/*
 *  Copyright 2014 The WebRTC Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

package org.appspot.apprtc;

import android.content.Context;
import android.util.Log;

import org.appspot.apprtc.AppRTCClient.SignalingParameters;
import org.appspot.apprtc.util.LooperExecutor;
import org.webrtc.CameraEnumerationAndroid;
import org.webrtc.DataChannel;
import org.webrtc.IceCandidate;
import org.webrtc.Logging;
import org.webrtc.MediaCodecVideoEncoder;
import org.webrtc.MediaConstraints;
import org.webrtc.MediaConstraints.KeyValuePair;
import org.webrtc.MediaStream;
import org.webrtc.PeerConnection;
import org.webrtc.PeerConnection.IceConnectionState;
import org.webrtc.PeerConnectionFactory;
import org.webrtc.SdpObserver;
import org.webrtc.SessionDescription;
import org.webrtc.StatsObserver;
import org.webrtc.StatsReport;
import org.webrtc.VideoCapturerAndroid;
import org.webrtc.VideoRenderer;
import org.webrtc.VideoSource;
import org.webrtc.VideoTrack;
import org.webrtc.voiceengine.WebRtcAudioManager;

import java.util.EnumSet;
import java.util.LinkedList;
import java.util.Timer;
import java.util.TimerTask;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.microedition.khronos.egl.EGLContext;

/**
 * Peer connection client implementation.
 *
 * <p>All public methods are routed to local looper thread.
 * All PeerConnectionEvents callbacks are invoked from the same looper thread.
 * This class is a singleton.
 */
public class PeerConnectionClient {
  public static final String VIDEO_TRACK_ID = "ARDAMSv0";
  public static final String AUDIO_TRACK_ID = "ARDAMSa0";
  private static final String TAG = "PCRTCClient";
  private static final String FIELD_TRIAL_AUTOMATIC_RESIZE =
      "WebRTC-MediaCodecVideoEncoder-AutomaticResize/Enabled/";
  private static final String VIDEO_CODEC_VP8 = "VP8";
  private static final String VIDEO_CODEC_VP9 = "VP9";
  private static final String VIDEO_CODEC_H264 = "H264";
  private static final String AUDIO_CODEC_OPUS = "opus";
  private static final String AUDIO_CODEC_ISAC = "ISAC";
  private static final String VIDEO_CODEC_PARAM_START_BITRATE =
      "x-google-start-bitrate";
  private static final String AUDIO_CODEC_PARAM_BITRATE = "maxaveragebitrate";
  private static final String AUDIO_ECHO_CANCELLATION_CONSTRAINT = "googEchoCancellation";
  private static final String AUDIO_AUTO_GAIN_CONTROL_CONSTRAINT= "googAutoGainControl";
  private static final String AUDIO_HIGH_PASS_FILTER_CONSTRAINT  = "googHighpassFilter";
  private static final String AUDIO_NOISE_SUPPRESSION_CONSTRAINT = "googNoiseSuppression";
  private static final String MAX_VIDEO_WIDTH_CONSTRAINT = "maxWidth";
  private static final String MIN_VIDEO_WIDTH_CONSTRAINT = "minWidth";
  private static final String MAX_VIDEO_HEIGHT_CONSTRAINT = "maxHeight";
  private static final String MIN_VIDEO_HEIGHT_CONSTRAINT = "minHeight";
  private static final String MAX_VIDEO_FPS_CONSTRAINT = "maxFrameRate";
  private static final String MIN_VIDEO_FPS_CONSTRAINT = "minFrameRate";
  private static final String DTLS_SRTP_KEY_AGREEMENT_CONSTRAINT = "DtlsSrtpKeyAgreement";
  private static final int HD_VIDEO_WIDTH = 1280;
  private static final int HD_VIDEO_HEIGHT = 720;
  private static final int MAX_VIDEO_WIDTH = 1280;
  private static final int MAX_VIDEO_HEIGHT = 1280;
  private static final int MAX_VIDEO_FPS = 30;

  private static final PeerConnectionClient instance = new PeerConnectionClient();
  private final PCObserver pcObserver = new PCObserver();
  private final SDPObserver sdpObserver = new SDPObserver();
  private final LooperExecutor executor;

