rooms-android/app/src/main/java/com/nextcloud/talk/webrtc/PeerConnectionWrapper.java

/*
 * Nextcloud Talk application
 *
 * @author Mario Danic
 * @author Tim Krüger
 * Copyright (C) 2022 Tim Krüger <t@timkrueger.me>
 * Copyright (C) 2017 Mario Danic <mario@lovelyhq.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package com.nextcloud.talk.webrtc;

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

import com.bluelinelabs.logansquare.LoganSquare;
import com.nextcloud.talk.R;
import com.nextcloud.talk.application.NextcloudTalkApplication;
import com.nextcloud.talk.events.MediaStreamEvent;
import com.nextcloud.talk.events.PeerConnectionEvent;
import com.nextcloud.talk.events.SessionDescriptionSendEvent;
import com.nextcloud.talk.events.WebSocketCommunicationEvent;
import com.nextcloud.talk.models.json.signaling.DataChannelMessage;
import com.nextcloud.talk.models.json.signaling.DataChannelMessageNick;
import com.nextcloud.talk.models.json.signaling.NCIceCandidate;
import com.nextcloud.talk.signaling.SignalingMessageReceiver;

import org.greenrobot.eventbus.EventBus;
import org.webrtc.AudioTrack;
import org.webrtc.DataChannel;
import org.webrtc.IceCandidate;
import org.webrtc.MediaConstraints;
import org.webrtc.MediaStream;
import org.webrtc.MediaStreamTrack;
import org.webrtc.PeerConnection;
import org.webrtc.PeerConnectionFactory;
import org.webrtc.RtpReceiver;
import org.webrtc.RtpTransceiver;
import org.webrtc.SdpObserver;
import org.webrtc.SessionDescription;
import org.webrtc.VideoTrack;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Objects;

import javax.inject.Inject;

import androidx.annotation.Nullable;
import autodagger.AutoInjector;

import static java.lang.Boolean.FALSE;
import static java.lang.Boolean.TRUE;

@AutoInjector(NextcloudTalkApplication.class)
public class PeerConnectionWrapper {

    private static final String TAG = PeerConnectionWrapper.class.getCanonicalName();

    private final SignalingMessageReceiver signalingMessageReceiver;
    private final WebRtcMessageListener webRtcMessageListener = new WebRtcMessageListener();

    private List<IceCandidate> iceCandidates = new ArrayList<>();
    private PeerConnection peerConnection;
    private String sessionId;
    private String nick;
    private final MediaConstraints mediaConstraints;
    private DataChannel dataChannel;
    private final MagicSdpObserver magicSdpObserver;
    private MediaStream remoteStream;

    private final boolean hasInitiated;

    private final MediaStream localStream;
    private final boolean isMCUPublisher;
    private final String videoStreamType;

    @Inject
    Context context;

    public PeerConnectionWrapper(PeerConnectionFactory peerConnectionFactory,
                                 List<PeerConnection.IceServer> iceServerList,
                                 MediaConstraints mediaConstraints,
                                 String sessionId, String localSession, @Nullable MediaStream localStream,
                                 boolean isMCUPublisher, boolean hasMCU, String videoStreamType,
                                 SignalingMessageReceiver signalingMessageReceiver) {

        Objects.requireNonNull(NextcloudTalkApplication.Companion.getSharedApplication()).getComponentApplication().inject(this);

        this.localStream = localStream;
        this.videoStreamType = videoStreamType;

        this.sessionId = sessionId;
        this.mediaConstraints = mediaConstraints;

        magicSdpObserver = new MagicSdpObserver();
        hasInitiated = sessionId.compareTo(localSession) < 0;
        this.isMCUPublisher = isMCUPublisher;

        PeerConnection.RTCConfiguration configuration = new PeerConnection.RTCConfiguration(iceServerList);
        configuration.sdpSemantics = PeerConnection.SdpSemantics.UNIFIED_PLAN;
        peerConnection = peerConnectionFactory.createPeerConnection(configuration, new MagicPeerConnectionObserver());

        this.signalingMessageReceiver = signalingMessageReceiver;
        this.signalingMessageReceiver.addListener(webRtcMessageListener, sessionId, videoStreamType);

        if (peerConnection != null) {
            if (this.localStream != null) {
                List<String> localStreamIds = Collections.singletonList(this.localStream.getId());
                for(AudioTrack track : this.localStream.audioTracks) {
                    peerConnection.addTrack(track, localStreamIds);
                }
                for(VideoTrack track : this.localStream.videoTracks) {
                    peerConnection.addTrack(track, localStreamIds);
                }
            }

