CastVideos.js

// Copyright 2014 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


(function() {
  'use strict';

/**
 * Media source root URL
 **/
var MEDIA_SOURCE_ROOT = 'http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/';

/**
 * Media source URL JSON
 **/
var MEDIA_SOURCE_URL = 'http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/videos.json';

/**
 * Width of progress bar in pixel
 **/
var PROGRESS_BAR_WIDTH = 600;

/**
 * Constants of states for Chromecast device 
 **/
var DEVICE_STATE = {
  'IDLE' : 0, 
  'ACTIVE' : 1, 
  'WARNING' : 2, 
  'ERROR' : 3,
};

/**
 * Constants of states for CastPlayer 
 **/
var PLAYER_STATE = {
  'IDLE' : 'IDLE', 
  'LOADING' : 'LOADING', 
  'LOADED' : 'LOADED', 
  'PLAYING' : 'PLAYING',
  'PAUSED' : 'PAUSED',
  'STOPPED' : 'STOPPED',
  'SEEKING' : 'SEEKING',
  'ERROR' : 'ERROR'
};

/**
 * Cast player object
 * main variables:
 *  - deviceState for Cast mode: 
 *    IDLE: Default state indicating that Cast extension is installed, but showing no current activity
 *    ACTIVE: Shown when Chrome has one or more local activities running on a receiver
 *    WARNING: Shown when the device is actively being used, but when one or more issues have occurred
 *    ERROR: Should not normally occur, but shown when there is a failure 
 *  - Cast player variables for controlling Cast mode media playback 
 *  - Local player variables for controlling local mode media playbacks
 *  - Current media variables for transition between Cast and local modes
 */
var CastPlayer = function() {
  /* device variables */
  // @type {DEVICE_STATE} A state for device
  this.deviceState = DEVICE_STATE.IDLE;

  /* receivers available */
  // @type {boolean} A boolean to indicate availability of receivers
  this.receivers_available = false;

  /* Cast player variables */
  // @type {Object} a chrome.cast.media.Media object
  this.currentMediaSession = null;
  // @type {Number} volume
  this.currentVolume = 0.5;
  // @type {Boolean} A flag for autoplay after load
  this.autoplay = true;
  // @type {string} a chrome.cast.Session object
  this.session = null;
  // @type {PLAYER_STATE} A state for Cast media player
  this.castPlayerState = PLAYER_STATE.IDLE;

  /* Local player variables */
  // @type {PLAYER_STATE} A state for local media player
  this.localPlayerState = PLAYER_STATE.IDLE;
  // @type {HTMLElement} local player
  this.localPlayer = null;
  // @type {Boolean} Fullscreen mode on/off
  this.fullscreen = false;

  /* Current media variables */
  // @type {Boolean} Audio on and off
  this.audio = true;
  // @type {Number} A number for current media index
  this.currentMediaIndex = 0;
  // @type {Number} A number for current media time
  this.currentMediaTime = 0;
  // @type {Number} A number for current media duration
  this.currentMediaDuration = -1;
  // @type {Timer} A timer for tracking progress of media
  this.timer = null;
  // @type {Boolean} A boolean to stop timer update of progress when triggered by media status event 
  this.progressFlag = true;
  // @type {Number} A number in milliseconds for minimal progress update
  this.timerStep = 1000;

  /* media contents from JSON */
  this.mediaContents = null;

  this.initializeCastPlayer();
  this.initializeLocalPlayer();
};

/**
 * Initialize local media player 
 */
CastPlayer.prototype.initializeLocalPlayer = function() {
  this.localPlayer = document.getElementById('video_element');
  this.localPlayer.addEventListener('loadeddata', this.onMediaLoadedLocally.bind(this));
};

/**
 * Initialize Cast media player 
 * Initializes the API. Note that either successCallback and errorCallback will be
 * invoked once the API has finished initialization. The sessionListener and 
 * receiverListener may be invoked at any time afterwards, and possibly more than once. 
 */
CastPlayer.prototype.initializeCastPlayer = function() {

  if (!chrome.cast || !chrome.cast.isAvailable) {
    setTimeout(this.initializeCastPlayer.bind(this), 1000);
    return;
  }
  // default set to the default media receiver app ID
  // optional: you may change it to point to your own
  //var applicationID = chrome.cast.media.DEFAULT_MEDIA_RECEIVER_APP_ID;
  var applicationID = '4F8B3483';

  // auto join policy can be one of the following three
  var autoJoinPolicy = chrome.cast.AutoJoinPolicy.ORIGIN_SCOPED;
  //var autoJoinPolicy = chrome.cast.AutoJoinPolicy.PAGE_SCOPED;
  //var autoJoinPolicy = chrome.cast.AutoJoinPolicy.TAB_AND_ORIGIN_SCOPED;

  // request session
  var sessionRequest = new chrome.cast.SessionRequest(applicationID);
  var apiConfig = new chrome.cast.ApiConfig(sessionRequest,
    this.sessionListener.bind(this),
    this.receiverListener.bind(this),
    autoJoinPolicy);

  chrome.cast.initialize(apiConfig, this.onInitSuccess.bind(this), this.onError.bind(this));

  this.addVideoThumbs();
  this.initializeUI();
};