  private PeerConnectionFactory factory;
  private PeerConnection peerConnection;
  PeerConnectionFactory.Options options = null;
  private VideoSource videoSource;
  private boolean videoCallEnabled;
  private boolean preferIsac;
  private String preferredVideoCodec;
  private boolean videoSourceStopped;
  private boolean isError;
  private Timer statsTimer;
  private VideoRenderer.Callbacks localRender;
  private VideoRenderer.Callbacks remoteRender;
  private SignalingParameters signalingParameters;
  private MediaConstraints pcConstraints;
  private MediaConstraints videoConstraints;
  private MediaConstraints audioConstraints;
  private MediaConstraints sdpMediaConstraints;
  private PeerConnectionParameters peerConnectionParameters;
  // Queued remote ICE candidates are consumed only after both local and
  // remote descriptions are set. Similarly local ICE candidates are sent to
  // remote peer after both local and remote description are set.
  private LinkedList<IceCandidate> queuedRemoteCandidates;
  private PeerConnectionEvents events;
  private boolean isInitiator;
  private SessionDescription localSdp; // either offer or answer SDP
  private MediaStream mediaStream;
  private int numberOfCameras;
  private VideoCapturerAndroid videoCapturer;
  // enableVideo is set to true if video should be rendered and sent.
  private boolean renderVideo;
  private VideoTrack localVideoTrack;
  private VideoTrack remoteVideoTrack;

  /**
   * Peer connection parameters.
   */
  public static class PeerConnectionParameters {
    public final boolean videoCallEnabled;
    public final boolean loopback;
    public final int videoWidth;
    public final int videoHeight;
    public final int videoFps;
    public final int videoStartBitrate;
    public final String videoCodec;
    public final boolean videoCodecHwAcceleration;
    public final boolean captureToTexture;
    public final int audioStartBitrate;
    public final String audioCodec;
    public final boolean noAudioProcessing;
    public final boolean useOpenSLES;

    public PeerConnectionParameters(
        boolean videoCallEnabled, boolean loopback,
        int videoWidth, int videoHeight, int videoFps, int videoStartBitrate,
        String videoCodec, boolean videoCodecHwAcceleration, boolean captureToTexture,
        int audioStartBitrate, String audioCodec,
        boolean noAudioProcessing, boolean useOpenSLES) {
      this.videoCallEnabled = videoCallEnabled;
      this.loopback = loopback;
      this.videoWidth = videoWidth;
      this.videoHeight = videoHeight;
      this.videoFps = videoFps;
      this.videoStartBitrate = videoStartBitrate;
      this.videoCodec = videoCodec;
      this.videoCodecHwAcceleration = videoCodecHwAcceleration;
      this.captureToTexture = captureToTexture;
      this.audioStartBitrate = audioStartBitrate;
      this.audioCodec = audioCodec;
      this.noAudioProcessing = noAudioProcessing;
      this.useOpenSLES = useOpenSLES;
    }
  }

  /**
   * Peer connection events.
   */
  public static interface PeerConnectionEvents {
    /**
     * Callback fired once local SDP is created and set.
     */
    public void onLocalDescription(final SessionDescription sdp);

    /**
     * Callback fired once local Ice candidate is generated.
     */
    public void onIceCandidate(final IceCandidate candidate);

    /**
     * Callback fired once connection is established (IceConnectionState is
     * CONNECTED).
     */
    public void onIceConnected();

    /**
     * Callback fired once connection is closed (IceConnectionState is
     * DISCONNECTED).
     */
    public void onIceDisconnected();

    /**
     * Callback fired once peer connection is closed.
     */
    public void onPeerConnectionClosed();

    /**
     * Callback fired once peer connection statistics is ready.
     */
    public void onPeerConnectionStatsReady(final StatsReport[] reports);

    /**
     * Callback fired once peer connection error happened.
     */
    public void onPeerConnectionError(final String description);
  }

  private PeerConnectionClient() {
    executor = new LooperExecutor();
    // Looper thread is started once in private ctor and is used for all
    // peer connection API calls to ensure new peer connection factory is
    // created on the same thread as previously destroyed factory.
    executor.requestStart();
  }

  public static PeerConnectionClient getInstance() {
    return instance;
  }

  public void setPeerConnectionFactoryOptions(PeerConnectionFactory.Options options) {
    this.options = options;
  }

  public void createPeerConnectionFactory(
      final Context context,
      final PeerConnectionParameters peerConnectionParameters,
      final PeerConnectionEvents events) {
    this.peerConnectionParameters = peerConnectionParameters;
    this.events = events;
    videoCallEnabled = peerConnectionParameters.videoCallEnabled;
    // Reset variables to initial states.
    factory = null;
    peerConnection = null;
    preferIsac = false;
    videoSourceStopped = false;
    isError = false;
    queuedRemoteCandidates = null;
    localSdp = null; // either offer or answer SDP
    mediaStream = null;
    videoCapturer = null;
    renderVideo = true;
    localVideoTrack = null;
    remoteVideoTrack = null;
    statsTimer = new Timer();

    executor.execute(new Runnable() {
      @Override
      public void run() {
        createPeerConnectionFactoryInternal(context);
      }
    });
  }

