session-android/src/org/thoughtcrime/securesms/audio/AudioSlidePlayer.java

package org.thoughtcrime.securesms.audio;

import android.content.Context;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.Log;
import android.util.Pair;

import org.thoughtcrime.securesms.crypto.MasterSecret;
import org.thoughtcrime.securesms.mms.AudioSlide;
import org.thoughtcrime.securesms.util.Util;
import org.whispersystems.libaxolotl.util.guava.Optional;

import java.io.IOException;
import java.lang.ref.WeakReference;

public class AudioSlidePlayer {

  private static final String TAG = AudioSlidePlayer.class.getSimpleName();

  private static @NonNull Optional<AudioSlidePlayer> playing = Optional.absent();

  private final @NonNull Context      context;
  private final @NonNull MasterSecret masterSecret;
  private final @NonNull AudioSlide   slide;
  private final @NonNull Handler      progressEventHandler;

  private @NonNull  WeakReference<Listener> listener;
  private @Nullable MediaPlayer             mediaPlayer;
  private @Nullable AudioAttachmentServer   audioAttachmentServer;

  public synchronized static AudioSlidePlayer createFor(@NonNull Context context,
                                                        @NonNull MasterSecret masterSecret,
                                                        @NonNull AudioSlide slide,
                                                        @NonNull Listener listener)
  {
    if (playing.isPresent() && playing.get().getAudioSlide().equals(slide)) {
      playing.get().setListener(listener);
      return playing.get();
    } else {
      return new AudioSlidePlayer(context, masterSecret, slide, listener);
    }
  }

  private AudioSlidePlayer(@NonNull Context context,
                           @NonNull MasterSecret masterSecret,
                           @NonNull AudioSlide slide,
                           @NonNull Listener listener)
  {
    this.context              = context;
    this.masterSecret         = masterSecret;
    this.slide                = slide;
    this.listener             = new WeakReference<>(listener);
    this.progressEventHandler = new ProgressEventHandler(this);
  }

  public void play(final double progress) throws IOException {
    if (this.mediaPlayer != null) return;

    this.mediaPlayer           = new MediaPlayer();
    this.audioAttachmentServer = new AudioAttachmentServer(context, masterSecret, slide.asAttachment());

    audioAttachmentServer.start();

    mediaPlayer.setDataSource(context, audioAttachmentServer.getUri());
    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
    mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
      @Override
      public void onPrepared(MediaPlayer mp) {
        Log.w(TAG, "onPrepared");
        if (progress > 0) {
          mediaPlayer.seekTo((int)(mediaPlayer.getDuration() * progress));
        }

        mediaPlayer.start();

        notifyOnStart();
        setPlaying(AudioSlidePlayer.this);
        progressEventHandler.sendEmptyMessage(0);
      }
    });

    mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
      @Override
      public void onCompletion(MediaPlayer mp) {
        Log.w(TAG, "onComplete");
        mediaPlayer = null;
        audioAttachmentServer.stop();
        audioAttachmentServer = null;

        notifyOnStop();
        progressEventHandler.removeMessages(0);
      }
    });

    mediaPlayer.setOnErrorListener(new MediaPlayer.OnErrorListener() {
      @Override
      public boolean onError(MediaPlayer mp, int what, int extra) {
        Log.w(TAG, "MediaPlayer Error: " + what + " , " + extra);
        notifyOnStop();
        return true;
      }
    });

    mediaPlayer.prepareAsync();
  }

  public void stop() {
    Log.w(TAG, "Stop called!");
    shutdown();
  }

  public void setListener(@NonNull Listener listener) {
    this.listener = new WeakReference<>(listener);

    if (this.mediaPlayer != null && this.mediaPlayer.isPlaying()) {
      notifyOnStart();
    }
  }

  public @NonNull AudioSlide getAudioSlide() {
    return slide;
  }

  private void shutdown() {
    removePlaying(this);

    if (this.mediaPlayer != null) {
      this.mediaPlayer.stop();
    }

    if (this.audioAttachmentServer != null) {
      this.audioAttachmentServer.stop();
    }

    this.mediaPlayer           = null;
    this.audioAttachmentServer = null;
  }

  private Pair<Double, Integer> getProgress() {
    if (mediaPlayer == null || mediaPlayer.getCurrentPosition() <= 0 || mediaPlayer.getDuration() <= 0) {
      return new Pair<>(0D, 0);
    } else {
      return new Pair<>((double) mediaPlayer.getCurrentPosition() / (double) mediaPlayer.getDuration(),
                        mediaPlayer.getCurrentPosition());
    }
  }

  private void notifyOnStart() {
    Util.runOnMain(new Runnable() {
      @Override
      public void run() {
        getListener().onStart();
      }
    });
  }

  private void notifyOnStop() {
    Util.runOnMain(new Runnable() {
      @Override
      public void run() {
        getListener().onStop();
      }
    });
  }

  private void notifyOnProgress(final double progress, final long millis) {
    Util.runOnMain(new Runnable() {
      @Override
      public void run() {
        getListener().onProgress(progress, millis);
      }
    });
  }

  private @NonNull Listener getListener() {
    Listener listener = this.listener.get();

    if (listener != null) return listener;
    else                  return new Listener() {
      @Override
      public void onStart() {}
      @Override
      public void onStop() {}
      @Override
      public void onProgress(double progress, long millis) {}
    };
  }

  private synchronized static void setPlaying(@NonNull AudioSlidePlayer player) {
    if (playing.isPresent() && playing.get() != player) {
      playing.get().notifyOnStop();
      playing.get().stop();
    }

    playing = Optional.of(player);
  }

  private synchronized static void removePlaying(@NonNull AudioSlidePlayer player) {
    if (playing.isPresent() && playing.get() == player) {
      playing = Optional.absent();
    }
  }

  public interface Listener {
    public void onStart();
    public void onStop();
    public void onProgress(double progress, long millis);
  }

  private static class ProgressEventHandler extends Handler {

    private final WeakReference<AudioSlidePlayer> playerReference;

    private ProgressEventHandler(@NonNull AudioSlidePlayer player) {
      this.playerReference = new WeakReference<>(player);
    }

    @Override
    public void handleMessage(Message msg) {
      AudioSlidePlayer player = playerReference.get();

      if (player == null || player.mediaPlayer == null || !player.mediaPlayer.isPlaying()) {
        return;
      }

      Pair<Double, Integer> progress = player.getProgress();
      player.notifyOnProgress(progress.first, progress.second);
      sendEmptyMessageDelayed(0, 50);
    }
  }

}