import { EventEmitter2 } from 'eventemitter2';
import {
  stopStream,
  stopTrack,
  silentConsole,
} from '/imports/ui/services/webrtc-base/utils';

export default class WebRtcPeer extends EventEmitter2 {
  constructor(mode, options = {}) {
    super({ newListener: true });

    this.mode = mode;
    this.options = options;
    this.peerConnection = this.options.peerConnection;
    this.videoStream = this.options.videoStream;
    this.audioStream = this.options.audioStream;
    this.mediaConstraints = this.options.mediaConstraints;
    this.trace = this.options.trace;
    this.configuration = this.options.configuration;
    this.onicecandidate = this.options.onicecandidate;
    this.oncandidategatheringdone = this.options.oncandidategatheringdone;
    // this.networkPriorities: <{
    //  audio: <'very-low' | 'low' | 'medium' | 'high' | undefined>
    //  video: <'very-low' | 'low' | 'medium' | 'high' | undefined>
    // } | undefined >
    this.networkPriorities = this.options.networkPriorities;

    this.candidateGatheringDone = false;

    this._outboundCandidateQueue = [];
    this._inboundCandidateQueue = [];
    this._waitForGatheringPromise = null;
    this._waitForGatheringTimeout = null;

    this._handleIceCandidate = this._handleIceCandidate.bind(this);
    this._handleSignalingStateChange = this._handleSignalingStateChange.bind(this);
    this._gatheringTimeout = this.options.gatheringTimeout;

    this._assignOverrides();
  }

  _assignOverrides() {
    if (typeof this.onicecandidate === 'function') {
      this.on('icecandidate', this.onicecandidate);
    }
    if (typeof this.oncandidategatheringdone === 'function') {
      this.on('candidategatheringdone', this.oncandidategatheringdone);
    }
    if (typeof this.options.mediaStreamFactory === 'function') {
      this._mediaStreamFactory = this.options.mediaStreamFactory.bind(this);
    }
  }

  _processEncodingOptions() {
    this.peerConnection?.getSenders().forEach((sender) => {
      const { track } = sender;
      if (track) {
        // TODO: this is not ideal and a bit anti-spec. The correct thing to do
        // would be to set this in the transceiver creation via sendEncodings in
        // addTransceiver, but FF doesn't support that. So we should split this
        // between Chromium/WebKit (addTransceiver) and FF (this way) later - prlanzarin
        const parameters = sender.getParameters();
        // The encoder parameters might not be up yet; if that's the case,
        // add a filler object so we can alter the parameters anyways
        if (parameters.encodings == null || parameters.encodings.length === 0) {
          parameters.encodings = [{}];
        }

        parameters.encodings.forEach((encoding) => {
          // networkPriority
          if (this.networkPriorities && this.networkPriorities[track.kind]) {
            // eslint-disable-next-line no-param-reassign
            encoding.networkPriority = this.networkPriorities[track.kind];
          }

          // Add further custom encoding parameters here
        });

        try {
          sender.setParameters(parameters);
        } catch (error) {
          this.logger.error('BBB::WebRtcPeer::_processEncodingOptions - setParameters failed', error);
        }
      }
    });
  }

  _flushInboundCandidateQueue() {
    while (this._inboundCandidateQueue.length) {
      const entry = this._inboundCandidateQueue.shift();
      if (entry.candidate && entry.promise) {
        try {
          if (this.isPeerConnectionClosed()) {
            entry.promise.resolve();
          } else {
            this.peerConnection.addIceCandidate(entry.candidate)
              .then(entry.promise.resolve)
              .catch(entry.promise.reject);
          }
        } catch (error) {
          entry.promise.reject(error);
        }
      }
    }
  }

  _trackQueueFlushEvents() {
    this.on('newListener', (event) => {
      if (event === 'icecandidate' || event === 'candidategatheringdone') {
        while (this._outboundCandidateQueue.length) {
          const candidate = this._outboundCandidateQueue.shift();

          if (!candidate) this._emitCandidateGatheringDone();
        }
      }
    });

    this.peerConnection?.addEventListener('signalingstatechange', this._handleSignalingStateChange);
  }

  _emitCandidateGatheringDone() {
    if (!this.candidateGatheringDone) {
      this.emit('candidategatheringdone');
      this.candidateGatheringDone = true;
    }
  }

  _handleIceCandidate({ candidate }) {
    if (this.hasListeners('icecandidate') || this.hasListeners('candidategatheringdone')) {
      if (candidate) {
        this.emit('icecandidate', candidate);
        this.candidateGatheringDone = false;
      } else this._emitCandidateGatheringDone();
    } else if (!this.candidateGatheringDone) {
      this._outboundCandidateQueue.push(candidate);
      if (!candidate) this.candidateGatheringDone = true;
    }
  }

