private Callable<Void> createItemLoader(final String identifier, final AudioLoadResultHandler resultHandler, boolean isPatron) {
    return () -> {
        final boolean[] reported = new boolean[1];

        try {
            if (!checkSourcesForItem(new AudioReference(identifier, null), resultHandler, reported, isPatron)) {
                log.debug("No matches for track with identifier {}.", identifier);
                resultHandler.noMatches();
            }
        } catch (Throwable throwable) {
            if (reported[0]) {
                log.warn("Load result handler for {} threw an exception", identifier, throwable);
            } else {
                dispatchItemLoadFailure(identifier, resultHandler, throwable);
            }

            ExceptionTools.rethrowErrors(throwable);
        }

        return null;
    };
}
 

private boolean loadFromStream(String identifier, AudioLoadResultHandler resultHandler) {
  try {
    StreamInstance stream;

    synchronized (streams) {
      String finalIdentifier = defaultOnNull(resolutionCache.get(identifier), identifier);
      stream = streams.get(finalIdentifier);
    }

    if (stream != null) {
      AudioTrack track = stream.getTrack().makeClone();
      log.debug("Track {} (originally {}) loaded using existing stream.", track.getIdentifier(), identifier);

      resultHandler.trackLoaded(track);
      return true;
    }
  } catch (Exception e) {
    log.error("Error when checking streams for identifier {}.", identifier);
  }

  return false;
}
 

private void loadTrack(String identifier, Member author, Message msg) {


        Guild guild = author.getGuild();
        getPlayer(guild);

        msg.getTextChannel().sendTyping().queue();
        myManager.setFrameBufferDuration(5000);
        myManager.loadItemOrdered(guild, identifier, new AudioLoadResultHandler() {

            @Override
            public void trackLoaded(AudioTrack track) {

                getTrackManager(guild).queue(track, author);
            }

            @Override
            public void playlistLoaded(AudioPlaylist playlist) {
                if (playlist.getSelectedTrack() != null) {
                    trackLoaded(playlist.getSelectedTrack());
                } else if (playlist.isSearchResult()) {
                    trackLoaded(playlist.getTracks().get(0));
                } else {

                    for (int i = 0; i < Math.min(playlist.getTracks().size(), PLAYLIST_LIMIT); i++) {
                        getTrackManager(guild).queue(playlist.getTracks().get(i), author);
                    }
                }
            }

            @Override
            public void noMatches() {
            }

            @Override
            public void loadFailed(FriendlyException exception) {
            }
        });
    }
 

public Future<Void> loadItemOrdered(final Object orderingKey, final String identifier,
                                    final AudioLoadResultHandler resultHandler, final boolean isPatron) {

    try {
        return orderedInfoExecutor.get().submit(orderingKey, createItemLoader(identifier, resultHandler, isPatron));
    } catch (RejectedExecutionException e) {
        return handleLoadRejected(identifier, resultHandler, e);
    }
}
 

private Future<Void> handleLoadRejected(String identifier, AudioLoadResultHandler resultHandler, RejectedExecutionException e) {
    final FriendlyException exception = new FriendlyException("Cannot queue loading a track, queue is full.", SUSPICIOUS, e);
    ExceptionTools.log(log, exception, "queueing item " + identifier);

    resultHandler.loadFailed(exception);

    return ExecutorTools.COMPLETED_VOID;
}
 

private void dispatchItemLoadFailure(String identifier, AudioLoadResultHandler resultHandler, Throwable throwable) {
    final FriendlyException exception = ExceptionTools.wrapUnfriendlyExceptions("Something went wrong when looking up the track", FAULT, throwable);

    if (!(throwable instanceof LimitReachedException)) {
        ExceptionTools.log(log, exception, "loading item " + identifier);
    }

    resultHandler.loadFailed(exception);
}
 

private AudioItem checkSourcesForItemOnce(AudioReference reference, AudioLoadResultHandler resultHandler, boolean[] reported, boolean isPatron) {
    for (final AudioSourceManager sourceManager : sourceManagers.get()) {
        if (reference.containerDescriptor != null && !(sourceManager instanceof ProbingAudioSourceManager)) {
            continue;
        }

        final AudioItem item;

        if (sourceManager instanceof SpotifyAudioSourceManager) {
            item = ((SpotifyAudioSourceManager) sourceManager).loadItem(reference, isPatron);
        } else {
            item = sourceManager.loadItem(this, reference);
        }

        if (item != null) {
            if (item instanceof AudioTrack) {
                log.debug("Loaded a track with identifier {} using {}.", reference.identifier, sourceManager.getClass().getSimpleName());
                reported[0] = true;
                resultHandler.trackLoaded((AudioTrack) item);
            } else if (item instanceof AudioPlaylist) {
                log.debug("Loaded a playlist with identifier {} using {}.", reference.identifier, sourceManager.getClass().getSimpleName());
                reported[0] = true;
                resultHandler.playlistLoaded((AudioPlaylist) item);
            }
            return item;
        }
    }

