? = null
-    private var lifecycleObjects = mutableListOf<LifecycleObject<VB, *>>()
 
     /**
      * Inflate the [ViewBinding] during [onCreateView].
@@ -75,26 +72,6 @@ abstract class ViewBindingFragment<VB : ViewBinding> : Fragment() {
         }
     }
 
-    /**
-     * Delegate to automatically create and destroy an object derived from the [ViewBinding].
-     * @param create Block to create the object from the [ViewBinding].
-     */
-    fun <T> lifecycleObject(create: (VB) -> T): ReadOnlyProperty<Fragment, T> {
-        // TODO: Phase this out.
-        lifecycleObjects.add(LifecycleObject(null, create))
-
-        return object : ReadOnlyProperty<Fragment, T> {
-            private val objIdx = lifecycleObjects.lastIndex
-
-            @Suppress("UNCHECKED_CAST")
-            override fun getValue(thisRef: Fragment, property: KProperty<*>) =
-                requireNotNull(lifecycleObjects[objIdx].data) {
-                    "Cannot access lifecycle object when view does not exist"
-                }
-                    as T
-        }
-    }
-
     final override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -103,9 +80,6 @@ abstract class ViewBindingFragment<VB : ViewBinding> : Fragment() {
 
     final override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        val binding = unlikelyToBeNull(_binding)
-        // Populate lifecycle-dependent objects
-        lifecycleObjects.forEach { it.populate(binding) }
         // Configure binding
         onBindingCreated(requireBinding(), savedInstanceState)
         logD("Fragment created")
@@ -114,21 +88,8 @@ abstract class ViewBindingFragment<VB : ViewBinding> : Fragment() {
     final override fun onDestroyView() {
         super.onDestroyView()
         onDestroyBinding(unlikelyToBeNull(_binding))
-        // Clear the lifecycle-dependent objects
-        lifecycleObjects.forEach { it.clear() }
         // Clear binding
         _binding = null
         logD("Fragment destroyed")
     }
-
-    /** Internal implementation of [lifecycleObject]. */
-    private data class LifecycleObject<VB, T>(var data: T?, val create: (VB) -> T) {
-        fun populate(binding: VB) {
-            data = create(binding)
-        }
-
-        fun clear() {
-            data = null
-        }
-    }
 }

app/src/main/java/org/oxycblt/auxio/ui/accent/AccentAdapter.kt

@@ -41,7 +41,8 @@ class AccentAdapter(private val listener: ClickableListListener) :
 
     override fun getItemCount() = Accent.MAX
 
-    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = AccentViewHolder.new(parent)
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
+        AccentViewHolder.from(parent)
 
     override fun onBindViewHolder(holder: AccentViewHolder, position: Int) =
         throw NotImplementedError()
@@ -75,13 +76,13 @@ class AccentAdapter(private val listener: ClickableListListener) :
         notifyItemChanged(accent.index, PAYLOAD_SELECTION_CHANGED)
     }
 
-    companion object {
+    private companion object {
-        private val PAYLOAD_SELECTION_CHANGED = Any()
+        val PAYLOAD_SELECTION_CHANGED = Any()
     }
 }
 
 /**
- * A [RecyclerView.ViewHolder] that displays an [Accent] choice. Use [new] to create an instance.
+ * A [RecyclerView.ViewHolder] that displays an [Accent] choice. Use [from] to create an instance.
  * @author Alexander Capehart (OxygenCobalt)
  */
 class AccentViewHolder private constructor(private val binding: ItemAccentBinding) :
@@ -93,13 +94,13 @@ class AccentViewHolder private constructor(private val binding: ItemAccentBindin
      * @param listener A [ClickableListListener] to bind interactions to.
      */
     fun bind(accent: Accent, listener: ClickableListListener) {
+        listener.bind(accent, this, binding.accent)
         binding.accent.apply {
-            setOnClickListener { listener.onClick(accent) }
-            backgroundTintList = context.getColorCompat(accent.primary)
             // Add a Tooltip based on the content description so that the purpose of this
             // button can be clear.
             contentDescription = context.getString(accent.name)
             TooltipCompat.setTooltipText(this, contentDescription)
+            backgroundTintList = context.getColorCompat(accent.primary)
         }
     }
 
