playback: add scaffold for new playback mode

Add the scaffold for PlaySong, a new version of playback modes that
- Supports playback of a song by itself, requested by #424.
- Will make direct playback from the song menu feasible (given
additional reworks)
- Prevents the invalid state of playing a song by it's playlist,
as the sealed interface implementation of PlaySong requires a Playlist
to be provided to it's respective variant.

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

@@ -101,8 +101,6 @@ object IntegerTable {
     const val SORT_BY_TRACK = 0xA117
     /** Sort.Mode.ByDateAdded */
     const val SORT_BY_DATE_ADDED = 0xA118
-    /** Sort.Mode.None */
-    const val SORT_BY_NONE = 0xA11F
     /** ReplayGainMode.Off (No longer used but still reserved) */
     // const val REPLAY_GAIN_MODE_OFF = 0xA110
     /** ReplayGainMode.Track */
@@ -123,4 +121,16 @@ object IntegerTable {
     const val COVER_MODE_MEDIA_STORE = 0xA11D
     /** CoverMode.Quality */
     const val COVER_MODE_QUALITY = 0xA11E
+    /** PlaySong.Itself */
+    const val PLAY_SONG_ITSELF = 0xA11F
+    /** PlaySong.FromAll */
+    const val PLAY_SONG_FROM_ALL = 0xA120
+    /** PlaySong.FromAlbum */
+    const val PLAY_SONG_FROM_ALBUM = 0xA121
+    /** PlaySong.FromArtist */
+    const val PLAY_SONG_FROM_ARTIST = 0xA122
+    /** PlaySong.FromGenre */
+    const val PLAY_SONG_FROM_GENRE = 0xA123
+    /** PlaySong.FromPlaylist */
+    const val PLAY_SONG_FROM_PLAYLIST = 0xA124
 }

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

@@ -180,8 +180,12 @@ class AlbumDetailFragment :
     }
 
     override fun onRealClick(item: Song) {
-        // There can only be one album, so a null mode and an ALBUMS mode will function the same.
+        val mode = detailModel.playbackMode
-        playbackModel.playFrom(item, detailModel.playbackMode ?: MusicMode.ALBUMS)
+        if (mode != null) {
+            playbackModel.play(item, detailModel.playbackMode ?: MusicMode.ALBUMS)
+        } else {
+            playbackModel.playFromAlbum(item)
+        }
     }
 
     override fun onOpenMenu(item: Song, anchor: View) {

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

@@ -182,7 +182,7 @@ class ArtistDetailFragment :
             is Song -> {
                 val playbackMode = detailModel.playbackMode
                 if (playbackMode != null) {
-                    playbackModel.playFrom(item, playbackMode)
+                    playbackModel.play(item, playbackMode)
                 } else {
                     // When configured to play from the selected item, we already have an Artist
                     // to play from.

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

@@ -180,7 +180,7 @@ class GenreDetailFragment :
             is Song -> {
                 val playbackMode = detailModel.playbackMode
                 if (playbackMode != null) {
-                    playbackModel.playFrom(item, playbackMode)
+                    playbackModel.play(item, playbackMode)
                 } else {
                     // When configured to play from the selected item, we already have an Genre
                     // to play from.

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

@@ -137,7 +137,7 @@ class SongListFragment :
     }
 
     override fun onRealClick(item: Song) {
-        playbackModel.playFrom(item, homeModel.playbackMode)
+        playbackModel.play(item, homeModel.playbackMode)
     }
 
     override fun onOpenMenu(item: Song, anchor: View) {

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

@@ -180,32 +180,31 @@ constructor(
 
     // --- PLAYING FUNCTIONS ---
 
+    fun play(song: Song, playbackMode: MusicMode) {
+        play(song, PlaySong.fromPlaybackModeTemporary(playbackMode))
+    }
+
+    fun play(song: Song, with: PlaySong) {
+        logD("Playing $song with $with")
+        playWithImpl(song, with, isImplicitlyShuffled())
+    }
+
+    //    fun playExplicit(song: Song, with: PlaySong) {
+    //        playWithImpl(song, with, false)
+    //    }
+    //
+    //    fun shuffleExplicit(song: Song, with: PlaySong) {
+    //        playWithImpl(song, with, true)
+    //    }
+
     /** Shuffle all songs in the music library. */
     fun shuffleAll() {
         logD("Shuffling all songs")
-        playImpl(null, null, true)
+        playFromAllImpl(null, true)
     }
 