/**
 * Callback function for init success 
 */
CastPlayer.prototype.onInitSuccess = function() {
  console.log("init success");
  this.updateMediaControlUI();
};

/**
 * Generic error callback function 
 */
CastPlayer.prototype.onError = function() {
  console.log("error");
};

/**
 * @param {!Object} e A new session
 * This handles auto-join when a page is reloaded
 * When active session is detected, playback will automatically
 * join existing session and occur in Cast mode and media
 * status gets synced up with current media of the session 
 */
CastPlayer.prototype.sessionListener = function(e) {
  this.session = e;
  if( this.session ) {
    this.deviceState = DEVICE_STATE.ACTIVE;
    if( this.session.media[0] ) {
      this.onMediaDiscovered('activeSession', this.session.media[0]);
      this.syncCurrentMedia(this.session.media[0].media.contentId);
      this.selectMediaUpdateUI(this.currentMediaIndex);
      this.updateDisplayMessage();
    }
    else {
      this.loadMedia(this.currentMediaIndex);
    }
    this.session.addUpdateListener(this.sessionUpdateListener.bind(this));
  }
}

/**
 * @param {string} currentMediaURL
 */
CastPlayer.prototype.syncCurrentMedia = function(currentMediaURL) {
  for(var i=0; i < this.mediaContents.length; i++) {
    if( currentMediaURL == this.mediaContents[i]['sources'][0] ) {
      this.currentMediaIndex = i;
    }
  }
}

/**
 * @param {string} e Receiver availability
 * This indicates availability of receivers but
 * does not provide a list of device IDs
 */
CastPlayer.prototype.receiverListener = function(e) {
  if( e === 'available' ) {
    this.receivers_available = true;
    this.updateMediaControlUI();
    console.log("receiver found");
  }
  else {
    console.log("receiver list empty");
  }
};

/**
 * session update listener
 */
CastPlayer.prototype.sessionUpdateListener = function(isAlive) {
  if (!isAlive) {
    this.session = null;
    this.deviceState = DEVICE_STATE.IDLE;
    this.castPlayerState = PLAYER_STATE.IDLE;
    this.currentMediaSession = null;
    clearInterval(this.timer);
    this.updateDisplayMessage();

    var online = navigator.onLine;
    if( online == true ) {
      // continue to play media locally
      console.log("current time: " + this.currentMediaTime);
      this.playMediaLocally();
      this.updateMediaControlUI();
    }
  }
};


/**
 * Select a media content
 * @param {Number} mediaIndex A number for media index 
 */
CastPlayer.prototype.selectMedia = function(mediaIndex) {
  console.log("media selected" + mediaIndex);

  this.currentMediaIndex = mediaIndex;
  // reset progress bar
  var pi = document.getElementById("progress_indicator"); 
  var p = document.getElementById("progress"); 

  // reset currentMediaTime
  this.currentMediaTime = 0;

  p.style.width = '0px';
  pi.style.marginLeft = -21 - PROGRESS_BAR_WIDTH + 'px';

  if( !this.currentMediaSession ) {
    this.localPlayerState = PLAYER_STATE.IDLE;
    this.playMediaLocally();
  }
  else {
    this.castPlayerState = PLAYER_STATE.IDLE;
    this.playMedia();
  }
  this.selectMediaUpdateUI(mediaIndex);
};

/**
 * Requests that a receiver application session be created or joined. By default, the SessionRequest
 * passed to the API at initialization time is used; this may be overridden by passing a different
 * session request in opt_sessionRequest. 
 */
CastPlayer.prototype.launchApp = function() {
  console.log("launching app...");
  chrome.cast.requestSession(
    this.sessionListener.bind(this),
    this.onLaunchError.bind(this));
  if( this.timer ) {
    clearInterval(this.timer);
  }
};

/**
 * Callback function for request session success 
 * @param {Object} e A chrome.cast.Session object
 */
CastPlayer.prototype.onRequestSessionSuccess = function(e) {
  console.log("session success: " + e.sessionId);
  this.session = e;
  this.deviceState = DEVICE_STATE.ACTIVE;
  this.updateMediaControlUI();
  this.loadMedia(this.currentMediaIndex);
  this.session.addUpdateListener(this.sessionUpdateListener.bind(this));
};

/**
 * Callback function for launch error
 */
CastPlayer.prototype.onLaunchError = function() {
  console.log("launch error");
  this.deviceState = DEVICE_STATE.ERROR;
};

/**
 * Stops the running receiver application associated with the session.
 */
CastPlayer.prototype.stopApp = function() {
  this.session.stop(this.onStopAppSuccess.bind(this, 'Session stopped'),
      this.onError.bind(this));    

};

/**
 * Callback function for stop app success 
 */
CastPlayer.prototype.onStopAppSuccess = function(message) {
  console.log(message);
  this.deviceState = DEVICE_STATE.IDLE;
  this.castPlayerState = PLAYER_STATE.IDLE;
  this.currentMediaSession = null;
  clearInterval(this.timer);
  this.updateDisplayMessage();

  // continue to play media locally
  console.log("current time: " + this.currentMediaTime);
  this.playMediaLocally();
  this.updateMediaControlUI();
};