  public void createPeerConnection(
      final EGLContext renderEGLContext,
      final VideoRenderer.Callbacks localRender,
      final VideoRenderer.Callbacks remoteRender,
      final SignalingParameters signalingParameters) {
    if (peerConnectionParameters == null) {
      Log.e(TAG, "Creating peer connection without initializing factory.");
      return;
    }
    this.localRender = localRender;
    this.remoteRender = remoteRender;
    this.signalingParameters = signalingParameters;
    executor.execute(new Runnable() {
      @Override
      public void run() {
        createMediaConstraintsInternal();
        createPeerConnectionInternal(renderEGLContext);
      }
    });
  }

  public void close() {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        closeInternal();
      }
    });
  }

  public boolean isVideoCallEnabled() {
    return videoCallEnabled;
  }

  private void createPeerConnectionFactoryInternal(Context context) {
    Log.d(TAG, "Create peer connection factory. Use video: " +
        peerConnectionParameters.videoCallEnabled);
    isError = false;

    // Initialize field trials.
    PeerConnectionFactory.initializeFieldTrials(FIELD_TRIAL_AUTOMATIC_RESIZE);

    // Check preferred video codec.
    preferredVideoCodec = VIDEO_CODEC_VP8;
    if (videoCallEnabled && peerConnectionParameters.videoCodec != null) {
      if (peerConnectionParameters.videoCodec.equals(VIDEO_CODEC_VP9)) {
        preferredVideoCodec = VIDEO_CODEC_VP9;
      } else if (peerConnectionParameters.videoCodec.equals(VIDEO_CODEC_H264)) {
        preferredVideoCodec = VIDEO_CODEC_H264;
      }
    }
    Log.d(TAG, "Pereferred video codec: " + preferredVideoCodec);

    // Check if ISAC is used by default.
    preferIsac = false;
    if (peerConnectionParameters.audioCodec != null
        && peerConnectionParameters.audioCodec.equals(AUDIO_CODEC_ISAC)) {
      preferIsac = true;
    }

    // Enable/disable OpenSL ES playback.
    if (!peerConnectionParameters.useOpenSLES) {
      Log.d(TAG, "Disable OpenSL ES audio even if device supports it");
      WebRtcAudioManager.setBlacklistDeviceForOpenSLESUsage(true /* enable */);
    } else {
      Log.d(TAG, "Allow OpenSL ES audio if device supports it");
      WebRtcAudioManager.setBlacklistDeviceForOpenSLESUsage(false);
    }

    // Create peer connection factory.
    if (!PeerConnectionFactory.initializeAndroidGlobals(context, true, true,
        peerConnectionParameters.videoCodecHwAcceleration)) {
      events.onPeerConnectionError("Failed to initializeAndroidGlobals");
    }
    factory = new PeerConnectionFactory();
    if (options != null) {
      Log.d(TAG, "Factory networkIgnoreMask option: " + options.networkIgnoreMask);
      factory.setOptions(options);
    }
    Log.d(TAG, "Peer connection factory created.");
  }

  private void createMediaConstraintsInternal() {
    // Create peer connection constraints.
    pcConstraints = new MediaConstraints();
    // Enable DTLS for normal calls and disable for loopback calls.
    if (peerConnectionParameters.loopback) {
      pcConstraints.optional.add(
          new MediaConstraints.KeyValuePair(DTLS_SRTP_KEY_AGREEMENT_CONSTRAINT, "false"));
    } else {
      pcConstraints.optional.add(
          new MediaConstraints.KeyValuePair(DTLS_SRTP_KEY_AGREEMENT_CONSTRAINT, "true"));
    }

    // Check if there is a camera on device and disable video call if not.
    numberOfCameras = CameraEnumerationAndroid.getDeviceCount();
    if (numberOfCameras == 0) {
      Log.w(TAG, "No camera on device. Switch to audio only call.");
      videoCallEnabled = false;
    }
    // Create video constraints if video call is enabled.
    if (videoCallEnabled) {
      videoConstraints = new MediaConstraints();
      int videoWidth = peerConnectionParameters.videoWidth;
      int videoHeight = peerConnectionParameters.videoHeight;

      // If VP8 HW video encoder is supported and video resolution is not
      // specified force it to HD.
      if ((videoWidth == 0 || videoHeight == 0)
          && peerConnectionParameters.videoCodecHwAcceleration
          && MediaCodecVideoEncoder.isVp8HwSupported()) {
        videoWidth = HD_VIDEO_WIDTH;
        videoHeight = HD_VIDEO_HEIGHT;
      }

