playback: fix more build errors

I need to make a setting to switch between gapless and single-item playback
to accomodate extremely large queues, so extract the crazy hacky queue
stuff into a new PlayerKernel construct.

Single-item will be added at a later point.

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

@@ -49,8 +49,9 @@ class AuxioService :
     override fun onCreate() {
         super.onCreate()
         playbackFragment = playbackFragmentFactory.create(this, this)
-        sessionToken = playbackFragment.token
+        sessionToken = playbackFragment.attach()
         musicFragment = musicFragmentFactory.create(this, this, this)
+        musicFragment.attach()
     }
 
     override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
@@ -80,7 +81,6 @@ class AuxioService :
         super.onDestroy()
         musicFragment.release()
         playbackFragment.release()
-        sessionToken = null
     }
 
     override fun onGetRoot(
@@ -88,9 +88,7 @@ class AuxioService :
         clientUid: Int,
         rootHints: Bundle?
     ): BrowserRoot {
-        val maximumRootChildLimit =
-            rootHints?.getInt(MediaConstants.BROWSER_ROOT_HINTS_KEY_ROOT_CHILDREN_LIMIT, 4) ?: 4
-        return musicFragment.getRoot(maximumRootChildLimit)
+        return musicFragment.getRoot()
     }
 
     override fun onLoadItem(itemId: String, result: Result<MediaItem>) {
@@ -98,7 +96,10 @@ class AuxioService :
     }
 
     override fun onLoadChildren(parentId: String, result: Result<MutableList<MediaItem>>) {
-        musicFragment.getChildren(parentId, result)
+        val maximumRootChildLimit =
+            browserRootHints?.getInt(MediaConstants.BROWSER_ROOT_HINTS_KEY_ROOT_CHILDREN_LIMIT, 4)
+                ?: 4
+        musicFragment.getChildren(parentId, maximumRootChildLimit, result)
     }
 
     override fun onSearch(query: String, extras: Bundle?, result: Result<MutableList<MediaItem>>) {

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

@@ -1,9 +1,26 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * DetailGenerator.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
 package org.oxycblt.auxio.detail
 
-import android.content.Context
 import androidx.annotation.StringRes
+import javax.inject.Inject
 import org.oxycblt.auxio.R
-import org.oxycblt.auxio.detail.list.DiscHeader
 import org.oxycblt.auxio.list.ListSettings
 import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Album
@@ -18,15 +35,20 @@ import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.music.info.Disc
 import org.oxycblt.auxio.music.info.ReleaseType
 import org.oxycblt.auxio.util.logD
-import java.util.SortedMap
-import javax.inject.Inject
 
 interface DetailGenerator {
     fun any(uid: Music.UID): Detail<out MusicParent>?
+
     fun album(uid: Music.UID): Detail<Album>?
+
     fun artist(uid: Music.UID): Detail<Artist>?
+
     fun genre(uid: Music.UID): Detail<Genre>?
+
     fun playlist(uid: Music.UID): Detail<Playlist>?
+
+    fun attach()
+
     fun release()
 
     interface Factory {
@@ -38,10 +60,10 @@ interface DetailGenerator {
     }
 }
 
-class DetailGeneratorFactoryImpl @Inject constructor(
-    private val listSettings: ListSettings,
-    private val musicRepository: MusicRepository
-) : DetailGenerator.Factory {
+class DetailGeneratorFactoryImpl
+@Inject
+constructor(private val listSettings: ListSettings, private val musicRepository: MusicRepository) :
+    DetailGenerator.Factory {
     override fun create(invalidator: DetailGenerator.Invalidator): DetailGenerator =
         DetailGeneratorImpl(invalidator, listSettings, musicRepository)
 }
@@ -51,7 +73,7 @@ private class DetailGeneratorImpl(
     private val listSettings: ListSettings,
     private val musicRepository: MusicRepository
 ) : DetailGenerator, MusicRepository.UpdateListener, ListSettings.Listener {
-    init {
+    override fun attach() {
         listSettings.registerListener(this)
         musicRepository.addUpdateListener(this)
     }
@@ -102,7 +124,8 @@ private class DetailGeneratorImpl(
         val album = musicRepository.deviceLibrary?.findAlbum(uid) ?: return null
         val songs = listSettings.albumSongSort.songs(album.songs)
         val discs = songs.groupBy { it.disc }
-        val section = if (discs.size > 1 || discs.keys.first() != null) {
+        val section =
+            if (discs.size > 1) {
                 DetailSection.Discs(discs)
             } else {
                 DetailSection.Songs(songs)
@@ -138,11 +161,12 @@ private class DetailGeneratorImpl(
             // implicit album list into the mapping.
             logD("Implicit albums present, adding to list")
             @Suppress("UNCHECKED_CAST")
-            (grouping as MutableMap<DetailSection.Albums.Category, Collection<Album>>)[DetailSection.Albums.Category.APPEARANCES] =
-                artist.implicitAlbums
+            (grouping as MutableMap<DetailSection.Albums.Category, Collection<Album>>)[
+                DetailSection.Albums.Category.APPEARANCES] = artist.implicitAlbums
         }
 
-        val sections = grouping.mapTo(mutableListOf<DetailSection>()) { (category, albums) ->
+        val sections =
+            grouping.mapTo(mutableListOf<DetailSection>()) { (category, albums) ->
                 DetailSection.Albums(category, ARTIST_ALBUM_SORT.albums(albums))
             }
         val songs = DetailSection.Songs(listSettings.artistSongSort.songs(artist.songs))
@@ -184,7 +208,8 @@ sealed interface DetailSection {
         override val stringRes = R.string.lbl_songs
     }
 
-    data class Albums(val category: Category, override val items: List<Album>) : PlainSection<Album>() {
+    data class Albums(val category: Category, override val items: List<Album>) :
+        PlainSection<Album>() {
         override val order = 1 + category.ordinal
         override val stringRes = category.stringRes
 
@@ -203,7 +228,6 @@ sealed interface DetailSection {
         }
     }
 
-
     data class Songs(override val items: List<Song>) : PlainSection<Song>() {
         override val order = 12
         override val stringRes = R.string.lbl_songs

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

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2024 Auxio Project
- * HomeModule.kt is part of Auxio.
+ * DetailModule.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

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

@@ -72,9 +72,6 @@ constructor(
     private val playbackSettings: PlaybackSettings,
     detailGeneratorFactory: DetailGenerator.Factory
 ) : ViewModel(), DetailGenerator.Invalidator {
-    private val detailGenerator = detailGeneratorFactory.create(this)
-
-
     private val _toShow = MutableEvent<Show>()
     /**
      * A [Show] command that is awaiting a view capable of responding to it. Null if none currently.
@@ -198,6 +195,12 @@ constructor(
             playbackSettings.inParentPlaybackMode
                 ?: PlaySong.FromPlaylist(unlikelyToBeNull(currentPlaylist.value))
 
+    private val detailGenerator = detailGeneratorFactory.create(this)
+
+    init {
+        detailGenerator.attach()
+    }
+
     override fun onCleared() {
         detailGenerator.release()
     }
@@ -208,21 +211,18 @@ constructor(
                 val album = detailGenerator.album(currentAlbum.value?.uid ?: return)
                 refreshDetail(album, _currentAlbum, _albumSongList, _albumSongInstructions, replace)
             }
-
             MusicType.ARTISTS -> {
                 val artist = detailGenerator.artist(currentArtist.value?.uid ?: return)
-                refreshDetail(artist, _currentArtist, _artistSongList, _artistSongInstructions, replace)
+                refreshDetail(
+                    artist, _currentArtist, _artistSongList, _artistSongInstructions, replace)
             }
-
             MusicType.GENRES -> {
                 val genre = detailGenerator.genre(currentGenre.value?.uid ?: return)
                 refreshDetail(genre, _currentGenre, _genreSongList, _genreSongInstructions, replace)
             }
-
             MusicType.PLAYLISTS -> {
                 refreshPlaylist(currentPlaylist.value?.uid ?: return)
             }
-
             else -> error("Unexpected music type $type")
         }
     }
@@ -522,7 +522,6 @@ constructor(
             }
     }
 
-
     private fun <T : MusicParent> refreshDetail(
         detail: Detail<T>?,
         parent: MutableStateFlow<T?>,
@@ -537,22 +536,21 @@ constructor(
         val newList = mutableListOf<Item>()
         var newInstructions: UpdateInstructions = UpdateInstructions.Diff
         for ((i, section) in detail.sections.withIndex()) {
-            val items = when (section) {
+            val items =
+                when (section) {
                     is DetailSection.PlainSection<*> -> {
-                    val header = if (section is DetailSection.Songs)
-                        SortHeader(section.stringRes) else BasicHeader(section.stringRes)
+                        val header =
+                            if (section is DetailSection.Songs) SortHeader(section.stringRes)
+                            else BasicHeader(section.stringRes)
                         newList.add(Divider(header))
                         newList.add(header)
                         section.items
                     }
-
                     is DetailSection.Discs -> {
-                    val header = BasicHeader(section.stringRes)
+                        val header = SortHeader(section.stringRes)
                         newList.add(Divider(header))
                         newList.add(header)
-                    section.discs.flatMap {
-                        listOf(DiscHeader(it.key)) + it.value
-                    }
+                        section.discs.flatMap { listOf(DiscHeader(it.key)) + it.value }
                     }
                 }
             // Currently only the final section (songs, which can be sorted) are invalidatable
@@ -564,16 +562,20 @@ constructor(
             newList.addAll(items)
         }
         parent.value = detail.parent
-        list.value = newList
         instructions.put(newInstructions)
+        list.value = newList
     }
 
-    private fun refreshPlaylist(uid: Music.UID, instructions: UpdateInstructions = UpdateInstructions.Diff) {
+    private fun refreshPlaylist(
+        uid: Music.UID,
+        instructions: UpdateInstructions = UpdateInstructions.Diff
+    ) {
         logD("Refreshing playlist list")
         val edited = editedPlaylist.value
         if (edited == null) {
             val playlist = detailGenerator.playlist(uid)
-            refreshDetail(playlist, _currentPlaylist, _playlistSongList, _playlistSongInstructions, null)
+            refreshDetail(
+                playlist, _currentPlaylist, _playlistSongList, _playlistSongInstructions, null)
             return
         }
         val list = mutableListOf<Item>()
@@ -583,8 +585,8 @@ constructor(
             list.add(header)
             list.addAll(edited)
         }
-        _playlistSongList.value = list
         _playlistSongInstructions.put(instructions)
+        _playlistSongList.value = list
     }
 }
 

