music: rework callback configuration

Rework the asynchronous aspects of MusicStore to rely on a more
conventional callback system.

In preparation for automatic rescanning, it would be more elegant
for music consumers to use a callback, so that updates can be
registered easier than if a co-routine continued to be used.
Convert MusicStore to this new model and rework the accesses of
MusicStore in-app to line up with this new system.

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

@@ -38,7 +38,7 @@ import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.MainNavigationAction
 import org.oxycblt.auxio.ui.NavigationViewModel
 import org.oxycblt.auxio.ui.ViewBindingFragment
-import org.oxycblt.auxio.util.logW
+import org.oxycblt.auxio.util.logD
 
 /**
  * A wrapper around the home fragment that shows the playback fragment and controls the more
@@ -122,32 +122,30 @@ class MainFragment : ViewBindingFragment<FragmentMainBinding>() {
 
             // Error, show the error to the user
             is MusicStore.Response.Err -> {
-                logW("Received Error")
+                logD("Received Response.Err")
-
+                Snackbar.make(binding.root, R.string.err_load_failed, Snackbar.LENGTH_INDEFINITE)
-                val errorRes =
+                    .apply {
-                    when (response.kind) {
+                        setAction(R.string.lbl_retry) { musicModel.reloadMusic(context) }
-                        MusicStore.ErrorKind.NO_MUSIC -> R.string.err_no_music
+                        show()
-                        MusicStore.ErrorKind.NO_PERMS -> R.string.err_no_perms
-                        MusicStore.ErrorKind.FAILED -> R.string.err_load_failed
                     }
-
+            }
-                val snackbar =
+            is MusicStore.Response.NoMusic -> {
-                    Snackbar.make(binding.root, getString(errorRes), Snackbar.LENGTH_INDEFINITE)
+                logD("Received Response.NoMusic")
-
+                Snackbar.make(binding.root, R.string.err_no_music, Snackbar.LENGTH_INDEFINITE)
-                when (response.kind) {
+                    .apply {
-                    MusicStore.ErrorKind.FAILED, MusicStore.ErrorKind.NO_MUSIC -> {
+                        setAction(R.string.lbl_retry) { musicModel.reloadMusic(context) }
-                        snackbar.setAction(R.string.lbl_retry) {
+                        show()
-                            musicModel.reloadMusic(requireContext())
-                        }
                     }
-                    MusicStore.ErrorKind.NO_PERMS -> {
+            }
-                        snackbar.setAction(R.string.lbl_grant) {
+            is MusicStore.Response.NoPerms -> {
+                logD("Received Response.NoPerms")
+                Snackbar.make(binding.root, R.string.err_no_perms, Snackbar.LENGTH_INDEFINITE)
+                    .apply {
+                        setAction(R.string.lbl_grant) {
                             permLauncher.launch(Manifest.permission.READ_EXTERNAL_STORAGE)
                         }
+                        show()
                     }
-                }
-
-                snackbar.show()
             }
             null -> {}
         }

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

@@ -31,6 +31,7 @@ import org.oxycblt.auxio.ui.Header
 import org.oxycblt.auxio.ui.Item
 import org.oxycblt.auxio.ui.Sort
 import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.unlikelyToBeNull
 
 /**
  * ViewModel that stores data for the [DetailFragment]s. This includes:
@@ -40,6 +41,7 @@ import org.oxycblt.auxio.util.logD
  * @author OxygenCobalt
  */
 class DetailViewModel : ViewModel() {
+    private val musicStore = MusicStore.getInstance()
     private val settingsManager = SettingsManager.getInstance()
 
     private val mCurrentAlbum = MutableLiveData<Album?>()
@@ -87,9 +89,9 @@ class DetailViewModel : ViewModel() {
 
     fun setAlbumId(id: Long) {
         if (mCurrentAlbum.value?.id == id) return
-        val musicStore = MusicStore.requireInstance()
+        val library = unlikelyToBeNull(musicStore.library)
         val album =
-            requireNotNull(musicStore.albums.find { it.id == id }) { "Invalid album id provided " }
+            requireNotNull(library.albums.find { it.id == id }) { "Invalid album id provided " }
 
         mCurrentAlbum.value = album
         refreshAlbumData(album)
@@ -97,16 +99,18 @@ class DetailViewModel : ViewModel() {
 
     fun setArtistId(id: Long) {
         if (mCurrentArtist.value?.id == id) return
-        val musicStore = MusicStore.requireInstance()
+        val library = unlikelyToBeNull(musicStore.library)
-        val artist = requireNotNull(musicStore.artists.find { it.id == id }) {}
+        val artist =
+            requireNotNull(library.artists.find { it.id == id }) { "Invalid artist id provided" }
         mCurrentArtist.value = artist
         refreshArtistData(artist)
     }
 
     fun setGenreId(id: Long) {
         if (mCurrentGenre.value?.id == id) return
-        val musicStore = MusicStore.requireInstance()
+        val library = unlikelyToBeNull(musicStore.library)
-        val genre = requireNotNull(musicStore.genres.find { it.id == id })
+        val genre =
+            requireNotNull(library.genres.find { it.id == id }) { "Invalid genre id provided" }
         mCurrentGenre.value = genre
         refreshGenreData(genre)
     }