      // Add video resolution constraints.
      if (videoWidth > 0 && videoHeight > 0) {
        videoWidth = Math.min(videoWidth, MAX_VIDEO_WIDTH);
        videoHeight = Math.min(videoHeight, MAX_VIDEO_HEIGHT);
        videoConstraints.mandatory.add(new KeyValuePair(
            MIN_VIDEO_WIDTH_CONSTRAINT, Integer.toString(videoWidth)));
        videoConstraints.mandatory.add(new KeyValuePair(
            MAX_VIDEO_WIDTH_CONSTRAINT, Integer.toString(videoWidth)));
        videoConstraints.mandatory.add(new KeyValuePair(
            MIN_VIDEO_HEIGHT_CONSTRAINT, Integer.toString(videoHeight)));
        videoConstraints.mandatory.add(new KeyValuePair(
            MAX_VIDEO_HEIGHT_CONSTRAINT, Integer.toString(videoHeight)));
      }

      // Add fps constraints.
      int videoFps = peerConnectionParameters.videoFps;
      if (videoFps > 0) {
        videoFps = Math.min(videoFps, MAX_VIDEO_FPS);
        videoConstraints.mandatory.add(new KeyValuePair(
            MIN_VIDEO_FPS_CONSTRAINT, Integer.toString(videoFps)));
        videoConstraints.mandatory.add(new KeyValuePair(
            MAX_VIDEO_FPS_CONSTRAINT, Integer.toString(videoFps)));
      }
    }

    // Create audio constraints.
    audioConstraints = new MediaConstraints();
    // added for audio performance measurements
    if (peerConnectionParameters.noAudioProcessing) {
      Log.d(TAG, "Disabling audio processing");
      audioConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
            AUDIO_ECHO_CANCELLATION_CONSTRAINT, "false"));
      audioConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
            AUDIO_AUTO_GAIN_CONTROL_CONSTRAINT, "false"));
      audioConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
            AUDIO_HIGH_PASS_FILTER_CONSTRAINT, "false"));
      audioConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
           AUDIO_NOISE_SUPPRESSION_CONSTRAINT , "false"));
    }
    // Create SDP constraints.
    sdpMediaConstraints = new MediaConstraints();
    sdpMediaConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
        "OfferToReceiveAudio", "true"));
    if (videoCallEnabled || peerConnectionParameters.loopback) {
      sdpMediaConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
          "OfferToReceiveVideo", "true"));
    } else {
      sdpMediaConstraints.mandatory.add(new MediaConstraints.KeyValuePair(
          "OfferToReceiveVideo", "false"));
    }
  }

  private void createPeerConnectionInternal(EGLContext renderEGLContext) {
    if (factory == null || isError) {
      Log.e(TAG, "Peerconnection factory is not created");
      return;
    }
    Log.d(TAG, "Create peer connection.");

    Log.d(TAG, "PCConstraints: " + pcConstraints.toString());
    if (videoConstraints != null) {
      Log.d(TAG, "VideoConstraints: " + videoConstraints.toString());
    }
    queuedRemoteCandidates = new LinkedList<IceCandidate>();

    if (videoCallEnabled) {
      Log.d(TAG, "EGLContext: " + renderEGLContext);
      factory.setVideoHwAccelerationOptions(renderEGLContext, renderEGLContext);
    }

    PeerConnection.RTCConfiguration rtcConfig =
        new PeerConnection.RTCConfiguration(signalingParameters.iceServers);
    // TCP candidates are only useful when connecting to a server that supports
    // ICE-TCP.
    rtcConfig.tcpCandidatePolicy = PeerConnection.TcpCandidatePolicy.DISABLED;
    rtcConfig.bundlePolicy = PeerConnection.BundlePolicy.MAXBUNDLE;
    rtcConfig.rtcpMuxPolicy = PeerConnection.RtcpMuxPolicy.REQUIRE;
    // Use ECDSA encryption.
    rtcConfig.keyType = PeerConnection.KeyType.ECDSA;

    peerConnection = factory.createPeerConnection(
        rtcConfig, pcConstraints, pcObserver);
    isInitiator = false;

    // Set default WebRTC tracing and INFO libjingle logging.
    // NOTE: this _must_ happen while |factory| is alive!
    Logging.enableTracing(
        "logcat:",
        EnumSet.of(Logging.TraceLevel.TRACE_DEFAULT),
        Logging.Severity.LS_INFO);

    mediaStream = factory.createLocalMediaStream("ARDAMS");
    if (videoCallEnabled) {
      String cameraDeviceName = CameraEnumerationAndroid.getDeviceName(0);
      String frontCameraDeviceName =
          CameraEnumerationAndroid.getNameOfFrontFacingDevice();
      if (numberOfCameras > 1 && frontCameraDeviceName != null) {
        cameraDeviceName = frontCameraDeviceName;
      }
      Log.d(TAG, "Opening camera: " + cameraDeviceName);
      videoCapturer = VideoCapturerAndroid.create(cameraDeviceName, null,
            peerConnectionParameters.captureToTexture ?  renderEGLContext : null);
      if (videoCapturer == null) {
        reportError("Failed to open camera");
        return;
      }
      mediaStream.addTrack(createVideoTrack(videoCapturer));
    }

    mediaStream.addTrack(factory.createAudioTrack(
        AUDIO_TRACK_ID,
        factory.createAudioSource(audioConstraints)));
    peerConnection.addStream(mediaStream);

