playback: fix index bug

Fix some index bugs by using inc/dec instead of ++/--.

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

@@ -161,7 +161,7 @@ class PlaybackStateManager private constructor() {
         // Increment the index, if it cannot be incremented any further, then
         // repeat and pause/resume playback depending on the setting
         if (index < mutableQueue.lastIndex) {
-            goto(++index, true)
+            goto(index.inc(), true)
         } else {
             goto(0, repeatMode == RepeatMode.ALL)
         }
@@ -174,7 +174,7 @@ class PlaybackStateManager private constructor() {
             rewind()
             isPlaying = true
         } else {
-            goto(max(--index, 0), true)
+            goto(max(index.dec(), 0), true)
         }
     }
 
@@ -187,13 +187,13 @@ class PlaybackStateManager private constructor() {
 
     /** Add a [song] to the top of the queue. */
     fun playNext(song: Song) {
-        mutableQueue.add(++index, song)
+        mutableQueue.add(index.inc(), song)
         notifyQueueChanged()
     }
 
     /** Add a list of [songs] to the top of the queue. */
     fun playNext(songs: List<Song>) {
-        mutableQueue.addAll(++index, songs)
+        mutableQueue.addAll(index.inc(), songs)
         notifyQueueChanged()
     }
 

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

@@ -65,7 +65,8 @@ import org.oxycblt.auxio.widgets.WidgetProvider
  * therefore there's no need to bind to it to deliver commands.
  * @author OxygenCobalt
  *
- * TODO: Synchronize components in a less awful way.
+ * TODO: Synchronize components in a less awful way (Fix issue where rapid-fire updates results
+ * in a desynced notification)
  */
 class PlaybackService :
     Service(), Player.Listener, PlaybackStateManager.Callback, SettingsManager.Callback {
@@ -374,7 +375,6 @@ class PlaybackService :
 
             if (!isForeground) {
                 startForeground(IntegerTable.NOTIFICATION_CODE, notificationComponent.build())
-
                 isForeground = true
             } else {
                 // If we are already in foreground just update the notification