@@ -124,6 +125,7 @@ class AccentViewHolder private constructor(private val binding: ItemAccentBindin
          * @param parent The parent to inflate this instance from.
          * @return A new instance.
          */
-        fun new(parent: View) = AccentViewHolder(ItemAccentBinding.inflate(parent.context.inflater))
+        fun from(parent: View) =
+            AccentViewHolder(ItemAccentBinding.inflate(parent.context.inflater))
     }
 }

app/src/main/java/org/oxycblt/auxio/ui/accent/AccentCustomizeDialog.kt

@@ -20,6 +20,7 @@ package org.oxycblt.auxio.ui.accent
 import android.os.Bundle
 import android.view.LayoutInflater
 import androidx.appcompat.app.AlertDialog
+import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogAccentBinding
@@ -27,7 +28,6 @@ import org.oxycblt.auxio.list.ClickableListListener
 import org.oxycblt.auxio.list.Item
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
-import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
@@ -38,7 +38,6 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
 class AccentCustomizeDialog :
     ViewBindingDialogFragment<DialogAccentBinding>(), ClickableListListener {
     private var accentAdapter = AccentAdapter(this)
-    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
 
     override fun onCreateBinding(inflater: LayoutInflater) = DialogAccentBinding.inflate(inflater)
 
@@ -46,6 +45,7 @@ class AccentCustomizeDialog :
         builder
             .setTitle(R.string.set_accent)
             .setPositiveButton(R.string.lbl_ok) { _, _ ->
+                val settings = Settings(requireContext())
                 if (accentAdapter.selectedAccent == settings.accent) {
                     // Nothing to do.
                     return@setPositiveButton
@@ -66,7 +66,7 @@ class AccentCustomizeDialog :
             if (savedInstanceState != null) {
                 Accent.from(savedInstanceState.getInt(KEY_PENDING_ACCENT))
             } else {
-                settings.accent
+                Settings(requireContext()).accent
             })
     }
 
@@ -80,12 +80,12 @@ class AccentCustomizeDialog :
         binding.accentRecycler.adapter = null
     }
 
-    override fun onClick(item: Item) {
+    override fun onClick(item: Item, viewHolder: RecyclerView.ViewHolder) {
         check(item is Accent) { "Unexpected datatype: ${item::class.java}" }
         accentAdapter.setSelectedAccent(item)
     }
 
-    companion object {
+    private companion object {
-        private const val KEY_PENDING_ACCENT = BuildConfig.APPLICATION_ID + ".key.PENDING_ACCENT"
+        const val KEY_PENDING_ACCENT = BuildConfig.APPLICATION_ID + ".key.PENDING_ACCENT"
     }
 }

app/src/main/java/org/oxycblt/auxio/widgets/WidgetComponent.kt

@@ -18,6 +18,7 @@
 package org.oxycblt.auxio.widgets
 
 import android.content.Context
+import android.content.SharedPreferences
 import android.graphics.Bitmap
 import android.os.Build
 import coil.request.ImageRequest
@@ -41,14 +42,15 @@ import org.oxycblt.auxio.util.logD
  * @author Alexander Capehart (OxygenCobalt)
  */
 class WidgetComponent(private val context: Context) :
-    PlaybackStateManager.Callback, Settings.Callback {
+    PlaybackStateManager.Listener, SharedPreferences.OnSharedPreferenceChangeListener {
     private val playbackManager = PlaybackStateManager.getInstance()
-    private val settings = Settings(context, this)
+    private val settings = Settings(context)
     private val widgetProvider = WidgetProvider()
     private val provider = BitmapProvider(context)
 
     init {
-        playbackManager.addCallback(this)
+        playbackManager.addListener(this)
+        settings.addListener(this)
     }
 