/**
 * Loads media into a running receiver application
 * @param {Number} mediaIndex An index number to indicate current media content
 */
CastPlayer.prototype.loadMedia = function(mediaIndex) {
  if (!this.session) {
    console.log("no session");
    return;
  }
  console.log("loading..." + this.mediaContents[mediaIndex]['title']);
  var mediaInfo = new chrome.cast.media.MediaInfo(this.mediaContents[mediaIndex]['sources'][0]);

  mediaInfo.metadata = new chrome.cast.media.GenericMediaMetadata();
  mediaInfo.metadata.metadataType = chrome.cast.media.MetadataType.GENERIC;
  mediaInfo.contentType = 'video/mp4';

  mediaInfo.metadata.title = this.mediaContents[mediaIndex]['title'];
  mediaInfo.metadata.images = [{'url': MEDIA_SOURCE_ROOT + this.mediaContents[mediaIndex]['thumb']}];

  var request = new chrome.cast.media.LoadRequest(mediaInfo);
  request.autoplay = this.autoplay;
  if( this.localPlayerState == PLAYER_STATE.PLAYING ) {
    request.currentTime = this.localPlayer.currentTime;
    this.localPlayer.pause();
    this.localPlayerState = PLAYER_STATE.STOPPED;
  }
  else {
    request.currentTime = 0;
  } 

  this.castPlayerState = PLAYER_STATE.LOADING;
  this.session.loadMedia(request,
    this.onMediaDiscovered.bind(this, 'loadMedia'),
    this.onLoadMediaError.bind(this));

  document.getElementById("media_title").innerHTML = this.mediaContents[this.currentMediaIndex]['title'];
  document.getElementById("media_subtitle").innerHTML = this.mediaContents[this.currentMediaIndex]['subtitle'];
  document.getElementById("media_desc").innerHTML = this.mediaContents[this.currentMediaIndex]['description'];

};

/**
 * Callback function for loadMedia success
 * @param {Object} mediaSession A new media object.
 */
CastPlayer.prototype.onMediaDiscovered = function(how, mediaSession) {
  console.log("new media session ID:" + mediaSession.mediaSessionId + ' (' + how + ')');
  this.currentMediaSession = mediaSession;
  if( how == 'loadMedia' ) {
    if( this.autoplay ) {
      this.castPlayerState = PLAYER_STATE.PLAYING;
    }
    else {
      this.castPlayerState = PLAYER_STATE.LOADED;
    }
  }

  if( how == 'activeSession' ) {
    this.castPlayerState = this.session.media[0].playerState; 
    this.currentMediaTime = this.session.media[0].currentTime; 
  }

  if( this.castPlayerState == PLAYER_STATE.PLAYING ) {
    // start progress timer
    this.startProgressTimer(this.incrementMediaTime);
  }

  this.currentMediaSession.addUpdateListener(this.onMediaStatusUpdate.bind(this));

  this.currentMediaDuration = this.currentMediaSession.media.duration;
  var duration = this.currentMediaDuration;
  var hr = parseInt(duration/3600);
  duration -= hr * 3600;
  var min = parseInt(duration/60);
  var sec = parseInt(duration % 60);
  if ( hr > 0 ) {
    duration = hr + ":" + min + ":" + sec;
  }
  else {
    if( min > 0 ) {
      duration = min + ":" + sec;
    }
    else {
      duration = sec;
    }
  }
  document.getElementById("duration").innerHTML = duration;

  if( this.localPlayerState == PLAYER_STATE.PLAYING ) {
    this.localPlayerState == PLAYER_STATE.STOPPED;
    var vi = document.getElementById('video_image')
    vi.style.display = 'block';
    this.localPlayer.style.display = 'none';
    // start progress timer
    this.startProgressTimer(this.incrementMediaTime);
  }
  // update UIs
  this.updateMediaControlUI();
  this.updateDisplayMessage();
};

/**
 * Callback function when media load returns error 
 */
CastPlayer.prototype.onLoadMediaError = function(e) {
  console.log("media error");
  this.castPlayerState = PLAYER_STATE.IDLE;
  // update UIs
  this.updateMediaControlUI();
  this.updateDisplayMessage();
};

/**
 * Callback function for media status update from receiver
 * @param {!Boolean} e true/false
 */
CastPlayer.prototype.onMediaStatusUpdate = function(e) {
  if( e == false ) {
    this.currentMediaTime = 0;
    this.castPlayerState = PLAYER_STATE.IDLE;
  }
  console.log("updating media");
  this.updateProgressBar(e);
  this.updateDisplayMessage();
  this.updateMediaControlUI();
};

/**
 * Helper function
 * Increment media current position by 1 second 
 */
CastPlayer.prototype.incrementMediaTime = function() {
  if( this.castPlayerState == PLAYER_STATE.PLAYING || this.localPlayerState == PLAYER_STATE.PLAYING ) {
    if( this.currentMediaTime < this.currentMediaDuration ) {
      this.currentMediaTime += 1;
      this.updateProgressBarByTimer();
    }
    else {
      this.currentMediaTime = 0;
      clearInterval(this.timer);
    }
  }
};

