var RTCPeerConnection = null;
var getUserMedia = null;
var attachMediaStream = null;
var reattachMediaStream = null;
var webrtcDetectedBrowser = null;
var webrtcDetectedVersion = null;

function trace(text) {
  // This function is used for logging.
  if (text[text.length - 1] == '\n') {
    text = text.substring(0, text.length - 1);
  }
  console.log((performance.now() / 1000).toFixed(3) + ": " + text);
}

if (navigator.mozGetUserMedia) {
  console.log("This appears to be Firefox");

  webrtcDetectedBrowser = "firefox";

  // The RTCPeerConnection object.
  RTCPeerConnection = mozRTCPeerConnection;

  // The RTCSessionDescription object.
  RTCSessionDescription = mozRTCSessionDescription;

  // The RTCIceCandidate object.
  RTCIceCandidate = mozRTCIceCandidate;

  // Get UserMedia (only difference is the prefix).
  // Code from Adam Barth.
  getUserMedia = navigator.mozGetUserMedia.bind(navigator);

  // Creates Turn Uri with new turn format.
  createIceServer = function(turn_url, username, password) {
    var iceServer = { 'url': turn_url,
                      'credential': password,
                      'username': username };
    return iceServer;
  };

  // Attach a media stream to an element.
  attachMediaStream = function(element, stream) {
    console.log("Attaching media stream");
    element.mozSrcObject = stream;
    element.play();
  };

  reattachMediaStream = function(to, from) {
    console.log("Reattaching media stream");
    to.mozSrcObject = from.mozSrcObject;
    to.play();
  };

  // Fake get{Video,Audio}Tracks
  MediaStream.prototype.getVideoTracks = function() {
    return [];
  };

  MediaStream.prototype.getAudioTracks = function() {
    return [];
  };
} else if (navigator.webkitGetUserMedia) {
  console.log("This appears to be Chrome");

  webrtcDetectedBrowser = "chrome";
  webrtcDetectedVersion =
             parseInt(navigator.userAgent.match(/Chrom(e|ium)\/([0-9]+)\./)[2]);

  // For pre-M28 chrome versions use old turn format, else use the new format.
  if (webrtcDetectedVersion < 28) {
    createIceServer = function(turn_url, username, password) {
      var iceServer = { 'url': 'turn:' + username + '@' + turn_url,
                        'credential': password };
      return iceServer;
    };
  } else {
    createIceServer = function(turn_url, username, password) {
      var iceServer = { 'url': turn_url,
                        'credential': password,
                        'username': username };
      return iceServer;
    };
  }

  // The RTCPeerConnection object.
  RTCPeerConnection = webkitRTCPeerConnection;

  // Get UserMedia (only difference is the prefix).
  // Code from Adam Barth.
  getUserMedia = navigator.webkitGetUserMedia.bind(navigator);

  // Attach a media stream to an element.
  attachMediaStream = function(element, stream) {
    if (typeof element.srcObject !== 'undefined') {
      element.srcObject = stream;
    } else if (typeof element.mozSrcObject !== 'undefined') {
      element.mozSrcObject = stream;
    } else if (typeof element.src !== 'undefined') {
      element.src = URL.createObjectURL(stream);
    } else {
      console.log('Error attaching stream to element.');
    }
  };

  reattachMediaStream = function(to, from) {
    to.src = from.src;
  };

  // The representation of tracks in a stream is changed in M26.
  // Unify them for earlier Chrome versions in the coexisting period.
  if (!webkitMediaStream.prototype.getVideoTracks) {
    webkitMediaStream.prototype.getVideoTracks = function() {
      return this.videoTracks;
    };
    webkitMediaStream.prototype.getAudioTracks = function() {
      return this.audioTracks;
    };
  }

  // New syntax of getXXXStreams method in M26.
  if (!webkitRTCPeerConnection.prototype.getLocalStreams) {
    webkitRTCPeerConnection.prototype.getLocalStreams = function() {
      return this.localStreams;
    };
    webkitRTCPeerConnection.prototype.getRemoteStreams = function() {
      return this.remoteStreams;
    };
  }
} else {
  console.log("Browser does not appear to be WebRTC-capable");
}