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

@@ -20,8 +20,6 @@ package org.oxycblt.auxio.home
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.viewModelScope
-import kotlinx.coroutines.launch
 import org.oxycblt.auxio.home.tabs.Tab
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
@@ -38,7 +36,8 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
  * The ViewModel for managing [HomeFragment]'s data, sorting modes, and tab state.
  * @author OxygenCobalt
  */
-class HomeViewModel : ViewModel(), SettingsManager.Callback {
+class HomeViewModel : ViewModel(), SettingsManager.Callback, MusicStore.Callback {
+    private val musicStore = MusicStore.getInstance()
     private val settingsManager = SettingsManager.getInstance()
 
     private val mSongs = MutableLiveData(listOf<Song>())
@@ -78,15 +77,8 @@ class HomeViewModel : ViewModel(), SettingsManager.Callback {
     val fastScrolling: LiveData<Boolean> = mFastScrolling
 
     init {
+        musicStore.addCallback(this)
         settingsManager.addCallback(this)
-
-        viewModelScope.launch {
-            val musicStore = MusicStore.awaitInstance()
-            mSongs.value = settingsManager.libSongSort.songs(musicStore.songs)
-            mAlbums.value = settingsManager.libAlbumSort.albums(musicStore.albums)
-            mArtists.value = settingsManager.libArtistSort.artists(musicStore.artists)
-            mGenres.value = settingsManager.libGenreSort.genres(musicStore.genres)
-        }
     }
 
     /** Update the current tab based off of the new ViewPager position. */
@@ -142,6 +134,16 @@ class HomeViewModel : ViewModel(), SettingsManager.Callback {
 
     // --- OVERRIDES ---
 
+    override fun onMusicUpdate(response: MusicStore.Response) {
+        if (response is MusicStore.Response.Ok) {
+            val library = response.library
+            mSongs.value = settingsManager.libSongSort.songs(library.songs)
+            mAlbums.value = settingsManager.libAlbumSort.albums(library.albums)
+            mArtists.value = settingsManager.libArtistSort.artists(library.artists)
+            mGenres.value = settingsManager.libGenreSort.genres(library.genres)
+        }
+    }
+
     override fun onLibTabsUpdate(libTabs: Array<Tab>) {
         tabs = visibleTabs
         mRecreateTabs.value = true
@@ -149,6 +151,7 @@ class HomeViewModel : ViewModel(), SettingsManager.Callback {
 
     override fun onCleared() {
         super.onCleared()
+        musicStore.addCallback(this)
         settingsManager.removeCallback(this)
     }
 }

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

@@ -89,15 +89,24 @@ import org.oxycblt.auxio.util.logD
  *
  * @author OxygenCobalt
  */
-class MusicLoader {
+object Indexer {
-    data class Library(
+    /**
-        val genres: List<Genre>,
+     * The album_artist MediaStore field has existed since at least API 21, but until API 30 it was
-        val artists: List<Artist>,
+     * a proprietary extension for Google Play Music and was not documented. Since this field
-        val albums: List<Album>,
+     * probably works on all versions Auxio supports, we suppress the warning about using a
-        val songs: List<Song>
+     * possibly-unsupported constant.
-    )
+     */
+    @Suppress("InlinedApi")
+    private const val AUDIO_COLUMN_ALBUM_ARTIST = MediaStore.Audio.AudioColumns.ALBUM_ARTIST
 
-    fun load(context: Context): Library? {
+    /**
+     * Gets a content resolver in a way that does not mangle metadata on certain OEM skins. See
+     * https://github.com/OxygenCobalt/Auxio/issues/50 for more info.
+     */
+    private val Context.contentResolverSafe: ContentResolver
+        get() = applicationContext.contentResolver
+
+    fun run(context: Context): MusicStore.Library? {
         val songs = loadSongs(context)
         if (songs.isEmpty()) return null
 