-    /**
+    fun playFromAlbum(song: Song) {
-     * Play a [Song] from the [MusicParent] outlined by the given [MusicMode].
+        playFromAlbumImpl(song, isImplicitlyShuffled())
-     * - If [MusicMode.SONGS], the [Song] is played from all songs.
-     * - If [MusicMode.ALBUMS], the [Song] is played from it's [Album].
-     * - If [MusicMode.ARTISTS], the [Song] is played from one of it's [Artist]s.
-     * - If [MusicMode.GENRES], the [Song] is played from one of it's [Genre]s.
-     *   [MusicMode.PLAYLISTS] is disallowed here.
-     *
-     * @param song The [Song] to play.
-     * @param playbackMode The [MusicMode] to play from.
-     */
-    fun playFrom(song: Song, playbackMode: MusicMode) {
-        logD("Playing $song from $playbackMode")
-        when (playbackMode) {
-            MusicMode.SONGS -> playImpl(song, null)
-            MusicMode.ALBUMS -> playImpl(song, song.album)
-            MusicMode.ARTISTS -> playFromArtist(song)
-            MusicMode.GENRES -> playFromGenre(song)
-            MusicMode.PLAYLISTS -> error("Playing from a playlist is not supported.")
-        }
     }
 
     /**
@@ -216,16 +215,7 @@ constructor(
      *   be prompted on what artist to play. Defaults to null.
      */
     fun playFromArtist(song: Song, artist: Artist? = null) {
-        if (artist != null) {
+        playFromArtistImpl(song, artist, isImplicitlyShuffled())
-            logD("Playing $song from $artist")
-            playImpl(song, artist)
-        } else if (song.artists.size == 1) {
-            logD("$song has one artist, playing from it")
-            playImpl(song, song.artists[0])
-        } else {
-            logD("$song has multiple artists, showing choice dialog")
-            startPlaybackDecisionImpl(PlaybackDecision.PlayFromArtist(song))
-        }
     }
 
     /**
@@ -236,19 +226,77 @@ constructor(
      *   be prompted on what artist to play. Defaults to null.
      */
     fun playFromGenre(song: Song, genre: Genre? = null) {
-        if (genre != null) {
+        playFromGenreImpl(song, genre, isImplicitlyShuffled())
-            logD("Playing $song from $genre")
+    }
-            playImpl(song, genre)
+
-        } else if (song.genres.size == 1) {
+    /**
-            logD("$song has one genre, playing from it")
+     * Play a [Song] from one of it's [Playlist]s.
-            playImpl(song, song.genres[0])
+     *
-        } else {
+     * @param song The [Song] to play.
-            logD("$song has multiple genres, showing choice dialog")
+     * @param playlist The [Playlist] to play from. Must be linked to the [Song].
-            startPlaybackDecisionImpl(PlaybackDecision.PlayFromGenre(song))
+     */
+    fun playFromPlaylist(song: Song, playlist: Playlist) {
+        playFromPlaylistImpl(song, playlist, isImplicitlyShuffled())
+    }
+
+    private fun isImplicitlyShuffled() =
+        playbackManager.queue.isShuffled && playbackSettings.keepShuffle
+
+    private fun playWithImpl(song: Song, with: PlaySong, shuffled: Boolean) {
+        when (with) {
+            is PlaySong.ByItself -> playItselfImpl(song, shuffled)
+            is PlaySong.FromAll -> playFromAllImpl(song, shuffled)
+            is PlaySong.FromAlbum -> playFromAlbumImpl(song, shuffled)
+            is PlaySong.FromArtist -> playFromArtistImpl(song, with.which, shuffled)
+            is PlaySong.FromGenre -> playFromGenreImpl(song, with.which, shuffled)
+            is PlaySong.FromPlaylist -> playFromPlaylistImpl(song, with.which, shuffled)
         }
     }
 
-    private fun startPlaybackDecisionImpl(decision: PlaybackDecision) {
+    private fun playItselfImpl(song: Song, shuffled: Boolean) {
+        playImpl(song, listOf(song), shuffled)
+    }
+
+    private fun playFromAllImpl(song: Song?, shuffled: Boolean) {
+        playImpl(song, null, shuffled)
+    }
+
+    private fun playFromAlbumImpl(song: Song, shuffled: Boolean) {
+        playImpl(song, song.album, shuffled)
+    }
+
+    private fun playFromArtistImpl(song: Song, artist: Artist?, shuffled: Boolean) {
+        if (artist != null) {
+            logD("Playing $song from $artist")
+            playImpl(song, artist, shuffled)
+        } else if (song.artists.size == 1) {
+            logD("$song has one artist, playing from it")
+            playImpl(song, song.artists[0], shuffled)
+        } else {
+            logD("$song has multiple artists, showing choice dialog")
+            startPlaybackDecision(PlaybackDecision.PlayFromArtist(song))
+        }
+    }
+
+    private fun playFromGenreImpl(song: Song, genre: Genre?, shuffled: Boolean) {
+        if (genre != null) {
+            logD("Playing $song from $genre")
+            playImpl(song, genre, shuffled)
+        } else if (song.genres.size == 1) {
+            logD("$song has one genre, playing from it")
+            playImpl(song, song.genres[0], shuffled)
+        } else {
+            logD("$song has multiple genres, showing choice dialog")
+            startPlaybackDecision(PlaybackDecision.PlayFromGenre(song))
+        }
+    }
+
+    private fun playFromPlaylistImpl(song: Song, playlist: Playlist, shuffled: Boolean) {
+        logD("Playing $song from $playlist")
+        playImpl(song, playlist, shuffled)
+    }
+
+    private fun startPlaybackDecision(decision: PlaybackDecision) {
         val existing = _playbackDecision.flow.value
         if (existing != null) {
             logD("Already handling decision $existing, ignoring $decision")
@@ -257,17 +305,6 @@ constructor(
         _playbackDecision.put(decision)
     }
 
