(function () {
  'use strict';

  var API = '/app/androidcast_project/sfu/api';
  var WS_PATH = '/app/androidcast_project/sfu/ws';
  var ICE = [
    { urls: 'stun:stun.l.google.com:19302' },
    { urls: 'stun:stun1.l.google.com:19302' },
  ];

  function wsUrl() {
    var proto = location.protocol === 'https:' ? 'wss:' : 'ws:';
    return proto + '//' + location.host + WS_PATH;
  }

  function log(el, msg) {
    if (!el) return;
    var line = document.createElement('div');
    line.textContent = new Date().toISOString().slice(11, 19) + ' ' + msg;
    el.prepend(line);
  }

  function JanusSession(sessionId, handleId, logEl) {
    this.sessionId = sessionId;
    this.handleId = handleId;
    this.logEl = logEl;
    this.tx = 0;
    this.ws = null;
  }

  JanusSession.prototype.tid = function () {
    this.tx += 1;
    return 'lab-' + this.tx;
  };

  JanusSession.prototype.connect = function () {
    var self = this;
    return new Promise(function (resolve, reject) {
      self.ws = new WebSocket(wsUrl());
      self.ws.onopen = function () {
        log(self.logEl, 'Janus WS open');
        self.keepalive = setInterval(function () {
          if (self.ws && self.ws.readyState === WebSocket.OPEN) {
            self.ws.send(
              JSON.stringify({
                janus: 'keepalive',
                session_id: self.sessionId,
                transaction: self.tid(),
              })
            );
          }
        }, 25000);
        resolve();
      };
      self.ws.onerror = function () {
        reject(new Error('WebSocket error'));
      };
      self.ws.onmessage = function (ev) {
        var msg;
        try {
          msg = JSON.parse(ev.data);
        } catch (e) {
          return;
        }
        if (msg.janus === 'trickle' && msg.candidate && self.onTrickle) {
          self.onTrickle(msg.candidate);
        }
        if (msg.janus === 'webrtcup') {
          log(self.logEl, 'WebRTC up');
        }
        if (msg.jsep && self.onJsep) {
          self.onJsep(msg.jsep);
        }
      };
    });
  };

  JanusSession.prototype.sendTrickle = function (candidate) {
    if (!this.ws || this.ws.readyState !== WebSocket.OPEN) return;
    this.ws.send(
      JSON.stringify({
        janus: 'trickle',
        session_id: this.sessionId,
        handle_id: this.handleId,
        transaction: this.tid(),
        candidate: candidate,
      })
    );
  };

  JanusSession.prototype.close = function () {
    if (this.keepalive) clearInterval(this.keepalive);
    if (this.ws) this.ws.close();
  };

  function wireIce(pc, janus) {
    pc.onicecandidate = function (ev) {
      if (!janus) return;
      if (ev.candidate) {
        janus.sendTrickle({
          candidate: ev.candidate.candidate,
          sdpMid: ev.candidate.sdpMid,
          sdpMLineIndex: ev.candidate.sdpMLineIndex,
        });
      } else {
        janus.sendTrickle({ completed: true });
      }
    };
    janus.onTrickle = function (c) {
      if (c.completed) return;
      pc.addIceCandidate(c).catch(function () {});
    };
  }

  async function apiJoin(body) {
    var r = await fetch(API + '/join', {
      method: 'POST',
      credentials: 'same-origin',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(body),
    });
    var j = await r.json();
    if (!j.ok) throw new Error(j.error || 'join failed');
    return j;
  }

