playback: fix crash on state restore

Fix a crash stemming from applying the playback state on the main
thread instead of the background thread.

all: add misc todos

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

@@ -51,7 +51,7 @@ import org.oxycblt.auxio.util.systemBarInsetsCompat
  * TODO: Unit testing
  * TODO: Fix UID naming
  * TODO: Leverage FlexibleListAdapter more in dialogs (Disable item anims)
- * TODO: Try to move on from synchronized and volatile in shared objs
+ * TODO: Improve multi-threading support in shared objects
  */
 @AndroidEntryPoint
 class MainActivity : AppCompatActivity() {

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

@@ -22,6 +22,7 @@ import android.view.View
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.logW
 
 /**
  * A [RecyclerView.Adapter] that supports indicating the playback status of a particular item.
@@ -71,7 +72,7 @@ abstract class PlayingIndicatorAdapter<T, VH : RecyclerView.ViewHolder>(
                 if (pos > -1) {
                     notifyItemChanged(pos, PAYLOAD_PLAYING_INDICATOR_CHANGED)
                 } else {
-                    logD("oldItem was not in adapter data")
+                    logW("oldItem was not in adapter data")
                 }
             }
 
@@ -81,7 +82,7 @@ abstract class PlayingIndicatorAdapter<T, VH : RecyclerView.ViewHolder>(
                 if (pos > -1) {
                     notifyItemChanged(pos, PAYLOAD_PLAYING_INDICATOR_CHANGED)
                 } else {
-                    logD("newItem was not in adapter data")
+                    logW("newItem was not in adapter data")
                 }
             }
 
@@ -99,7 +100,7 @@ abstract class PlayingIndicatorAdapter<T, VH : RecyclerView.ViewHolder>(
                 if (pos > -1) {
                     notifyItemChanged(pos, PAYLOAD_PLAYING_INDICATOR_CHANGED)
                 } else {
-                    logD("newItem was not in adapter data")
+                    logW("newItem was not in adapter data")
                 }
             }
         }

app/src/main/java/org/oxycblt/auxio/music/user/UserLibrary.kt

@@ -161,6 +161,7 @@ private class UserLibraryImpl(
     override fun findPlaylist(name: String) = playlistMap.values.find { it.name.raw == name }
 
     override suspend fun createPlaylist(name: String, songs: List<Song>) {
+        // TODO: Use synchronized with value access too
         val playlistImpl = PlaylistImpl.from(name, songs, musicSettings)
         synchronized(this) { playlistMap[playlistImpl.uid] = playlistImpl }
         val rawPlaylist =

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

@@ -236,13 +236,11 @@ class PlaybackPanelFragment :
         requireBinding().playbackShuffle.isActivated = isShuffled
     }
 
-    /** Navigate to one of the currently playing [Song]'s Artists. */
     private fun navigateToCurrentArtist() {
         val song = playbackModel.song.value ?: return
         navModel.exploreNavigateToParentArtist(song)
     }
 
-    /** Navigate to the currently playing [Song]'s albums. */
     private fun navigateToCurrentAlbum() {
         val song = playbackModel.song.value ?: return
         navModel.exploreNavigateTo(song.album)

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

@@ -44,6 +44,7 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.music.MusicRepository
 import org.oxycblt.auxio.music.MusicSettings
@@ -355,7 +356,9 @@ class PlaybackService :
                 logD("Restoring playback state")
                 restoreScope.launch {
                     persistenceRepository.readState()?.let {
-                        playbackManager.applySavedState(it, false)
+                        // Apply the saved state on the main thread to prevent code expecting
+                        // state updates on the main thread from crashing.
+                        withContext(Dispatchers.Main) { playbackManager.applySavedState(it, false) }
                     }
                 }
             }