  _handleSignalingStateChange() {
    if (this.peerConnection?.signalingState === 'stable') {
      this._flushInboundCandidateQueue();
    }
  }

  waitForGathering(timeout = 0) {
    if (timeout <= 0) return Promise.resolve();
    if (this.isPeerConnectionClosed()) throw new Error('PeerConnection is closed');
    if (this.peerConnection.iceGatheringState === 'complete') return Promise.resolve();
    if (this._waitForGatheringPromise) return this._waitForGatheringPromise;

    this._waitForGatheringPromise = new Promise((resolve) => {
      this.once('candidategatheringdone', resolve);
      this._waitForGatheringTimeout = setTimeout(() => {
        this._emitCandidateGatheringDone();
      }, timeout);
    });

    return this._waitForGatheringPromise;
  }

  _setRemoteDescription(rtcSessionDescription) {
    if (this.isPeerConnectionClosed()) {
      this.logger.error('BBB::WebRtcPeer::_setRemoteDescription - peer connection closed');
      throw new Error('Peer connection is closed');
    }

    this.logger.debug('BBB::WebRtcPeer::_setRemoteDescription - setting remote description', rtcSessionDescription);
    return this.peerConnection.setRemoteDescription(rtcSessionDescription);
  }

  _setLocalDescription(rtcSessionDescription) {
    if (this.isPeerConnectionClosed()) {
      this.logger.error('BBB::WebRtcPeer::_setLocalDescription - peer connection closed');
      throw new Error('Peer connection is closed');
    }

    if (typeof this._gatheringTimeout === 'number' && this._gatheringTimeout > 0) {
      this.logger.debug('BBB::WebRtcPeer::_setLocalDescription - setting description with gathering timer', rtcSessionDescription, this._gatheringTimeout);
      return this.peerConnection.setLocalDescription(rtcSessionDescription)
        .then(() => this.waitForGathering(this._gatheringTimeout));
    }

    this.logger.debug('BBB::WebRtcPeer::_setLocalDescription- setting description', rtcSessionDescription);
    return this.peerConnection.setLocalDescription(rtcSessionDescription);
  }

  // Public method can be overridden via options
  mediaStreamFactory() {
    if (this.videoStream || this.audioStream) {
      return Promise.resolve();
    }

    const handleGUMResolution = (stream) => {
      if (stream.getAudioTracks().length > 0) {
        this.audioStream = stream;
        this.logger.debug('BBB::WebRtcPeer::mediaStreamFactory - generated audio', this.audioStream);
      }
      if (stream.getVideoTracks().length > 0) {
        this.videoStream = stream;
        this.logger.debug('BBB::WebRtcPeer::mediaStreamFactory - generated video', this.videoStream);
      }

      return stream;
    }

    if (typeof this._mediaStreamFactory === 'function') {
      return this._mediaStreamFactory(this.mediaConstraints).then(handleGUMResolution);
    }

    this.logger.info('BBB::WebRtcPeer::mediaStreamFactory - running default factory', this.mediaConstraints);

    return navigator.mediaDevices.getUserMedia(this.mediaConstraints)
      .then(handleGUMResolution)
      .catch((error) => {
        this.logger.error('BBB::WebRtcPeer::mediaStreamFactory - gUM failed', error);
        throw error;
      });
  }

  set peerConnection(pc) {
    this._pc = pc;
  }

  get peerConnection() {
    return this._pc;
  }

  get logger() {
    if (this.trace) return console;
    return silentConsole;
  }

  getLocalSessionDescriptor() {
    return this.peerConnection?.localDescription;
  }

  getRemoteSessionDescriptor() {
    return this.peerConnection?.remoteDescription;
  }

  getLocalStream() {
    if (this.peerConnection) {
      if (this.localStream == null) this.localStream = new MediaStream();
      const senders = this.peerConnection.getSenders();
      const oldTracks = this.localStream.getTracks();

      senders.forEach(({ track }) => {
        if (track && !oldTracks.includes(track)) {
          this.localStream.addTrack(track);
        }
      });

      oldTracks.forEach((oldTrack) => {
        if (!senders.some(({ track }) => track && track.id === oldTrack.id)) {
          this.localStream.removeTrack(oldTrack);
        }
      });

      return this.localStream;
    }

    return null;
  }

  getRemoteStream() {
    if (this.remoteStream) {
      return this.remoteStream;
    }

    if (this.peerConnection) {
      this.remoteStream = new MediaStream();
      this.peerConnection.getReceivers().forEach(({ track }) => {
        if (track) {
          this.remoteStream.addTrack(track);
        }
      });
      return this.remoteStream;
    }

    return null;
  }

  isPeerConnectionClosed() {
    return !this.peerConnection || this.peerConnection.signalingState === 'closed';
  }

  start() {
    // Init PeerConnection
    if (!this.peerConnection) {
      this.peerConnection = new RTCPeerConnection(this.configuration);
    }

    if (this.isPeerConnectionClosed()) {
      this.logger.trace('BBB::WebRtcPeer::start - peer connection closed');
      throw new Error('Invalid peer state: closed');
    }

    this.peerConnection.addEventListener('icecandidate', this._handleIceCandidate);
    this._trackQueueFlushEvents();
  }

  addIceCandidate(iceCandidate) {
    const candidate = new RTCIceCandidate(iceCandidate);