    return null;
}
 

@PostConstruct
public void init() {
    try {
        sourceMethod = DefaultAudioPlayerManager.class.getDeclaredMethod("checkSourcesForItem",
                AudioReference.class, AudioLoadResultHandler.class, boolean[].class);
        sourceMethod.setAccessible(true);
    } catch (NoSuchMethodException e) {
        log.warn("Could not get LavaPlayer init method");
    }
}
 

private boolean checkSourcesForItem(DefaultAudioPlayerManager manager, AudioReference reference, AudioLoadResultHandler resultHandler) {
    if (sourceMethod == null) {
        return false;
    }
    try {
        Object result = sourceMethod.invoke(manager, reference, resultHandler, new boolean[1]);
        return Boolean.TRUE.equals(result);
    } catch (IllegalAccessException | InvocationTargetException e) {
        log.warn("Could not invoke checkSourcesForItem of LavaPlayer");
        return false;
    }
}
 

@Override
public Future<Void> loadItem(String identifier, AudioLoadResultHandler resultHandler) {
  if (loadFromStream(identifier, resultHandler)) {
    return ExecutorTools.COMPLETED_VOID;
  }

  return super.loadItem(identifier, new SpyingHandler(resultHandler, identifier));
}
 

@Override
public Future<Void> loadItemOrdered(Object orderingKey, String identifier, AudioLoadResultHandler resultHandler) {
  if (loadFromStream(identifier, resultHandler)) {
    // This bypasses the ordering but oh well.
    return ExecutorTools.COMPLETED_VOID;
  }

  return super.loadItemOrdered(orderingKey, identifier, resultHandler);
}
 

private void loadAndPlay(TextChannel channel, final String trackUrl) {
  GuildMusicManager musicManager = getGuildAudioPlayer(channel.getGuild().block());

  playerManager.loadItemOrdered(musicManager, trackUrl, new AudioLoadResultHandler() {
    @Override
    public void trackLoaded(AudioTrack track) {
      sendMessageToChannel(channel, "Adding to queue " + track.getInfo().title);

      play(channel.getGuild().block(), musicManager, track);
    }

    @Override
    public void playlistLoaded(AudioPlaylist playlist) {
      AudioTrack firstTrack = playlist.getSelectedTrack();

      if (firstTrack == null) {
        firstTrack = playlist.getTracks().get(0);
      }

      sendMessageToChannel(channel, "Adding to queue " + firstTrack.getInfo().title + " (first track of playlist " + playlist.getName() + ")");

      play(channel.getGuild().block(), musicManager, firstTrack);
    }

    @Override
    public void noMatches() {
      sendMessageToChannel(channel, "Nothing found by " + trackUrl);
    }

    @Override
    public void loadFailed(FriendlyException exception) {
      sendMessageToChannel(channel, "Could not play: " + exception.getMessage());
    }
  });
}
 

private void loadAndPlay(final TextChannel channel, final String trackUrl) {
  GuildMusicManager musicManager = getGuildAudioPlayer(channel.getGuild());

  playerManager.loadItemOrdered(musicManager, trackUrl, new AudioLoadResultHandler() {
    @Override
    public void trackLoaded(AudioTrack track) {
      channel.sendMessage("Adding to queue " + track.getInfo().title).queue();

      play(channel.getGuild(), musicManager, track);
    }

    @Override
    public void playlistLoaded(AudioPlaylist playlist) {
      AudioTrack firstTrack = playlist.getSelectedTrack();

      if (firstTrack == null) {
        firstTrack = playlist.getTracks().get(0);
      }

      channel.sendMessage("Adding to queue " + firstTrack.getInfo().title + " (first track of playlist " + playlist.getName() + ")").queue();

      play(channel.getGuild(), musicManager, firstTrack);
    }

    @Override
    public void noMatches() {
      channel.sendMessage("Nothing found by " + trackUrl).queue();
    }

    @Override
    public void loadFailed(FriendlyException exception) {
      channel.sendMessage("Could not play: " + exception.getMessage()).queue();
    }
  });
}
 

public static void load(AudioPlayerManager manager, Lavalink<?> lavalink, String query,
                        AudioLoadResultHandler handler) {
    Iterator<LavalinkSocket> sockets = lavalink.getNodes().iterator();
    if (!sockets.hasNext()) {
        manager.loadItem(query, handler);
        return;
    }