@@ -118,16 +127,9 @@ class MusicLoader {
             }
         }
 
-        return Library(genres, artists, albums, songs)
+        return MusicStore.Library(genres, artists, albums, songs)
     }
 
-    /**
-     * Gets a content resolver in a way that does not mangle metadata on certain OEM skins. See
-     * https://github.com/OxygenCobalt/Auxio/issues/50 for more info.
-     */
-    private val Context.contentResolverSafe: ContentResolver
-        get() = applicationContext.contentResolver
-
     /**
      * Does the initial query over the song database, including excluded directory checks. The songs
      * returned by this function are **not** well-formed. The companion [buildAlbums],
@@ -404,15 +406,4 @@ class MusicLoader {
 
         return genreSongs.ifEmpty { null }
     }
-
-    companion object {
-        /**
-         * The album_artist MediaStore field has existed since at least API 21, but until API 30 it
-         * was a proprietary extension for Google Play Music and was not documented. Since this
-         * field probably works on all versions Auxio supports, we suppress the warning about using
-         * a possibly-unsupported constant.
-         */
-        @Suppress("InlinedApi")
-        private const val AUDIO_COLUMN_ALBUM_ARTIST = MediaStore.Audio.AudioColumns.ALBUM_ARTIST
-    }
 }

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

@@ -29,9 +29,7 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
 
 // --- MUSIC MODELS ---
 
-/**
+/** [Item] variant that represents a music item. */
- * [Item] variant that represents a music item.
- */
 sealed class Music : Item() {
     /** The raw name of this item. Null if unknown. */
     abstract val rawName: String?
@@ -116,8 +114,8 @@ data class Song(
         get() = internalMediaStoreArtistName ?: album.artist.rawName
 
     /**
-     * Resolve the artist name for this song in particular. First uses the artist tag, and
+     * Resolve the artist name for this song in particular. First uses the artist tag, and then
-     * then falls back to the album artist tag (i.e parent artist name)
+     * falls back to the album artist tag (i.e parent artist name)
      */
     fun resolveIndividualArtistName(context: Context) =
         internalMediaStoreArtistName ?: album.artist.resolveName(context)

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

@@ -38,76 +38,95 @@ import org.oxycblt.auxio.util.logE
  * @author OxygenCobalt
  */
 class MusicStore private constructor() {
-    private var mGenres = listOf<Genre>()
+    private var response: Response? = null
-    val genres: List<Genre>
+    val library: Library?
-        get() = mGenres
+        get() =
+            response?.let { currentResponse ->
+                if (currentResponse is Response.Ok) {
+                    currentResponse.library
+                } else {
+                    null
+                }
+            }
 
-    private var mArtists = listOf<Artist>()
+    private val callbacks = mutableListOf<Callback>()
-    val artists: List<Artist>
-        get() = mArtists
 
-    private var mAlbums = listOf<Album>()
+    fun addCallback(callback: Callback) {
-    val albums: List<Album>
+        callbacks.add(callback)
-        get() = mAlbums
+    }
 
-    private var mSongs = listOf<Song>()
+    fun removeCallback(callback: Callback) {
-    val songs: List<Song>
+        callbacks.remove(callback)
-        get() = mSongs
+    }
 
     /** Load/Sort the entire music library. Should always be ran on a coroutine. */
-    private fun load(context: Context): Response {
+    suspend fun index(context: Context): Response {
         logD("Starting initial music load")
+        val newResponse = withContext(Dispatchers.IO) { indexImpl(context) }.also { response = it }
+        for (callback in callbacks) {
+            callback.onMusicUpdate(newResponse)
+        }
+        return newResponse
+    }
 
+    private fun indexImpl(context: Context): Response {
         val notGranted =
             ContextCompat.checkSelfPermission(context, Manifest.permission.READ_EXTERNAL_STORAGE) ==
                 PackageManager.PERMISSION_DENIED
 
         if (notGranted) {
-            return Response.Err(ErrorKind.NO_PERMS)
+            return Response.NoPerms
         }
 
-        try {
+        val response =
-            val start = System.currentTimeMillis()
+            try {
+                val start = System.currentTimeMillis()
+                val library = Indexer.run(context)
+                if (library != null) {
+                    logD(
+                        "Music load completed successfully in ${System.currentTimeMillis() - start}ms")
+                    Response.Ok(library)
+                } else {
+                    logE("No music found")
+                    Response.NoMusic
+                }
+            } catch (e: Exception) {
+                logE("Music loading failed.")
+                logE(e.stackTraceToString())
+                Response.Err(e)
+            }
 