/**
 * Play media in local player
 */
CastPlayer.prototype.playMediaLocally = function() {
  var vi = document.getElementById('video_image')
  vi.style.display = 'none';
  this.localPlayer.style.display = 'block';
  if( this.localPlayerState != PLAYER_STATE.PLAYING && this.localPlayerState != PLAYER_STATE.PAUSED ) { 
    this.localPlayer.src = this.mediaContents[this.currentMediaIndex]['sources'][0];
    this.localPlayer.load();
  }
  else {
    this.localPlayer.play();
    // start progress timer
    this.startProgressTimer(this.incrementMediaTime);
  }
  this.localPlayerState = PLAYER_STATE.PLAYING;
  this.updateMediaControlUI();
};

/**
 * Callback when media is loaded in local player 
 */
CastPlayer.prototype.onMediaLoadedLocally = function() {
  this.currentMediaDuration = this.localPlayer.duration;
  var duration = this.currentMediaDuration;
      
  var hr = parseInt(duration/3600);
  duration -= hr * 3600;
  var min = parseInt(duration/60);
  var sec = parseInt(duration % 60);
  if ( hr > 0 ) {
    duration = hr + ":" + min + ":" + sec;
  }
  else {
    if( min > 0 ) {
      duration = min + ":" + sec;
    }
    else {
      duration = sec;
    }
  }
  document.getElementById("duration").innerHTML = duration;
  this.localPlayer.currentTime = this.currentMediaTime;

  this.localPlayer.play();
  // start progress timer
  this.startProgressTimer(this.incrementMediaTime);
};

/**
 * Play media in Cast mode 
 */
CastPlayer.prototype.playMedia = function() {
  if( !this.currentMediaSession ) {
    this.playMediaLocally();
    return;
  }

  switch( this.castPlayerState ) 
  {
    case PLAYER_STATE.LOADED:
    case PLAYER_STATE.PAUSED:
      this.currentMediaSession.play(null, 
        this.mediaCommandSuccessCallback.bind(this,"playing started for " + this.currentMediaSession.sessionId),
        this.onError.bind(this));
      this.currentMediaSession.addUpdateListener(this.onMediaStatusUpdate.bind(this));
      this.castPlayerState = PLAYER_STATE.PLAYING;
      // start progress timer
      this.startProgressTimer(this.incrementMediaTime);
      break;
    case PLAYER_STATE.IDLE:
    case PLAYER_STATE.LOADING:
    case PLAYER_STATE.STOPPED:
      this.loadMedia(this.currentMediaIndex);
      this.currentMediaSession.addUpdateListener(this.onMediaStatusUpdate.bind(this));
      this.castPlayerState = PLAYER_STATE.PLAYING;
      break;
    default:
      break;
  }
  this.updateMediaControlUI();
  this.updateDisplayMessage();
};

/**
 * Pause media playback in Cast mode  
 */
CastPlayer.prototype.pauseMedia = function() {
  if( !this.currentMediaSession ) {
    this.pauseMediaLocally();
    return;
  }

  if( this.castPlayerState == PLAYER_STATE.PLAYING ) {
    this.castPlayerState = PLAYER_STATE.PAUSED;
    this.currentMediaSession.pause(null,
      this.mediaCommandSuccessCallback.bind(this,"paused " + this.currentMediaSession.sessionId),
      this.onError.bind(this));
    this.updateMediaControlUI();
    this.updateDisplayMessage();
    clearInterval(this.timer);
  }
};

/**
 * Pause media playback in local player 
 */
CastPlayer.prototype.pauseMediaLocally = function() {
  this.localPlayer.pause();
  this.localPlayerState = PLAYER_STATE.PAUSED;
  this.updateMediaControlUI();
  clearInterval(this.timer);
};

/**
 * Stop media playback in either Cast or local mode  
 */
CastPlayer.prototype.stopMedia = function() {
  if( !this.currentMediaSession ) {
    this.stopMediaLocally();
    return;
  }

  this.currentMediaSession.stop(null,
    this.mediaCommandSuccessCallback.bind(this,"stopped " + this.currentMediaSession.sessionId),
    this.onError.bind(this));
  this.castPlayerState = PLAYER_STATE.STOPPED;
  clearInterval(this.timer);

  this.updateDisplayMessage();
  this.updateMediaControlUI();
};

/**
 * Stop media playback in local player
 */
CastPlayer.prototype.stopMediaLocally = function() {
  var vi = document.getElementById('video_image')
  vi.style.display = 'block';
  this.localPlayer.style.display = 'none';
  this.localPlayer.stop();
  this.localPlayerState = PLAYER_STATE.STOPPED;
  this.updateMediaControlUI();
};