  async function startPublisher(opts) {
    var roomId = opts.roomId;
    var videoEl = opts.videoEl;
    var logEl = opts.logEl;
    var stream = await navigator.mediaDevices.getDisplayMedia({
      video: true,
      audio: true,
    });
    videoEl.srcObject = stream;
    var pc = new RTCPeerConnection({ iceServers: ICE });
    stream.getTracks().forEach(function (t) {
      pc.addTrack(t, stream);
    });
    var offer = await pc.createOffer();
    await pc.setLocalDescription(offer);
    var join = await apiJoin({
      room_id: roomId,
      role: 'publisher',
      jsep: { type: offer.type, sdp: offer.sdp },
    });
    var janus = new JanusSession(join.session_id, join.handle_id, logEl);
    wireIce(pc, janus);
    await janus.connect();
    if (join.jsep && join.jsep.sdp) {
      await pc.setRemoteDescription(join.jsep);
    }
    log(logEl, 'Publisher joined room ' + roomId + ' feed=' + (join.publisher_id || '?'));
    return { pc: pc, janus: janus, stream: stream, publisherId: join.publisher_id };
  }

  async function startSubscriber(opts) {
    var roomId = opts.roomId;
    var feedId = parseInt(opts.feedId, 10);
    var videoEl = opts.videoEl;
    var logEl = opts.logEl;
    if (!feedId) throw new Error('publisher feed id required');
    var pc = new RTCPeerConnection({ iceServers: ICE });
    pc.ontrack = function (ev) {
      if (ev.streams && ev.streams[0]) {
        videoEl.srcObject = ev.streams[0];
      }
    };
    pc.addTransceiver('video', { direction: 'recvonly' });
    pc.addTransceiver('audio', { direction: 'recvonly' });
    var offer = await pc.createOffer();
    await pc.setLocalDescription(offer);
    var join = await apiJoin({
      room_id: roomId,
      role: 'subscriber',
      feed_id: feedId,
      jsep: { type: offer.type, sdp: offer.sdp },
    });
    var janus = new JanusSession(join.session_id, join.handle_id, logEl);
    wireIce(pc, janus);
    await janus.connect();
    if (join.jsep && join.jsep.sdp) {
      await pc.setRemoteDescription(join.jsep);
    }
    log(logEl, 'Subscriber watching feed ' + feedId);
    return { pc: pc, janus: janus };
  }

  function bindUi() {
    var pubLog = document.getElementById('pub-log');
    var subLog = document.getElementById('sub-log');
    var pubVideo = document.getElementById('pub-video');
    var subVideo = document.getElementById('sub-video');
    var pubState = null;

    document.getElementById('btn-pub').addEventListener('click', function () {
      var roomId = parseInt(document.getElementById('room-id').value, 10);
      if (!roomId) {
        alert('Enter Janus room id (from dashboard)');
        return;
      }
      document.getElementById('btn-pub').disabled = true;
      startPublisher({ roomId: roomId, videoEl: pubVideo, logEl: pubLog })
        .then(function (s) {
          pubState = s;
          if (s.publisherId) {
            document.getElementById('feed-id').value = String(s.publisherId);
          }
        })
        .catch(function (e) {
          log(pubLog, 'ERROR: ' + e.message);
          document.getElementById('btn-pub').disabled = false;
        });
    });

    document.getElementById('btn-sub').addEventListener('click', function () {
      var roomId = parseInt(document.getElementById('room-id').value, 10);
      var feedId = document.getElementById('feed-id').value;
      document.getElementById('btn-sub').disabled = true;
      startSubscriber({ roomId: roomId, feedId: feedId, videoEl: subVideo, logEl: subLog })
        .catch(function (e) {
          log(subLog, 'ERROR: ' + e.message);
          document.getElementById('btn-sub').disabled = false;
        });
    });

    document.getElementById('btn-stop-pub').addEventListener('click', function () {
      if (pubState) {
        pubState.stream.getTracks().forEach(function (t) {
          t.stop();
        });
        pubState.janus.close();
        pubState.pc.close();
        pubState = null;
        pubVideo.srcObject = null;
        document.getElementById('btn-pub').disabled = false;
      }
    });
  }

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', bindUi);
  } else {
    bindUi();
  }
})();