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

@@ -35,10 +35,10 @@ import org.oxycblt.auxio.list.adapter.SimpleDiffCallback
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.music.info.Disc
+import org.oxycblt.auxio.music.info.resolveNumber
 import org.oxycblt.auxio.playback.formatDurationMs
 import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.inflater
-import org.oxycblt.auxio.util.logD
 
 /**
  * An [DetailListAdapter] implementing the header and sub-items for the [Album] detail view.
@@ -111,16 +111,10 @@ private class DiscHeaderViewHolder(private val binding: ItemDiscHeaderBinding) :
      */
     fun bind(discHeader: DiscHeader) {
         val disc = discHeader.inner
-        if (disc != null) {
-            binding.discNumber.text = binding.context.getString(R.string.fmt_disc_no, disc.number)
+        binding.discNumber.text = disc.resolveNumber(binding.context)
         binding.discName.apply {
-                text = disc.name
-                isGone = disc.name == null
-            }
-        } else {
-            logD("Disc is null, defaulting to no disc")
-            binding.discNumber.text = binding.context.getString(R.string.def_disc)
-            binding.discName.isGone = true
+            text = disc?.name
+            isGone = disc?.name == null
         }
     }
 

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

@@ -32,6 +32,10 @@ import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.util.logD
 
 interface HomeGenerator {
+    fun attach()
+
+    fun release()
+
     fun songs(): List<Song>
 
     fun albums(): List<Album>
@@ -44,8 +48,6 @@ interface HomeGenerator {
 
     fun tabs(): List<MusicType>
 
-    fun release()
-
     interface Invalidator {
         fun invalidateMusic(type: MusicType, instructions: UpdateInstructions)
 
@@ -74,41 +76,14 @@ private class HomeGeneratorImpl(
     private val listSettings: ListSettings,
     private val musicRepository: MusicRepository,
 ) : HomeGenerator, HomeSettings.Listener, ListSettings.Listener, MusicRepository.UpdateListener {
-    override fun songs() =
-        musicRepository.deviceLibrary?.let { listSettings.songSort.songs(it.songs) } ?: emptyList()
-
-    override fun albums() =
-        musicRepository.deviceLibrary?.let { listSettings.albumSort.albums(it.albums) }
-            ?: emptyList()
-
-    override fun artists() =
-        musicRepository.deviceLibrary?.let { listSettings.artistSort.artists(it.artists) }
-            ?: emptyList()
-
-    override fun genres() =
-        musicRepository.deviceLibrary?.let { listSettings.genreSort.genres(it.genres) }
-            ?: emptyList()
-
-    override fun playlists() =
-        musicRepository.userLibrary?.let { listSettings.playlistSort.playlists(it.playlists) }
-            ?: emptyList()
-
-    override fun tabs() = homeSettings.homeTabs.filterIsInstance<Tab.Visible>().map { it.type }
-
-    override fun onTabsChanged() {
-        invalidator.invalidateTabs()
-    }
-
-    init {
+    override fun attach() {
         homeSettings.registerListener(this)
         listSettings.registerListener(this)
         musicRepository.addUpdateListener(this)
     }
 
-    override fun release() {
-        musicRepository.removeUpdateListener(this)
-        listSettings.unregisterListener(this)
-        homeSettings.unregisterListener(this)
+    override fun onTabsChanged() {
+        invalidator.invalidateTabs()
     }
 
     override fun onHideCollaboratorsChanged() {
@@ -161,4 +136,31 @@ private class HomeGeneratorImpl(
             invalidator.invalidateMusic(MusicType.PLAYLISTS, UpdateInstructions.Diff)
         }
     }
+
+    override fun release() {
+        musicRepository.removeUpdateListener(this)
+        listSettings.unregisterListener(this)
+        homeSettings.unregisterListener(this)
+    }
+
+    override fun songs() =
+        musicRepository.deviceLibrary?.let { listSettings.songSort.songs(it.songs) } ?: emptyList()
+
+    override fun albums() =
+        musicRepository.deviceLibrary?.let { listSettings.albumSort.albums(it.albums) }
+            ?: emptyList()
+
+    override fun artists() =
+        musicRepository.deviceLibrary?.let { listSettings.artistSort.artists(it.artists) }
+            ?: emptyList()
+
+    override fun genres() =
+        musicRepository.deviceLibrary?.let { listSettings.genreSort.genres(it.genres) }
+            ?: emptyList()
+
+    override fun playlists() =
+        musicRepository.userLibrary?.let { listSettings.playlistSort.playlists(it.playlists) }
+            ?: emptyList()
+
+    override fun tabs() = homeSettings.homeTabs.filterIsInstance<Tab.Visible>().map { it.type }
 }

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

@@ -52,8 +52,6 @@ constructor(
     private val playbackSettings: PlaybackSettings,
     homeGeneratorFactory: HomeGenerator.Factory
 ) : ViewModel(), HomeGenerator.Invalidator {
-    private val homeGenerator = homeGeneratorFactory.create(this)
-
     private val _songList = MutableStateFlow(listOf<Song>())
     /** A list of [Song]s, sorted by the preferred [Sort], to be shown in the home view. */
     val songList: StateFlow<List<Song>>
@@ -131,6 +129,8 @@ constructor(
     val playlistSort: Sort
         get() = listSettings.playlistSort
 
+    private val homeGenerator = homeGeneratorFactory.create(this)
+
     /**
      * A list of [MusicType] corresponding to the current [Tab] configuration, excluding invisible
      * [Tab]s.
@@ -163,6 +163,10 @@ constructor(
     val showOuter: Event<Outer>
         get() = _showOuter
 
+    init {
+        homeGenerator.attach()
+    }
+
     override fun onCleared() {
         super.onCleared()
         homeGenerator.release()
@@ -171,24 +175,24 @@ constructor(
     override fun invalidateMusic(type: MusicType, instructions: UpdateInstructions) {
         when (type) {
             MusicType.SONGS -> {
-                _songList.value = homeGenerator.songs()
                 _songInstructions.put(instructions)
+                _songList.value = homeGenerator.songs()
             }
             MusicType.ALBUMS -> {
-                _albumList.value = homeGenerator.albums()
                 _albumInstructions.put(instructions)
+                _albumList.value = homeGenerator.albums()
             }
             MusicType.ARTISTS -> {
-                _artistList.value = homeGenerator.artists()
                 _artistInstructions.put(instructions)
+                _artistList.value = homeGenerator.artists()
             }
             MusicType.GENRES -> {
-                _genreList.value = homeGenerator.genres()
                 _genreInstructions.put(instructions)
+                _genreList.value = homeGenerator.genres()
             }
             MusicType.PLAYLISTS -> {
-                _playlistList.value = homeGenerator.playlists()
                 _playlistInstructions.put(instructions)
+                _playlistList.value = homeGenerator.playlists()
             }
         }
     }

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

@@ -52,7 +52,7 @@ class AdaptiveTabStrategy(context: Context, private val tabs: List<MusicType>) :
             // On small screens, only display an icon.
             width < 370 -> tab.setIcon(icon).setContentDescription(homeTab.nameRes)
             // On large screens, display an icon and text.
-            width < 600 -> tab.setText(homeTab.nameRes).setIcon(icon)
+            width < 600 -> tab.setText(homeTab.nameRes)
             // On medium-size screens, display text.
             else -> tab.setIcon(icon).setText(homeTab.nameRes)
         }

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

@@ -46,12 +46,19 @@ interface ListSettings : Settings<ListSettings.Listener> {
 
     interface Listener {
         fun onSongSortChanged() {}
+
         fun onAlbumSortChanged() {}
+
         fun onAlbumSongSortChanged() {}
+
         fun onArtistSortChanged() {}
+
         fun onArtistSongSortChanged() {}
+
         fun onGenreSortChanged() {}
+
         fun onGenreSongSortChanged() {}
+
         fun onPlaylistSortChanged() {}
     }
 }

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

@@ -18,6 +18,8 @@
  
 package org.oxycblt.auxio.music.info
 
+import android.content.Context
+import org.oxycblt.auxio.R
 import org.oxycblt.auxio.list.Item
 
 /**
@@ -34,3 +36,7 @@ class Disc(val number: Int, val name: String?) : Item, Comparable<Disc> {
 
     override fun compareTo(other: Disc) = number.compareTo(other.number)
 }
+
+fun Disc?.resolveNumber(context: Context) =
+    this?.run { context.getString(R.string.fmt_disc_no, number) }
+        ?: context.getString(R.string.def_disc)

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

@@ -80,7 +80,7 @@ private constructor(
             .newWakeLock(
                 PowerManager.PARTIAL_WAKE_LOCK, BuildConfig.APPLICATION_ID + ":IndexingComponent")
 
-    init {
+    fun attach() {
         musicSettings.registerListener(this)
         musicRepository.addUpdateListener(this)
         musicRepository.addIndexingListener(this)

app/src/main/java/org/oxycblt/auxio/music/service/MediaItemTranslation.kt

@@ -18,17 +18,12 @@
  
 package org.oxycblt.auxio.music.service
 
-import android.annotation.SuppressLint
 import android.content.Context
 import android.graphics.BitmapFactory
 import android.os.Bundle
 import android.support.v4.media.MediaBrowserCompat.MediaItem
 import android.support.v4.media.MediaDescriptionCompat
-import android.view.MenuInflater
-import androidx.annotation.MenuRes
 import androidx.annotation.StringRes
-import androidx.appcompat.view.menu.MenuBuilder
-import androidx.core.view.children
 import androidx.media.utils.MediaConstants
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
@@ -83,46 +78,6 @@ sealed interface MediaSessionUID {
     }
 }
 
