/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.android.exoplayer;

import com.google.android.exoplayer.MediaCodecUtil.DecoderQueryException;
import com.google.android.exoplayer.audio.AudioCapabilities;
import com.google.android.exoplayer.audio.AudioTrack;
import com.google.android.exoplayer.drm.DrmSessionManager;
import com.google.android.exoplayer.util.MimeTypes;
import com.google.android.exoplayer.util.Util;

import android.annotation.TargetApi;
import android.media.AudioManager;
import android.media.MediaCodec;
import android.media.MediaCrypto;
import android.media.PlaybackParams;
import android.media.audiofx.Virtualizer;
import android.os.Handler;
import android.os.SystemClock;

import java.nio.ByteBuffer;

/**
 * Decodes and renders audio using {@link MediaCodec} and {@link android.media.AudioTrack}.
 */
@TargetApi(16)
public class MediaCodecAudioTrackRenderer extends MediaCodecTrackRenderer implements MediaClock {

  /**
   * Interface definition for a callback to be notified of {@link MediaCodecAudioTrackRenderer}
   * events.
   */
  public interface EventListener extends MediaCodecTrackRenderer.EventListener {

    /**
     * Invoked when an {@link AudioTrack} fails to initialize.
     *
     * @param e The corresponding exception.
     */
    void onAudioTrackInitializationError(AudioTrack.InitializationException e);

    /**
     * Invoked when an {@link AudioTrack} write fails.
     *
     * @param e The corresponding exception.
     */
    void onAudioTrackWriteError(AudioTrack.WriteException e);

    /**
     * Invoked when an {@link AudioTrack} underrun occurs.
     *
     * @param bufferSize The size of the {@link AudioTrack}'s buffer, in bytes.
     * @param bufferSizeMs The size of the {@link AudioTrack}'s buffer, in milliseconds, if it is
     *     configured for PCM output. -1 if it is configured for passthrough output, as the buffered
     *     media can have a variable bitrate so the duration may be unknown.
     * @param elapsedSinceLastFeedMs The time since the {@link AudioTrack} was last fed data.
     */
    void onAudioTrackUnderrun(int bufferSize, long bufferSizeMs, long elapsedSinceLastFeedMs);

  }

  /**
   * The type of a message that can be passed to an instance of this class via
   * {@link ExoPlayer#sendMessage} or {@link ExoPlayer#blockingSendMessage}. The message object
   * should be a {@link Float} with 0 being silence and 1 being unity gain.
   */
  public static final int MSG_SET_VOLUME = 1;

  /**
   * The type of a message that can be passed to an instance of this class via
   * {@link ExoPlayer#sendMessage} or {@link ExoPlayer#blockingSendMessage}. The message object
   * should be a {@link android.media.PlaybackParams}, which will be used to configure the
   * underlying {@link android.media.AudioTrack}. The message object should not be modified by the
   * caller after it has been passed
   */
  public static final int MSG_SET_PLAYBACK_PARAMS = 2;

  private final EventListener eventListener;
  private final AudioTrack audioTrack;

  private boolean passthroughEnabled;
  private android.media.MediaFormat passthroughMediaFormat;
  private int audioSessionId;
  private long currentPositionUs;
  private boolean allowPositionDiscontinuity;

  private boolean audioTrackHasData;
  private long lastFeedElapsedRealtimeMs;

  /**
   * @param mediaCodecSelector A decoder selector.
   */
  public MediaCodecAudioTrackRenderer(MediaCodecSelector mediaCodecSelector) {
    this(mediaCodecSelector, null, true);
  }

  /**
   * @param mediaCodecSelector A decoder selector.
   * @param drmSessionManager For use with encrypted content. May be null if support for encrypted
   *     content is not required.
   * @param playClearSamplesWithoutKeys Encrypted media may contain clear (un-encrypted) regions.
   *     For example a media file may start with a short clear region so as to allow playback to
   *     begin in parallel with key acquisition. This parameter specifies whether the renderer is
   *     permitted to play clear regions of encrypted media files before {@code drmSessionManager}
   *     has obtained the keys necessary to decrypt encrypted regions of the media.
   */
  public MediaCodecAudioTrackRenderer(MediaCodecSelector mediaCodecSelector,
      DrmSessionManager drmSessionManager, boolean playClearSamplesWithoutKeys) {
    this(mediaCodecSelector, drmSessionManager, playClearSamplesWithoutKeys, null, null);
  }

