/*
 * Copyright (C) 2022 Savoir-faire Linux Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this program.  If not, see
 * <https://www.gnu.org/licenses/>.
 */

import { WebRtcIceCandidate, WebRtcSdp, WebSocketMessageType } from 'jami-web-common';
import { createContext, useCallback, useContext, useEffect, useMemo, useState } from 'react';

import LoadingPage from '../components/Loading';
import { WithChildren } from '../utils/utils';
import { useAuthContext } from './AuthProvider';
import { ConversationContext } from './ConversationProvider';
import { IWebSocketContext, WebSocketContext } from './WebSocketProvider';

interface IWebRtcContext {
  iceConnectionState: RTCIceConnectionState | undefined;

  mediaDevices: Record<MediaDeviceKind, MediaDeviceInfo[]>;
  localStream: MediaStream | undefined;
  remoteStreams: readonly MediaStream[] | undefined;
  getUserMedia: () => Promise<void>;

  sendWebRtcOffer: () => Promise<void>;
  closeConnection: () => void;
}

const defaultWebRtcContext: IWebRtcContext = {
  iceConnectionState: undefined,
  mediaDevices: {
    audioinput: [],
    audiooutput: [],
    videoinput: [],
  },
  localStream: undefined,
  remoteStreams: undefined,
  getUserMedia: async () => {},
  sendWebRtcOffer: async () => {},
  closeConnection: () => {},
};

export const WebRtcContext = createContext<IWebRtcContext>(defaultWebRtcContext);

export default ({ children }: WithChildren) => {
  const { account } = useAuthContext();
  const [webRtcConnection, setWebRtcConnection] = useState<RTCPeerConnection | undefined>();
  const webSocket = useContext(WebSocketContext);

  useEffect(() => {
    if (!webRtcConnection && account) {
      const iceServers: RTCIceServer[] = [];

      if (account.getDetails()['TURN.enable'] === 'true') {
        iceServers.push({
          urls: 'turn:' + account.getDetails()['TURN.server'],
          username: account.getDetails()['TURN.username'],
          credential: account.getDetails()['TURN.password'],
        });
      }

      if (account.getDetails()['STUN.enable'] === 'true') {
        iceServers.push({
          urls: 'stun:' + account.getDetails()['STUN.server'],
        });
      }

      setWebRtcConnection(new RTCPeerConnection({ iceServers }));
    }
  }, [account, webRtcConnection]);

  if (!webRtcConnection || !webSocket) {
    return <LoadingPage />;
  }

  return (
    <WebRtcProvider webRtcConnection={webRtcConnection} webSocket={webSocket}>
      {children}
    </WebRtcProvider>
  );
};

const WebRtcProvider = ({
  children,
  webRtcConnection,
  webSocket,
}: WithChildren & {
  webRtcConnection: RTCPeerConnection;
  webSocket: IWebSocketContext;
}) => {
  const { conversation, conversationId } = useContext(ConversationContext);
  const [localStream, setLocalStream] = useState<MediaStream>();
  const [remoteStreams, setRemoteStreams] = useState<readonly MediaStream[]>();
  const [iceConnectionState, setIceConnectionState] = useState<RTCIceConnectionState | undefined>();
  const [mediaDevices, setMediaDevices] = useState<Record<MediaDeviceKind, MediaDeviceInfo[]>>(
    defaultWebRtcContext.mediaDevices
  );

  // TODO: The ICE candidate queue is used to cache candidates that were received before `setRemoteDescription` was
  //       called. This is currently necessary, because the jami-daemon is unreliable as a WebRTC signaling channel,
  //       because messages can be received with a delay or out of order. This queue is a temporary workaround that
  //       should be replaced if there is a better way to send messages with the daemon.
  //       Relevant links:
  //       - https://github.com/w3c/webrtc-pc/issues/2519#issuecomment-622055440
  //       - https://stackoverflow.com/questions/57256828/how-to-fix-invalidstateerror-cannot-add-ice-candidate-when-there-is-no-remote-s
  const [isReadyForIceCandidates, setIsReadyForIceCandidates] = useState(false);
  const [iceCandidateQueue, setIceCandidateQueue] = useState<RTCIceCandidate[]>([]);