-enum class BrowserOption(val actionId: String, val labelRes: Int, val iconRes: Int) {
-    PLAY(BuildConfig.APPLICATION_ID + ".menu.PLAY", R.string.lbl_play, R.drawable.ic_play_24),
-    SHUFFLE(
-        BuildConfig.APPLICATION_ID + ".menu.SHUFFLE",
-        R.string.lbl_shuffle,
-        R.drawable.ic_shuffle_off_24),
-    PLAY_NEXT(
-        BuildConfig.APPLICATION_ID + ".menu.PLAY_NEXT",
-        R.string.lbl_play_next,
-        R.drawable.ic_play_next_24),
-    ADD_TO_QUEUE(
-        BuildConfig.APPLICATION_ID + ".menu.ADD_TO_QUEUE",
-        R.string.lbl_queue_add,
-        R.drawable.ic_queue_add_24),
-    DETAILS(
-        BuildConfig.APPLICATION_ID + ".menu.DETAILS",
-        R.string.lbl_parent_detail,
-        R.drawable.ic_details_24),
-    ALBUM_DETAILS(
-        BuildConfig.APPLICATION_ID + ".menu.ALBUM_DETAILS",
-        R.string.lbl_album_details,
-        R.drawable.ic_album_24),
-    ARTIST_DETAILS(
-        BuildConfig.APPLICATION_ID + ".menu.ARTIST_DETAILS",
-        R.string.lbl_artist_details,
-        R.drawable.ic_artist_24);
-
-    companion object {
-        val ITEM_ID_MAP =
-            mapOf(
-                R.id.action_play to PLAY,
-                R.id.action_shuffle to SHUFFLE,
-                R.id.action_play_next to PLAY_NEXT,
-                R.id.action_queue_add to ADD_TO_QUEUE,
-                R.id.action_detail to DETAILS,
-                R.id.action_album_details to ALBUM_DETAILS,
-                R.id.action_artist_details to ARTIST_DETAILS)
-    }
-}
-
 typealias Sugar = Bundle.(Context) -> Unit
 
 fun header(@StringRes nameRes: Int): Sugar = {
@@ -138,16 +93,6 @@ private fun style(style: Int): Sugar = {
     putInt(MediaConstants.DESCRIPTION_EXTRAS_KEY_CONTENT_STYLE_SINGLE_ITEM, style)
 }
 
-private fun menu(@MenuRes res: Int): Sugar = { context ->
-    @SuppressLint("RestrictedApi") val builder = MenuBuilder(context)
-    MenuInflater(context).inflate(res, builder)
-    val menuIds =
-        builder.children.mapNotNullTo(ArrayList()) {
-            BrowserOption.ITEM_ID_MAP[it.itemId]?.actionId
-        }
-    putStringArrayList(MediaConstants.DESCRIPTION_EXTRAS_KEY_CUSTOM_BROWSER_ACTION_ID_LIST, menuIds)
-}
-
 private fun makeExtras(context: Context, vararg sugars: Sugar): Bundle {
     return Bundle().apply { sugars.forEach { this.it(context) } }
 }
@@ -181,7 +126,7 @@ fun Song.toMediaDescription(
         } else {
             MediaSessionUID.ChildItem(parent.uid, uid)
         }
-    val extras = makeExtras(context, *sugar, menu(R.menu.song))
+    val extras = makeExtras(context, *sugar)
     return MediaDescriptionCompat.Builder()
         .setMediaId(mediaSessionUID.toString())
         .setTitle(name.resolve(context))
@@ -212,7 +157,7 @@ fun Album.toMediaItem(
         } else {
             MediaSessionUID.ChildItem(parent.uid, uid)
         }
-    val extras = makeExtras(context, *sugar, menu(R.menu.album))
+    val extras = makeExtras(context, *sugar)
     val counts = context.getPlural(R.plurals.fmt_song_count, songs.size)
     val description =
         MediaDescriptionCompat.Builder()
@@ -241,7 +186,7 @@ fun Artist.toMediaItem(context: Context, vararg sugar: Sugar): MediaItem {
             } else {
                 context.getString(R.string.def_song_count)
             })
-    val extras = makeExtras(context, *sugar, menu(R.menu.parent))
+    val extras = makeExtras(context, *sugar)
     val description =
         MediaDescriptionCompat.Builder()
             .setMediaId(mediaSessionUID.toString())
@@ -262,7 +207,7 @@ fun Genre.toMediaItem(context: Context, vararg sugar: Sugar): MediaItem {
         } else {
             context.getString(R.string.def_song_count)
         }
-    val extras = makeExtras(context, *sugar, menu(R.menu.parent))
+    val extras = makeExtras(context, *sugar)
     val description =
         MediaDescriptionCompat.Builder()
             .setMediaId(mediaSessionUID.toString())
@@ -282,7 +227,7 @@ fun Playlist.toMediaItem(context: Context, vararg sugar: Sugar): MediaItem {
         } else {
             context.getString(R.string.def_song_count)
         }
-    val extras = makeExtras(context, *sugar, menu(R.menu.playlist))
+    val extras = makeExtras(context, *sugar)
     val description =
         MediaDescriptionCompat.Builder()
             .setMediaId(mediaSessionUID.toString())

app/src/main/java/org/oxycblt/auxio/music/service/MusicBrowser.kt

@@ -24,13 +24,8 @@ import javax.inject.Inject
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.detail.DetailGenerator
 import org.oxycblt.auxio.detail.DetailSection
-import org.oxycblt.auxio.detail.list.SortHeader
 import org.oxycblt.auxio.home.HomeGenerator
-import org.oxycblt.auxio.list.BasicHeader
-import org.oxycblt.auxio.list.Divider
-import org.oxycblt.auxio.list.ListSettings
 import org.oxycblt.auxio.list.adapter.UpdateInstructions
-import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Genre
@@ -39,6 +34,7 @@ import org.oxycblt.auxio.music.MusicRepository
 import org.oxycblt.auxio.music.MusicType
 import org.oxycblt.auxio.music.Playlist
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.music.info.resolveNumber
 import org.oxycblt.auxio.search.SearchEngine
 
 class MusicBrowser
@@ -76,6 +72,11 @@ private constructor(
     private val homeGenerator = homeGeneratorFactory.create(this)
     private val detailGenerator = detailGeneratorFactory.create(this)
 
+    fun attach() {
+        homeGenerator.attach()
+        detailGenerator.attach()
+    }
+
     fun release() {
         homeGenerator.release()
         detailGenerator.release()
@@ -87,18 +88,16 @@ private constructor(
     }
 
     override fun invalidateTabs() {
-        for (i in 0..10) {
-            // TODO: Temporary bodge, move the amount parameter to a bundle extra
-            val rootId = MediaSessionUID.Tab(TabNode.Root(i)).toString()
-            val moreId = MediaSessionUID.Tab(TabNode.More(i)).toString()
+        val rootId = MediaSessionUID.Tab(TabNode.Root).toString()
+        val moreId = MediaSessionUID.Tab(TabNode.More).toString()
         invalidator.invalidateMusic(setOf(rootId, moreId))
     }
-    }
 
     override fun invalidate(type: MusicType, replace: Int?) {
         val deviceLibrary = musicRepository.deviceLibrary ?: return
         val userLibrary = musicRepository.userLibrary ?: return
-        val music = when (type) {
+        val music =
+            when (type) {
                 MusicType.ALBUMS -> deviceLibrary.albums
                 MusicType.ARTISTS -> deviceLibrary.artists
                 MusicType.GENRES -> deviceLibrary.genres
@@ -133,14 +132,13 @@ private constructor(
         }
     }
 
-    fun getChildren(parentId: String): List<MediaItem>? {
+    fun getChildren(parentId: String, maxTabs: Int): List<MediaItem>? {
         val deviceLibrary = musicRepository.deviceLibrary
         val userLibrary = musicRepository.userLibrary
         if (deviceLibrary == null || userLibrary == null) {
             return listOf()
         }
-
-        return getMediaItemList(parentId)
+        return getMediaItemList(parentId, maxTabs)
     }
 
     suspend fun search(query: String): MutableList<MediaItem> {
@@ -179,10 +177,10 @@ private constructor(
         return music
     }
 
-    private fun getMediaItemList(id: String): List<MediaItem>? {
+    private fun getMediaItemList(id: String, maxTabs: Int): List<MediaItem>? {
         return when (val mediaSessionUID = MediaSessionUID.fromString(id)) {
             is MediaSessionUID.Tab -> {
-                getCategoryMediaItems(mediaSessionUID.node)
+                getCategoryMediaItems(mediaSessionUID.node, maxTabs)
             }
             is MediaSessionUID.SingleItem -> {
                 getChildMediaItems(mediaSessionUID.uid)
@@ -196,21 +194,21 @@ private constructor(
         }
     }
 