-            val loader = MusicLoader()
+        return response
-            val library = loader.load(context) ?: return Response.Err(ErrorKind.NO_MUSIC)
-
-            mSongs = library.songs
-            mAlbums = library.albums
-            mArtists = library.artists
-            mGenres = library.genres
-
-            logD("Music load completed successfully in ${System.currentTimeMillis() - start}ms")
-        } catch (e: Exception) {
-            logE("Music loading failed.")
-            logE(e.stackTraceToString())
-            return Response.Err(ErrorKind.FAILED)
-        }
-
-        return Response.Ok(this)
     }
 
-    /** Find a song in a faster manner using an ID for its album as well. */
+    data class Library(
-    fun findSongFast(songId: Long, albumId: Long): Song? {
+        val genres: List<Genre>,
-        return albums.find { it.id == albumId }?.songs?.find { it.id == songId }
+        val artists: List<Artist>,
-    }
+        val albums: List<Album>,
-
+        val songs: List<Song>
-    /**
+    ) {
-     * Find a song for a [uri], this is similar to [findSongFast], but with some kind of content
+        /** Find a song in a faster manner using an ID for its album as well. */
-     * uri.
+        fun findSongFast(songId: Long, albumId: Long): Song? {
-     * @return The corresponding [Song] for this [uri], null if there isn't one.
+            return albums.find { it.id == albumId }?.songs?.find { it.id == songId }
-     */
-    fun findSongForUri(uri: Uri, resolver: ContentResolver): Song? {
-        resolver.query(uri, arrayOf(OpenableColumns.DISPLAY_NAME), null, null, null)?.use { cursor
-            ->
-            cursor.moveToFirst()
-            val fileName =
-                cursor.getString(cursor.getColumnIndexOrThrow(OpenableColumns.DISPLAY_NAME))
-
-            return songs.find { it.fileName == fileName }
         }
 
-        return null
+        /**
+         * Find a song for a [uri], this is similar to [findSongFast], but with some kind of content
+         * uri.
+         * @return The corresponding [Song] for this [uri], null if there isn't one.
+         */
+        fun findSongForUri(uri: Uri, resolver: ContentResolver): Song? {
+            resolver.query(uri, arrayOf(OpenableColumns.DISPLAY_NAME), null, null, null)?.use {
+                cursor ->
+                cursor.moveToFirst()
+                val fileName =
+                    cursor.getString(cursor.getColumnIndexOrThrow(OpenableColumns.DISPLAY_NAME))
+
+                return songs.find { it.fileName == fileName }
+            }
+
+            return null
+        }
     }
 
     /**
@@ -117,93 +136,31 @@ class MusicStore private constructor() {
      * TODO: Add the exception to the "FAILED" ErrorKind
      */
     sealed class Response {
-        class Ok(val musicStore: MusicStore) : Response()
+        class Ok(val library: Library) : Response()
-        class Err(val kind: ErrorKind) : Response()
+        class Err(throwable: Throwable) : Response()
+        object NoMusic : Response()
+        object NoPerms : Response()
     }
 
-    enum class ErrorKind {
+    interface Callback {
-        NO_PERMS,
+        fun onMusicUpdate(response: Response)
-        NO_MUSIC,
-        FAILED
     }
 
     companion object {
-        @Volatile private var RESPONSE: Response? = null
+        @Volatile private var INSTANCE: MusicStore? = null
 
-        /**
+        fun getInstance(): MusicStore {
-         * Initialize the loading process for this instance. This must be ran on a background
+            val currentInstance = INSTANCE
-         * thread. If the instance has already been loaded successfully, then it will be returned
-         * immediately.
-         */
-        suspend fun initInstance(context: Context): Response {
-            val currentInstance = RESPONSE
 
-            if (currentInstance is Response.Ok) {
+            if (currentInstance != null) {
                 return currentInstance
             }
 