    switch (this.peerConnection?.signalingState) {
      case 'closed':
        this.logger.trace('BBB::WebRtcPeer::addIceCandidate - peer connection closed');
        throw new Error('PeerConnection object is closed');
      case 'stable': {
        if (this.peerConnection.remoteDescription) {
          this.logger.debug('BBB::WebRtcPeer::addIceCandidate - adding candidate', candidate);
          return this.peerConnection.addIceCandidate(candidate);
        }
      }
      // eslint-ignore-next-line no-fallthrough
      default: {
        this.logger.debug('BBB::WebRtcPeer::addIceCandidate - buffering inbound candidate', candidate);
        const promise = new Promise();
        this._inboundCandidateQueue.push({
          candidate,
          promise,
        });
        return promise;
      }
    }
  }

  async generateOffer() {
    switch (this.mode) {
      case 'recvonly': {
        const useAudio = this.mediaConstraints
        && ((typeof this.mediaConstraints.audio === 'boolean' && this.mediaConstraints.audio)
          || (typeof this.mediaConstraints.audio === 'object'));
        const useVideo = this.mediaConstraints
        && ((typeof this.mediaConstraints.video === 'boolean' && this.mediaConstraints.video)
          || (typeof this.mediaConstraints.video === 'object'));

        if (useAudio) {
          this.peerConnection.addTransceiver('audio', {
            direction: 'recvonly',
          });
        }

        if (useVideo) {
          this.peerConnection.addTransceiver('video', {
            direction: 'recvonly',
          });
        }
        break;
      }

      case 'sendonly':
      case 'sendrecv': {
        await this.mediaStreamFactory();

        if (this.videoStream) {
          this.videoStream.getTracks().forEach((track) => {
            this.peerConnection.addTrack(track, this.videoStream);
          });
        }

        if (this.audioStream) {
          this.audioStream.getTracks().forEach((track) => {
            this.peerConnection.addTrack(track, this.audioStream);
          });
        }

        this.peerConnection.getTransceivers().forEach((transceiver) => {
          // eslint-disable-next-line no-param-reassign
          transceiver.direction = this.mode;
        });
        break;
      }

      default:
        break;
    }

    return this.peerConnection.createOffer()
      .then((offer) => {
        this.logger.debug('BBB::WebRtcPeer::generateOffer - created offer', offer);
        return this._setLocalDescription(offer);
      })
      .then(() => {
        this._processEncodingOptions();
        const localDescription = this.getLocalSessionDescriptor();
        this.logger.debug('BBB::WebRtcPeer::generateOffer - local description set', localDescription);
        return localDescription.sdp;
      });
  }

  processAnswer(sdp) {
    const answer = new RTCSessionDescription({
      type: 'answer',
      sdp,
    });

    return this._setRemoteDescription(answer);
  }

  processOffer(sdp) {
    const offer = new RTCSessionDescription({
      type: 'offer',
      sdp,
    });

    return this._setRemoteDescription(offer)
      .then(async () => {
        if (this.mode === 'sendonly' || this.mode === 'sendrecv') {
          await this.mediaStreamFactory();

          if (this.videoStream) {
            this.videoStream.getTracks().forEach((track) => {
              this.peerConnection.addTrack(track, this.videoStream);
            });
          }

          if (this.audioStream) {
            this.audioStream.getTracks().forEach((track) => {
              this.peerConnection.addTrack(track, this.audioStream);
            });
          }

          this.peerConnection.getTransceivers().forEach((transceiver) => {
            // eslint-disable-next-line no-param-reassign
            transceiver.direction = this.mode;
          });
        }
      })
      .then(() => this.peerConnection.createAnswer())
      .then((answer) => {
        this.logger.debug('BBB::WebRtcPeer::processOffer - created answer', answer);
        return this._setLocalDescription(answer);
      })
      .then(() => {
        const localDescription = this.getLocalSessionDescriptor();
        this.logger.debug('BBB::WebRtcPeer::processOffer - local description set', localDescription.sdp);
        return localDescription.sdp;
      });
  }

  dispose() {
    this.logger.debug('BBB::WebRtcPeer::dispose');

    try {
      if (this.peerConnection) {
        this.peerConnection.getSenders().forEach(({ track }) => stopTrack(track));
        if (!this.isPeerConnectionClosed()) this.peerConnection.close();
        this.peerConnection = null;
      }

      if (this.localStream) {
        stopStream(this.localStream);
        this.localStream = null;
      }

      if (this.remoteStream) {
        stopStream(this.remoteStream);
        this.remoteStream = null;
      }

      this._outboundCandidateQueue = [];
      this.candidateGatheringDone = false;

      if (this._waitForGatheringPromise) this._waitForGatheringPromise = null;
      if (this._waitForGatheringTimeout) {
        clearTimeout(this._waitForGatheringTimeout);
        this._waitForGatheringTimeout = null;
      }
    } catch (error) {
      this.logger.trace('BBB::WebRtcPeer::dispose - failed', error);
    }

    this.removeAllListeners();
  }
}