Improve code slightly

Add some documentation and remove useless code/bugs.

app/src/main/java/org/oxycblt/auxio/loading/LoadingViewModel.kt

@@ -5,21 +5,14 @@ import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-import kotlinx.coroutines.CoroutineScope
+import androidx.lifecycle.viewModelScope
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.processing.MusicLoaderResponse
 
 class LoadingViewModel(private val app: Application) : ViewModel() {
-    // Coroutine
-    private val loadingJob = Job()
-    private val ioScope = CoroutineScope(
-        loadingJob + Dispatchers.IO
-    )
-
     // UI control
     private val mResponse = MutableLiveData<MusicLoaderResponse>()
     val response: LiveData<MusicLoaderResponse> get() = mResponse
@@ -42,10 +35,12 @@ class LoadingViewModel(private val app: Application) : ViewModel() {
     }
 
     private fun doLoad() {
-        ioScope.launch {
+        viewModelScope.launch {
             val musicStore = MusicStore.getInstance()
 
-            val response = musicStore.load(app)
+            val response = withContext(Dispatchers.IO) {
+                return@withContext musicStore.load(app)
+            }
 
             withContext(Dispatchers.Main) {
                 mResponse.value = response
@@ -75,13 +70,6 @@ class LoadingViewModel(private val app: Application) : ViewModel() {
         mDoGrant.value = false
     }
 
-    override fun onCleared() {
-        super.onCleared()
-
-        // Cancel the current loading job if the app has been stopped
-        loadingJob.cancel()
-    }
-
     class Factory(private val application: Application) : ViewModelProvider.Factory {
         @Suppress("unchecked_cast")
         override fun <T : ViewModel?> create(modelClass: Class<T>): T {

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

@@ -8,7 +8,9 @@ import org.oxycblt.auxio.music.processing.MusicLoaderResponse
 import org.oxycblt.auxio.music.processing.MusicSorter
 import org.oxycblt.auxio.recycler.ShowMode
 
-// Storage for Music Data. Only use getInstance() to access this object.
+/**
+ * The main storage for music items. Use [MusicStore.from()] to get the instance.
+ */
 class MusicStore private constructor() {
     private var mGenres = listOf<Genre>()
     val genres: List<Genre> get() = mGenres
@@ -70,9 +72,7 @@ class MusicStore private constructor() {
                 this::class.simpleName,
                 "Music load completed successfully in ${elapsed}ms."
             )
-        }
 
-        if (loader.response == MusicLoaderResponse.DONE) {
             loaded = true
         }
 

app/src/main/java/org/oxycblt/auxio/music/coil/CoilUtils.kt

@@ -98,16 +98,6 @@ fun ImageView.bindGenreImage(genre: Genre) {
 
         Log.d(this::class.simpleName, genre.numAlbums.toString())
 
-        // Try to create a 4x4 mosaic if possible, if not, just create a 2x2 mosaic.
-        if (genre.numAlbums >= 16) {
-            while (uris.size < 16) {
-                genre.artists.forEach { artist ->
-                    artist.albums.forEach {
-                        uris.add(it.coverUri)
-                    }
-                }
-            }
-        } else {
         // Get the Nth cover from each artist, if possible.
         for (i in 0..3) {
             val artist = genre.artists[i]
@@ -120,7 +110,6 @@ fun ImageView.bindGenreImage(genre: Genre) {
                 }
             )
         }
-        }
 
         val fetcher = MosaicFetcher(context)
 

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

@@ -15,6 +15,13 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentCompactPlaybackBinding
 import org.oxycblt.auxio.music.MusicStore
 
+/**
+ * A [Fragment] that displays the currently played song at a glance, with some basic controls.
+ * Extends into [PlaybackFragment] when clicked on.
+ *
+ * Instantiation is done by the navigation component, **do not instantiate this fragment manually.**
+ * @author OxygenCobalt
+ */
 class CompactPlaybackFragment : Fragment() {
     private val playbackModel: PlaybackViewModel by activityViewModels()
 

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

@@ -36,7 +36,6 @@ fun NotificationManager.createMediaNotification(
     context: Context,
     mediaSession: MediaSessionCompat
 ): NotificationCompat.Builder {
-
     // Create a notification channel if required
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
         val channel = NotificationChannel(
@@ -97,6 +96,7 @@ fun NotificationCompat.Builder.setMetadata(song: Song, context: Context, onDone:
     }
 }
 