-            val response =
+            synchronized(this) {
-                withContext(Dispatchers.IO) {
+                val newInstance = MusicStore()
-                    val response = MusicStore().load(context)
+                INSTANCE = newInstance
-                    synchronized(this) { RESPONSE = response }
+                return newInstance
-                    response
-                }
-
-            return response
-        }
-
-        /**
-         * Await the successful creation of a [MusicStore] instance. The co-routine calling this
-         * will block until the successful creation of a [MusicStore], in which it will then be
-         * returned.
-         */
-        suspend fun awaitInstance() =
-            withContext(Dispatchers.Default) {
-                // We have to do a withContext call so we don't block the JVM thread
-                val musicStore: MusicStore
-
-                while (true) {
-                    val response = RESPONSE
-
-                    if (response is Response.Ok) {
-                        musicStore = response.musicStore
-                        break
-                    }
-                }
-
-                musicStore
             }
-
-        /**
-         * Maybe get a MusicStore instance. This is useful if you are running code while the loading
-         * process may still be going on.
-         *
-         * @return null if the music store instance is still loading or if the loading process has
-         * encountered an error. An instance is returned otherwise.
-         */
-        fun maybeGetInstance(): MusicStore? {
-            val currentInstance = RESPONSE
-
-            return if (currentInstance is Response.Ok) {
-                currentInstance.musicStore
-            } else {
-                null
-            }
-        }
-
-        /**
-         * Require a MusicStore instance. This function is dangerous and should only be used if it's
-         * guaranteed that the caller's code will only be called after the initial loading process.
-         */
-        fun requireInstance(): MusicStore {
-            return requireNotNull(maybeGetInstance()) {
-                "Required MusicStore instance was not available"
-            }
-        }
-
-        /** Check if this instance has successfully loaded or not. */
-        fun loaded(): Boolean {
-            return maybeGetInstance() != null
         }
     }
 }

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

@@ -25,12 +25,18 @@ import androidx.lifecycle.viewModelScope
 import kotlinx.coroutines.launch
 import org.oxycblt.auxio.util.logD
 
-class MusicViewModel : ViewModel() {
+class MusicViewModel : ViewModel(), MusicStore.Callback {
+    private val musicStore = MusicStore.getInstance()
+
     private val mLoaderResponse = MutableLiveData<MusicStore.Response?>(null)
     val loaderResponse: LiveData<MusicStore.Response?> = mLoaderResponse
 
     private var isBusy = false
 
+    init {
+        musicStore.addCallback(this)
+    }
+
     /**
      * Initiate the loading process. This is done here since HomeFragment will be the first fragment
      * navigated to and because SnackBars will have the best UX here.
@@ -45,7 +51,7 @@ class MusicViewModel : ViewModel() {
         mLoaderResponse.value = null
 
         viewModelScope.launch {
-            val result = MusicStore.initInstance(context)
+            val result = musicStore.index(context)
             mLoaderResponse.value = result
             isBusy = false
         }
@@ -56,4 +62,13 @@ class MusicViewModel : ViewModel() {
         mLoaderResponse.value = null
         loadMusic(context)
     }
+
+    override fun onMusicUpdate(response: MusicStore.Response) {
+        mLoaderResponse.value = response
+    }
+
+    override fun onCleared() {
+        super.onCleared()
+        musicStore.removeCallback(this)
+    }
 }

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

@@ -51,6 +51,10 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
  * - DO NOT REWRITE IT! THAT'S BAD AND WILL PROBABLY RE-INTRODUCE A TON OF BUGS.
  */
 class PlaybackViewModel : ViewModel(), PlaybackStateManager.Callback {
+    private val musicStore = MusicStore.getInstance()
+    private val settingsManager = SettingsManager.getInstance()
+    private val playbackManager = PlaybackStateManager.getInstance()
+
     // Playback
     private val mSong = MutableLiveData<Song?>()
     private val mParent = MutableLiveData<MusicParent?>()
@@ -94,9 +98,6 @@ class PlaybackViewModel : ViewModel(), PlaybackStateManager.Callback {
     val playbackMode: LiveData<PlaybackMode>
         get() = mMode
 
-    private val playbackManager = PlaybackStateManager.getInstance()
-    private val settingsManager = SettingsManager.getInstance()
-
     init {
         playbackManager.addCallback(this)
 
@@ -166,7 +167,7 @@ class PlaybackViewModel : ViewModel(), PlaybackStateManager.Callback {
      */
     fun playWithUri(uri: Uri, context: Context) {
         // Check if everything is already running to run the URI play
-        if (playbackManager.isRestored && MusicStore.loaded()) {
+        if (playbackManager.isRestored && musicStore.library != null) {
             playWithUriInternal(uri, context)
         } else {
             logD("Cant play this URI right now, waiting")
@@ -178,9 +179,8 @@ class PlaybackViewModel : ViewModel(), PlaybackStateManager.Callback {
     /** Play with a file URI. This is called after [playWithUri] once its deemed safe to do so. */
     private fun playWithUriInternal(uri: Uri, context: Context) {
         logD("Playing with uri $uri")
-
+        val library = musicStore.library ?: return
-        val musicStore = MusicStore.maybeGetInstance() ?: return
+        library.findSongForUri(uri, context.contentResolver)?.let { song -> playSong(song) }
-        musicStore.findSongForUri(uri, context.contentResolver)?.let { song -> playSong(song) }
     }
 
