package eu.siacs.conversations.xmpp.jingle;

import android.content.Context;
import android.os.Build;
import android.os.Handler;
import android.os.Looper;
import android.util.Log;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.SettableFuture;

import org.webrtc.AudioSource;
import org.webrtc.AudioTrack;
import org.webrtc.Camera1Enumerator;
import org.webrtc.Camera2Enumerator;
import org.webrtc.CameraEnumerationAndroid;
import org.webrtc.CameraEnumerator;
import org.webrtc.CameraVideoCapturer;
import org.webrtc.CandidatePairChangeEvent;
import org.webrtc.DataChannel;
import org.webrtc.DefaultVideoDecoderFactory;
import org.webrtc.DefaultVideoEncoderFactory;
import org.webrtc.EglBase;
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.SurfaceTextureHelper;
import org.webrtc.VideoSource;
import org.webrtc.VideoTrack;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import eu.siacs.conversations.Config;
import eu.siacs.conversations.services.AppRTCAudioManager;

public class WebRTCWrapper {

    private static final String EXTENDED_LOGGING_TAG = WebRTCWrapper.class.getSimpleName();

    private static final int CAPTURING_RESOLUTION = 1920;
    private static final int CAPTURING_MAX_FRAME_RATE = 30;

    private final EventCallback eventCallback;
    private final AppRTCAudioManager.AudioManagerEvents audioManagerEvents = new AppRTCAudioManager.AudioManagerEvents() {
        @Override
        public void onAudioDeviceChanged(AppRTCAudioManager.AudioDevice selectedAudioDevice, Set<AppRTCAudioManager.AudioDevice> availableAudioDevices) {
            eventCallback.onAudioDeviceChanged(selectedAudioDevice, availableAudioDevices);
        }
    };
    private final Handler mainHandler = new Handler(Looper.getMainLooper());
    private VideoTrack localVideoTrack = null;
    private VideoTrack remoteVideoTrack = null;
    private final PeerConnection.Observer peerConnectionObserver = new PeerConnection.Observer() {
        @Override
        public void onSignalingChange(PeerConnection.SignalingState signalingState) {
            Log.d(EXTENDED_LOGGING_TAG, "onSignalingChange(" + signalingState + ")");
            //this is called after removeTrack or addTrack
            //and should then trigger a content-add or content-remove or something
            //https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/removeTrack
        }

        @Override
        public void onConnectionChange(PeerConnection.PeerConnectionState newState) {
            eventCallback.onConnectionChange(newState);
        }

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

        }

        @Override
        public void onSelectedCandidatePairChanged(CandidatePairChangeEvent event) {
            Log.d(Config.LOGTAG, "remote candidate selected: " + event.remote);
            Log.d(Config.LOGTAG, "local candidate selected: " + event.local);
        }

        @Override
        public void onIceConnectionReceivingChange(boolean b) {

        }

        @Override
        public void onIceGatheringChange(PeerConnection.IceGatheringState iceGatheringState) {
            Log.d(EXTENDED_LOGGING_TAG, "onIceGatheringChange(" + iceGatheringState + ")");
        }

        @Override
        public void onIceCandidate(IceCandidate iceCandidate) {
            eventCallback.onIceCandidate(iceCandidate);
        }

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

        }

        @Override
        public void onAddStream(MediaStream mediaStream) {
            Log.d(EXTENDED_LOGGING_TAG, "onAddStream(numAudioTracks=" + mediaStream.audioTracks.size() + ",numVideoTracks=" + mediaStream.videoTracks.size() + ")");
            final List<VideoTrack> videoTracks = mediaStream.videoTracks;
            if (videoTracks.size() > 0) {
                remoteVideoTrack = videoTracks.get(0);
                Log.d(Config.LOGTAG, "remote video track enabled?=" + remoteVideoTrack.enabled());
            } else {
                Log.d(Config.LOGTAG, "no remote video tracks found");
            }
        }

        @Override
        public void onRemoveStream(MediaStream mediaStream) {

        }

        @Override
        public void onDataChannel(DataChannel dataChannel) {

        }

        @Override
        public void onRenegotiationNeeded() {

        }

        @Override
        public void onAddTrack(RtpReceiver rtpReceiver, MediaStream[] mediaStreams) {
            final MediaStreamTrack track = rtpReceiver.track();
            Log.d(EXTENDED_LOGGING_TAG, "onAddTrack(kind=" + (track == null ? "null" : track.kind()) + ",numMediaStreams=" + mediaStreams.length + ")");
        }

        @Override
        public void onTrack(RtpTransceiver transceiver) {
            Log.d(EXTENDED_LOGGING_TAG, "onTrack(mid=" + transceiver.getMid() + ",media=" + transceiver.getMediaType() + ")");
        }
    };
    @Nullable
    private PeerConnection peerConnection = null;
    private AudioTrack localAudioTrack = null;
    private AppRTCAudioManager appRTCAudioManager = null;
    private Context context = null;
    private EglBase eglBase = null;
    private CapturerChoice capturerChoice;