+// I have no idea how to update actions on the fly so I have to use these restricted APIs.
 @SuppressLint("RestrictedApi")
 fun NotificationCompat.Builder.updatePlaying(context: Context) {
     mActions[2] = newAction(NotificationUtils.ACTION_PLAY_PAUSE, context)

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

@@ -19,7 +19,12 @@ import org.oxycblt.auxio.playback.state.LoopMode
 import org.oxycblt.auxio.ui.accent
 import org.oxycblt.auxio.ui.toColor
 
-// TODO: Add a swipe-to-next-track function using a ViewPager
+/**
+ * A [Fragment] that displays more information about the song, along with more media controls.
+ *
+ * Instantiation is done by the navigation component, **do not instantiate this fragment manually.**
+ * @author OxygenCobalt
+ */
 class PlaybackFragment : Fragment(), SeekBar.OnSeekBarChangeListener {
     private val playbackModel: PlaybackViewModel by activityViewModels()
 
@@ -30,6 +35,8 @@ class PlaybackFragment : Fragment(), SeekBar.OnSeekBarChangeListener {
     ): View? {
         val binding = FragmentPlaybackBinding.inflate(inflater)
 
+        // TODO: Add a swipe-to-next-track function using a ViewPager
+
         // Create accents & icons to use
         val accentColor = ColorStateList.valueOf(accent.first.toColor(requireContext()))
         val controlColor = ColorStateList.valueOf(R.color.control_color.toColor(requireContext()))
@@ -173,7 +180,7 @@ class PlaybackFragment : Fragment(), SeekBar.OnSeekBarChangeListener {
         }
 
         playbackModel.userQueue.observe(viewLifecycleOwner) {
-            if (it.isEmpty() && playbackModel.queue.value!!.isEmpty()) {
+            if (it.isEmpty() && playbackModel.nextItemsInQueue.value!!.isEmpty()) {
                 queueMenuItem.isEnabled = false
                 queueMenuItem.icon = iconQueueInactive
             } else {

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

@@ -40,8 +40,18 @@ import org.oxycblt.auxio.playback.state.LoopMode
 import org.oxycblt.auxio.playback.state.PlaybackMode
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 
-// A Service that manages the single ExoPlayer instance and manages the system-side
+/**
-// aspects of playback.
+ * A service that manages the system-side aspects of playback, such as:
+ * - The single [SimpleExoPlayer] instance.
+ * - The [MediaSessionCompat]
+ * - The Media Notification
+ * - Audio Focus
+ * - Headset management
+ *
+ * This service relies on [PlaybackStateManager.Callback], so therefore there's no need to bind
+ * to it to deliver commands.
+ * @author OxygenCobalt
+ */
 class PlaybackService : Service(), Player.EventListener, PlaybackStateManager.Callback {
     private val player: SimpleExoPlayer by lazy {
         SimpleExoPlayer.Builder(applicationContext).build()

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

@@ -15,8 +15,10 @@ import org.oxycblt.auxio.playback.state.LoopMode
 import org.oxycblt.auxio.playback.state.PlaybackMode
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 
-// A ViewModel that acts as an intermediary between the UI and PlaybackStateManager
+/**
-// TODO: Implement Persistence through a Database
+ * The ViewModel that provides a UI-Focused frontend for [PlaybackStateManager].
+ * @author OxygenCobalt
+ */
 class PlaybackViewModel : ViewModel(), PlaybackStateManager.Callback {
     // Playback
     private val mSong = MutableLiveData<Song?>()
@@ -198,6 +200,9 @@ class PlaybackViewModel : ViewModel(), PlaybackStateManager.Callback {
 
                 from -= mUserQueue.value!!.size.inc()
                 to -= mUserQueue.value!!.size.inc()
+
+                // Ignore movements that are past the next songs
+                if (to <= mIndex.value!!) return false
             }
 
             playbackManager.moveQueueItems(from, to)

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

@@ -14,15 +14,12 @@ class QueueDragCallback(private val playbackModel: PlaybackViewModel) : ItemTouc
         recyclerView: RecyclerView,
         viewHolder: RecyclerView.ViewHolder
     ): Int {
-        // Make header objects unswipable by only returning the swipe flags if the ViewHolder
+        // Only allow dragging/swiping with the queue item ViewHolder, not the header items.
-        // is for a queue item.
         return if (viewHolder is QueueAdapter.ViewHolder) {
             makeFlag(
                 ItemTouchHelper.ACTION_STATE_DRAG, ItemTouchHelper.UP or ItemTouchHelper.DOWN
             ) or makeFlag(ItemTouchHelper.ACTION_STATE_SWIPE, ItemTouchHelper.START)
-        } else {
+        } else 0
-            0
-        }
     }
 
     override fun interpolateOutOfBoundsScroll(

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

@@ -49,7 +49,6 @@ class QueueFragment : Fragment() {
             }
 
             queueAdapter.submitList(createQueueDisplay()) {
-                binding.queueRecycler.scrollToPosition(0)
                 scrollRecyclerIfNeeded(binding)
             }
         }

