From 4581532928fa038c3ad63f477a2b64e1a1576942 Mon Sep 17 00:00:00 2001
From: Alexander Capehart <alex@oxycblt.org>
Date: Fri, 2 Jun 2023 13:34:00 -0600
Subject: [PATCH] queue: shift back if removing playing end

Shift the queue index backwards if the current song at the end of a
queue is removed.

Without this, the index becomes OOB and makes the queue be interpreted
as entirely empty when it actually isn't, which is compounded by a
remove-1 update intruction leading to a RecyclerView inconsistency
crash.
---
 .../main/java/org/oxycblt/auxio/playback/queue/Queue.kt  | 9 +++++++--
 .../oxycblt/auxio/playback/state/PlaybackStateManager.kt | 4 ++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/org/oxycblt/auxio/playback/queue/Queue.kt b/app/src/main/java/org/oxycblt/auxio/playback/queue/Queue.kt
index 9d9352ef4..c5ebf9904 100644
--- a/app/src/main/java/org/oxycblt/auxio/playback/queue/Queue.kt
+++ b/app/src/main/java/org/oxycblt/auxio/playback/queue/Queue.kt
@@ -107,7 +107,7 @@ interface Queue {
     }
 }
 
-class EditableQueue : Queue {
+class MutableQueue : Queue {
     @Volatile private var heap = mutableListOf<Song>()
     @Volatile private var orderedMapping = mutableListOf<Int>()
     @Volatile private var shuffledMapping = mutableListOf<Int>()
@@ -302,6 +302,7 @@ class EditableQueue : Queue {
      * @return A [Queue.Change] instance that reflects the changes made.
      */
     fun remove(at: Int): Queue.Change {
+        val lastIndex = orderedMapping.lastIndex
         if (shuffledMapping.isNotEmpty()) {
             // Remove the specified index in the shuffled mapping and the analogous song in the
             // ordered mapping.
@@ -321,12 +322,16 @@ class EditableQueue : Queue {
                 // We just removed the currently playing song.
                 index == at -> {
                     logD("Removed current song")
+                    if (lastIndex == index) {
+                        logD("Current song at end of queue, shift back")
+                        --index
+                    }
                     Queue.Change.Type.SONG
                 }
                 // Index was ahead of removed song, shift back to preserve consistency.
                 index > at -> {
                     logD("Removed before current song, shift back")
-                    index -= 1
+                    --index
                     Queue.Change.Type.INDEX
                 }
                 // Nothing to do
diff --git a/app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateManager.kt b/app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateManager.kt
index 4f2dbb5c0..388087653 100644
--- a/app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateManager.kt
+++ b/app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateManager.kt
@@ -22,7 +22,7 @@ import javax.inject.Inject
 import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
-import org.oxycblt.auxio.playback.queue.EditableQueue
+import org.oxycblt.auxio.playback.queue.MutableQueue
 import org.oxycblt.auxio.playback.queue.Queue
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logW
@@ -305,7 +305,7 @@ class PlaybackStateManagerImpl @Inject constructor() : PlaybackStateManager {
     @Volatile private var pendingAction: InternalPlayer.Action? = null
     @Volatile private var isInitialized = false
 
-    override val queue = EditableQueue()
+    override val queue = MutableQueue()
     @Volatile
     override var parent: MusicParent? = null
         private set