    WebRTCWrapper(final EventCallback eventCallback) {
        this.eventCallback = eventCallback;
    }

    public void setup(final Context context, final AppRTCAudioManager.SpeakerPhonePreference speakerPhonePreference) {
        PeerConnectionFactory.initialize(
                PeerConnectionFactory.InitializationOptions.builder(context).createInitializationOptions()
        );
        this.eglBase = EglBase.create();
        this.context = context;
        mainHandler.post(() -> {
            appRTCAudioManager = AppRTCAudioManager.create(context, speakerPhonePreference);
            appRTCAudioManager.start(audioManagerEvents);
            eventCallback.onAudioDeviceChanged(appRTCAudioManager.getSelectedAudioDevice(), appRTCAudioManager.getAudioDevices());
        });
    }

    synchronized void initializePeerConnection(final Set<Media> media, final List<PeerConnection.IceServer> iceServers) throws InitializationException {
        Preconditions.checkState(this.eglBase != null);
        Preconditions.checkNotNull(media);
        Preconditions.checkArgument(media.size() > 0, "media can not be empty when initializing peer connection");
        PeerConnectionFactory peerConnectionFactory = PeerConnectionFactory.builder()
                .setVideoDecoderFactory(new DefaultVideoDecoderFactory(eglBase.getEglBaseContext()))
                .setVideoEncoderFactory(new DefaultVideoEncoderFactory(eglBase.getEglBaseContext(), true, true))
                .createPeerConnectionFactory();


        final MediaStream stream = peerConnectionFactory.createLocalMediaStream("my-media-stream");

        final Optional<CapturerChoice> optionalCapturerChoice = media.contains(Media.VIDEO) ? getVideoCapturer() : Optional.absent();

        if (optionalCapturerChoice.isPresent()) {
            this.capturerChoice = optionalCapturerChoice.get();
            final CameraVideoCapturer capturer = this.capturerChoice.cameraVideoCapturer;
            final VideoSource videoSource = peerConnectionFactory.createVideoSource(false);
            SurfaceTextureHelper surfaceTextureHelper = SurfaceTextureHelper.create("webrtc", eglBase.getEglBaseContext());
            capturer.initialize(surfaceTextureHelper, requireContext(), videoSource.getCapturerObserver());
            Log.d(Config.LOGTAG, String.format("start capturing at %dx%d@%d", capturerChoice.captureFormat.width, capturerChoice.captureFormat.height, capturerChoice.getFrameRate()));
            capturer.startCapture(capturerChoice.captureFormat.width, capturerChoice.captureFormat.height, capturerChoice.getFrameRate());

            this.localVideoTrack = peerConnectionFactory.createVideoTrack("my-video-track", videoSource);

            stream.addTrack(this.localVideoTrack);
        }


        if (media.contains(Media.AUDIO)) {
            //set up audio track
            final AudioSource audioSource = peerConnectionFactory.createAudioSource(new MediaConstraints());
            this.localAudioTrack = peerConnectionFactory.createAudioTrack("my-audio-track", audioSource);
            stream.addTrack(this.localAudioTrack);
        }


        final PeerConnection.RTCConfiguration rtcConfig = new PeerConnection.RTCConfiguration(iceServers);
        rtcConfig.tcpCandidatePolicy = PeerConnection.TcpCandidatePolicy.DISABLED; //XEP-0176 doesn't support tcp
        final PeerConnection peerConnection = peerConnectionFactory.createPeerConnection(rtcConfig, peerConnectionObserver);
        if (peerConnection == null) {
            throw new InitializationException("Unable to create PeerConnection");
        }
        peerConnection.addStream(stream);
        peerConnection.setAudioPlayout(true);
        peerConnection.setAudioRecording(true);
        this.peerConnection = peerConnection;
    }

    synchronized void close() {
        final PeerConnection peerConnection = this.peerConnection;
        final CapturerChoice capturerChoice = this.capturerChoice;
        final AppRTCAudioManager audioManager = this.appRTCAudioManager;
        final EglBase eglBase = this.eglBase;
        if (peerConnection != null) {
            dispose(peerConnection);
            this.peerConnection = null;
        }
        if (audioManager != null) {
            mainHandler.post(audioManager::stop);
        }
        this.localVideoTrack = null;
        this.remoteVideoTrack = null;
        if (capturerChoice != null) {
            try {
                capturerChoice.cameraVideoCapturer.stopCapture();
            } catch (InterruptedException e) {
                Log.e(Config.LOGTAG, "unable to stop capturing");
            }
        }
        if (eglBase != null) {
            eglBase.release();
            this.eglBase = null;
        }
    }