    Log.d(TAG, "Peer connection created.");
  }

  private void closeInternal() {
    Log.d(TAG, "Closing peer connection.");
    statsTimer.cancel();
    if (peerConnection != null) {
      peerConnection.dispose();
      peerConnection = null;
    }
    Log.d(TAG, "Closing video source.");
    if (videoSource != null) {
      videoSource.dispose();
      videoSource = null;
    }
    Log.d(TAG, "Closing peer connection factory.");
    if (factory != null) {
      factory.dispose();
      factory = null;
    }
    options = null;
    Log.d(TAG, "Closing peer connection done.");
    events.onPeerConnectionClosed();
  }

  public boolean isHDVideo() {
    if (!videoCallEnabled) {
      return false;
    }
    int minWidth = 0;
    int minHeight = 0;
    for (KeyValuePair keyValuePair : videoConstraints.mandatory) {
      if (keyValuePair.getKey().equals("minWidth")) {
        try {
          minWidth = Integer.parseInt(keyValuePair.getValue());
        } catch (NumberFormatException e) {
          Log.e(TAG, "Can not parse video width from video constraints");
        }
      } else if (keyValuePair.getKey().equals("minHeight")) {
        try {
          minHeight = Integer.parseInt(keyValuePair.getValue());
        } catch (NumberFormatException e) {
          Log.e(TAG, "Can not parse video height from video constraints");
        }
      }
    }
    if (minWidth * minHeight >= 1280 * 720) {
      return true;
    } else {
      return false;
    }
  }

  private void getStats() {
    if (peerConnection == null || isError) {
      return;
    }
    boolean success = peerConnection.getStats(new StatsObserver() {
      @Override
      public void onComplete(final StatsReport[] reports) {
        events.onPeerConnectionStatsReady(reports);
      }
    }, null);
    if (!success) {
      Log.e(TAG, "getStats() returns false!");
    }
  }

  public void enableStatsEvents(boolean enable, int periodMs) {
    if (enable) {
      try {
        statsTimer.schedule(new TimerTask() {
          @Override
          public void run() {
            executor.execute(new Runnable() {
              @Override
              public void run() {
                getStats();
              }
            });
          }
        }, 0, periodMs);
      } catch (Exception e) {
        Log.e(TAG, "Can not schedule statistics timer", e);
      }
    } else {
      statsTimer.cancel();
    }
  }

  public void setVideoEnabled(final boolean enable) {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        renderVideo = enable;
        if (localVideoTrack != null) {
          localVideoTrack.setEnabled(renderVideo);
        }
        if (remoteVideoTrack != null) {
          remoteVideoTrack.setEnabled(renderVideo);
        }
      }
    });
  }

  public void createOffer() {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (peerConnection != null && !isError) {
          Log.d(TAG, "PC Create OFFER");
          isInitiator = true;
          peerConnection.createOffer(sdpObserver, sdpMediaConstraints);
        }
      }
    });
  }

  public void createAnswer() {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (peerConnection != null && !isError) {
          Log.d(TAG, "PC create ANSWER");
          isInitiator = false;
          peerConnection.createAnswer(sdpObserver, sdpMediaConstraints);
        }
      }
    });
  }

  public void addRemoteIceCandidate(final IceCandidate candidate) {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (peerConnection != null && !isError) {
          if (queuedRemoteCandidates != null) {
            queuedRemoteCandidates.add(candidate);
          } else {
            peerConnection.addIceCandidate(candidate);
          }
        }
      }
    });
  }