-    private fun getCategoryMediaItems(node: TabNode) =
+    private fun getCategoryMediaItems(node: TabNode, maxTabs: Int) =
         when (node) {
             is TabNode.Root -> {
                 val tabs = homeGenerator.tabs()
-                val base = tabs.take(node.amount - 1).map { TabNode.Home(it) }
+                val base = tabs.take(maxTabs - 1).map { TabNode.Home(it) }
                 if (base.size < tabs.size) {
-                        base + TabNode.More(tabs.size - base.size)
+                        base + TabNode.More
                     } else {
                         base
                     }
                     .map { it.toMediaItem(context) }
             }
-            is TabNode.More ->
-                homeGenerator.tabs().takeLast(node.remainder).map {
-                    TabNode.Home(it).toMediaItem(context)
+            is TabNode.More -> {
+                val tabs = homeGenerator.tabs()
+                tabs.takeLast(tabs.size - maxTabs).map { TabNode.Home(it).toMediaItem(context) }
             }
             is TabNode.Home ->
                 when (node.type) {
@@ -226,19 +224,16 @@ private constructor(
         val detail = detailGenerator.any(uid) ?: return null
         return detail.sections.flatMap { section ->
             when (section) {
-                is DetailSection.Songs -> section.items.map { it.toMediaItem(context, null, header(section.stringRes)) }
-                is DetailSection.Albums -> section.items.map { it.toMediaItem(context, null, header(section.stringRes)) }
-                is DetailSection.Artists -> section.items.map { it.toMediaItem(context, header(section.stringRes)) }
-                is DetailSection.Discs -> section.discs.flatMap {
-                    section.discs.flatMap { entry ->
-                        val disc = entry.key
-                        val discString = if (disc != null) {
-                            context.getString(R.string.fmt_disc_no, disc.number)
-                        } else {
-                            context.getString(R.string.def_disc)
-                        }
-                        entry.value.map { it.toMediaItem(context, null, header(discString)) }
-                    }
+                is DetailSection.Songs ->
+                    section.items.map { it.toMediaItem(context, null, header(section.stringRes)) }
+                is DetailSection.Albums ->
+                    section.items.map { it.toMediaItem(context, null, header(section.stringRes)) }
+                is DetailSection.Artists ->
+                    section.items.map { it.toMediaItem(context, header(section.stringRes)) }
+                is DetailSection.Discs ->
+                    section.discs.flatMap { (disc, songs) ->
+                        val discString = disc.resolveNumber(context)
+                        songs.map { it.toMediaItem(context, null, header(discString)) }
                     }
                 else -> error("Unknown section type: $section")
             }

app/src/main/java/org/oxycblt/auxio/music/service/MusicServiceFragment.kt

@@ -23,7 +23,6 @@ import android.os.Bundle
 import android.support.v4.media.MediaBrowserCompat.MediaItem
 import androidx.media.MediaBrowserServiceCompat.BrowserRoot
 import androidx.media.MediaBrowserServiceCompat.Result
-import androidx.media.utils.MediaConstants
 import javax.inject.Inject
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -75,6 +74,11 @@ constructor(
         fun invalidateMusic(mediaId: String)
     }
 
+    fun attach() {
+        indexer.attach()
+        musicBrowser.attach()
+    }
+
     fun release() {
         dispatchJob.cancel()
         musicBrowser.release()
@@ -95,30 +99,17 @@ constructor(
         indexer.createNotification(post)
     }
 
-    fun getRoot(maxItems: Int) =
-        BrowserRoot(
-            MediaSessionUID.Tab(TabNode.Root(maxItems)).toString(),
-            Bundle().apply {
-                val actions =
-                    BrowserOption.entries.mapTo(ArrayList()) {
-                        Bundle().apply {
-                            putString(
-                                MediaConstants.EXTRAS_KEY_CUSTOM_BROWSER_ACTION_ID, it.actionId)
-                            putString(
-                                MediaConstants.EXTRAS_KEY_CUSTOM_BROWSER_ACTION_LABEL,
-                                context.getString(it.labelRes))
-                        }
-                    }
-                putParcelableArrayList(
-                    MediaConstants.BROWSER_SERVICE_EXTRAS_KEY_CUSTOM_BROWSER_ACTION_ROOT_LIST,
-                    actions)
-            })
+    fun getRoot() = BrowserRoot(MediaSessionUID.Tab(TabNode.Root).toString(), Bundle())
 
     fun getItem(mediaId: String, result: Result<MediaItem>) =
-        result.dispatch { musicBrowser.getItem(mediaId) }
+        result.dispatch {
+            musicBrowser.getItem(
+                mediaId,
+            )
+        }
 
-    fun getChildren(mediaId: String, result: Result<MutableList<MediaItem>>) =
-        result.dispatch { musicBrowser.getChildren(mediaId)?.toMutableList() }
+    fun getChildren(mediaId: String, maxTabs: Int, result: Result<MutableList<MediaItem>>) =
+        result.dispatch { musicBrowser.getChildren(mediaId, maxTabs)?.toMutableList() }
 
     fun search(query: String, result: Result<MutableList<MediaItem>>) =
         result.dispatchAsync { musicBrowser.search(query) }

app/src/main/java/org/oxycblt/auxio/music/service/TabNode.kt

@@ -23,37 +23,27 @@ import org.oxycblt.auxio.music.MusicType
 
 sealed class TabNode {
     abstract val id: String
-    abstract val data: Int
     abstract val nameRes: Int
     abstract val bitmapRes: Int?
 
-    override fun toString() = "${id}/${data}"
+    override fun toString() = id
 
-    data class Root(val amount: Int) : TabNode() {
-        override val id = ID
-        override val data = amount
+    data object Root : TabNode() {
+        override val id = "root"
         override val nameRes = R.string.info_app_name
         override val bitmapRes = null
 
-        companion object {
-            const val ID = "root"
-        }
+        override fun toString() = id
     }
 
-    data class More(val remainder: Int) : TabNode() {
-        override val id = ID
-        override val data = remainder
+    data object More : TabNode() {
+        override val id = "more"
         override val nameRes = R.string.lbl_more
-        override val bitmapRes = null
-
-        companion object {
-            const val ID = "more"
-        }
+        override val bitmapRes = R.drawable.ic_more_bitmap_24
     }
 
     data class Home(val type: MusicType) : TabNode() {
-        override val id = ID
-        override val data = type.intCode
+        override val id = "$ID/${type.intCode}"
         override val bitmapRes: Int
             get() =
                 when (type) {
@@ -73,15 +63,15 @@ sealed class TabNode {
 
     companion object {
         fun fromString(str: String): TabNode? {
-            val split = str.split("/", limit = 2)
-            if (split.size != 2) {
-                return null
+            return when {
+                str == Root.id -> Root
+                str == More.id -> More
+                str.startsWith(Home.ID) -> {
+                    val split = str.split("/")
+                    if (split.size != 2) return null
+                    val intCode = split[1].toIntOrNull() ?: return null
+                    Home(MusicType.fromIntCode(intCode) ?: return null)
                 }
-            val data = split[1].toIntOrNull() ?: return null
-            return when (split[0]) {
-                Root.ID -> Root(data)
-                More.ID -> More(data)
-                Home.ID -> Home(MusicType.fromIntCode(data) ?: return null)
                 else -> null
             }
         }

app/src/main/java/org/oxycblt/auxio/playback/player/BetterShuffleOrder.kt

@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.playback.service
+package org.oxycblt.auxio.playback.player
 
 import androidx.media3.common.C
 import androidx.media3.exoplayer.source.ShuffleOrder