-    /**
-     * PLay a [Song] from one of it's [Playlist]s.
-     *
-     * @param song The [Song] to play.
-     * @param playlist The [Playlist] to play from. Must be linked to the [Song].
-     */
-    fun playFromPlaylist(song: Song, playlist: Playlist) {
-        logD("Playing $song from $playlist")
-        playImpl(song, playlist)
-    }
-
     /**
      * Play an [Album].
      *
@@ -278,46 +315,6 @@ constructor(
         playImpl(null, album, false)
     }
 
-    /**
-     * Play an [Artist].
-     *
-     * @param artist The [Artist] to play.
-     */
-    fun play(artist: Artist) {
-        logD("Playing $artist")
-        playImpl(null, artist, false)
-    }
-
-    /**
-     * Play a [Genre].
-     *
-     * @param genre The [Genre] to play.
-     */
-    fun play(genre: Genre) {
-        logD("Playing $genre")
-        playImpl(null, genre, false)
-    }
-
-    /**
-     * Play a [Playlist].
-     *
-     * @param playlist The [Playlist] to play.
-     */
-    fun play(playlist: Playlist) {
-        logD("Playing $playlist")
-        playImpl(null, playlist, false)
-    }
-
-    /**
-     * Play a list of [Song]s.
-     *
-     * @param songs The [Song]s to play.
-     */
-    fun play(songs: List<Song>) {
-        logD("Playing ${songs.size} songs")
-        playbackManager.play(null, null, songs, false)
-    }
-
     /**
      * Shuffle an [Album].
      *
@@ -328,6 +325,16 @@ constructor(
         playImpl(null, album, true)
     }
 
+    /**
+     * Play an [Artist].
+     *
+     * @param artist The [Artist] to play.
+     */
+    fun play(artist: Artist) {
+        logD("Playing $artist")
+        playImpl(null, artist, false)
+    }
+
     /**
      * Shuffle an [Artist].
      *
@@ -338,6 +345,16 @@ constructor(
         playImpl(null, artist, true)
     }
 
+    /**
+     * Play a [Genre].
+     *
+     * @param genre The [Genre] to play.
+     */
+    fun play(genre: Genre) {
+        logD("Playing $genre")
+        playImpl(null, genre, false)
+    }
+
     /**
      * Shuffle a [Genre].
      *
@@ -348,6 +365,16 @@ constructor(
         playImpl(null, genre, true)
     }
 
+    /**
+     * Play a [Playlist].
+     *
+     * @param playlist The [Playlist] to play.
+     */
+    fun play(playlist: Playlist) {
+        logD("Playing $playlist")
+        playImpl(null, playlist, false)
+    }
+
     /**
      * Shuffle a [Playlist].
      *
@@ -358,6 +385,16 @@ constructor(
         playImpl(null, playlist, true)
     }
 
+    /**
+     * Play a list of [Song]s.
+     *
+     * @param songs The [Song]s to play.
+     */
+    fun play(songs: List<Song>) {
+        logD("Playing ${songs.size} songs")
+        playbackManager.play(null, null, songs, false)
+    }
+
     /**
      * Shuffle a list of [Song]s.
      *
@@ -368,11 +405,12 @@ constructor(
         playbackManager.play(null, null, songs, true)
     }
 
-    private fun playImpl(
+    private fun playImpl(song: Song?, queue: List<Song>, shuffled: Boolean) {
-        song: Song?,
+        check(song == null || queue.contains(song)) { "Song to play not in queue" }
-        parent: MusicParent?,
+        playbackManager.play(song, null, queue, shuffled)
-        shuffled: Boolean = playbackManager.queue.isShuffled && playbackSettings.keepShuffle
+    }
-    ) {
+
+    private fun playImpl(song: Song?, parent: MusicParent?, shuffled: Boolean) {
         check(song == null || parent == null || parent.songs.contains(song)) {
             "Song to play not in parent"
         }

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

@@ -174,7 +174,7 @@ class SearchFragment : ListFragment<Music, FragmentSearchBinding>() {
 
     override fun onRealClick(item: Music) {
         when (item) {
-            is Song -> playbackModel.playFrom(item, searchModel.playbackMode)
+            is Song -> playbackModel.play(item, searchModel.playbackMode)
             is Album -> detailModel.showAlbum(item)
             is Artist -> detailModel.showArtist(item)
             is Genre -> detailModel.showGenre(item)