     /** Update [WidgetProvider] with the current playback state. */
@@ -104,9 +106,9 @@ class WidgetComponent(private val context: Context) :
     /** Release this instance, preventing any further events from updating the widget instances. */
     fun release() {
         provider.release()
-        settings.release()
+        settings.removeListener(this)
         widgetProvider.reset(context)
-        playbackManager.removeCallback(this)
+        playbackManager.removeListener(this)
     }
 
     // --- CALLBACKS ---
@@ -118,7 +120,8 @@ class WidgetComponent(private val context: Context) :
     override fun onStateChanged(state: InternalPlayer.State) = update()
     override fun onShuffledChanged(isShuffled: Boolean) = update()
     override fun onRepeatChanged(repeatMode: RepeatMode) = update()
-    override fun onSettingChanged(key: String) {
+
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
         if (key == context.getString(R.string.set_key_cover_mode) ||
             key == context.getString(R.string.set_key_round_mode)) {
             update()

app/src/main/java/org/oxycblt/auxio/widgets/WidgetUtil.kt

@@ -80,8 +80,8 @@ fun RemoteViews.setLayoutDirection(@IdRes viewId: Int, layoutDirection: Int) {
 }
 
 /**
- * Update the app widget layouts corresponding to the given [WidgetProvider] [ComponentName] with
+ * Update the app widget layouts corresponding to the given [WidgetProvider] [ComponentName] with an
- * an adaptive layout, in a version-compatible manner.
+ * adaptive layout, in a version-compatible manner.
  * @param context [Context] required to backport adaptive layout behavior.
  * @param component [ComponentName] of the app widget layout to update.
  * @param views Mapping between different size classes and [RemoteViews] instances.

app/src/main/res/layout/fragment_about.xml

@@ -9,7 +9,7 @@
     android:transitionGroup="true"
     tools:context=".settings.AboutFragment">
 
-    <org.oxycblt.auxio.ui.AuxioAppBarLayout
+    <org.oxycblt.auxio.ui.CoordinatorAppBarLayout
         android:id="@+id/about_appbar"
         style="@style/Widget.Auxio.AppBarLayout"
         app:liftOnScroll="true">
@@ -21,7 +21,7 @@
             app:navigationIcon="@drawable/ic_back_24"
             app:title="@string/lbl_about" />
 
-    </org.oxycblt.auxio.ui.AuxioAppBarLayout>
+    </org.oxycblt.auxio.ui.CoordinatorAppBarLayout>
 
     <androidx.core.widget.NestedScrollView
         android:id="@+id/about_contents"

app/src/main/res/layout/fragment_home.xml

@@ -8,7 +8,7 @@
     android:background="?attr/colorSurface"
     android:transitionGroup="true">
 
-    <org.oxycblt.auxio.ui.AuxioAppBarLayout
+    <org.oxycblt.auxio.ui.CoordinatorAppBarLayout
         android:id="@+id/home_appbar"
         style="@style/Widget.Auxio.AppBarLayout"
         android:fitsSystemWindows="true">
@@ -37,7 +37,7 @@
             app:tabGravity="start"
             app:tabMode="scrollable" />
 
-    </org.oxycblt.auxio.ui.AuxioAppBarLayout>
+    </org.oxycblt.auxio.ui.CoordinatorAppBarLayout>
 
 
     <FrameLayout

app/src/main/res/layout/fragment_search.xml

@@ -7,7 +7,7 @@
     android:background="?attr/colorSurface"
     android:transitionGroup="true">
 
-    <org.oxycblt.auxio.ui.AuxioAppBarLayout
+    <org.oxycblt.auxio.ui.CoordinatorAppBarLayout
         style="@style/Widget.Auxio.AppBarLayout"
         app:liftOnScroll="true"
         app:liftOnScrollTargetViewId="@id/search_recycler">
@@ -51,7 +51,7 @@
 
         </org.oxycblt.auxio.list.selection.SelectionToolbarOverlay>
 
-    </org.oxycblt.auxio.ui.AuxioAppBarLayout>
+    </org.oxycblt.auxio.ui.CoordinatorAppBarLayout>
 