app/src/main/java/org/oxycblt/auxio/playback/player/GaplessQueuer.kt

@@ -0,0 +1,227 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * GaplessQueuer.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.playback.player
+
+import androidx.media3.common.C
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player
+import androidx.media3.common.Player.RepeatMode
+import androidx.media3.exoplayer.ExoPlayer
+import javax.inject.Inject
+import org.oxycblt.auxio.playback.PlaybackSettings
+
+/**  */
+class GaplessQueuer
+private constructor(
+    private val exoPlayer: ExoPlayer,
+    private val listener: Queuer.Listener,
+    private val playbackSettings: PlaybackSettings
+) : Queuer, PlaybackSettings.Listener, Player.Listener {
+    class Factory @Inject constructor(private val playbackSettings: PlaybackSettings) :
+        Queuer.Factory {
+        override fun create(exoPlayer: ExoPlayer, listener: Queuer.Listener) =
+            GaplessQueuer(exoPlayer, listener, playbackSettings)
+    }
+
+    override val currentMediaItem: MediaItem? = exoPlayer.currentMediaItem
+    override val currentMediaItemIndex: Int = exoPlayer.currentMediaItemIndex
+    override val shuffleModeEnabled: Boolean = exoPlayer.shuffleModeEnabled
+    @get:RepeatMode
+    override var repeatMode: Int = exoPlayer.repeatMode
+        set(value) {
+            field = value
+            exoPlayer.repeatMode = value
+            updatePauseOnRepeat()
+        }
+
+    override fun attach() {
+        playbackSettings.registerListener(this)
+        exoPlayer.addListener(this)
+    }
+
+    override fun release() {
+        playbackSettings.unregisterListener(this)
+        exoPlayer.removeListener(this)
+    }
+
+    override fun computeHeap(): List<MediaItem> {
+        return (0 until exoPlayer.mediaItemCount).map { exoPlayer.getMediaItemAt(it) }
+    }
+
+    override fun computeMapping(): List<Int> {
+        val timeline = exoPlayer.currentTimeline
+        if (timeline.isEmpty) {
+            return emptyList()
+        }
+        val queue = mutableListOf<Int>()
+
+        // Add the active queue item.
+        val currentMediaItemIndex = currentMediaItemIndex
+        queue.add(currentMediaItemIndex)
+
+        // Fill queue alternating with next and/or previous queue items.
+        var firstMediaItemIndex = currentMediaItemIndex
+        var lastMediaItemIndex = currentMediaItemIndex
+        val shuffleModeEnabled = exoPlayer.shuffleModeEnabled
+        while ((firstMediaItemIndex != C.INDEX_UNSET || lastMediaItemIndex != C.INDEX_UNSET)) {
+            // Begin with next to have a longer tail than head if an even sized queue needs to be
+            // trimmed.
+            if (lastMediaItemIndex != C.INDEX_UNSET) {
+                lastMediaItemIndex =
+                    timeline.getNextWindowIndex(
+                        lastMediaItemIndex, Player.REPEAT_MODE_OFF, shuffleModeEnabled)
+                if (lastMediaItemIndex != C.INDEX_UNSET) {
+                    queue.add(lastMediaItemIndex)
+                }
+            }
+            if (firstMediaItemIndex != C.INDEX_UNSET) {
+                firstMediaItemIndex =
+                    timeline.getPreviousWindowIndex(
+                        firstMediaItemIndex, Player.REPEAT_MODE_OFF, shuffleModeEnabled)
+                if (firstMediaItemIndex != C.INDEX_UNSET) {
+                    queue.add(0, firstMediaItemIndex)
+                }
+            }
+        }
+
+        return queue
+    }
+
+    override fun computeFirstMediaItemIndex() =
+        exoPlayer.currentTimeline.getFirstWindowIndex(exoPlayer.shuffleModeEnabled)
+
+    override fun goto(mediaItemIndex: Int) = exoPlayer.seekTo(mediaItemIndex, C.TIME_UNSET)
+
+    override fun seekToNext() = exoPlayer.seekToNext()
+
+    override fun hasNextMediaItem() = exoPlayer.hasNextMediaItem()
+
+    override fun seekToPrevious() = exoPlayer.seekToPrevious()
+
+    override fun seekToPreviousMediaItem() = exoPlayer.seekToPreviousMediaItem()
+
+    override fun hasPreviousMediaItem() = exoPlayer.hasPreviousMediaItem()
+
+    override fun prepareNew(mediaItems: List<MediaItem>, startIndex: Int?, shuffled: Boolean) {
+        exoPlayer.shuffleModeEnabled = shuffled
+        exoPlayer.setMediaItems(mediaItems)
+        if (shuffled) {
+            exoPlayer.setShuffleOrder(BetterShuffleOrder(mediaItems.size, startIndex ?: -1))
+        }
+        val target = startIndex ?: exoPlayer.currentTimeline.getFirstWindowIndex(shuffled)
+        exoPlayer.seekTo(target, C.TIME_UNSET)
+        exoPlayer.prepare()
+    }
+
+    override fun prepareSaved(
+        mediaItems: List<MediaItem>,
+        mapping: List<Int>,
+        index: Int,
+        shuffled: Boolean
+    ) {
+        exoPlayer.setMediaItems(mediaItems)
+        if (shuffled) {
+            exoPlayer.shuffleModeEnabled = true
+            exoPlayer.setShuffleOrder(BetterShuffleOrder(mapping.toIntArray()))
+        } else {
+            exoPlayer.shuffleModeEnabled = false
+        }
+        exoPlayer.seekTo(index, C.TIME_UNSET)
+        exoPlayer.prepare()
+    }
+
+    override fun discard() {
+        exoPlayer.setMediaItems(emptyList())
+    }
+
+    override fun addTopMediaItems(mediaItems: List<MediaItem>) {
+        val currTimeline = exoPlayer.currentTimeline
+        val nextIndex =
+            if (currTimeline.isEmpty) {
+                C.INDEX_UNSET
+            } else {
+                currTimeline.getNextWindowIndex(
+                    exoPlayer.currentMediaItemIndex,
+                    Player.REPEAT_MODE_OFF,
+                    exoPlayer.shuffleModeEnabled)
+            }
+
+        if (nextIndex == C.INDEX_UNSET) {
+            exoPlayer.addMediaItems(mediaItems)
+        } else {
+            exoPlayer.addMediaItems(nextIndex, mediaItems)
+        }
+    }
+
+    override fun addBottomMediaItems(mediaItems: List<MediaItem>) {
+        exoPlayer.addMediaItems(mediaItems)
+    }
+
+    override fun moveMediaItem(fromIndex: Int, toIndex: Int) {
+        // ExoPlayer does not actually update it's ShuffleOrder when moving items. Retain a
+        // semblance of "normalcy" by doing a weird no-op swap that actually moves the item.
+        when {
+            fromIndex > toIndex -> {
+                exoPlayer.moveMediaItem(fromIndex, toIndex)
+                exoPlayer.moveMediaItem(toIndex + 1, fromIndex)
+            }
+            toIndex > fromIndex -> {
+                exoPlayer.moveMediaItem(fromIndex, toIndex)
+                exoPlayer.moveMediaItem(toIndex - 1, fromIndex)
+            }
+        }
+    }
+
+    override fun removeMediaItem(index: Int) = exoPlayer.removeMediaItem(index)
+
+    override fun shuffled(shuffled: Boolean) {
+        exoPlayer.setShuffleModeEnabled(shuffled)
+        if (exoPlayer.shuffleModeEnabled) {
+            // Have to manually refresh the shuffle seed and anchor it to the new current songs
+            exoPlayer.setShuffleOrder(
+                BetterShuffleOrder(exoPlayer.mediaItemCount, exoPlayer.currentMediaItemIndex))
+        }
+    }
+
+    override fun onPauseOnRepeatChanged() {
+        super.onPauseOnRepeatChanged()
+        updatePauseOnRepeat()
+    }
+
+    private fun updatePauseOnRepeat() {
+        exoPlayer.pauseAtEndOfMediaItems =
+            exoPlayer.repeatMode == Player.REPEAT_MODE_ONE && playbackSettings.pauseOnRepeat
+    }
+
+    override fun onPlaybackStateChanged(playbackState: Int) {
+        super.onPlaybackStateChanged(playbackState)
+
+        if (playbackState == Player.STATE_ENDED && exoPlayer.repeatMode == Player.REPEAT_MODE_OFF) {
+            goto(0)
+            exoPlayer.pause()
+        }
+    }
+
+    override fun onMediaItemTransition(mediaItem: MediaItem?, reason: Int) {
+        super.onMediaItemTransition(mediaItem, reason)
+        if (reason == Player.MEDIA_ITEM_TRANSITION_REASON_AUTO) {
+            listener.onAutoTransition()
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/playback/player/PlayerKernel.kt

@@ -0,0 +1,190 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * PlayerKernel.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.playback.player
+
+import android.content.Context
+import androidx.media3.common.AudioAttributes
+import androidx.media3.common.C
+import androidx.media3.common.PlaybackException
+import androidx.media3.common.Player
+import androidx.media3.decoder.ffmpeg.FfmpegAudioRenderer
+import androidx.media3.exoplayer.ExoPlayer
+import androidx.media3.exoplayer.RenderersFactory
+import androidx.media3.exoplayer.audio.AudioCapabilities
+import androidx.media3.exoplayer.audio.MediaCodecAudioRenderer
+import androidx.media3.exoplayer.mediacodec.MediaCodecSelector
+import androidx.media3.exoplayer.source.MediaSource
+import javax.inject.Inject
+import org.oxycblt.auxio.playback.replaygain.ReplayGainAudioProcessor
+
+interface PlayerKernel {
+    val isPlaying: Boolean
+    var playWhenReady: Boolean
+    val currentPosition: Long
+    val audioSessionId: Int
+    val queuer: Queuer
+
+    fun attach()
+
+    fun release()
+
+    fun play()
+
+    fun pause()
+
+    fun seekTo(positionMs: Long)
+
+    fun replaceQueuer(queuerFactory: Queuer.Factory)
+
+    interface Listener {
+        fun onPlayWhenReadyChanged()
+
+        fun onIsPlayingChanged()
+
+        fun onPositionDiscontinuity()
+
+        fun onError(error: PlaybackException)
+    }
+
+    interface Factory {
+        fun create(
+            context: Context,
+            playerListener: Listener,
+            queuerFactory: Queuer.Factory,
+            queuerListener: Queuer.Listener
+        ): PlayerKernel
+    }
+}
+
+class PlayerKernelFactoryImpl
+@Inject
+constructor(
+    private val mediaSourceFactory: MediaSource.Factory,
+    private val replayGainProcessor: ReplayGainAudioProcessor
+) : PlayerKernel.Factory {
+    override fun create(
+        context: Context,
+        playerListener: PlayerKernel.Listener,
+        queuerFactory: Queuer.Factory,
+        queuerListener: Queuer.Listener
+    ): PlayerKernel {
+        // Since Auxio is a music player, only specify an audio renderer to save
+        // battery/apk size/cache size
+        val audioRenderer = RenderersFactory { handler, _, audioListener, _, _ ->
+            arrayOf(
+                FfmpegAudioRenderer(handler, audioListener, replayGainProcessor),
+                MediaCodecAudioRenderer(
+                    context,
+                    MediaCodecSelector.DEFAULT,
+                    handler,
+                    audioListener,
+                    AudioCapabilities.DEFAULT_AUDIO_CAPABILITIES,
+                    replayGainProcessor))
+        }
+
+        val exoPlayer =
+            ExoPlayer.Builder(context, audioRenderer)
+                .setMediaSourceFactory(mediaSourceFactory)
+                // Enable automatic WakeLock support
+                .setWakeMode(C.WAKE_MODE_LOCAL)
+                .setAudioAttributes(
+                    // Signal that we are a music player.
+                    AudioAttributes.Builder()
+                        .setUsage(C.USAGE_MEDIA)
+                        .setContentType(C.AUDIO_CONTENT_TYPE_MUSIC)
+                        .build(),
+                    true)
+                .build()
+
+        return PlayerKernelImpl(
+            exoPlayer, replayGainProcessor, playerListener, queuerListener, queuerFactory)
+    }
+}
+
+private class PlayerKernelImpl(
+    private val exoPlayer: ExoPlayer,
+    private val replayGainProcessor: ReplayGainAudioProcessor,
+    private val playerListener: PlayerKernel.Listener,
+    private val queuerListener: Queuer.Listener,
+    queuerFactory: Queuer.Factory
+) : PlayerKernel, Player.Listener {
+    override var queuer: Queuer = queuerFactory.create(exoPlayer, queuerListener)
+    override val isPlaying: Boolean
+        get() = exoPlayer.isPlaying
+
+    override var playWhenReady: Boolean
+        get() = exoPlayer.playWhenReady
+        set(value) {
+            exoPlayer.playWhenReady = value
+        }
+
+    override val currentPosition: Long
+        get() = exoPlayer.currentPosition
+
+    override val audioSessionId: Int
+        get() = exoPlayer.audioSessionId
+
+    override fun attach() {
+        exoPlayer.addListener(this)
+        replayGainProcessor.attach()
+        queuer.attach()
+    }
+
+    override fun release() {
+        queuer.release()
+        replayGainProcessor.release()
+        exoPlayer.release()
+    }
+
+    override fun play() = exoPlayer.play()
+
+    override fun pause() = exoPlayer.pause()
+
+    override fun seekTo(positionMs: Long) = exoPlayer.seekTo(positionMs)
+
+    override fun replaceQueuer(queuerFactory: Queuer.Factory) {
+        queuer.release()
+        queuer = queuerFactory.create(exoPlayer, queuerListener)
+        queuer.attach()
+    }
+
+    override fun onPlayWhenReadyChanged(playWhenReady: Boolean, reason: Int) {
+        super.onPlayWhenReadyChanged(playWhenReady, reason)
+        playerListener.onPlayWhenReadyChanged()
+    }
+
+    override fun onIsPlayingChanged(isPlaying: Boolean) {
+        super.onIsPlayingChanged(isPlaying)
+        playerListener.onIsPlayingChanged()
+    }
+
+    override fun onPositionDiscontinuity(
+        oldPosition: Player.PositionInfo,
+        newPosition: Player.PositionInfo,
+        reason: Int
+    ) {
+        super.onPositionDiscontinuity(oldPosition, newPosition, reason)
+        playerListener.onPositionDiscontinuity()
+    }
+
+    override fun onPlayerError(error: PlaybackException) {
+        super.onPlayerError(error)
+        playerListener.onError(error)
+    }
+}

app/src/main/java/org/oxycblt/auxio/playback/player/PlayerModule.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2023 Auxio Project
- * SystemModule.kt is part of Auxio.
+ * PlayerModule.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.playback.service
+package org.oxycblt.auxio.playback.player
 
 import android.content.Context
 import androidx.media3.datasource.ContentDataSource
@@ -32,6 +32,7 @@ import androidx.media3.extractor.mp4.Mp4Extractor
 import androidx.media3.extractor.ogg.OggExtractor
 import androidx.media3.extractor.ts.AdtsExtractor
 import androidx.media3.extractor.wav.WavExtractor
+import dagger.Binds
 import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
@@ -40,7 +41,13 @@ import dagger.hilt.components.SingletonComponent
 