     /** Shuffle all songs */

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

@@ -105,7 +105,7 @@ class PlaybackStateDatabase(context: Context) :
      * @param musicStore Required to transform database songs/parents into actual instances
      * @return The stored [SavedState], null if there isn't one.
      */
-    fun readState(musicStore: MusicStore): SavedState? {
+    fun readState(library: MusicStore.Library): SavedState? {
         requireBackgroundThread()
 
         var state: SavedState? = null
@@ -124,16 +124,16 @@ class PlaybackStateDatabase(context: Context) :
             cursor.moveToFirst()
 
             val song =
-                cursor.getLongOrNull(songIndex)?.let { id -> musicStore.songs.find { it.id == id } }
+                cursor.getLongOrNull(songIndex)?.let { id -> library.songs.find { it.id == id } }
 
             val mode = PlaybackMode.fromInt(cursor.getInt(modeIndex)) ?: PlaybackMode.ALL_SONGS
 
             val parent =
                 cursor.getLongOrNull(parentIndex)?.let { id ->
                     when (mode) {
-                        PlaybackMode.IN_GENRE -> musicStore.genres.find { it.id == id }
+                        PlaybackMode.IN_GENRE -> library.genres.find { it.id == id }
-                        PlaybackMode.IN_ARTIST -> musicStore.artists.find { it.id == id }
+                        PlaybackMode.IN_ARTIST -> library.artists.find { it.id == id }
-                        PlaybackMode.IN_ALBUM -> musicStore.albums.find { it.id == id }
+                        PlaybackMode.IN_ALBUM -> library.albums.find { it.id == id }
                         PlaybackMode.ALL_SONGS -> null
                     }
                 }
@@ -186,7 +186,7 @@ class PlaybackStateDatabase(context: Context) :
      * Read a list of queue items from this database.
      * @param musicStore Required to transform database songs into actual song instances
      */
-    fun readQueue(musicStore: MusicStore): MutableList<Song> {
+    fun readQueue(library: MusicStore.Library): MutableList<Song> {
         requireBackgroundThread()
 
         val queue = mutableListOf<Song>()
@@ -198,8 +198,10 @@ class PlaybackStateDatabase(context: Context) :
             val albumIndex = cursor.getColumnIndexOrThrow(QueueColumns.ALBUM_HASH)
 
             while (cursor.moveToNext()) {
-                musicStore.findSongFast(cursor.getLong(songIndex), cursor.getLong(albumIndex))
+                library.findSongFast(cursor.getLong(songIndex), cursor.getLong(albumIndex))?.let {
-                    ?.let { song -> queue.add(song) }
+                    song ->
+                    queue.add(song)
+                }
             }
         }
 

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

@@ -43,6 +43,9 @@ import org.oxycblt.auxio.util.logE
  * @author OxygenCobalt
  */
 class PlaybackStateManager private constructor() {
+    private val musicStore = MusicStore.getInstance()
+    private val settingsManager = SettingsManager.getInstance()
+
     // Playback
     private var mSong: Song? = null
         set(value) {
@@ -124,8 +127,6 @@ class PlaybackStateManager private constructor() {
     val hasPlayed: Boolean
         get() = mHasPlayed
 
-    private val settingsManager = SettingsManager.getInstance()
-
     // --- CALLBACKS ---
 
     private val callbacks = mutableListOf<Callback>()
@@ -154,8 +155,7 @@ class PlaybackStateManager private constructor() {
 
         when (mode) {
             PlaybackMode.ALL_SONGS -> {
-                val musicStore = MusicStore.maybeGetInstance() ?: return
+                val musicStore = musicStore.library ?: return
-
                 mParent = null
                 mQueue = musicStore.songs.toMutableList()
             }
@@ -211,10 +211,11 @@ class PlaybackStateManager private constructor() {
 
     /** Shuffle all songs. */
     fun shuffleAll() {
-        val musicStore = MusicStore.maybeGetInstance() ?: return
+        logD("RETARD. ${musicStore.library}")
+        val library = musicStore.library ?: return
 
         mPlaybackMode = PlaybackMode.ALL_SONGS
-        mQueue = musicStore.songs.toMutableList()
+        mQueue = library.songs.toMutableList()
         mParent = null
 
         setShuffling(true, keepSong = false)
@@ -370,13 +371,13 @@ class PlaybackStateManager private constructor() {
      * @param keepSong Whether the current song should be kept as the queue is un-shuffled
      */
     private fun resetShuffle(keepSong: Boolean) {
-        val musicStore = MusicStore.maybeGetInstance() ?: return
+        val library = musicStore.library ?: return
         val lastSong = mSong
 
         mQueue =
             when (mPlaybackMode) {
                 PlaybackMode.ALL_SONGS ->
-                    settingsManager.libSongSort.songs(musicStore.songs).toMutableList()
+                    settingsManager.libSongSort.songs(library.songs).toMutableList()
                 PlaybackMode.IN_ALBUM ->
                     settingsManager.detailAlbumSort.album(mParent as Album).toMutableList()
                 PlaybackMode.IN_ARTIST ->
@@ -496,7 +497,7 @@ class PlaybackStateManager private constructor() {
     suspend fun restoreFromDatabase(context: Context) {
         logD("Getting state from DB")
 