  public void setRemoteDescription(final SessionDescription sdp) {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (peerConnection == null || isError) {
          return;
        }
        String sdpDescription = sdp.description;
        if (preferIsac) {
          sdpDescription = preferCodec(sdpDescription, AUDIO_CODEC_ISAC, true);
        }
        if (videoCallEnabled) {
          sdpDescription = preferCodec(sdpDescription, preferredVideoCodec, false);
        }
        if (videoCallEnabled && peerConnectionParameters.videoStartBitrate > 0) {
          sdpDescription = setStartBitrate(VIDEO_CODEC_VP8, true,
              sdpDescription, peerConnectionParameters.videoStartBitrate);
          sdpDescription = setStartBitrate(VIDEO_CODEC_VP9, true,
              sdpDescription, peerConnectionParameters.videoStartBitrate);
          sdpDescription = setStartBitrate(VIDEO_CODEC_H264, true,
              sdpDescription, peerConnectionParameters.videoStartBitrate);
        }
        if (peerConnectionParameters.audioStartBitrate > 0) {
          sdpDescription = setStartBitrate(AUDIO_CODEC_OPUS, false,
              sdpDescription, peerConnectionParameters.audioStartBitrate);
        }
        Log.d(TAG, "Set remote SDP.");
        SessionDescription sdpRemote = new SessionDescription(
            sdp.type, sdpDescription);
        peerConnection.setRemoteDescription(sdpObserver, sdpRemote);
      }
    });
  }

  public void stopVideoSource() {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (videoSource != null && !videoSourceStopped) {
          Log.d(TAG, "Stop video source.");
          videoSource.stop();
          videoSourceStopped = true;
        }
      }
    });
  }

  public void startVideoSource() {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (videoSource != null && videoSourceStopped) {
          Log.d(TAG, "Restart video source.");
          videoSource.restart();
          videoSourceStopped = false;
        }
      }
    });
  }

  private void reportError(final String errorMessage) {
    Log.e(TAG, "Peerconnection error: " + errorMessage);
    executor.execute(new Runnable() {
      @Override
      public void run() {
        if (!isError) {
          events.onPeerConnectionError(errorMessage);
          isError = true;
        }
      }
    });
  }

  private VideoTrack createVideoTrack(VideoCapturerAndroid capturer) {
    videoSource = factory.createVideoSource(capturer, videoConstraints);

    localVideoTrack = factory.createVideoTrack(VIDEO_TRACK_ID, videoSource);
    localVideoTrack.setEnabled(renderVideo);
    localVideoTrack.addRenderer(new VideoRenderer(localRender));
    return localVideoTrack;
  }

  private static String setStartBitrate(String codec, boolean isVideoCodec,
      String sdpDescription, int bitrateKbps) {
    String[] lines = sdpDescription.split("\r\n");
    int rtpmapLineIndex = -1;
    boolean sdpFormatUpdated = false;
    String codecRtpMap = null;
    // Search for codec rtpmap in format
    // a=rtpmap:<payload type> <encoding name>/<clock rate> [/<encoding parameters>]
    String regex = "^a=rtpmap:(\\d+) " + codec + "(/\\d+)+[\r]?$";
    Pattern codecPattern = Pattern.compile(regex);
    for (int i = 0; i < lines.length; i++) {
      Matcher codecMatcher = codecPattern.matcher(lines[i]);
      if (codecMatcher.matches()) {
        codecRtpMap = codecMatcher.group(1);
        rtpmapLineIndex = i;
        break;
      }
    }
    if (codecRtpMap == null) {
      Log.w(TAG, "No rtpmap for " + codec + " codec");
      return sdpDescription;
    }
    Log.d(TAG, "Found " +  codec + " rtpmap " + codecRtpMap
        + " at " + lines[rtpmapLineIndex]);

    // Check if a=fmtp string already exist in remote SDP for this codec and
    // update it with new bitrate parameter.
    regex = "^a=fmtp:" + codecRtpMap + " \\w+=\\d+.*[\r]?$";
    codecPattern = Pattern.compile(regex);
    for (int i = 0; i < lines.length; i++) {
      Matcher codecMatcher = codecPattern.matcher(lines[i]);
      if (codecMatcher.matches()) {
        Log.d(TAG, "Found " +  codec + " " + lines[i]);
        if (isVideoCodec) {
          lines[i] += "; " + VIDEO_CODEC_PARAM_START_BITRATE
              + "=" + bitrateKbps;
        } else {
          lines[i] += "; " + AUDIO_CODEC_PARAM_BITRATE
              + "=" + (bitrateKbps * 1000);
        }
        Log.d(TAG, "Update remote SDP line: " + lines[i]);
        sdpFormatUpdated = true;
        break;
      }
    }

    StringBuilder newSdpDescription = new StringBuilder();
    for (int i = 0; i < lines.length; i++) {
      newSdpDescription.append(lines[i]).append("\r\n");
      // Append new a=fmtp line if no such line exist for a codec.
      if (!sdpFormatUpdated && i == rtpmapLineIndex) {
        String bitrateSet;
        if (isVideoCodec) {
          bitrateSet = "a=fmtp:" + codecRtpMap + " "
              + VIDEO_CODEC_PARAM_START_BITRATE + "=" + bitrateKbps;
        } else {
          bitrateSet = "a=fmtp:" + codecRtpMap + " "
              + AUDIO_CODEC_PARAM_BITRATE + "=" + (bitrateKbps * 1000);
        }
        Log.d(TAG, "Add remote SDP line: " + bitrateSet);
        newSdpDescription.append(bitrateSet).append("\r\n");
      }

