=Work on Music command

src/utils/audio/TrackScheduler.java

@@ -0,0 +1,62 @@
+package utils.audio;
+
+import com.sedmelluq.discord.lavaplayer.player.AudioPlayer;
+import com.sedmelluq.discord.lavaplayer.player.event.AudioEventAdapter;
+import com.sedmelluq.discord.lavaplayer.track.AudioTrack;
+import com.sedmelluq.discord.lavaplayer.track.AudioTrackEndReason;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+/**
+ * This class schedules tracks for the audio player. It contains the queue of tracks.
+ */
+public class TrackScheduler extends AudioEventAdapter {
+  private final AudioPlayer player;
+  private final BlockingQueue<AudioTrack> queue;
+
+  /**
+   * @param player The audio player this scheduler uses
+   */
+  public TrackScheduler(AudioPlayer player) 
+  {
+    this.player = player;
+    this.queue = new LinkedBlockingQueue<>();
+  }
+
+  /**
+   * Add the next track to queue or play right away if nothing is in the queue.
+   *
+   * @param track The track to play or add to queue.
+   */
+  public void queue(AudioTrack track) 
+  {
+    // Calling startTrack with the noInterrupt set to true will start the track only if nothing is currently playing. If
+    // something is playing, it returns false and does nothing. In that case the player was already playing so this
+    // track goes to the queue instead.
+    if (!player.startTrack(track, true)) 
+    {
+      queue.offer(track);
+    }
+  }
+
+  /**
+   * Start the next track, stopping the current one if it is playing.
+   */
+  public void nextTrack() 
+  {
+    // Start the next track, regardless of if something is already playing or not. In case queue was empty, we are
+    // giving null to startTrack, which is a valid argument and will simply stop the player.
+    player.startTrack(queue.poll(), false);
+  }
+
+  @Override
+  public void onTrackEnd(AudioPlayer player, AudioTrack track, AudioTrackEndReason endReason) 
+  {
+    // Only start the next track if the end reason is suitable for it (FINISHED or LOAD_FAILED)
+    if (endReason.mayStartNext) 
+    {
+      nextTrack();
+    }
+  }
+}