/**
 * Set media volume in Cast mode
 * @param {Boolean} mute A boolean  
 */
CastPlayer.prototype.setReceiverVolume = function(mute) {
  var p = document.getElementById("audio_bg_level"); 
  if( event.currentTarget.id == 'audio_bg_track' ) {
    var pos = 100 - parseInt(event.offsetY);
  }
  else {
    var pos = parseInt(p.clientHeight) - parseInt(event.offsetY);
  }
  if( !this.currentMediaSession ) {
      this.localPlayer.volume = pos < 100 ? pos/100 : 1;
      p.style.height = pos + 'px';
      p.style.marginTop = -pos + 'px';
      return;
  }

  if( event.currentTarget.id == 'audio_bg_track' || event.currentTarget.id == 'audio_bg_level' ) {
    // add a drag to avoid loud volume
    if( pos < 100 ) {
      var vScale = this.currentVolume * 100;
      if( pos > vScale ) {
        pos = vScale + (pos - vScale)/2;
      }
      p.style.height = pos + 'px';
      p.style.marginTop = -pos + 'px';
      this.currentVolume = pos/100;
    }
    else {
      this.currentVolume = 1;
    }
  }

  if( !mute ) {
    this.session.setReceiverVolumeLevel(this.currentVolume,
      this.mediaCommandSuccessCallback.bind(this),
      this.onError.bind(this));
  }
  else {
    this.session.setReceiverMuted(true,
      this.mediaCommandSuccessCallback.bind(this),
      this.onError.bind(this));
  }
  this.updateMediaControlUI();
};

/**
 * Mute media function in either Cast or local mode 
 */
CastPlayer.prototype.muteMedia = function() {
  if( this.audio == true ) {
    this.audio = false;
    document.getElementById('audio_on').style.display = 'none';
    document.getElementById('audio_off').style.display = 'block';
    if( this.currentMediaSession ) {
      this.setReceiverVolume(true);
    }
    else {
      this.localPlayer.muted = true;
    }
  }
  else {
    this.audio = true;
    document.getElementById('audio_on').style.display = 'block';
    document.getElementById('audio_off').style.display = 'none';
    if( this.currentMediaSession ) {
      this.setReceiverVolume(false);
    }
    else {
      this.localPlayer.muted = false;
    }
  } 
  this.updateMediaControlUI();
};


/**
 * media seek function in either Cast or local mode
 * @param {Event} e An event object from seek 
 */
CastPlayer.prototype.seekMedia = function(event) {
  var pos = parseInt(event.offsetX);
  var pi = document.getElementById("progress_indicator"); 
  var p = document.getElementById("progress"); 
  if( event.currentTarget.id == 'progress_indicator' ) {
    var curr = parseInt(this.currentMediaTime + this.currentMediaDuration * pos / PROGRESS_BAR_WIDTH);
    var pp = parseInt(pi.style.marginLeft) + pos;
    var pw = parseInt(p.style.width) + pos;
  }
  else {
    var curr = parseInt(pos * this.currentMediaDuration / PROGRESS_BAR_WIDTH);
    var pp = pos -21 - PROGRESS_BAR_WIDTH;
    var pw = pos;
  }

  if( this.localPlayerState == PLAYER_STATE.PLAYING || this.localPlayerState == PLAYER_STATE.PAUSED ) {
    this.localPlayer.currentTime= curr;
    this.currentMediaTime = curr;
    this.localPlayer.play();
  }

  if( this.localPlayerState == PLAYER_STATE.PLAYING || this.localPlayerState == PLAYER_STATE.PAUSED 
      || this.castPlayerState == PLAYER_STATE.PLAYING || this.castPlayerState == PLAYER_STATE.PAUSED ) {
    p.style.width = pw + 'px';
    pi.style.marginLeft = pp + 'px';
  }

  if( this.castPlayerState != PLAYER_STATE.PLAYING && this.castPlayerState != PLAYER_STATE.PAUSED ) {
    return;
  }

  this.currentMediaTime = curr;
  console.log('Seeking ' + this.currentMediaSession.sessionId + ':' +
    this.currentMediaSession.mediaSessionId + ' to ' + pos + "%");
  var request = new chrome.cast.media.SeekRequest();
  request.currentTime = this.currentMediaTime;
  this.currentMediaSession.seek(request,
    this.onSeekSuccess.bind(this, 'media seek done'),
    this.onError.bind(this));
  this.castPlayerState = PLAYER_STATE.SEEKING;

  this.updateDisplayMessage();
  this.updateMediaControlUI();
};

/**
 * Callback function for seek success
 * @param {String} info A string that describe seek event
 */
CastPlayer.prototype.onSeekSuccess = function(info) {
  console.log(info);
  this.castPlayerState = PLAYER_STATE.PLAYING;
  this.updateDisplayMessage();
  this.updateMediaControlUI();
};

/**
 * Callback function for media command success 
 */
CastPlayer.prototype.mediaCommandSuccessCallback = function(info, e) {
  console.log(info);
};

/**
 * Update progress bar when there is a media status update
 * @param {Object} e An media status update object 
 */
CastPlayer.prototype.updateProgressBar = function(e) {
  var p = document.getElementById("progress"); 
  var pi = document.getElementById("progress_indicator"); 
  if( e == false ) {
    p.style.width = '0px';
    pi.style.marginLeft = -21 - PROGRESS_BAR_WIDTH + 'px';
    clearInterval(this.timer);
    this.castPlayerState = PLAYER_STATE.STOPPED;
    this.updateDisplayMessage();
  } else {
    p.style.width = Math.ceil(PROGRESS_BAR_WIDTH * this.currentMediaSession.currentTime / this.currentMediaSession.media.duration + 1) + 'px';
    this.progressFlag = false; 
    setTimeout(this.setProgressFlag.bind(this),1000); // don't update progress in 1 second
    var pp = Math.ceil(PROGRESS_BAR_WIDTH * this.currentMediaSession.currentTime / this.currentMediaSession.media.duration);
    pi.style.marginLeft = -21 - PROGRESS_BAR_WIDTH + pp + 'px';
  }
};