  /**
   * @param mediaCodecSelector A decoder selector.
   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
   *     null if delivery of events is not required.
   * @param eventListener A listener of events. May be null if delivery of events is not required.
   */
  public MediaCodecAudioTrackRenderer(MediaCodecSelector mediaCodecSelector, Handler eventHandler,
      EventListener eventListener) {
    this(mediaCodecSelector, null, true, eventHandler, eventListener);
  }

  /**
   * @param mediaCodecSelector A decoder selector.
   * @param drmSessionManager For use with encrypted content. May be null if support for encrypted
   *     content is not required.
   * @param playClearSamplesWithoutKeys Encrypted media may contain clear (un-encrypted) regions.
   *     For example a media file may start with a short clear region so as to allow playback to
   *     begin in parallel with key acquisition. This parameter specifies whether the renderer is
   *     permitted to play clear regions of encrypted media files before {@code drmSessionManager}
   *     has obtained the keys necessary to decrypt encrypted regions of the media.
   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
   *     null if delivery of events is not required.
   * @param eventListener A listener of events. May be null if delivery of events is not required.
   */
  public MediaCodecAudioTrackRenderer(MediaCodecSelector mediaCodecSelector,
      DrmSessionManager drmSessionManager, boolean playClearSamplesWithoutKeys,
      Handler eventHandler, EventListener eventListener) {
    this(mediaCodecSelector, drmSessionManager, playClearSamplesWithoutKeys, eventHandler,
        eventListener, null, AudioManager.STREAM_MUSIC);
  }

  /**
   * @param mediaCodecSelector A decoder selector.
   * @param drmSessionManager For use with encrypted content. May be null if support for encrypted
   *     content is not required.
   * @param playClearSamplesWithoutKeys Encrypted media may contain clear (un-encrypted) regions.
   *     For example a media file may start with a short clear region so as to allow playback to
   *     begin in parallel with key acquisition. This parameter specifies whether the renderer is
   *     permitted to play clear regions of encrypted media files before {@code drmSessionManager}
   *     has obtained the keys necessary to decrypt encrypted regions of the media.
   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
   *     null if delivery of events is not required.
   * @param eventListener A listener of events. May be null if delivery of events is not required.
   * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
   *     default capabilities (no encoded audio passthrough support) should be assumed.
   * @param streamType The type of audio stream for the {@link AudioTrack}.
   */
  public MediaCodecAudioTrackRenderer(MediaCodecSelector mediaCodecSelector,
      DrmSessionManager drmSessionManager, boolean playClearSamplesWithoutKeys,
      Handler eventHandler, EventListener eventListener, AudioCapabilities audioCapabilities,
      int streamType) {
    super(mediaCodecSelector, drmSessionManager, playClearSamplesWithoutKeys, eventHandler,
        eventListener);
    this.eventListener = eventListener;
    this.audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
    this.audioTrack = new AudioTrack(audioCapabilities, streamType);
  }

  @Override
  protected int supportsFormat(MediaCodecSelector mediaCodecSelector, MediaFormat mediaFormat)
      throws DecoderQueryException {
    String mimeType = mediaFormat.mimeType;
    if (!MimeTypes.isAudio(mimeType)) {
      return TrackRenderer.FORMAT_UNSUPPORTED_TYPE;
    }
    if (allowPassthrough(mimeType) && mediaCodecSelector.getPassthroughDecoderName() != null) {
      return TrackRenderer.FORMAT_HANDLED;
    }
    // TODO[REFACTOR]: Propagate requiresSecureDecoder to this point. Note that we need to check
    // that the drm session can make use of a secure decoder, as well as that a secure decoder
    // exists.
    DecoderInfo decoderInfo = mediaCodecSelector.getDecoderInfo(mediaFormat.mimeType, false);
    if (decoderInfo == null) {
      return TrackRenderer.FORMAT_UNSUPPORTED_TYPE;
    }
    if (Util.SDK_INT >= 21) {
      // Note: We assume support in the case that the sampleRate or channelCount is unknown.
      if (mediaFormat.sampleRate != MediaFormat.NO_VALUE
          && !decoderInfo.isAudioSampleRateSupportedV21(mediaFormat.sampleRate)) {
        return TrackRenderer.FORMAT_EXCEEDS_CAPABILITIES;
      }
      if (mediaFormat.channelCount != MediaFormat.NO_VALUE
          && !decoderInfo.isAudioChannelCountSupportedV21(mediaFormat.channelCount)) {
        return TrackRenderer.FORMAT_EXCEEDS_CAPABILITIES;
      }
    }
    return TrackRenderer.FORMAT_HANDLED;
  }