     <org.oxycblt.auxio.list.recycler.AuxioRecyclerView
         android:id="@+id/search_recycler"

app/src/main/res/layout/fragment_settings.xml

@@ -8,7 +8,7 @@
     android:orientation="vertical"
     android:transitionGroup="true">
 
-    <org.oxycblt.auxio.ui.AuxioAppBarLayout
+    <org.oxycblt.auxio.ui.CoordinatorAppBarLayout
         android:id="@+id/settings_appbar"
         style="@style/Widget.Auxio.AppBarLayout"
         android:clickable="true"
@@ -22,7 +22,7 @@
             app:navigationIcon="@drawable/ic_back_24"
             app:title="@string/set_title" />
 
-    </org.oxycblt.auxio.ui.AuxioAppBarLayout>
+    </org.oxycblt.auxio.ui.CoordinatorAppBarLayout>
 
     <androidx.fragment.app.FragmentContainerView
         android:id="@+id/settings_list_fragment"

app/src/main/res/layout/item_music_dir.xml

@@ -25,6 +25,7 @@
         style="@style/Widget.Auxio.Button.Icon.Small"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
+        android:layout_gravity="center"
         android:layout_marginEnd="@dimen/spacing_mid_large"
         android:contentDescription="@string/desc_music_dir_delete"
         app:icon="@drawable/ic_delete_24"

app/src/main/res/navigation/nav_main.xml

@@ -106,12 +106,12 @@
         tools:layout="@layout/dialog_pre_amp" />
     <dialog
         android:id="@+id/music_dirs_dialog"
-        android:name="org.oxycblt.auxio.music.storage.MusicDirsDialog"
+        android:name="org.oxycblt.auxio.music.filesystem.MusicDirsDialog"
         android:label="music_dirs_dialog"
         tools:layout="@layout/dialog_music_dirs" />
     <dialog
         android:id="@+id/separators_dialog"
-        android:name="org.oxycblt.auxio.music.extractor.SeparatorsDialog"
+        android:name="org.oxycblt.auxio.music.parsing.SeparatorsDialog"
         android:label="music_dirs_dialog"
         tools:layout="@layout/dialog_separators" />
 

app/src/main/res/values-cs/strings.xml

@@ -268,4 +268,6 @@
     <string name="lbl_shuffle_selected">Náhodně přehrát vybrané</string>
     <string name="set_playback_mode_genre">Přehrát z žánru</string>
     <string name="lbl_wiki">Wiki</string>
+    <string name="fmt_list">%1$s, %2$s</string>
+    <string name="lbl_reset">Obnovit</string>
 </resources>

app/src/main/res/values-de/strings.xml

@@ -259,4 +259,5 @@
     <string name="fmt_selected">%d ausgewählt</string>
     <string name="set_playback_mode_genre">Vom Genre abspielen</string>
     <string name="lbl_wiki">Wiki</string>
+    <string name="fmt_list">%1$s, %2$s</string>
 </resources>

app/src/main/res/values-es/strings.xml

@@ -128,12 +128,10 @@
     <string name="fmt_lib_song_count">Canciones cargadas: %d</string>
     <plurals name="fmt_song_count">
         <item quantity="one">%d canción</item>
-        <item quantity="many">%d canciones</item>
         <item quantity="other">%d canciones</item>
     </plurals>
     <plurals name="fmt_album_count">
         <item quantity="one">%d álbum</item>
-        <item quantity="many">%d álbumes</item>
         <item quantity="other">%d álbumes</item>
     </plurals>
     <string name="lbl_size">Tamaño</string>
@@ -263,4 +261,5 @@
     <string name="lbl_play_selected">Reproducir los seleccionados</string>
     <string name="set_playback_mode_genre">Reproducir desde el género</string>
     <string name="lbl_wiki">Wiki</string>
+    <string name="fmt_list">%1$s, %2$s</string>
 </resources>