            if (hasMCU || hasInitiated) {
                DataChannel.Init init = new DataChannel.Init();
                init.negotiated = false;
                dataChannel = peerConnection.createDataChannel("status", init);
                dataChannel.registerObserver(new MagicDataChannelObserver());
                if (isMCUPublisher) {
                    peerConnection.createOffer(magicSdpObserver, mediaConstraints);
                } else if (hasMCU && this.videoStreamType.equals("video")) {
                    // If the connection type is "screen" the client sharing the screen will send an
                    // offer; offers should be requested only for videos.
                    HashMap<String, String> hashMap = new HashMap<>();
                    hashMap.put("sessionId", sessionId);
                    EventBus.getDefault().post(new WebSocketCommunicationEvent("peerReadyForRequestingOffer", hashMap));
                } else if (!hasMCU && hasInitiated) {
                    peerConnection.createOffer(magicSdpObserver, mediaConstraints);
                }
            }
        }
    }

    public String getVideoStreamType() {
        return videoStreamType;
    }

    public void removePeerConnection() {
        signalingMessageReceiver.removeListener(webRtcMessageListener);

        if (dataChannel != null) {
            dataChannel.dispose();
            dataChannel = null;
            Log.d(TAG, "Disposed DataChannel");
        } else {
            Log.d(TAG, "DataChannel is null.");
        }

        if (peerConnection != null) {
            peerConnection.close();
            peerConnection = null;
            Log.d(TAG, "Disposed PeerConnection");
        } else {
            Log.d(TAG, "PeerConnection is null.");
        }
    }

    private void drainIceCandidates() {

        if (peerConnection != null) {
            for (IceCandidate iceCandidate : iceCandidates) {
                peerConnection.addIceCandidate(iceCandidate);
            }

            iceCandidates = new ArrayList<>();
        }
    }

    private void addCandidate(IceCandidate iceCandidate) {
        if (peerConnection != null && peerConnection.getRemoteDescription() != null) {
            peerConnection.addIceCandidate(iceCandidate);
        } else {
            iceCandidates.add(iceCandidate);
        }
    }

    public void sendNickChannelData(DataChannelMessageNick dataChannelMessage) {
        ByteBuffer buffer;
        if (dataChannel != null) {
            try {
                buffer = ByteBuffer.wrap(LoganSquare.serialize(dataChannelMessage).getBytes());
                dataChannel.send(new DataChannel.Buffer(buffer, false));
            } catch (IOException e) {
                Log.d(TAG, "Failed to send channel data, attempting regular " + dataChannelMessage);
            }
        }
    }

    public void sendChannelData(DataChannelMessage dataChannelMessage) {
        ByteBuffer buffer;
        if (dataChannel != null) {
            try {
                buffer = ByteBuffer.wrap(LoganSquare.serialize(dataChannelMessage).getBytes());
                dataChannel.send(new DataChannel.Buffer(buffer, false));
            } catch (IOException e) {
                Log.d(TAG, "Failed to send channel data, attempting regular " + dataChannelMessage);
            }
        }
    }

    public PeerConnection getPeerConnection() {
        return peerConnection;
    }

    public String getSessionId() {
        return sessionId;
    }

    public String getNick() {
        if (!TextUtils.isEmpty(nick)) {
            return nick;
        } else {
            return Objects.requireNonNull(NextcloudTalkApplication.Companion.getSharedApplication()).getString(R.string.nc_nick_guest);
        }
    }

    private void setNick(String nick) {
        this.nick = nick;
    }

    private void sendInitialMediaStatus() {
        if (localStream != null) {
            if (localStream.videoTracks.size() == 1 && localStream.videoTracks.get(0).enabled()) {
                sendChannelData(new DataChannelMessage("videoOn"));
            } else {
                sendChannelData(new DataChannelMessage("videoOff"));
            }

            if (localStream.audioTracks.size() == 1 && localStream.audioTracks.get(0).enabled()) {
                sendChannelData(new DataChannelMessage("audioOn"));
            } else {
                sendChannelData(new DataChannelMessage("audioOff"));
            }
        }
    }

    public boolean isMCUPublisher() {
        return isMCUPublisher;
    }

    private boolean shouldNotReceiveVideo() {
        for (MediaConstraints.KeyValuePair keyValuePair : mediaConstraints.mandatory) {
            if ("OfferToReceiveVideo".equals(keyValuePair.getKey())) {
                return !Boolean.parseBoolean(keyValuePair.getValue());
            }
        }
        return false;
    }

    private class WebRtcMessageListener implements SignalingMessageReceiver.WebRtcMessageListener {

        public void onOffer(String sdp, String nick) {
            onOfferOrAnswer("offer", sdp, nick);
        }

        public void onAnswer(String sdp, String nick) {
            onOfferOrAnswer("answer", sdp, nick);
        }

        private void onOfferOrAnswer(String type, String sdp, String nick) {
            setNick(nick);

