Fix detection of current window index in CastPlayer

Issue:#5955
PiperOrigin-RevId: 251616118

RELEASENOTES.md

@@ -37,6 +37,8 @@
 * Fix bug caused by parallel adaptive track selection using `Format`s without
   bitrate information
   ([#5971](https://github.com/google/ExoPlayer/issues/5971)).
+* Fix bug in `CastPlayer.getCurrentWindowIndex()`
+  ([#5955](https://github.com/google/ExoPlayer/issues/5955)).
 
 ### 2.10.1 ###
 

extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastPlayer.java

@@ -551,7 +551,17 @@ public final class CastPlayer extends BasePlayer {
       notificationsBatch.add(
           new ListenerNotificationTask(listener -> listener.onRepeatModeChanged(this.repeatMode)));
     }
-    int currentWindowIndex = fetchCurrentWindowIndex(getMediaStatus());
+    maybeUpdateTimelineAndNotify();
+
+    int currentWindowIndex = C.INDEX_UNSET;
+    MediaQueueItem currentItem = remoteMediaClient.getCurrentItem();
+    if (currentItem != null) {
+      currentWindowIndex = currentTimeline.getIndexOfPeriod(currentItem.getItemId());
+    }
+    if (currentWindowIndex == C.INDEX_UNSET) {
+      // The timeline is empty. Fall back to index 0, which is what ExoPlayer would do.
+      currentWindowIndex = 0;
+    }
     if (this.currentWindowIndex != currentWindowIndex && pendingSeekCount == 0) {
       this.currentWindowIndex = currentWindowIndex;
       notificationsBatch.add(
@@ -564,7 +574,6 @@ public final class CastPlayer extends BasePlayer {
           new ListenerNotificationTask(
               listener -> listener.onTracksChanged(currentTrackGroups, currentTrackSelection)));
     }
-    maybeUpdateTimelineAndNotify();
     flushNotifications();
   }
 
@@ -714,16 +723,6 @@ public final class CastPlayer extends BasePlayer {
     }
   }
 
-  /**
-   * Retrieves the current item index from {@code mediaStatus} and maps it into a window index. If
-   * there is no media session, returns 0.
-   */
-  private static int fetchCurrentWindowIndex(@Nullable MediaStatus mediaStatus) {
-    Integer currentItemId = mediaStatus != null
-        ? mediaStatus.getIndexById(mediaStatus.getCurrentItemId()) : null;
-    return currentItemId != null ? currentItemId : 0;
-  }
-
   private static boolean isTrackActive(long id, long[] activeTrackIds) {
     for (long activeTrackId : activeTrackIds) {
       if (activeTrackId == id) {