    }
    return newSdpDescription.toString();
  }

  private static String preferCodec(
      String sdpDescription, String codec, boolean isAudio) {
    String[] lines = sdpDescription.split("\r\n");
    int mLineIndex = -1;
    String codecRtpMap = null;
    // a=rtpmap:<payload type> <encoding name>/<clock rate> [/<encoding parameters>]
    String regex = "^a=rtpmap:(\\d+) " + codec + "(/\\d+)+[\r]?$";
    Pattern codecPattern = Pattern.compile(regex);
    String mediaDescription = "m=video ";
    if (isAudio) {
      mediaDescription = "m=audio ";
    }
    for (int i = 0; (i < lines.length)
        && (mLineIndex == -1 || codecRtpMap == null); i++) {
      if (lines[i].startsWith(mediaDescription)) {
        mLineIndex = i;
        continue;
      }
      Matcher codecMatcher = codecPattern.matcher(lines[i]);
      if (codecMatcher.matches()) {
        codecRtpMap = codecMatcher.group(1);
        continue;
      }
    }
    if (mLineIndex == -1) {
      Log.w(TAG, "No " + mediaDescription + " line, so can't prefer " + codec);
      return sdpDescription;
    }
    if (codecRtpMap == null) {
      Log.w(TAG, "No rtpmap for " + codec);
      return sdpDescription;
    }
    Log.d(TAG, "Found " +  codec + " rtpmap " + codecRtpMap + ", prefer at "
        + lines[mLineIndex]);
    String[] origMLineParts = lines[mLineIndex].split(" ");
    if (origMLineParts.length > 3) {
      StringBuilder newMLine = new StringBuilder();
      int origPartIndex = 0;
      // Format is: m=<media> <port> <proto> <fmt> ...
      newMLine.append(origMLineParts[origPartIndex++]).append(" ");
      newMLine.append(origMLineParts[origPartIndex++]).append(" ");
      newMLine.append(origMLineParts[origPartIndex++]).append(" ");
      newMLine.append(codecRtpMap);
      for (; origPartIndex < origMLineParts.length; origPartIndex++) {
        if (!origMLineParts[origPartIndex].equals(codecRtpMap)) {
          newMLine.append(" ").append(origMLineParts[origPartIndex]);
        }
      }
      lines[mLineIndex] = newMLine.toString();
      Log.d(TAG, "Change media description: " + lines[mLineIndex]);
    } else {
      Log.e(TAG, "Wrong SDP media description format: " + lines[mLineIndex]);
    }
    StringBuilder newSdpDescription = new StringBuilder();
    for (String line : lines) {
      newSdpDescription.append(line).append("\r\n");
    }
    return newSdpDescription.toString();
  }

  private void drainCandidates() {
    if (queuedRemoteCandidates != null) {
      Log.d(TAG, "Add " + queuedRemoteCandidates.size() + " remote candidates");
      for (IceCandidate candidate : queuedRemoteCandidates) {
        peerConnection.addIceCandidate(candidate);
      }
      queuedRemoteCandidates = null;
    }
  }

  private void switchCameraInternal() {
    if (!videoCallEnabled || numberOfCameras < 2 || isError || videoCapturer == null) {
      Log.e(TAG, "Failed to switch camera. Video: " + videoCallEnabled + ". Error : "
          + isError + ". Number of cameras: " + numberOfCameras);
      return;  // No video is sent or only one camera is available or error happened.
    }
    Log.d(TAG, "Switch camera");
    videoCapturer.switchCamera(null);
  }

  public void switchCamera() {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        switchCameraInternal();
      }
    });
  }

  public void changeCaptureFormat(final int width, final int height, final int framerate) {
    executor.execute(new Runnable() {
      @Override
      public void run() {
        changeCaptureFormatInternal(width, height, framerate);
      }
    });
  }

  private void changeCaptureFormatInternal(int width, int height, int framerate) {
    if (!videoCallEnabled || isError || videoCapturer == null) {
      Log.e(TAG, "Failed to change capture format. Video: " + videoCallEnabled + ". Error : "
          + isError);
      return;
    }
    videoCapturer.onOutputFormatRequest(width, height, framerate);
  }

  // Implementation detail: observe ICE & stream changes and react accordingly.
  private class PCObserver implements PeerConnection.Observer {
    @Override
    public void onIceCandidate(final IceCandidate candidate){
      executor.execute(new Runnable() {
        @Override
        public void run() {
          events.onIceCandidate(candidate);
        }
      });
    }