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

@@ -10,12 +10,14 @@ import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.Song
 import kotlin.random.Random
 
-// The manager of the current playback state [Current Song, Queue, Shuffling]
+/**
-// This class is for sole use by the code in /playback/.
+ * Master class for the playback state. This should ***not*** be used outside of the playback module.
-// If you want to add system-side things, add to PlaybackService.
+ * - If you want to show the playback state in the UI, use [org.oxycblt.auxio.playback.PlaybackViewModel].
-// If you want to add ui-side things, add to PlaybackViewModel.
+ * - If you want to add to the system aspects or the exoplayer instance, use [org.oxycblt.auxio.playback.PlaybackService].
-// [Yes, I know MediaSessionCompat exists, but I like having full control over the
+ *
-// playback state instead of dealing with android's likely buggy code.]
+ * All instantiation should be done with [PlaybackStateManager.from()].
+ * @author OxygenCobalt
+ */
 class PlaybackStateManager private constructor() {
     // Playback
     private var mSong: Song? = null
@@ -438,10 +440,32 @@ class PlaybackStateManager private constructor() {
         return final
     }
 
+    /**
+     * The interface for receiving updates from [PlaybackStateManager].
+     * Add the callback to [PlaybackStateManager] using [addCallback],
+     * remove them on destruction with [removeCallback].
+     */
+    interface Callback {
+        fun onSongUpdate(song: Song?) {}
+        fun onParentUpdate(parent: BaseModel?) {}
+        fun onPositionUpdate(position: Long) {}
+        fun onQueueUpdate(queue: MutableList<Song>) {}
+        fun onUserQueueUpdate(userQueue: MutableList<Song>) {}
+        fun onModeUpdate(mode: PlaybackMode) {}
+        fun onIndexUpdate(index: Int) {}
+        fun onPlayingUpdate(isPlaying: Boolean) {}
+        fun onShuffleUpdate(isShuffling: Boolean) {}
+        fun onLoopUpdate(mode: LoopMode) {}
+        fun onSeekConfirm(position: Long) {}
+    }
+
     companion object {
         @Volatile
         private var INSTANCE: PlaybackStateManager? = null
 
+        /**
+         * Get/Instantiate the single instance of [PlaybackStateManager].
+         */
         fun getInstance(): PlaybackStateManager {
             val currentInstance = INSTANCE
 
@@ -456,18 +480,4 @@ class PlaybackStateManager private constructor() {
             }
         }
     }
-
-    interface Callback {
-        fun onSongUpdate(song: Song?) {}
-        fun onParentUpdate(parent: BaseModel?) {}
-        fun onPositionUpdate(position: Long) {}
-        fun onQueueUpdate(queue: MutableList<Song>) {}
-        fun onUserQueueUpdate(userQueue: MutableList<Song>) {}
-        fun onModeUpdate(mode: PlaybackMode) {}
-        fun onIndexUpdate(index: Int) {}
-        fun onPlayingUpdate(isPlaying: Boolean) {}
-        fun onShuffleUpdate(isShuffling: Boolean) {}
-        fun onLoopUpdate(mode: LoopMode) {}
-        fun onSeekConfirm(position: Long) {}
-    }
 }

app/src/main/java/org/oxycblt/auxio/recycler/ShowMode.kt

@@ -1,8 +1,8 @@
 package org.oxycblt.auxio.recycler
 
 // TODO: Swap these temp values for actual constants
-enum class ShowMode(val constant: Long) {
+enum class ShowMode {
-    SHOW_GENRES(0), SHOW_ARTISTS(1), SHOW_ALBUMS(2), SHOW_SONGS(3);
+    SHOW_GENRES, SHOW_ARTISTS, SHOW_ALBUMS, SHOW_SONGS;
 
     // Make a slice of all the values that this ShowMode covers.
     // ex. SHOW_ARTISTS would return SHOW_ARTISTS, SHOW_ALBUMS, and SHOW_SONGS