  // TODO: This logic will have to change to support multiple people in a call
  const contactUri = useMemo(() => conversation.getFirstMember().contact.getUri(), [conversation]);

  const getMediaDevices = useCallback(async () => {
    try {
      const devices = await navigator.mediaDevices.enumerateDevices();
      const newMediaDevices: Record<MediaDeviceKind, MediaDeviceInfo[]> = {
        audioinput: [],
        audiooutput: [],
        videoinput: [],
      };

      for (const device of devices) {
        newMediaDevices[device.kind].push(device);
      }

      return newMediaDevices;
    } catch (e) {
      throw new Error('Could not get media devices', { cause: e });
    }
  }, []);

  useEffect(() => {
    if (iceConnectionState !== 'connected' && iceConnectionState !== 'completed') {
      return;
    }

    const updateMediaDevices = async () => {
      try {
        const newMediaDevices = await getMediaDevices();
        setMediaDevices(newMediaDevices);
      } catch (e) {
        console.error('Could not update media devices:', e);
      }
    };

    navigator.mediaDevices.addEventListener('devicechange', updateMediaDevices);
    updateMediaDevices();

    return () => {
      navigator.mediaDevices.removeEventListener('devicechange', updateMediaDevices);
    };
  }, [getMediaDevices, iceConnectionState]);

  const getUserMedia = useCallback(async () => {
    const devices = await getMediaDevices();

    const shouldGetAudio = devices.audioinput.length !== 0;
    const shouldGetVideo = devices.videoinput.length !== 0;

    if (!shouldGetAudio && !shouldGetVideo) {
      return;
    }

    try {
      const stream = await navigator.mediaDevices.getUserMedia({
        audio: shouldGetAudio,
        video: shouldGetVideo,
      });

      for (const track of stream.getTracks()) {
        track.enabled = false;
        webRtcConnection.addTrack(track, stream);
      }

      setLocalStream(stream);
    } catch (e) {
      throw new Error('Could not get media devices', { cause: e });
    }
  }, [webRtcConnection, getMediaDevices]);

  const sendWebRtcOffer = useCallback(async () => {
    const sdp = await webRtcConnection.createOffer({
      offerToReceiveAudio: true,
      offerToReceiveVideo: true,
    });

    const webRtcOffer: WebRtcSdp = {
      contactId: contactUri,
      conversationId: conversationId,
      sdp,
    };

    await webRtcConnection.setLocalDescription(new RTCSessionDescription(sdp));
    console.info('Sending WebRtcOffer', webRtcOffer);
    webSocket.send(WebSocketMessageType.WebRtcOffer, webRtcOffer);
  }, [webRtcConnection, webSocket, conversationId, contactUri]);

  const sendWebRtcAnswer = useCallback(async () => {
    const sdp = await webRtcConnection.createAnswer({
      offerToReceiveAudio: true,
      offerToReceiveVideo: true,
    });

    const webRtcAnswer: WebRtcSdp = {
      contactId: contactUri,
      conversationId: conversationId,
      sdp,
    };

    await webRtcConnection.setLocalDescription(new RTCSessionDescription(sdp));
    console.info('Sending WebRtcAnswer', webRtcAnswer);
    webSocket.send(WebSocketMessageType.WebRtcAnswer, webRtcAnswer);
  }, [contactUri, conversationId, webRtcConnection, webSocket]);

  /* WebSocket Listeners */

  useEffect(() => {
    const addQueuedIceCandidates = async () => {
      console.info('WebRTC remote description has been set. Ready to receive ICE candidates');
      setIsReadyForIceCandidates(true);
      if (iceCandidateQueue.length !== 0) {
        console.warn('Adding queued ICE candidates...', iceCandidateQueue);

        await Promise.all(iceCandidateQueue.map((iceCandidate) => webRtcConnection.addIceCandidate(iceCandidate)));
      }
    };

    const webRtcOfferListener = async (data: WebRtcSdp) => {
      console.info('Received event on WebRtcOffer', data);
      if (data.conversationId !== conversationId) {
        console.warn('Wrong incoming conversationId, ignoring action');
        return;
      }