            SessionDescription sessionDescriptionWithPreferredCodec;

            boolean isAudio = false;
            String sessionDescriptionStringWithPreferredCodec = MagicWebRTCUtils.preferCodec(sdp, "H264", isAudio);

            sessionDescriptionWithPreferredCodec = new SessionDescription(
                SessionDescription.Type.fromCanonicalForm(type),
                sessionDescriptionStringWithPreferredCodec);

            if (getPeerConnection() != null) {
                getPeerConnection().setRemoteDescription(magicSdpObserver, sessionDescriptionWithPreferredCodec);
            }
        }

        public void onCandidate(String sdpMid, int sdpMLineIndex, String sdp) {
            IceCandidate iceCandidate = new IceCandidate(sdpMid, sdpMLineIndex, sdp);
            addCandidate(iceCandidate);
        }

        public void onEndOfCandidates() {
            drainIceCandidates();
        }
    }

    private class MagicDataChannelObserver implements DataChannel.Observer {

        @Override
        public void onBufferedAmountChange(long l) {

        }

        @Override
        public void onStateChange() {
            if (dataChannel != null && dataChannel.state() == DataChannel.State.OPEN &&
                    dataChannel.label().equals("status")) {
                sendInitialMediaStatus();
            }
        }

        @Override
        public void onMessage(DataChannel.Buffer buffer) {
            if (buffer.binary) {
                Log.d(TAG, "Received binary msg over " + TAG + " " + sessionId);
                return;
            }

            ByteBuffer data = buffer.data;
            final byte[] bytes = new byte[data.capacity()];
            data.get(bytes);
            String strData = new String(bytes);
            Log.d(TAG, "Got msg: " + strData + " over " + TAG + " " + sessionId);

            try {
                DataChannelMessage dataChannelMessage = LoganSquare.parse(strData, DataChannelMessage.class);

                String internalNick;
                if ("nickChanged".equals(dataChannelMessage.getType())) {
                    if (dataChannelMessage.getPayload() instanceof String) {
                        internalNick = (String) dataChannelMessage.getPayload();
                        if (!internalNick.equals(nick)) {
                            setNick(internalNick);
                            EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                                    .NICK_CHANGE, sessionId, getNick(), null, videoStreamType));
                        }
                    } else {
                        if (dataChannelMessage.getPayload() != null) {
                            HashMap<String, String> payloadHashMap = (HashMap<String, String>) dataChannelMessage.getPayload();
                            EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                                    .NICK_CHANGE, sessionId, payloadHashMap.get("name"), null, videoStreamType));
                        }
                    }
                } else if ("audioOn".equals(dataChannelMessage.getType())) {
                    EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                            .AUDIO_CHANGE, sessionId, null, TRUE, videoStreamType));
                } else if ("audioOff".equals(dataChannelMessage.getType())) {
                    EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                            .AUDIO_CHANGE, sessionId, null, FALSE, videoStreamType));
                } else if ("videoOn".equals(dataChannelMessage.getType())) {
                    EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                            .VIDEO_CHANGE, sessionId, null, TRUE, videoStreamType));
                } else if ("videoOff".equals(dataChannelMessage.getType())) {
                    EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                            .VIDEO_CHANGE, sessionId, null, FALSE, videoStreamType));
                }
            } catch (IOException e) {
                Log.d(TAG, "Failed to parse data channel message");
            }
        }
    }

    private class MagicPeerConnectionObserver implements PeerConnection.Observer {

        @Override
        public void onSignalingChange(PeerConnection.SignalingState signalingState) {
        }

        @Override
        public void onIceConnectionChange(PeerConnection.IceConnectionState iceConnectionState) {

            Log.d("iceConnectionChangeTo: ", iceConnectionState.name() + " over " + peerConnection.hashCode() + " " + sessionId);
            if (iceConnectionState == PeerConnection.IceConnectionState.CONNECTED) {
                EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType.PEER_CONNECTED,
                                                                   sessionId, null, null, videoStreamType));

                if (!isMCUPublisher) {
                    EventBus.getDefault().post(new MediaStreamEvent(remoteStream, sessionId, videoStreamType));
                }

                if (hasInitiated) {
                    sendInitialMediaStatus();
                }
            } else if (iceConnectionState == PeerConnection.IceConnectionState.COMPLETED) {
                EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType.PEER_CONNECTED,
                                                                   sessionId, null, null, videoStreamType));
            } else if (iceConnectionState == PeerConnection.IceConnectionState.CLOSED) {
                EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType
                        .PEER_CLOSED, sessionId, null, null, videoStreamType));
            } else if (iceConnectionState == PeerConnection.IceConnectionState.DISCONNECTED ||
                    iceConnectionState == PeerConnection.IceConnectionState.NEW ||
                    iceConnectionState == PeerConnection.IceConnectionState.CHECKING) {
                EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType.PEER_DISCONNECTED,
                                                                   sessionId, null, null, videoStreamType));
            } else if (iceConnectionState == PeerConnection.IceConnectionState.FAILED) {
                EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType.PEER_DISCONNECTED,
                                                                   sessionId, null, null, videoStreamType));
                if (isMCUPublisher) {
                    EventBus.getDefault().post(new PeerConnectionEvent(PeerConnectionEvent.PeerConnectionEventType.PUBLISHER_FAILED, sessionId, null, null, videoStreamType));
                }
            }
        }

