Delay autoplay triggering until the current track nears its end.

src/main/java/me/bobert/netneutrality/music/TrackScheduler.java

@@ -37,6 +37,7 @@ public class TrackScheduler {
     private final StuckTrackRecoveryHandler stuckTrackRecoveryHandler;
     private static final long POSITION_THROTTLE_MS = 5000;
     private volatile long lastPositionSent = Long.MIN_VALUE;
+    private static final long AUTOPLAY_REMAINING_MS = 30_000;
     private final AutoplayService autoplayService;
     private volatile boolean autoplayEnabled;
     private final AtomicBoolean autoplayLoading = new AtomicBoolean();
@@ -91,14 +92,11 @@ public class TrackScheduler {
     }
 
     /**
-     * Enables or disables autoplay. Enabling it while the last track of the queue is already
+     * Enables or disables autoplay. Recommendations are only loaded once the last track of the
-     * playing loads its recommendations immediately.
+     * queue is close to its end, so users still get a chance to queue their own tracks.
      */
     public void setAutoplayEnabled(boolean enabled) {
         this.autoplayEnabled = enabled;
-        if (enabled) {
-            maybeAutoplay();
-        }
     }
 
     boolean tryBeginAutoplayLoad() {
@@ -109,9 +107,13 @@ public class TrackScheduler {
         autoplayLoading.set(false);
     }
 
-    private void maybeAutoplay() {
+    private void maybeAutoplay(long position) {
         Track track = currentTrack;
-        if (autoplayEnabled && track != null && queueManager.getQueueSize() <= 1) {
+        if (!autoplayEnabled || track == null || queueManager.getQueueSize() > 1) {
+            return;
+        }
+        long length = track.getInfo().getLength();
+        if (length > 0 && length - position <= AUTOPLAY_REMAINING_MS) {
             autoplayService.loadFor(this, track);
         }
     }
@@ -146,7 +148,6 @@ public class TrackScheduler {
         currentTrack = track;
         stuckTrackRecoveryHandler.reset();
         publish(MusicEvent.Type.TRACK_START, track, null);
-        maybeAutoplay();
     }
 
     public void onTrackEnd(Track track, TrackEndEvent.AudioTrackEndReason endReason) {
@@ -236,6 +237,7 @@ public class TrackScheduler {
     }
 
     void onPlayerUpdate(long timestamp, long position, boolean connected, long ping, long now) {
+        maybeAutoplay(position);
         if (manager.getEvents() == null || currentTrack == null) {
             return;
         }

src/test/java/me/bobert/netneutrality/music/TrackSchedulerTest.java

@@ -147,13 +147,29 @@ public class TrackSchedulerTest {
     }
 
     @Test
-    public void onTrackStartLoadsAutoplayWhenEnabledAndLastTrack() {
+    public void onTrackStartDoesNotLoadAutoplayImmediately() {
         AutoplayService service = mock(AutoplayService.class);
         TrackScheduler autoplay = new TrackScheduler(musicManager, service);
         Track track = QueueManagerTest.mockTrack("t1");
+        when(track.getInfo().getLength()).thenReturn(200_000L);
         autoplay.setAutoplayEnabled(true);
 
         autoplay.onTrackStart(track);
+        autoplay.onPlayerUpdate(1L, 1_000L, true, 20L, 1000L);
+
+        verify(service, never()).loadFor(any(), any());
+    }
+
+    @Test
+    public void autoplayLoadsWhenLastTrackNearsItsEnd() {
+        AutoplayService service = mock(AutoplayService.class);
+        TrackScheduler autoplay = new TrackScheduler(musicManager, service);
+        Track track = QueueManagerTest.mockTrack("t1");
+        when(track.getInfo().getLength()).thenReturn(200_000L);
+        autoplay.setAutoplayEnabled(true);
+        autoplay.onTrackStart(track);
+
+        autoplay.onPlayerUpdate(1L, 175_000L, true, 20L, 1000L);
 
         verify(service).loadFor(autoplay, track);
     }
@@ -180,20 +196,20 @@ public class TrackSchedulerTest {
         clearInvocations(service);
 
         autoplay.onTrackStart(t1);
+        autoplay.onPlayerUpdate(1L, 999_999L, true, 20L, 1000L);
 
         verify(service, never()).loadFor(any(), any());
     }
 
     @Test
-    public void enablingAutoplayWhileLastTrackPlayingTriggersLoad() {
+    public void enablingAutoplayDoesNotLoadImmediately() {
         AutoplayService service = mock(AutoplayService.class);
         TrackScheduler autoplay = new TrackScheduler(musicManager, service);
-        Track track = QueueManagerTest.mockTrack("t1");
+        autoplay.onTrackStart(QueueManagerTest.mockTrack("t1"));
-        autoplay.onTrackStart(track);
 
         autoplay.setAutoplayEnabled(true);
 
-        verify(service).loadFor(autoplay, track);
+        verify(service, never()).loadFor(any(), any());
     }
 
     @Test