 @Module
 @InstallIn(SingletonComponent::class)
-class SystemModule {
+interface PlayerModule {
+    @Binds fun playerKernelFactory(factory: PlayerKernelFactoryImpl): PlayerKernel.Factory
+}
+
+@Module
+@InstallIn(SingletonComponent::class)
+class ExoPlayerModule {
     @Provides
     fun mediaSourceFactory(
         dataSourceFactory: DataSource.Factory,

app/src/main/java/org/oxycblt/auxio/playback/player/PlayerStateHolder.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2024 Auxio Project
- * ExoPlaybackStateHolder.kt is part of Auxio.
+ * PlayerStateHolder.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,24 +16,14 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.playback.service
+package org.oxycblt.auxio.playback.player
 
 import android.content.Context
 import android.content.Intent
 import android.media.audiofx.AudioEffect
-import androidx.media3.common.AudioAttributes
-import androidx.media3.common.C
 import androidx.media3.common.MediaItem
 import androidx.media3.common.PlaybackException
 import androidx.media3.common.Player
-import androidx.media3.decoder.ffmpeg.FfmpegAudioRenderer
-import androidx.media3.exoplayer.ExoPlayer
-import androidx.media3.exoplayer.RenderersFactory
-import androidx.media3.exoplayer.audio.AudioCapabilities
-import androidx.media3.exoplayer.audio.MediaCodecAudioRenderer
-import androidx.media3.exoplayer.mediacodec.MediaCodecSelector
-import androidx.media3.exoplayer.source.MediaSource
-import dagger.hilt.android.qualifiers.ApplicationContext
 import javax.inject.Inject
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -61,9 +51,10 @@ import org.oxycblt.auxio.playback.state.StateAck
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logE
 
-class ExoPlaybackStateHolder(
+class PlayerStateHolder(
     private val context: Context,
-    private val player: ExoPlayer,
+    playerKernelFactory: PlayerKernel.Factory,
+    gaplessQueuerFactory: GaplessQueuer.Factory,
     private val playbackManager: PlaybackStateManager,
     private val persistenceRepository: PersistenceRepository,
     private val playbackSettings: PlaybackSettings,
@@ -73,30 +64,58 @@ class ExoPlaybackStateHolder(
     private val imageSettings: ImageSettings
 ) :
     PlaybackStateHolder,
-    Player.Listener,
+    PlayerKernel.Listener,
+    Queuer.Listener,
     MusicRepository.UpdateListener,
-    PlaybackSettings.Listener,
     ImageSettings.Listener {
+    class Factory
+    @Inject
+    constructor(
+        private val playbackManager: PlaybackStateManager,
+        private val persistenceRepository: PersistenceRepository,
+        private val playbackSettings: PlaybackSettings,
+        private val playerFactory: PlayerKernel.Factory,
+        private val gaplessQueuerFactory: GaplessQueuer.Factory,
+        private val commandFactory: PlaybackCommand.Factory,
+        private val replayGainProcessor: ReplayGainAudioProcessor,
+        private val musicRepository: MusicRepository,
+        private val imageSettings: ImageSettings,
+    ) {
+        fun create(context: Context): PlayerStateHolder {
+            return PlayerStateHolder(
+                context,
+                playerFactory,
+                gaplessQueuerFactory,
+                playbackManager,
+                persistenceRepository,
+                playbackSettings,
+                commandFactory,
+                replayGainProcessor,
+                musicRepository,
+                imageSettings)
+        }
+    }
+
     private val saveJob = Job()
     private val saveScope = CoroutineScope(Dispatchers.IO + saveJob)
     private val restoreScope = CoroutineScope(Dispatchers.IO + saveJob)
     private var currentSaveJob: Job? = null
     private var openAudioEffectSession = false
+    private val player = playerKernelFactory.create(context, this, gaplessQueuerFactory, this)
 
     var sessionOngoing = false
         private set
 
-    init {
+    fun attach() {
+        player.attach()
         imageSettings.registerListener(this)
-        player.addListener(this)
         playbackManager.registerStateHolder(this)
-        playbackSettings.registerListener(this)
         musicRepository.addUpdateListener(this)
     }
 
     fun release() {
         saveJob.cancel()
-        player.removeListener(this)
+        player.release()
         playbackManager.unregisterStateHolder(this)
         musicRepository.removeUpdateListener(this)
         replayGainProcessor.release()
@@ -109,7 +128,7 @@ class ExoPlaybackStateHolder(
 
     override val progression: Progression
         get() {
-            val mediaItem = player.currentMediaItem ?: return Progression.nil()
+            val mediaItem = player.queuer.currentMediaItem ?: return Progression.nil()
             val duration = mediaItem.mediaMetadata.extras?.getLong("durationMs") ?: Long.MAX_VALUE
             val clampedPosition = player.currentPosition.coerceAtLeast(0).coerceAtMost(duration)
             return Progression.from(player.playWhenReady, player.isPlaying, clampedPosition)
@@ -117,7 +136,7 @@ class ExoPlaybackStateHolder(
 
     override val repeatMode
         get() =
-            when (val repeatMode = player.repeatMode) {
+            when (val repeatMode = player.queuer.repeatMode) {
                 Player.REPEAT_MODE_OFF -> RepeatMode.NONE
                 Player.REPEAT_MODE_ONE -> RepeatMode.TRACK
                 Player.REPEAT_MODE_ALL -> RepeatMode.ALL
@@ -128,18 +147,11 @@ class ExoPlaybackStateHolder(
         get() = player.audioSessionId
 
     override fun resolveQueue(): RawQueue {
-        val deviceLibrary =
-            musicRepository.deviceLibrary
-            // No library, cannot do anything.
-            ?: return RawQueue(emptyList(), emptyList(), 0)
-        val heap = (0 until player.mediaItemCount).map { player.getMediaItemAt(it) }
+        val heap = player.queuer.computeHeap()
         val shuffledMapping =
-            if (player.shuffleModeEnabled) {
-                player.unscrambleQueueIndices()
-            } else {
-                emptyList()
-            }
-        return RawQueue(heap.mapNotNull { it.song }, shuffledMapping, player.currentMediaItemIndex)
+            if (player.queuer.shuffleModeEnabled) player.queuer.computeMapping() else emptyList()
+        return RawQueue(
+            heap.mapNotNull { it.song }, shuffledMapping, player.queuer.currentMediaItemIndex)
     }
 
     override fun handleDeferred(action: DeferredPlayback): Boolean {
@@ -202,43 +214,31 @@ class ExoPlaybackStateHolder(
     }
 
     override fun repeatMode(repeatMode: RepeatMode) {
-        player.repeatMode =
+        player.queuer.repeatMode =
             when (repeatMode) {
                 RepeatMode.NONE -> Player.REPEAT_MODE_OFF
                 RepeatMode.ALL -> Player.REPEAT_MODE_ALL
                 RepeatMode.TRACK -> Player.REPEAT_MODE_ONE
             }
-        updatePauseOnRepeat()
         playbackManager.ack(this, StateAck.RepeatModeChanged)
         deferSave()
     }
 
     override fun newPlayback(command: PlaybackCommand) {
         parent = command.parent
-        player.shuffleModeEnabled = command.shuffled
-        player.setMediaItems(command.queue.map { it.buildMediaItem() })
+        val mediaItems = command.queue.map { it.buildMediaItem() }
         val startIndex =
             command.song
                 ?.let { command.queue.indexOf(it) }
                 .also { check(it != -1) { "Start song not in queue" } }
-        if (command.shuffled) {
-            player.setShuffleOrder(BetterShuffleOrder(command.queue.size, startIndex ?: -1))
-        }
-        val target = startIndex ?: player.currentTimeline.getFirstWindowIndex(command.shuffled)
-        player.seekTo(target, C.TIME_UNSET)
-        player.prepare()
+        player.queuer.prepareNew(mediaItems, startIndex, command.shuffled)
         player.play()
         playbackManager.ack(this, StateAck.NewPlayback)
         deferSave()
     }
 
     override fun shuffled(shuffled: Boolean) {
-        player.setShuffleModeEnabled(shuffled)
-        if (player.shuffleModeEnabled) {
-            // Have to manually refresh the shuffle seed and anchor it to the new current songs
-            player.setShuffleOrder(
-                BetterShuffleOrder(player.mediaItemCount, player.currentMediaItemIndex))
-        }
+        player.queuer.shuffled(shuffled)
         playbackManager.ack(this, StateAck.QueueReordered)
         deferSave()
     }
@@ -247,14 +247,14 @@ class ExoPlaybackStateHolder(
         // Replicate the old pseudo-circular queue behavior when no repeat option is implemented.
         // Basically, you can't skip back and wrap around the queue, but you can skip forward and
         // wrap around the queue, albeit playback will be paused.
-        if (player.repeatMode == Player.REPEAT_MODE_ALL || player.hasNextMediaItem()) {
-            player.seekToNext()
+        if (player.queuer.repeatMode == Player.REPEAT_MODE_ALL ||
+            player.queuer.hasNextMediaItem()) {
+            player.queuer.seekToNext()
             if (!playbackSettings.rememberPause) {
                 player.play()
             }
         } else {
-            player.seekTo(
-                player.currentTimeline.getFirstWindowIndex(player.shuffleModeEnabled), C.TIME_UNSET)
+            player.queuer.goto(player.queuer.computeFirstMediaItemIndex())
             // TODO: Dislike the UX implications of this, I feel should I bite the bullet
             //  and switch to dynamic skip enable/disable?
             if (!playbackSettings.rememberPause) {
@@ -267,9 +267,9 @@ class ExoPlaybackStateHolder(
 