        @Override
        public void onIceConnectionReceivingChange(boolean b) {

        }

        @Override
        public void onIceGatheringChange(PeerConnection.IceGatheringState iceGatheringState) {

        }

        @Override
        public void onIceCandidate(IceCandidate iceCandidate) {
            NCIceCandidate ncIceCandidate = new NCIceCandidate();
            ncIceCandidate.setSdpMid(iceCandidate.sdpMid);
            ncIceCandidate.setSdpMLineIndex(iceCandidate.sdpMLineIndex);
            ncIceCandidate.setCandidate(iceCandidate.sdp);
            EventBus.getDefault().post(new SessionDescriptionSendEvent(null, sessionId,
                    "candidate", ncIceCandidate, videoStreamType));
        }

        @Override
        public void onIceCandidatesRemoved(IceCandidate[] iceCandidates) {

        }

        @Override
        public void onAddStream(MediaStream mediaStream) {
            remoteStream = mediaStream;
        }

        @Override
        public void onRemoveStream(MediaStream mediaStream) {
            if (!isMCUPublisher) {
                EventBus.getDefault().post(new MediaStreamEvent(null, sessionId, videoStreamType));
            }
        }

        @Override
        public void onDataChannel(DataChannel dataChannel) {
            if (dataChannel.label().equals("status") || dataChannel.label().equals("JanusDataChannel")) {
                PeerConnectionWrapper.this.dataChannel = dataChannel;
                PeerConnectionWrapper.this.dataChannel.registerObserver(new MagicDataChannelObserver());
            }
        }

        @Override
        public void onRenegotiationNeeded() {

        }

        @Override
        public void onAddTrack(RtpReceiver rtpReceiver, MediaStream[] mediaStreams) {
        }
    }

    private class MagicSdpObserver implements SdpObserver {
        private static final String TAG = "MagicSdpObserver";

        @Override
        public void onCreateFailure(String s) {
            Log.d(TAG, "SDPObserver createFailure: " + s + " over " + peerConnection.hashCode() + " " + sessionId);

        }

        @Override
        public void onSetFailure(String s) {
            Log.d(TAG,"SDPObserver setFailure: " + s + " over " + peerConnection.hashCode() + " " + sessionId);
        }

        @Override
        public void onCreateSuccess(SessionDescription sessionDescription) {
            SessionDescription sessionDescriptionWithPreferredCodec;
            String sessionDescriptionStringWithPreferredCodec = MagicWebRTCUtils.preferCodec
                    (sessionDescription.description,
                            "H264", false);
            sessionDescriptionWithPreferredCodec = new SessionDescription(
                    sessionDescription.type,
                    sessionDescriptionStringWithPreferredCodec);


            EventBus.getDefault().post(new SessionDescriptionSendEvent(sessionDescriptionWithPreferredCodec, sessionId,
                    sessionDescription.type.canonicalForm(), null, videoStreamType));

            if (peerConnection != null) {
                peerConnection.setLocalDescription(magicSdpObserver, sessionDescriptionWithPreferredCodec);
            }
        }

        @Override
        public void onSetSuccess() {
            if (peerConnection != null) {
                if (peerConnection.getLocalDescription() == null) {

                    if (shouldNotReceiveVideo()) {
                        for (RtpTransceiver t : peerConnection.getTransceivers()) {
                            if (t.getMediaType() == MediaStreamTrack.MediaType.MEDIA_TYPE_VIDEO) {
                                t.stop();
                            }
                        }
                        Log.d(TAG, "Stop all Transceivers for MEDIA_TYPE_VIDEO.");
                    }

                    /*
                        Passed 'MediaConstraints' will be ignored by WebRTC when using UNIFIED PLAN.
                        See for details: https://docs.google.com/document/d/1PPHWV6108znP1tk_rkCnyagH9FK205hHeE9k5mhUzOg/edit#heading=h.9dcmkavg608r
                     */
                    peerConnection.createAnswer(magicSdpObserver, new MediaConstraints());

                }

                if (peerConnection.getRemoteDescription() != null) {
                    drainIceCandidates();
                }
            }
        }
    }
}