    CompletionStage<Runnable> last = tryLoad(manager, sockets.next().getRemoteUri(), query, handler);
    while (sockets.hasNext()) {
        URI uri = sockets.next().getRemoteUri();
        //TODO: java 12 replace this with the line commented below
        var cf = new CompletableFuture<Runnable>();
        last.thenApply(CompletableFuture::completedStage)
                .exceptionally(e -> tryLoad(manager, uri, query, handler))
                .thenCompose(Function.identity())
                .thenAccept(cf::complete)
                .exceptionally(e -> {
                    cf.completeExceptionally(e);
                    return null;
                });
        last = cf;
        //last = last.exceptionallyCompose(e -> tryLoad(manager, uri, query, handler));
    }
    last.whenComplete((ok, oof) -> {
        if (oof != null) {
            handler.loadFailed(new FriendlyException("Failed to load", FriendlyException.Severity.SUSPICIOUS, oof));
        } else {
            ok.run();
        }
    });
}
 

private SpyingHandler(AudioLoadResultHandler delegate, String identifier) {
  this.delegate = delegate;
  this.identifier = identifier;
}
 

private void addTrack(final Message message, final String identifier, final boolean now) {
  outputChannel.set((TextChannel) message.getChannel());

  manager.loadItemOrdered(this, identifier, new AudioLoadResultHandler() {
    @Override
    public void trackLoaded(AudioTrack track) {
      connectToFirstVoiceChannel(guild.getAudioManager());

      message.getChannel().sendMessage("Starting now: " + track.getInfo().title + " (length " + track.getDuration() + ")").queue();

      if (now) {
        scheduler.playNow(track, true);
      } else {
        scheduler.addToQueue(track);
      }
    }

    @Override
    public void playlistLoaded(AudioPlaylist playlist) {
      List<AudioTrack> tracks = playlist.getTracks();
      message.getChannel().sendMessage("Loaded playlist: " + playlist.getName() + " (" + tracks.size() + ")").queue();

      connectToFirstVoiceChannel(guild.getAudioManager());

      AudioTrack selected = playlist.getSelectedTrack();

      if (selected != null) {
        message.getChannel().sendMessage("Selected track from playlist: " + selected.getInfo().title).queue();
      } else {
        selected = tracks.get(0);
        message.getChannel().sendMessage("Added first track from playlist: " + selected.getInfo().title).queue();
      }

      if (now) {
        scheduler.playNow(selected, true);
      } else {
        scheduler.addToQueue(selected);
      }

      for (int i = 0; i < Math.min(10, playlist.getTracks().size()); i++) {
        if (tracks.get(i) != selected) {
          scheduler.addToQueue(tracks.get(i));
        }
      }
    }

    @Override
    public void noMatches() {
      message.getChannel().sendMessage("Nothing found for " + identifier).queue();
    }

    @Override
    public void loadFailed(FriendlyException throwable) {
      message.getChannel().sendMessage("Failed with message: " + throwable.getMessage() + " (" + throwable.getClass().getSimpleName() + ")").queue();
    }
  });
}
 

private void loadAndPlay(GuildMusicManager mng, final MessageChannel channel, String url, final boolean addPlaylist)
{
    final String trackUrl;

    //Strip <>'s that prevent discord from embedding link resources
    if (url.startsWith("<") && url.endsWith(">"))
        trackUrl = url.substring(1, url.length() - 1);
    else
        trackUrl = url;

    playerManager.loadItemOrdered(mng, trackUrl, new AudioLoadResultHandler()
    {
        @Override
        public void trackLoaded(AudioTrack track)
        {
            String msg = "Adding to queue: " + track.getInfo().title;
            if (mng.player.getPlayingTrack() == null)
                msg += "\nand the Player has started playing;";

            mng.scheduler.queue(track);
            channel.sendMessage(msg).queue();
        }

        @Override
        public void playlistLoaded(AudioPlaylist playlist)
        {
            AudioTrack firstTrack = playlist.getSelectedTrack();
            List<AudioTrack> tracks = playlist.getTracks();


            if (firstTrack == null) {
                firstTrack = playlist.getTracks().get(0);
            }

            if (addPlaylist)
            {
                channel.sendMessage("Adding **" + playlist.getTracks().size() +"** tracks to queue from playlist: " + playlist.getName()).queue();
                tracks.forEach(mng.scheduler::queue);
            }
            else
            {
                channel.sendMessage("Adding to queue " + firstTrack.getInfo().title + " (first track of playlist " + playlist.getName() + ")").queue();
                mng.scheduler.queue(firstTrack);
            }
        }

        @Override
        public void noMatches()
        {
            channel.sendMessage("Nothing found by " + trackUrl).queue();
        }

        @Override
        public void loadFailed(FriendlyException exception)
        {
            channel.sendMessage("Could not play: " + exception.getMessage()).queue();
        }
    });
}
 

/**
 * Schedules loading a track or playlist with the specified identifier. Items loaded with the same
 * guild ID are handled sequentially in the order of calls to this method.
 *
 * @return A future for this operation.
 */
protected Future<Void> loadItemOrdered(long guildId, String identifier, AudioLoadResultHandler listener) {
    return this.audioPlayerManager.loadItemOrdered(guildId, identifier, listener);
}