fix: ensure proper state cleanup for completion event handling

Author: gokadzev

lib/services/audio_service.dart

@@ -72,7 +72,6 @@ class MusifyAudioHandler extends BaseAudioHandler {
   bool _isUpdatingState = false;
   int _songTransitionCounter = 0;
   bool _completionEventPending = false;
-  bool _completionHandlerLoadStarted = false;
 
   String? _lastError;
   int _consecutiveErrors = 0;
@@ -301,37 +300,31 @@ class MusifyAudioHandler extends BaseAudioHandler {
   void _handleProcessingStateChange(ProcessingState state) {
     try {
       if (state == ProcessingState.completed) {
-        if (!sleepTimerExpired && !_completionEventPending) {
+        // Only process completion once - prevent re-entrancy
+        if (!_completionEventPending && !sleepTimerExpired) {
           _completionEventPending = true;
-
-          Future.microtask(() async {
-            try {
-              if (!sleepTimerExpired && _completionEventPending) {
-                await _handleSongCompletion();
-              }
-            } finally {
-              // Only reset if still marked as pending (another event didn't override)
-              if (_completionEventPending) {
-                _completionEventPending = false;
-                _completionHandlerLoadStarted = false;
-              } else {
-                logger.log(
-                  '[COMPLETION] Flag already false in finally block (was overridden)',
-                  null,
-                  null,
-                );
-              }
-            }
-          });
+          // Schedule immediately to process completion
+          Future.microtask(_processCompletion);
         }
-      } else if (state == ProcessingState.ready) {
-        _completionEventPending = false;
       }
     } catch (e, stackTrace) {
       logger.log('Error handling processing state change', e, stackTrace);
     }
   }
 
+  Future<void> _processCompletion() async {
+    try {
+      if (_completionEventPending && !sleepTimerExpired) {
+        await _handleSongCompletion();
+      }
+    } catch (e, stackTrace) {
+      logger.log('Error processing song completion', e, stackTrace);
+    } finally {
+      // Always reset the flag to allow next completion to be processed
+      _completionEventPending = false;
+    }
+  }
+
   void _handlePlaybackError() {
     _consecutiveErrors++;
     logger.log(
@@ -789,19 +782,8 @@ class MusifyAudioHandler extends BaseAudioHandler {
         return;
       }
 
-      // If already loading any song, skip the request
-      // UNLESS we're in the middle of handling a completion event (allow one load attempt)
-      if (_currentLoadingIndex >= 0 && !_completionEventPending) {
-        return;
-      }
-
-      if (_currentLoadingIndex >= 0 &&
-          _completionEventPending &&
-          !_completionHandlerLoadStarted) {
-        _completionHandlerLoadStarted = true;
-      } else if (_currentLoadingIndex >= 0 &&
-          _completionEventPending &&
-          _completionHandlerLoadStarted) {
+      // If already loading any song, skip to prevent race conditions
+      if (_currentLoadingIndex >= 0) {
         return;
       }
 
@@ -1053,10 +1035,6 @@ class MusifyAudioHandler extends BaseAudioHandler {
         audioSource,
         songUrl,
         isOffline,
-        onPlayStarted: () {
-          _currentLoadingIndex = -1;
-          _currentLoadingTransitionId = -1;
-        },
       );
     } catch (e, stackTrace) {
       logger.log('Error playing song', e, stackTrace);
@@ -1111,9 +1089,8 @@ class MusifyAudioHandler extends BaseAudioHandler {
     Map song,
     AudioSource audioSource,
     String songUrl,
-    bool isOffline, {
-    Function()? onPlayStarted,
-  }) async {
+    bool isOffline,
+  ) async {
     try {
       await audioPlayer
           .setAudioSource(audioSource)
@@ -1129,9 +1106,6 @@ class MusifyAudioHandler extends BaseAudioHandler {
 
       await audioPlayer.play();
 
-      // Invoke callback immediately after play() succeeds
-      onPlayStarted?.call();
-
       if (!isOffline) {
         final cacheKey =
             'song_${song['ytid']}_${audioQualitySetting.value}_url';