    private static void dispose(final PeerConnection peerConnection) {
        try {
            peerConnection.dispose();
        } catch (final IllegalStateException e) {
            Log.e(Config.LOGTAG,"unable to dispose of peer connection", e);
        }
    }

    synchronized void verifyClosed() {
        if (this.peerConnection != null
                || this.eglBase != null
                || this.localVideoTrack != null
                || this.remoteVideoTrack != null) {
            final IllegalStateException e = new IllegalStateException("WebRTCWrapper hasn't been closed properly");
            Log.e(Config.LOGTAG, "verifyClosed() failed. Going to throw", e);
            throw e;
        }
    }

    boolean isMicrophoneEnabled() {
        final AudioTrack audioTrack = this.localAudioTrack;
        if (audioTrack == null) {
            throw new IllegalStateException("Local audio track does not exist (yet)");
        }
        return audioTrack.enabled();
    }

    void setMicrophoneEnabled(final boolean enabled) {
        final AudioTrack audioTrack = this.localAudioTrack;
        if (audioTrack == null) {
            throw new IllegalStateException("Local audio track does not exist (yet)");
        }
        audioTrack.setEnabled(enabled);
    }

    boolean isVideoEnabled() {
        final VideoTrack videoTrack = this.localVideoTrack;
        if (videoTrack == null) {
            throw new IllegalStateException("Local video track does not exist");
        }
        return videoTrack.enabled();
    }

    void setVideoEnabled(final boolean enabled) {
        final VideoTrack videoTrack = this.localVideoTrack;
        if (videoTrack == null) {
            throw new IllegalStateException("Local video track does not exist");
        }
        videoTrack.setEnabled(enabled);
    }

    ListenableFuture<SessionDescription> createOffer() {
        return Futures.transformAsync(getPeerConnectionFuture(), peerConnection -> {
            final SettableFuture<SessionDescription> future = SettableFuture.create();
            peerConnection.createOffer(new CreateSdpObserver() {
                @Override
                public void onCreateSuccess(SessionDescription sessionDescription) {
                    future.set(sessionDescription);
                }

                @Override
                public void onCreateFailure(String s) {
                    future.setException(new IllegalStateException("Unable to create offer: " + s));
                }
            }, new MediaConstraints());
            return future;
        }, MoreExecutors.directExecutor());
    }

    ListenableFuture<SessionDescription> createAnswer() {
        return Futures.transformAsync(getPeerConnectionFuture(), peerConnection -> {
            final SettableFuture<SessionDescription> future = SettableFuture.create();
            peerConnection.createAnswer(new CreateSdpObserver() {
                @Override
                public void onCreateSuccess(SessionDescription sessionDescription) {
                    future.set(sessionDescription);
                }

                @Override
                public void onCreateFailure(String s) {
                    future.setException(new IllegalStateException("Unable to create answer: " + s));
                }
            }, new MediaConstraints());
            return future;
        }, MoreExecutors.directExecutor());
    }

    ListenableFuture<Void> setLocalDescription(final SessionDescription sessionDescription) {
        Log.d(EXTENDED_LOGGING_TAG, "setting local description:");
        for (final String line : sessionDescription.description.split(eu.siacs.conversations.xmpp.jingle.SessionDescription.LINE_DIVIDER)) {
            Log.d(EXTENDED_LOGGING_TAG, line);
        }
        return Futures.transformAsync(getPeerConnectionFuture(), peerConnection -> {
            final SettableFuture<Void> future = SettableFuture.create();
            peerConnection.setLocalDescription(new SetSdpObserver() {
                @Override
                public void onSetSuccess() {
                    future.set(null);
                }

                @Override
                public void onSetFailure(String s) {
                    Log.d(Config.LOGTAG, "unable to set local " + s);
                    future.setException(new IllegalArgumentException("unable to set local session description: " + s));

                }
            }, sessionDescription);
            return future;
        }, MoreExecutors.directExecutor());
    }

    ListenableFuture<Void> setRemoteDescription(final SessionDescription sessionDescription) {
        Log.d(EXTENDED_LOGGING_TAG, "setting remote description:");
        for (final String line : sessionDescription.description.split(eu.siacs.conversations.xmpp.jingle.SessionDescription.LINE_DIVIDER)) {
            Log.d(EXTENDED_LOGGING_TAG, line);
        }
        return Futures.transformAsync(getPeerConnectionFuture(), peerConnection -> {
            final SettableFuture<Void> future = SettableFuture.create();
            peerConnection.setRemoteDescription(new SetSdpObserver() {
                @Override
                public void onSetSuccess() {
                    future.set(null);
                }

                @Override
                public void onSetFailure(String s) {
                    future.setException(new IllegalArgumentException("unable to set remote session description: " + s));