  @Override
  protected DecoderInfo getDecoderInfo(MediaCodecSelector mediaCodecSelector, MediaFormat format,
      boolean requiresSecureDecoder) throws DecoderQueryException {
    if (allowPassthrough(format.mimeType)) {
      String passthroughDecoderName = mediaCodecSelector.getPassthroughDecoderName();
      if (passthroughDecoderName != null) {
        passthroughEnabled = true;
        return new DecoderInfo(passthroughDecoderName);
      }
    }
    passthroughEnabled = false;
    return super.getDecoderInfo(mediaCodecSelector, format, requiresSecureDecoder);
  }

  /**
   * Returns whether encoded audio passthrough should be used for playing back the input format.
   * This implementation returns true if the {@link AudioTrack}'s audio capabilities indicate that
   * passthrough is supported.
   *
   * @param mimeType The type of input media.
   * @return True if passthrough playback should be used. False otherwise.
   */
  protected boolean allowPassthrough(String mimeType) {
    return audioTrack.isPassthroughSupported(mimeType);
  }

  @Override
  protected void configureCodec(MediaCodec codec, MediaFormat format, MediaCrypto crypto) {
    if (passthroughEnabled) {
      // Override the MIME type used to configure the codec if we are using a passthrough decoder.
      passthroughMediaFormat = format.getFrameworkMediaFormatV16();
      passthroughMediaFormat.setString(android.media.MediaFormat.KEY_MIME, MimeTypes.AUDIO_RAW);
      codec.configure(passthroughMediaFormat, null, crypto, 0);
      passthroughMediaFormat.setString(android.media.MediaFormat.KEY_MIME, format.mimeType);
    } else {
      codec.configure(format.getFrameworkMediaFormatV16(), null, crypto, 0);
      passthroughMediaFormat = null;
    }
  }

  @Override
  protected MediaClock getMediaClock() {
    return this;
  }

  @Override
  protected void onOutputFormatChanged(android.media.MediaFormat outputFormat) {
    boolean passthrough = passthroughMediaFormat != null;
    audioTrack.configure(passthrough ? passthroughMediaFormat : outputFormat, passthrough);
  }

  /**
   * Invoked when the audio session id becomes known. Once the id is known it will not change
   * (and hence this method will not be invoked again) unless the renderer is disabled and then
   * subsequently re-enabled.
   * <p>
   * The default implementation is a no-op. One reason for overriding this method would be to
   * instantiate and enable a {@link Virtualizer} in order to spatialize the audio channels. For
   * this use case, any {@link Virtualizer} instances should be released in {@link #onDisabled()}
   * (if not before).
   *
   * @param audioSessionId The audio session id.
   */
  protected void onAudioSessionId(int audioSessionId) {
    // Do nothing.
  }

  @Override
  protected void onStarted() {
    super.onStarted();
    audioTrack.play();
  }

  @Override
  protected void onStopped() {
    audioTrack.pause();
    super.onStopped();
  }

  @Override
  protected boolean isEnded() {
    return super.isEnded() && !audioTrack.hasPendingData();
  }

  @Override
  protected boolean isReady() {
    return audioTrack.hasPendingData() || super.isReady();
  }

  @Override
  public long getPositionUs() {
    long newCurrentPositionUs = audioTrack.getCurrentPositionUs(isEnded());
    if (newCurrentPositionUs != AudioTrack.CURRENT_POSITION_NOT_SET) {
      currentPositionUs = allowPositionDiscontinuity ? newCurrentPositionUs
          : Math.max(currentPositionUs, newCurrentPositionUs);
      allowPositionDiscontinuity = false;
    }
    return currentPositionUs;
  }

  @Override
  protected void onDisabled() throws ExoPlaybackException {
    audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
    try {
      audioTrack.release();
    } finally {
      super.onDisabled();
    }
  }

  @Override
  protected void onReset(long positionUs) throws ExoPlaybackException {
    super.onReset(positionUs);
    audioTrack.reset();
    currentPositionUs = positionUs;
    allowPositionDiscontinuity = true;
  }