    @Override
    public void onSignalingChange(
        PeerConnection.SignalingState newState) {
      Log.d(TAG, "SignalingState: " + newState);
    }

    @Override
    public void onIceConnectionChange(
        final PeerConnection.IceConnectionState newState) {
      executor.execute(new Runnable() {
        @Override
        public void run() {
          Log.d(TAG, "IceConnectionState: " + newState);
          if (newState == IceConnectionState.CONNECTED) {
            events.onIceConnected();
          } else if (newState == IceConnectionState.DISCONNECTED) {
            events.onIceDisconnected();
          } else if (newState == IceConnectionState.FAILED) {
            reportError("ICE connection failed.");
          }
        }
      });
    }

    @Override
    public void onIceGatheringChange(
      PeerConnection.IceGatheringState newState) {
      Log.d(TAG, "IceGatheringState: " + newState);
    }

    @Override
    public void onIceConnectionReceivingChange(boolean receiving) {
      Log.d(TAG, "IceConnectionReceiving changed to " + receiving);
    }

    @Override
    public void onAddStream(final MediaStream stream){
      executor.execute(new Runnable() {
        @Override
        public void run() {
          if (peerConnection == null || isError) {
            return;
          }
          if (stream.audioTracks.size() > 1 || stream.videoTracks.size() > 1) {
            reportError("Weird-looking stream: " + stream);
            return;
          }
          if (stream.videoTracks.size() == 1) {
            remoteVideoTrack = stream.videoTracks.get(0);
            remoteVideoTrack.setEnabled(renderVideo);
            remoteVideoTrack.addRenderer(new VideoRenderer(remoteRender));
          }
        }
      });
    }

    @Override
    public void onRemoveStream(final MediaStream stream){
      executor.execute(new Runnable() {
        @Override
        public void run() {
          remoteVideoTrack = null;
        }
      });
    }

    @Override
    public void onDataChannel(final DataChannel dc) {
      reportError("AppRTC doesn't use data channels, but got: " + dc.label()
          + " anyway!");
    }

    @Override
    public void onRenegotiationNeeded() {
      // No need to do anything; AppRTC follows a pre-agreed-upon
      // signaling/negotiation protocol.
    }
  }

  // Implementation detail: handle offer creation/signaling and answer setting,
  // as well as adding remote ICE candidates once the answer SDP is set.
  private class SDPObserver implements SdpObserver {
    @Override
    public void onCreateSuccess(final SessionDescription origSdp) {
      if (localSdp != null) {
        reportError("Multiple SDP create.");
        return;
      }
      String sdpDescription = origSdp.description;
      if (preferIsac) {
        sdpDescription = preferCodec(sdpDescription, AUDIO_CODEC_ISAC, true);
      }
      if (videoCallEnabled) {
        sdpDescription = preferCodec(sdpDescription, preferredVideoCodec, false);
      }
      final SessionDescription sdp = new SessionDescription(
          origSdp.type, sdpDescription);
      localSdp = sdp;
      executor.execute(new Runnable() {
        @Override
        public void run() {
          if (peerConnection != null && !isError) {
            Log.d(TAG, "Set local SDP from " + sdp.type);
            peerConnection.setLocalDescription(sdpObserver, sdp);
          }
        }
      });
    }

    @Override
    public void onSetSuccess() {
      executor.execute(new Runnable() {
        @Override
        public void run() {
          if (peerConnection == null || isError) {
            return;
          }
          if (isInitiator) {
            // For offering peer connection we first create offer and set
            // local SDP, then after receiving answer set remote SDP.
            if (peerConnection.getRemoteDescription() == null) {
              // We've just set our local SDP so time to send it.
              Log.d(TAG, "Local SDP set succesfully");
              events.onLocalDescription(localSdp);
            } else {
              // We've just set remote description, so drain remote
              // and send local ICE candidates.
              Log.d(TAG, "Remote SDP set succesfully");
              drainCandidates();
            }
          } else {
            // For answering peer connection we set remote SDP and then
            // create answer and set local SDP.
            if (peerConnection.getLocalDescription() != null) {
              // We've just set our local SDP so time to send it, drain
              // remote and send local ICE candidates.
              Log.d(TAG, "Local SDP set succesfully");
              events.onLocalDescription(localSdp);
              drainCandidates();
            } else {
              // We've just set remote SDP - do nothing for now -
              // answer will be created soon.
              Log.d(TAG, "Remote SDP set succesfully");
            }
          }
        }
      });
    }

    @Override
    public void onCreateFailure(final String error) {
      reportError("createSDP error: " + error);
    }

    @Override
    public void onSetFailure(final String error) {
      reportError("setSDP error: " + error);
    }
  }
}