/**
 * Set progressFlag with a timeout of 1 second to avoid UI update
 * until a media status update from receiver 
 */
CastPlayer.prototype.setProgressFlag = function() {
  this.progressFlag = true;
};

/**
 * Update progress bar based on timer  
 */
CastPlayer.prototype.updateProgressBarByTimer = function() {
  var p = document.getElementById("progress"); 
  if( isNaN(parseInt(p.style.width)) ) {
    p.style.width = 0;
  } 
  if( this.currentMediaDuration > 0 ) {
    var pp = Math.floor(PROGRESS_BAR_WIDTH * this.currentMediaTime/this.currentMediaDuration);
  }
    
  if( this.progressFlag ) { 
    // don't update progress if it's been updated on media status update event
    p.style.width = pp + 'px'; 
    var pi = document.getElementById("progress_indicator"); 
    pi.style.marginLeft = -21 - PROGRESS_BAR_WIDTH + pp + 'px';
  }

  if( pp > PROGRESS_BAR_WIDTH ) {
    clearInterval(this.timer);
    this.deviceState = DEVICE_STATE.IDLE;
    this.castPlayerState = PLAYER_STATE.IDLE;
    this.updateDisplayMessage();
    this.updateMediaControlUI();
  }
};

/**
 * Update display message depending on cast mode by deviceState 
 */
CastPlayer.prototype.updateDisplayMessage = function() {
  if( this.deviceState != DEVICE_STATE.ACTIVE || this.castPlayerState == PLAYER_STATE.IDLE || this.castPlayerState == PLAYER_STATE.STOPPED ) {
    document.getElementById("playerstate").style.display = 'none';
    document.getElementById("playerstatebg").style.display = 'none';
    document.getElementById("play").style.display = 'block';
    document.getElementById("video_image_overlay").style.display = 'none';
  }
  else {
    document.getElementById("playerstate").style.display = 'block';
    document.getElementById("playerstatebg").style.display = 'block';
    document.getElementById("video_image_overlay").style.display = 'block';
    document.getElementById("playerstate").innerHTML = 
      this.mediaContents[this.currentMediaIndex]['title'] + " "
      + this.castPlayerState + " on " + this.session.receiver.friendlyName;
  }
}

/**
 * Update media control UI components based on localPlayerState or castPlayerState
 */
CastPlayer.prototype.updateMediaControlUI = function() {
  var playerState = this.deviceState == DEVICE_STATE.ACTIVE ? this.castPlayerState : this.localPlayerState;
  switch ( playerState )
  {
    case PLAYER_STATE.LOADED:
    case PLAYER_STATE.PLAYING:
      document.getElementById("play").style.display = 'none';
      document.getElementById("pause").style.display = 'block';
      break;
    case PLAYER_STATE.PAUSED:
    case PLAYER_STATE.IDLE:
    case PLAYER_STATE.LOADING:
    case PLAYER_STATE.STOPPED:
      document.getElementById("play").style.display = 'block';
      document.getElementById("pause").style.display = 'none';
      break;
    default:
      break;
  }

  if( !this.receivers_available ) {
    document.getElementById("casticonactive").style.display = 'none';
    document.getElementById("casticonidle").style.display = 'none';
    return;
  }

  if( this.deviceState == DEVICE_STATE.ACTIVE ) {
    document.getElementById("casticonactive").style.display = 'block';
    document.getElementById("casticonidle").style.display = 'none';
    this.hideFullscreenButton();
  }
  else {
    document.getElementById("casticonidle").style.display = 'block';
    document.getElementById("casticonactive").style.display = 'none';
    this.showFullscreenButton();
  }
}

/**
 * Update UI components after selectMedia call 
 * @param {Number} mediaIndex An number
 */
CastPlayer.prototype.selectMediaUpdateUI = function(mediaIndex) {
  document.getElementById('video_image').src = MEDIA_SOURCE_ROOT + this.mediaContents[mediaIndex]['thumb'];
  document.getElementById("progress").style.width = '0px';
  document.getElementById("media_title").innerHTML = this.mediaContents[mediaIndex]['title'];
  document.getElementById("media_subtitle").innerHTML = this.mediaContents[mediaIndex]['subtitle'];
  document.getElementById("media_desc").innerHTML = this.mediaContents[mediaIndex]['description'];
};

/**
 * Initialize UI components and add event listeners 
 */
CastPlayer.prototype.initializeUI = function() {
  // set initial values for title, subtitle, and description 
  document.getElementById("media_title").innerHTML = this.mediaContents[0]['title'];
  document.getElementById("media_subtitle").innerHTML = this.mediaContents[this.currentMediaIndex]['subtitle'];
  document.getElementById("media_desc").innerHTML = this.mediaContents[this.currentMediaIndex]['description'];