                }
            }, sessionDescription);
            return future;
        }, MoreExecutors.directExecutor());
    }

    @Nonnull
    private ListenableFuture<PeerConnection> getPeerConnectionFuture() {
        final PeerConnection peerConnection = this.peerConnection;
        if (peerConnection == null) {
            return Futures.immediateFailedFuture(new IllegalStateException("initialize PeerConnection first"));
        } else {
            return Futures.immediateFuture(peerConnection);
        }
    }

    void addIceCandidate(IceCandidate iceCandidate) {
        requirePeerConnection().addIceCandidate(iceCandidate);
    }

    private CameraEnumerator getCameraEnumerator() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            return new Camera2Enumerator(requireContext());
        } else {
            return new Camera1Enumerator();
        }
    }

    private Optional<CapturerChoice> getVideoCapturer() {
        final CameraEnumerator enumerator = getCameraEnumerator();
        final String[] deviceNames = enumerator.getDeviceNames();
        for (final String deviceName : deviceNames) {
            if (enumerator.isFrontFacing(deviceName)) {
                return Optional.fromNullable(of(enumerator, deviceName));
            }
        }
        if (deviceNames.length == 0) {
            return Optional.absent();
        } else {
            return Optional.fromNullable(of(enumerator, deviceNames[0]));
        }
    }

    @Nullable
    private static CapturerChoice of(CameraEnumerator enumerator, final String deviceName) {
        final CameraVideoCapturer capturer = enumerator.createCapturer(deviceName, null);
        if (capturer == null) {
            return null;
        }
        final ArrayList<CameraEnumerationAndroid.CaptureFormat> choices = new ArrayList<>(enumerator.getSupportedFormats(deviceName));
        Collections.sort(choices, (a, b) -> b.width - a.width);
        for (final CameraEnumerationAndroid.CaptureFormat captureFormat : choices) {
            if (captureFormat.width <= CAPTURING_RESOLUTION) {
                return new CapturerChoice(capturer, captureFormat);
            }
        }
        return null;
    }

    public PeerConnection.PeerConnectionState getState() {
        return requirePeerConnection().connectionState();
    }

    EglBase.Context getEglBaseContext() {
        return this.eglBase.getEglBaseContext();
    }

    Optional<VideoTrack> getLocalVideoTrack() {
        return Optional.fromNullable(this.localVideoTrack);
    }

    Optional<VideoTrack> getRemoteVideoTrack() {
        return Optional.fromNullable(this.remoteVideoTrack);
    }

    private PeerConnection requirePeerConnection() {
        final PeerConnection peerConnection = this.peerConnection;
        if (peerConnection == null) {
            throw new IllegalStateException("initialize PeerConnection first");
        }
        return peerConnection;
    }

    private Context requireContext() {
        final Context context = this.context;
        if (context == null) {
            throw new IllegalStateException("call setup first");
        }
        return context;
    }

    AppRTCAudioManager getAudioManager() {
        return appRTCAudioManager;
    }

    public interface EventCallback {
        void onIceCandidate(IceCandidate iceCandidate);

        void onConnectionChange(PeerConnection.PeerConnectionState newState);

        void onAudioDeviceChanged(AppRTCAudioManager.AudioDevice selectedAudioDevice, Set<AppRTCAudioManager.AudioDevice> availableAudioDevices);
    }

    private static abstract class SetSdpObserver implements SdpObserver {

        @Override
        public void onCreateSuccess(org.webrtc.SessionDescription sessionDescription) {
            throw new IllegalStateException("Not able to use SetSdpObserver");
        }

        @Override
        public void onCreateFailure(String s) {
            throw new IllegalStateException("Not able to use SetSdpObserver");
        }

    }

    private static abstract class CreateSdpObserver implements SdpObserver {


        @Override
        public void onSetSuccess() {
            throw new IllegalStateException("Not able to use CreateSdpObserver");
        }


        @Override
        public void onSetFailure(String s) {
            throw new IllegalStateException("Not able to use CreateSdpObserver");
        }
    }

    static class InitializationException extends Exception {

        private InitializationException(String message) {
            super(message);
        }
    }

    private static class CapturerChoice {
        private final CameraVideoCapturer cameraVideoCapturer;
        private final CameraEnumerationAndroid.CaptureFormat captureFormat;

        CapturerChoice(CameraVideoCapturer cameraVideoCapturer, CameraEnumerationAndroid.CaptureFormat captureFormat) {
            this.cameraVideoCapturer = cameraVideoCapturer;
            this.captureFormat = captureFormat;
        }

        int getFrameRate() {
            return Math.max(captureFormat.framerate.min, Math.min(CAPTURING_MAX_FRAME_RATE, captureFormat.framerate.max));
        }
    }
}