-        val musicStore = MusicStore.maybeGetInstance() ?: return
+        val library = musicStore.library ?: return
         val start: Long
         val playbackState: PlaybackStateDatabase.SavedState?
         val queue: MutableList<Song>
@@ -504,8 +505,8 @@ class PlaybackStateManager private constructor() {
         withContext(Dispatchers.IO) {
             start = System.currentTimeMillis()
             val database = PlaybackStateDatabase.getInstance(context)
-            playbackState = database.readState(musicStore)
+            playbackState = database.readState(library)
-            queue = database.readQueue(musicStore)
+            queue = database.readQueue(library)
         }
 
         // Get off the IO coroutine since it will cause LiveData updates to throw an exception

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

@@ -76,6 +76,8 @@ import org.oxycblt.auxio.widgets.WidgetProvider
  *
  * TODO: Move all external exposal from passing around PlaybackStateManager to passing around the
  * MediaMetadata instance. Generally makes it easier to encapsulate this class.
+ *
+ * TODO: Move restore and file opening to service
  */
 class PlaybackService :
     Service(), Player.Listener, PlaybackStateManager.Callback, SettingsManager.Callback {

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

@@ -115,11 +115,6 @@ class SearchFragment : ViewBindingFragment<FragmentSearchBinding>(), MenuItemLis
         musicModel.loaderResponse.observe(viewLifecycleOwner, ::handleLoaderResponse)
     }
 
-    override fun onResume() {
-        super.onResume()
-        searchModel.setNavigating(false)
-    }
-
     override fun onDestroyBinding(binding: FragmentSearchBinding) {
         super.onDestroyBinding(binding)
         binding.searchRecycler.adapter = null

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

@@ -40,8 +40,10 @@ import org.oxycblt.auxio.util.logD
  * @author OxygenCobalt
  */
 class SearchViewModel : ViewModel() {
+    private val musicStore = MusicStore.getInstance()
+    private val settingsManager = SettingsManager.getInstance()
+
     private val mSearchResults = MutableLiveData(listOf<Item>())
-    private var mIsNavigating = false
     private var mFilterMode: DisplayMode? = null
     private var mLastQuery: String? = null
 
@@ -51,8 +53,6 @@ class SearchViewModel : ViewModel() {
     val filterMode: DisplayMode?
         get() = mFilterMode
 
-    private val settingsManager = SettingsManager.getInstance()
-
     init {
         mFilterMode = settingsManager.searchFilterMode
     }
@@ -61,10 +61,10 @@ class SearchViewModel : ViewModel() {
      * Use [query] to perform a search of the music library. Will push results to [searchResults].
      */
     fun search(context: Context, query: String?) {
-        val musicStore = MusicStore.maybeGetInstance()
         mLastQuery = query
 
-        if (query.isNullOrEmpty() || musicStore == null) {
+        val library = musicStore.library
+        if (query.isNullOrEmpty() || library == null) {
             logD("No music/query, ignoring search")
             mSearchResults.value = listOf()
             return
@@ -80,28 +80,28 @@ class SearchViewModel : ViewModel() {
             // Note: a filter mode of null means to not filter at all.
 
             if (mFilterMode == null || mFilterMode == DisplayMode.SHOW_ARTISTS) {
-                musicStore.artists.filterByOrNull(context, query)?.let { artists ->
+                library.artists.filterByOrNull(context, query)?.let { artists ->
                     results.add(Header(-1, R.string.lbl_artists))
                     results.addAll(sort.artists(artists))
                 }
             }
 
             if (mFilterMode == null || mFilterMode == DisplayMode.SHOW_ALBUMS) {
-                musicStore.albums.filterByOrNull(context, query)?.let { albums ->
+                library.albums.filterByOrNull(context, query)?.let { albums ->
                     results.add(Header(-2, R.string.lbl_albums))
                     results.addAll(sort.albums(albums))
                 }
             }
 