  // add event handlers to UI components
  document.getElementById("casticonidle").addEventListener('click', this.launchApp.bind(this));
  document.getElementById("casticonactive").addEventListener('click', this.stopApp.bind(this));
  document.getElementById("progress_bg").addEventListener('click', this.seekMedia.bind(this));
  document.getElementById("progress").addEventListener('click', this.seekMedia.bind(this));
  document.getElementById("progress_indicator").addEventListener('dragend', this.seekMedia.bind(this));
  document.getElementById("audio_on").addEventListener('click', this.muteMedia.bind(this));
  document.getElementById("audio_off").addEventListener('click', this.muteMedia.bind(this));
  document.getElementById("audio_bg").addEventListener('mouseover', this.showVolumeSlider.bind(this));
  document.getElementById("audio_on").addEventListener('mouseover', this.showVolumeSlider.bind(this));
  document.getElementById("audio_bg_level").addEventListener('mouseover', this.showVolumeSlider.bind(this));
  document.getElementById("audio_bg_track").addEventListener('mouseover', this.showVolumeSlider.bind(this));
  document.getElementById("audio_bg_level").addEventListener('click', this.setReceiverVolume.bind(this, false));
  document.getElementById("audio_bg_track").addEventListener('click', this.setReceiverVolume.bind(this, false));
  document.getElementById("audio_bg").addEventListener('mouseout', this.hideVolumeSlider.bind(this));
  document.getElementById("audio_on").addEventListener('mouseout', this.hideVolumeSlider.bind(this));
  document.getElementById("media_control").addEventListener('mouseover', this.showMediaControl.bind(this));
  document.getElementById("media_control").addEventListener('mouseout', this.hideMediaControl.bind(this));
  document.getElementById("fullscreen_expand").addEventListener('click', this.requestFullScreen.bind(this));
  document.getElementById("fullscreen_collapse").addEventListener('click', this.cancelFullScreen.bind(this));
  document.addEventListener("fullscreenchange", this.changeHandler.bind(this), false);      
  document.addEventListener("webkitfullscreenchange", this.changeHandler.bind(this), false);

  // enable play/pause buttons
  document.getElementById("play").addEventListener('click', this.playMedia.bind(this));
  document.getElementById("pause").addEventListener('click', this.pauseMedia.bind(this));
  document.getElementById("progress_indicator").draggable = true;

};

/**
 * Show the media control 
 */
CastPlayer.prototype.showMediaControl = function() {
  document.getElementById('media_control').style.opacity = 0.7;
};    

/**
 * Hide the media control  
 */
CastPlayer.prototype.hideMediaControl = function() {
  document.getElementById('media_control').style.opacity = 0;
};    

/**
 * Show the volume slider
 */
CastPlayer.prototype.showVolumeSlider = function() {
  document.getElementById('audio_bg').style.opacity = 1;
  document.getElementById('audio_bg_track').style.opacity = 1;
  document.getElementById('audio_bg_level').style.opacity = 1;
  document.getElementById('audio_indicator').style.opacity = 1;
};    

/**
 * Hide the volume slider 
 */
CastPlayer.prototype.hideVolumeSlider = function() {
  document.getElementById('audio_bg').style.opacity = 0;
  document.getElementById('audio_bg_track').style.opacity = 0;
  document.getElementById('audio_bg_level').style.opacity = 0;
  document.getElementById('audio_indicator').style.opacity = 0;
};    

/**
 * Request full screen mode 
 */
CastPlayer.prototype.requestFullScreen = function() {
  // Supports most browsers and their versions.
  var element = document.getElementById("video_element");
  var requestMethod = element.requestFullScreen || element.webkitRequestFullScreen;

  if (requestMethod) { // Native full screen.
    requestMethod.call(element);
    console.log("requested fullscreen");
  }
};

/**
 * Exit full screen mode 
 */
CastPlayer.prototype.cancelFullScreen = function() {
  // Supports most browsers and their versions.
  var requestMethod = document.cancelFullScreen || document.webkitCancelFullScreen;

  if (requestMethod) { 
    requestMethod.call(document);
  } 
};

/**
 * Exit fullscreen mode by escape 
 */
CastPlayer.prototype.changeHandler = function(){
  this.fullscreen = !this.fullscreen;
  if (this.deviceState == DEVICE_STATE.ACTIVE) {
    this.hideFullscreenButton();
  }
  else {
    this.showFullscreenButton();
  }
};

/**
 * Show expand/collapse fullscreen button
 */
CastPlayer.prototype.showFullscreenButton = function(){
  if (this.fullscreen) {
    document.getElementById('fullscreen_expand').style.display = 'none';
    document.getElementById('fullscreen_collapse').style.display = 'block';
  }
  else {
    document.getElementById('fullscreen_expand').style.display = 'block';
    document.getElementById('fullscreen_collapse').style.display = 'none';
  }
};

/**
 * Hide expand/collapse fullscreen button
 */
CastPlayer.prototype.hideFullscreenButton = function(){
  document.getElementById('fullscreen_expand').style.display = 'none';
  document.getElementById('fullscreen_collapse').style.display = 'none';
};

/**
 * @param {function} A callback function for the function to start timer 
 */
CastPlayer.prototype.startProgressTimer = function(callback) {
  if( this.timer ) {
    clearInterval(this.timer);
    this.timer = null;
  }

  // start progress timer
  this.timer = setInterval(callback.bind(this), this.timerStep);
};