  @Override
  protected boolean processOutputBuffer(long positionUs, long elapsedRealtimeUs, MediaCodec codec,
      ByteBuffer buffer, MediaCodec.BufferInfo bufferInfo, int bufferIndex, boolean shouldSkip)
      throws ExoPlaybackException {
    if (shouldSkip) {
      codec.releaseOutputBuffer(bufferIndex, false);
      codecCounters.skippedOutputBufferCount++;
      audioTrack.handleDiscontinuity();
      return true;
    }

    if (!audioTrack.isInitialized()) {
      // Initialize the AudioTrack now.
      try {
        if (audioSessionId != AudioTrack.SESSION_ID_NOT_SET) {
          audioTrack.initialize(audioSessionId);
        } else {
          audioSessionId = audioTrack.initialize();
          onAudioSessionId(audioSessionId);
        }
        audioTrackHasData = false;
      } catch (AudioTrack.InitializationException e) {
        notifyAudioTrackInitializationError(e);
        throw new ExoPlaybackException(e);
      }
      if (getState() == TrackRenderer.STATE_STARTED) {
        audioTrack.play();
      }
    } else {
      // Check for AudioTrack underrun.
      boolean audioTrackHadData = audioTrackHasData;
      audioTrackHasData = audioTrack.hasPendingData();
      if (audioTrackHadData && !audioTrackHasData && getState() == TrackRenderer.STATE_STARTED) {
        long elapsedSinceLastFeedMs = SystemClock.elapsedRealtime() - lastFeedElapsedRealtimeMs;
        long bufferSizeUs = audioTrack.getBufferSizeUs();
        long bufferSizeMs = bufferSizeUs == C.UNKNOWN_TIME_US ? -1 : bufferSizeUs / 1000;
        notifyAudioTrackUnderrun(audioTrack.getBufferSize(), bufferSizeMs, elapsedSinceLastFeedMs);
      }
    }

    int handleBufferResult;
    try {
      handleBufferResult = audioTrack.handleBuffer(
          buffer, bufferInfo.offset, bufferInfo.size, bufferInfo.presentationTimeUs);
      lastFeedElapsedRealtimeMs = SystemClock.elapsedRealtime();
    } catch (AudioTrack.WriteException e) {
      notifyAudioTrackWriteError(e);
      throw new ExoPlaybackException(e);
    }

    // If we are out of sync, allow currentPositionUs to jump backwards.
    if ((handleBufferResult & AudioTrack.RESULT_POSITION_DISCONTINUITY) != 0) {
      handleAudioTrackDiscontinuity();
      allowPositionDiscontinuity = true;
    }

    // Release the buffer if it was consumed.
    if ((handleBufferResult & AudioTrack.RESULT_BUFFER_CONSUMED) != 0) {
      codec.releaseOutputBuffer(bufferIndex, false);
      codecCounters.renderedOutputBufferCount++;
      return true;
    }

    return false;
  }

  @Override
  protected void onOutputStreamEnded() {
    audioTrack.handleEndOfStream();
  }

  protected void handleAudioTrackDiscontinuity() {
    // Do nothing
  }

  @Override
  public void handleMessage(int messageType, Object message) throws ExoPlaybackException {
    switch (messageType) {
      case MSG_SET_VOLUME:
        audioTrack.setVolume((Float) message);
        break;
      case MSG_SET_PLAYBACK_PARAMS:
        audioTrack.setPlaybackParams((PlaybackParams) message);
        break;
      default:
        super.handleMessage(messageType, message);
        break;
    }
  }

  private void notifyAudioTrackInitializationError(final AudioTrack.InitializationException e) {
    if (eventHandler != null && eventListener != null) {
      eventHandler.post(new Runnable() {
        @Override
        public void run() {
          eventListener.onAudioTrackInitializationError(e);
        }
      });
    }
  }

  private void notifyAudioTrackWriteError(final AudioTrack.WriteException e) {
    if (eventHandler != null && eventListener != null) {
      eventHandler.post(new Runnable()  {
        @Override
        public void run() {
          eventListener.onAudioTrackWriteError(e);
        }
      });
    }
  }

  private void notifyAudioTrackUnderrun(final int bufferSize, final long bufferSizeMs,
      final long elapsedSinceLastFeedMs) {
    if (eventHandler != null && eventListener != null) {
      eventHandler.post(new Runnable()  {
        @Override
        public void run() {
          eventListener.onAudioTrackUnderrun(bufferSize, bufferSizeMs, elapsedSinceLastFeedMs);
        }
      });
    }
  }

}