             if (mFilterMode == null || mFilterMode == DisplayMode.SHOW_GENRES) {
-                musicStore.genres.filterByOrNull(context, query)?.let { genres ->
+                library.genres.filterByOrNull(context, query)?.let { genres ->
                     results.add(Header(-3, R.string.lbl_genres))
                     results.addAll(sort.genres(genres))
                 }
             }
 
             if (mFilterMode == null || mFilterMode == DisplayMode.SHOW_SONGS) {
-                musicStore.songs.filterByOrNull(context, query)?.let { songs ->
+                library.songs.filterByOrNull(context, query)?.let { songs ->
                     results.add(Header(-4, R.string.lbl_songs))
                     results.addAll(sort.songs(songs))
                 }
@@ -181,9 +181,4 @@ class SearchViewModel : ViewModel() {
 
         return sb.toString()
     }
-
-    /** Update the current navigation status to [isNavigating] */
-    fun setNavigating(isNavigating: Boolean) {
-        mIsNavigating = isNavigating
-    }
 }

app/src/main/res/layout-sw600dp/fragment_playback_panel.xml

@@ -18,7 +18,7 @@
     <org.oxycblt.auxio.coil.StyledImageView
         android:id="@+id/playback_cover"
         style="@style/Widget.Auxio.Image.Full"
-        android:layout_margin="@dimen/spacing_large"
+        android:layout_margin="@dimen/spacing_mid_large"
         app:layout_constraintBottom_toTopOf="@+id/playback_song"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
@@ -30,8 +30,8 @@
         style="@style/Widget.Auxio.TextView.Primary"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
-        android:layout_marginStart="@dimen/spacing_large"
+        android:layout_marginStart="@dimen/spacing_mid_large"
-        android:layout_marginEnd="@dimen/spacing_large"
+        android:layout_marginEnd="@dimen/spacing_mid_large"
         app:layout_constraintBottom_toTopOf="@+id/playback_artist"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
@@ -43,8 +43,8 @@
         style="@style/Widget.Auxio.TextView.Secondary"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
-        android:layout_marginStart="@dimen/spacing_large"
+        android:layout_marginStart="@dimen/spacing_mid_large"
-        android:layout_marginEnd="@dimen/spacing_large"
+        android:layout_marginEnd="@dimen/spacing_mid_large"
         app:layout_constraintBottom_toTopOf="@+id/playback_album"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
@@ -55,8 +55,8 @@
         style="@style/Widget.Auxio.TextView.Secondary"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
-        android:layout_marginStart="@dimen/spacing_large"
+        android:layout_marginStart="@dimen/spacing_mid_large"
-        android:layout_marginEnd="@dimen/spacing_large"
+        android:layout_marginEnd="@dimen/spacing_mid_large"
         app:layout_constraintBottom_toTopOf="@+id/playback_seek_bar"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
@@ -108,7 +108,7 @@
         android:id="@+id/playback_loop"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginEnd="@dimen/spacing_large"
+        android:layout_marginEnd="@dimen/spacing_mid_large"
         android:contentDescription="@string/desc_change_loop"
         android:src="@drawable/ic_loop"
         app:hasIndicator="true"
@@ -121,7 +121,7 @@
         android:id="@+id/playback_skip_prev"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginEnd="@dimen/spacing_large"
+        android:layout_marginEnd="@dimen/spacing_mid_large"
         android:contentDescription="@string/desc_skip_prev"
         android:src="@drawable/ic_skip_prev"
         app:layout_constraintBottom_toBottomOf="@+id/playback_play_pause"
@@ -133,7 +133,7 @@
         style="@style/Widget.Auxio.FloatingActionButton.PlayPause"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginBottom="@dimen/spacing_large"
+        android:layout_marginBottom="@dimen/spacing_mid_large"
         android:contentDescription="@string/desc_play_pause"
         android:src="@drawable/sel_playing_state"
         app:layout_constraintBottom_toBottomOf="parent"
@@ -145,7 +145,7 @@
         android:id="@+id/playback_skip_next"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginStart="@dimen/spacing_large"
+        android:layout_marginStart="@dimen/spacing_mid_large"
         android:contentDescription="@string/desc_skip_next"
         android:src="@drawable/ic_skip_next"
         app:layout_constraintBottom_toBottomOf="@+id/playback_play_pause"
@@ -156,7 +156,7 @@
         android:id="@+id/playback_shuffle"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginStart="@dimen/spacing_large"
+        android:layout_marginStart="@dimen/spacing_mid_large"
         android:contentDescription="@string/desc_shuffle"
         android:src="@drawable/ic_shuffle"
         app:hasIndicator="true"