     override fun prev() {
         if (playbackSettings.rewindWithPrev) {
-            player.seekToPrevious()
-        } else if (player.hasPreviousMediaItem()) {
-            player.seekToPreviousMediaItem()
+            player.queuer.seekToPrevious()
+        } else if (player.queuer.hasPreviousMediaItem()) {
+            player.queuer.seekToPreviousMediaItem()
         } else {
             player.seekTo(0)
         }
@@ -281,13 +281,12 @@ class ExoPlaybackStateHolder(
     }
 
     override fun goto(index: Int) {
-        val indices = player.unscrambleQueueIndices()
+        val indices = player.queuer.computeMapping()
         if (indices.isEmpty()) {
             return
         }
-
         val trueIndex = indices[index]
-        player.seekTo(trueIndex, C.TIME_UNSET) // Handles remaining custom logic
+        player.queuer.goto(trueIndex)
         if (!playbackSettings.rememberPause) {
             player.play()
         }
@@ -296,63 +295,40 @@ class ExoPlaybackStateHolder(
     }
 
     override fun playNext(songs: List<Song>, ack: StateAck.PlayNext) {
-        val currTimeline = player.currentTimeline
-        val nextIndex =
-            if (currTimeline.isEmpty) {
-                C.INDEX_UNSET
-            } else {
-                currTimeline.getNextWindowIndex(
-                    player.currentMediaItemIndex, Player.REPEAT_MODE_OFF, player.shuffleModeEnabled)
-            }
-
-        if (nextIndex == C.INDEX_UNSET) {
-            player.addMediaItems(songs.map { it.buildMediaItem() })
-        } else {
-            player.addMediaItems(nextIndex, songs.map { it.buildMediaItem() })
-        }
+        player.queuer.addBottomMediaItems(songs.map { it.buildMediaItem() })
         playbackManager.ack(this, ack)
         deferSave()
     }
 
     override fun addToQueue(songs: List<Song>, ack: StateAck.AddToQueue) {
-        player.addMediaItems(songs.map { it.buildMediaItem() })
+        player.queuer.addTopMediaItems(songs.map { it.buildMediaItem() })
         playbackManager.ack(this, ack)
         deferSave()
     }
 
     override fun move(from: Int, to: Int, ack: StateAck.Move) {
-        val indices = player.unscrambleQueueIndices()
+        val indices = player.queuer.computeMapping()
         if (indices.isEmpty()) {
             return
         }
 
         val trueFrom = indices[from]
         val trueTo = indices[to]
-        // ExoPlayer does not actually update it's ShuffleOrder when moving items. Retain a
-        // semblance of "normalcy" by doing a weird no-op swap that actually moves the item.
-        when {
-            trueFrom > trueTo -> {
-                player.moveMediaItem(trueFrom, trueTo)
-                player.moveMediaItem(trueTo + 1, trueFrom)
-            }
-            trueTo > trueFrom -> {
-                player.moveMediaItem(trueFrom, trueTo)
-                player.moveMediaItem(trueTo - 1, trueFrom)
-            }
-        }
+
+        player.queuer.moveMediaItem(trueFrom, trueTo)
         playbackManager.ack(this, ack)
         deferSave()
     }
 
     override fun remove(at: Int, ack: StateAck.Remove) {
-        val indices = player.unscrambleQueueIndices()
+        val indices = player.queuer.computeMapping()
         if (indices.isEmpty()) {
             return
         }
 
         val trueIndex = indices[at]
-        val songWillChange = player.currentMediaItemIndex == trueIndex
-        player.removeMediaItem(trueIndex)
+        val songWillChange = player.queuer.currentMediaItemIndex == trueIndex
+        player.queuer.removeMediaItem(trueIndex)
         if (songWillChange && !playbackSettings.rememberPause) {
             player.play()
         }
@@ -372,15 +348,11 @@ class ExoPlaybackStateHolder(
             sendEvent = true
         }
         if (rawQueue != resolveQueue()) {
-            player.setMediaItems(rawQueue.heap.map { it.buildMediaItem() })
-            if (rawQueue.isShuffled) {
-                player.shuffleModeEnabled = true
-                player.setShuffleOrder(BetterShuffleOrder(rawQueue.shuffledMapping.toIntArray()))
-            } else {
-                player.shuffleModeEnabled = false
-            }
-            player.seekTo(rawQueue.heapIndex, C.TIME_UNSET)
-            player.prepare()
+            player.queuer.prepareSaved(
+                rawQueue.heap.map { it.buildMediaItem() },
+                rawQueue.shuffledMapping,
+                rawQueue.heapIndex,
+                rawQueue.isShuffled)
             player.pause()
             sendEvent = true
         }
@@ -404,16 +376,14 @@ class ExoPlaybackStateHolder(
     }
 
     override fun reset(ack: StateAck.NewPlayback) {
-        player.setMediaItems(listOf())
+        player.queuer.discard()
         playbackManager.ack(this, ack)
         deferSave()
     }
 
     // --- PLAYER OVERRIDES ---
 
-    override fun onPlayWhenReadyChanged(playWhenReady: Boolean, reason: Int) {
-        super.onPlayWhenReadyChanged(playWhenReady, reason)
-
+    override fun onPlayWhenReadyChanged() {
         if (player.playWhenReady) {
             // Mark that we have started playing so that the notification can now be posted.
             logD("Player has started playing")
@@ -431,40 +401,27 @@ class ExoPlaybackStateHolder(
             broadcastAudioEffectAction(AudioEffect.ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION)
             openAudioEffectSession = false
         }
-    }
 
-    override fun onPlaybackStateChanged(playbackState: Int) {
-        super.onPlaybackStateChanged(playbackState)
-
-        if (playbackState == Player.STATE_ENDED && player.repeatMode == Player.REPEAT_MODE_OFF) {
-            goto(0)
-            player.pause()
-        }
-    }
-
-    override fun onMediaItemTransition(mediaItem: MediaItem?, reason: Int) {
-        super.onMediaItemTransition(mediaItem, reason)
-
-        if (reason == Player.MEDIA_ITEM_TRANSITION_REASON_AUTO) {
-            playbackManager.ack(this, StateAck.IndexMoved)
-        }
-    }
-
-    override fun onEvents(player: Player, events: Player.Events) {
-        super.onEvents(player, events)
-
-        // So many actions trigger progression changes that it becomes easier just to handle it
-        // in an ExoPlayer callback anyway. This doesn't really cause issues anywhere.
-        if (events.containsAny(
-            Player.EVENT_PLAY_WHEN_READY_CHANGED,
-            Player.EVENT_IS_PLAYING_CHANGED,
-            Player.EVENT_POSITION_DISCONTINUITY)) {
-            logD("Player state changed, must synchronize state")
         playbackManager.ack(this, StateAck.ProgressionChanged)
-        }
+        deferSave()
     }
 
-    override fun onPlayerError(error: PlaybackException) {
+    override fun onIsPlayingChanged() {
+        playbackManager.ack(this, StateAck.ProgressionChanged)
+        deferSave()
+    }
+
+    override fun onPositionDiscontinuity() {
+        playbackManager.ack(this, StateAck.ProgressionChanged)
+        deferSave()
+    }
+
+    override fun onAutoTransition() {
+        playbackManager.ack(this, StateAck.IndexMoved)
+        deferSave()
+    }
+
+    override fun onError(error: PlaybackException) {
         // TODO: Replace with no skipping and a notification instead
         // If there's any issue, just go to the next song.
         logE("Player error occurred")
@@ -491,17 +448,7 @@ class ExoPlaybackStateHolder(
         }
     }
 
-    // --- PLAYBACKSETTINGS OVERRIDES ---
-
-    override fun onPauseOnRepeatChanged() {
-        super.onPauseOnRepeatChanged()
-        updatePauseOnRepeat()
-    }
-
-    private fun updatePauseOnRepeat() {
-        player.pauseAtEndOfMediaItems =
-            player.repeatMode == Player.REPEAT_MODE_ONE && playbackSettings.pauseOnRepeat
-    }
+    // --- OVERRIDES ---
 
     private fun save(cb: () -> Unit) {
         saveJob {
@@ -533,101 +480,6 @@ class ExoPlaybackStateHolder(
     private val MediaItem.song: Song?
         get() = this.localConfiguration?.tag as? Song?
 