      await webRtcConnection.setRemoteDescription(new RTCSessionDescription(data.sdp));
      await sendWebRtcAnswer();
      await addQueuedIceCandidates();
    };

    const webRtcAnswerListener = async (data: WebRtcSdp) => {
      console.info('Received event on WebRtcAnswer', data);
      if (data.conversationId !== conversationId) {
        console.warn('Wrong incoming conversationId, ignoring action');
        return;
      }

      await webRtcConnection.setRemoteDescription(new RTCSessionDescription(data.sdp));
      await addQueuedIceCandidates();
    };

    webSocket.bind(WebSocketMessageType.WebRtcOffer, webRtcOfferListener);
    webSocket.bind(WebSocketMessageType.WebRtcAnswer, webRtcAnswerListener);

    return () => {
      webSocket.unbind(WebSocketMessageType.WebRtcOffer, webRtcOfferListener);
      webSocket.unbind(WebSocketMessageType.WebRtcAnswer, webRtcAnswerListener);
    };
  }, [webSocket, webRtcConnection, sendWebRtcAnswer, conversationId, iceCandidateQueue]);

  useEffect(() => {
    const webRtcIceCandidateListener = async (data: WebRtcIceCandidate) => {
      if (data.conversationId !== conversationId) {
        console.warn('Wrong incoming conversationId, ignoring action');
        return;
      }

      if (!data.candidate) {
        return;
      }

      if (isReadyForIceCandidates) {
        await webRtcConnection.addIceCandidate(data.candidate);
      } else {
        console.warn(
          "Received event on WebRtcIceCandidate before 'setRemoteDescription' was called. Pushing to ICE candidates queue...",
          data
        );
        setIceCandidateQueue((v) => {
          v.push(data.candidate);
          return v;
        });
      }
    };

    webSocket.bind(WebSocketMessageType.WebRtcIceCandidate, webRtcIceCandidateListener);

    return () => {
      webSocket.unbind(WebSocketMessageType.WebRtcIceCandidate, webRtcIceCandidateListener);
    };
  }, [webRtcConnection, webSocket, conversationId, isReadyForIceCandidates]);

  /* WebRTC Listeners */

  useEffect(() => {
    const iceCandidateEventListener = (event: RTCPeerConnectionIceEvent) => {
      if (event.candidate) {
        const webRtcIceCandidate: WebRtcIceCandidate = {
          contactId: contactUri,
          conversationId: conversationId,
          candidate: event.candidate,
        };

        webSocket.send(WebSocketMessageType.WebRtcIceCandidate, webRtcIceCandidate);
      }
    };
    webRtcConnection.addEventListener('icecandidate', iceCandidateEventListener);

    return () => {
      webRtcConnection.removeEventListener('icecandidate', iceCandidateEventListener);
    };
  }, [webRtcConnection, webSocket, contactUri, conversationId]);

  useEffect(() => {
    const trackEventListener = (event: RTCTrackEvent) => {
      console.info('Received WebRTC event on track', event);
      setRemoteStreams(event.streams);
    };

    const iceConnectionStateChangeEventListener = (event: Event) => {
      console.info(`Received WebRTC event on iceconnectionstatechange: ${webRtcConnection.iceConnectionState}`, event);
      setIceConnectionState(webRtcConnection.iceConnectionState);
    };

    webRtcConnection.addEventListener('track', trackEventListener);
    webRtcConnection.addEventListener('iceconnectionstatechange', iceConnectionStateChangeEventListener);

    return () => {
      webRtcConnection.removeEventListener('track', trackEventListener);
      webRtcConnection.removeEventListener('iceconnectionstatechange', iceConnectionStateChangeEventListener);
    };
  }, [webRtcConnection]);

  const closeConnection = useCallback(() => {
    const localTracks = localStream?.getTracks();
    if (localTracks) {
      for (const track of localTracks) {
        track.stop();
      }
    }

    webRtcConnection.close();
  }, [webRtcConnection, localStream]);

  return (
    <WebRtcContext.Provider
      value={{
        iceConnectionState,
        mediaDevices,
        localStream,
        remoteStreams,
        getUserMedia,
        sendWebRtcOffer,
        closeConnection,
      }}
    >
      {children}
    </WebRtcContext.Provider>
  );
};