-    private fun Player.unscrambleQueueIndices(): List<Int> {
-        val timeline = currentTimeline
-        if (timeline.isEmpty) {
-            return emptyList()
-        }
-        val queue = mutableListOf<Int>()
-
-        // Add the active queue item.
-        val currentMediaItemIndex = currentMediaItemIndex
-        queue.add(currentMediaItemIndex)
-
-        // Fill queue alternating with next and/or previous queue items.
-        var firstMediaItemIndex = currentMediaItemIndex
-        var lastMediaItemIndex = currentMediaItemIndex
-        val shuffleModeEnabled = shuffleModeEnabled
-        while ((firstMediaItemIndex != C.INDEX_UNSET || lastMediaItemIndex != C.INDEX_UNSET)) {
-            // Begin with next to have a longer tail than head if an even sized queue needs to be
-            // trimmed.
-            if (lastMediaItemIndex != C.INDEX_UNSET) {
-                lastMediaItemIndex =
-                    timeline.getNextWindowIndex(
-                        lastMediaItemIndex, Player.REPEAT_MODE_OFF, shuffleModeEnabled)
-                if (lastMediaItemIndex != C.INDEX_UNSET) {
-                    queue.add(lastMediaItemIndex)
-                }
-            }
-            if (firstMediaItemIndex != C.INDEX_UNSET) {
-                firstMediaItemIndex =
-                    timeline.getPreviousWindowIndex(
-                        firstMediaItemIndex, Player.REPEAT_MODE_OFF, shuffleModeEnabled)
-                if (firstMediaItemIndex != C.INDEX_UNSET) {
-                    queue.add(0, firstMediaItemIndex)
-                }
-            }
-        }
-
-        return queue
-    }
-
-    class Factory
-    @Inject
-    constructor(
-        @ApplicationContext private val context: Context,
-        private val playbackManager: PlaybackStateManager,
-        private val persistenceRepository: PersistenceRepository,
-        private val playbackSettings: PlaybackSettings,
-        private val commandFactory: PlaybackCommand.Factory,
-        private val mediaSourceFactory: MediaSource.Factory,
-        private val replayGainProcessorFactory: ReplayGainAudioProcessor.Factory,
-        private val musicRepository: MusicRepository,
-        private val imageSettings: ImageSettings,
-    ) {
-        fun create(): ExoPlaybackStateHolder {
-            // Since Auxio is a music player, only specify an audio renderer to save
-            // battery/apk size/cache size
-            val replayGainProcessor = replayGainProcessorFactory.create()
-            val audioRenderer = RenderersFactory { handler, _, audioListener, _, _ ->
-                arrayOf(
-                    FfmpegAudioRenderer(handler, audioListener, replayGainProcessor),
-                    MediaCodecAudioRenderer(
-                        context,
-                        MediaCodecSelector.DEFAULT,
-                        handler,
-                        audioListener,
-                        AudioCapabilities.DEFAULT_AUDIO_CAPABILITIES,
-                        replayGainProcessor))
-            }
-
-            val exoPlayer =
-                ExoPlayer.Builder(context, audioRenderer)
-                    .setMediaSourceFactory(mediaSourceFactory)
-                    // Enable automatic WakeLock support
-                    .setWakeMode(C.WAKE_MODE_LOCAL)
-                    .setAudioAttributes(
-                        // Signal that we are a music player.
-                        AudioAttributes.Builder()
-                            .setUsage(C.USAGE_MEDIA)
-                            .setContentType(C.AUDIO_CONTENT_TYPE_MUSIC)
-                            .build(),
-                        true)
-                    .build()
-
-            return ExoPlaybackStateHolder(
-                context,
-                exoPlayer,
-                playbackManager,
-                persistenceRepository,
-                playbackSettings,
-                commandFactory,
-                replayGainProcessor,
-                musicRepository,
-                imageSettings)
-        }
-    }
-
     private companion object {
         const val SAVE_BUFFER = 5000L
     }

app/src/main/java/org/oxycblt/auxio/playback/player/Queuer.kt

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * Queuer.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.playback.player
+
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player.RepeatMode
+import androidx.media3.exoplayer.ExoPlayer
+
+interface Queuer {
+    val currentMediaItem: MediaItem?
+    val currentMediaItemIndex: Int
+    val shuffleModeEnabled: Boolean
+
+    @get:RepeatMode var repeatMode: Int
+
+    fun attach()
+
+    fun release()
+
+    fun goto(mediaItemIndex: Int)
+
+    fun seekToNext()
+
+    fun hasNextMediaItem(): Boolean
+
+    fun seekToPrevious()
+
+    fun seekToPreviousMediaItem()
+
+    fun hasPreviousMediaItem(): Boolean
+
+    fun moveMediaItem(fromIndex: Int, toIndex: Int)
+
+    fun removeMediaItem(index: Int)
+
+    // EXTENSIONS
+    fun computeHeap(): List<MediaItem>
+
+    fun computeMapping(): List<Int>
+
+    fun computeFirstMediaItemIndex(): Int
+
+    fun prepareNew(mediaItems: List<MediaItem>, startIndex: Int?, shuffled: Boolean)
+
+    fun prepareSaved(mediaItems: List<MediaItem>, mapping: List<Int>, index: Int, shuffled: Boolean)
+
+    fun discard()
+
+    fun addTopMediaItems(mediaItems: List<MediaItem>)
+
+    fun addBottomMediaItems(mediaItems: List<MediaItem>)
+
+    fun shuffled(shuffled: Boolean)
+
+    interface Listener {
+        fun onAutoTransition()
+    }
+
+    interface Factory {
+        fun create(exoPlayer: ExoPlayer, listener: Listener): Queuer
+    }
+}

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

@@ -45,19 +45,11 @@ import org.oxycblt.auxio.util.logD
  * @author Alexander Capehart (OxygenCobalt)
  */
 class ReplayGainAudioProcessor
-private constructor(
+@Inject
+constructor(
     private val playbackManager: PlaybackStateManager,
     private val playbackSettings: PlaybackSettings
 ) : BaseAudioProcessor(), PlaybackStateManager.Listener, PlaybackSettings.Listener {
-    class Factory
-    @Inject
-    constructor(
-        private val playbackManager: PlaybackStateManager,
-        private val playbackSettings: PlaybackSettings
-    ) {
-        fun create() = ReplayGainAudioProcessor(playbackManager, playbackSettings)
-    }
-
     private var volume = 1f
         set(value) {
             field = value
@@ -65,7 +57,7 @@ private constructor(
             flush()
         }
 
-    init {
+    fun attach() {
         playbackManager.addListener(this)
         playbackSettings.registerListener(this)
     }

app/src/main/java/org/oxycblt/auxio/playback/service/MediaSessionHolder.kt

@@ -96,7 +96,7 @@ private constructor(
     val notification: ForegroundServiceNotification
         get() = _notification
 
-    init {
+    fun attach() {
         playbackManager.addListener(this)
         playbackSettings.registerListener(this)
         imageSettings.registerListener(this)

app/src/main/java/org/oxycblt/auxio/playback/service/PlaybackServiceFragment.kt

@@ -25,6 +25,7 @@ import kotlinx.coroutines.Job
 import org.oxycblt.auxio.ForegroundListener
 import org.oxycblt.auxio.ForegroundServiceNotification
 import org.oxycblt.auxio.IntegerTable
+import org.oxycblt.auxio.playback.player.PlayerStateHolder
 import org.oxycblt.auxio.playback.state.DeferredPlayback
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 import org.oxycblt.auxio.util.logD
@@ -35,7 +36,7 @@ private constructor(
     private val context: Context,
     private val foregroundListener: ForegroundListener,
     private val playbackManager: PlaybackStateManager,
-    exoHolderFactory: ExoPlaybackStateHolder.Factory,
+    playerHolderFactory: PlayerStateHolder.Factory,
     sessionHolderFactory: MediaSessionHolder.Factory,
     widgetComponentFactory: WidgetComponent.Factory,
     systemReceiverFactory: SystemPlaybackReceiver.Factory,
@@ -44,7 +45,7 @@ private constructor(
     @Inject
     constructor(
         private val playbackManager: PlaybackStateManager,
-        private val exoHolderFactory: ExoPlaybackStateHolder.Factory,
+        private val exoHolderFactory: PlayerStateHolder.Factory,
         private val sessionHolderFactory: MediaSessionHolder.Factory,
         private val widgetComponentFactory: WidgetComponent.Factory,
         private val systemReceiverFactory: SystemPlaybackReceiver.Factory,
@@ -61,18 +62,20 @@ private constructor(
     }
 
     private val waitJob = Job()
-    private val exoHolder = exoHolderFactory.create()
+    private val exoHolder = playerHolderFactory.create(context)
     private val sessionHolder = sessionHolderFactory.create(context, foregroundListener)
     private val widgetComponent = widgetComponentFactory.create(context)
-    private val systemReceiver = systemReceiverFactory.create(context)
-
-    val token: MediaSessionCompat.Token
-        get() = sessionHolder.token
+    private val systemReceiver = systemReceiverFactory.create(context, widgetComponent)
 
     // --- MEDIASESSION CALLBACKS ---
 
-    init {
+    fun attach(): MediaSessionCompat.Token {
+        exoHolder.attach()
+        sessionHolder.attach()
+        widgetComponent.attach()
+        systemReceiver.attach()
         playbackManager.addListener(this)
+        return sessionHolder.token
     }
 
     fun handleTaskRemoved() {

app/src/main/java/org/oxycblt/auxio/playback/service/SystemPlaybackReceiver.kt

@@ -37,6 +37,7 @@ import org.oxycblt.auxio.widgets.WidgetProvider
  */
 class SystemPlaybackReceiver
 private constructor(
+    private val context: Context,
     private val playbackManager: PlaybackStateManager,
     private val playbackSettings: PlaybackSettings,
     private val widgetComponent: WidgetComponent
@@ -47,16 +48,19 @@ private constructor(
     @Inject
     constructor(
         private val playbackManager: PlaybackStateManager,
-        private val playbackSettings: PlaybackSettings,
-        private val widgetComponent: WidgetComponent
+        private val playbackSettings: PlaybackSettings
     ) {
-        fun create(context: Context): SystemPlaybackReceiver {
-            val receiver =
-                SystemPlaybackReceiver(playbackManager, playbackSettings, widgetComponent)
-            ContextCompat.registerReceiver(
-                context, receiver, INTENT_FILTER, ContextCompat.RECEIVER_EXPORTED)
-            return receiver
+        fun create(context: Context, widgetComponent: WidgetComponent) =
+            SystemPlaybackReceiver(context, playbackManager, playbackSettings, widgetComponent)
     }
+
+    fun attach() {
+        ContextCompat.registerReceiver(
+            context, this, INTENT_FILTER, ContextCompat.RECEIVER_EXPORTED)
+    }
+
+    fun release() {
+        context.unregisterReceiver(this)
     }
 
     override fun onReceive(context: Context, intent: Intent) {

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

@@ -67,7 +67,7 @@ private constructor(
 
     private val widgetProvider = WidgetProvider()
 
-    init {
+    fun attach() {
         playbackManager.addListener(this)
         uiSettings.registerListener(this)
         imageSettings.registerListener(this)