/**
 * Do AJAX call to load media json
 * @param {String} src A URL for media json.
 */
CastPlayer.prototype.retrieveMediaJSON = function(src) {
  var xhr = new XMLHttpRequest();
  xhr.addEventListener('load', this.onMediaJsonLoad.bind(this));
  xhr.addEventListener('error', this.onMediaJsonError.bind(this));
  xhr.open('GET', src);
  xhr.setRequestHeader('Access-Control-Allow-Origin', '*');
  xhr.responseType = "json";
  xhr.send(null);
};

/**
 * Callback function for AJAX call on load success
 * @param {Object} evt An object returned from Ajax call
 */
CastPlayer.prototype.onMediaJsonLoad = function(evt) {
  var responseJson = evt.srcElement.response;
  this.mediaContents = responseJson['categories'][0]['videos'];
  var ni = document.getElementById('carousel');
  var newdiv = null;
  var divIdName = null;
  for( var i = 0; i < this.mediaContents.length; i++ ) {
    newdiv = document.createElement('div');
    divIdName = 'thumb'+i+'Div';
    newdiv.setAttribute('id',divIdName);
    newdiv.setAttribute('class','thumb');
    newdiv.innerHTML = '<img src="' + MEDIA_SOURCE_ROOT + this.mediaContents[i]['thumb'] + '" class="thumbnail">';
    newdiv.addEventListener('click', this.selectMedia.bind(this, i));
    ni.appendChild(newdiv);
  }
}

/**
 * Callback function for AJAX call on load error
 */
CastPlayer.prototype.onMediaJsonError = function() {
  console.log("Failed to load media JSON");
}

/**
 * Add video thumbnails div's to UI for media JSON contents 
 */
CastPlayer.prototype.addVideoThumbs = function() {
  this.mediaContents = mediaJSON['categories'][0]['videos'];
  var ni = document.getElementById('carousel');
  var newdiv = null;
  var newdivBG = null;
  var divIdName = null;
  for( var i = 0; i < this.mediaContents.length; i++ ) {
    newdiv = document.createElement('div');
    divIdName = 'thumb'+i+'Div';
    newdiv.setAttribute('id',divIdName);
    newdiv.setAttribute('class','thumb');
    newdiv.innerHTML = '<img src="' + MEDIA_SOURCE_ROOT + this.mediaContents[i]['thumb'] + '" class="thumbnail">';
    newdiv.addEventListener('click', this.selectMedia.bind(this, i));
    ni.appendChild(newdiv);
  }
}

/**
 * hardcoded media json objects
 */
var mediaJSON = { "categories" : [ { "name" : "Movies",
        "videos" : [ 
		    { "description" : "Big Buck Bunny tells the story of a giant rabbit with a heart bigger than himself. When one sunny day three rodents rudely harass him, something snaps... and the rabbit ain't no bunny anymore! In the typical cartoon tradition he prepares the nasty rodents a comical revenge.\n\nLicensed under the Creative Commons Attribution license\nhttp://www.bigbuckbunny.org",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4" ],
              "subtitle" : "By Blender Foundation",
              "thumb" : "images/BigBuckBunny.jpg",
              "title" : "Big Buck Bunny"
            },
            { "description" : "The first Blender Open Movie from 2006",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4" ],
              "subtitle" : "By Blender Foundation",
              "thumb" : "images/ElephantsDream.jpg",
              "title" : "Elephant Dream"
            },
            { "description" : "HBO GO now works with Chromecast -- the easiest way to enjoy online video on your TV. For when you want to settle into your Iron Throne to watch the latest episodes. For $35.\nLearn how to use Chromecast with HBO GO and more at google.com/chromecast.",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerBlazes.mp4" ],
              "subtitle" : "By Google",
              "thumb" : "images/ForBiggerBlazes.jpg",
              "title" : "For Bigger Blazes"
            },
            { "description" : "Introducing Chromecast. The easiest way to enjoy online video and music on your TV. For when Batman's escapes aren't quite big enough. For $35. Learn how to use Chromecast with Google Play Movies and more at google.com/chromecast.",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerEscapes.mp4" ],
              "subtitle" : "By Google",
              "thumb" : "images/ForBiggerEscapes.jpg",
              "title" : "For Bigger Escape"
            },
            { "description" : "Introducing Chromecast. The easiest way to enjoy online video and music on your TV. For $35.  Find out more at google.com/chromecast.",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerFun.mp4" ],
              "subtitle" : "By Google",
              "thumb" : "images/ForBiggerFun.jpg",
              "title" : "For Bigger Fun"
            },
            { "description" : "Introducing Chromecast. The easiest way to enjoy online video and music on your TV. For the times that call for bigger joyrides. For $35. Learn how to use Chromecast with YouTube and more at google.com/chromecast.",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerJoyrides.mp4" ],
              "subtitle" : "By Google",
              "thumb" : "images/ForBiggerJoyrides.jpg",
              "title" : "For Bigger Joyrides"
            },
            { "description" :"Introducing Chromecast. The easiest way to enjoy online video and music on your TV. For when you want to make Buster's big meltdowns even bigger. For $35. Learn how to use Chromecast with Netflix and more at google.com/chromecast.", 
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerMeltdowns.mp4" ],
              "subtitle" : "By Google",
              "thumb" : "images/ForBiggerMeltdowns.jpg",
              "title" : "For Bigger Meltdowns"
            },
			{ "description" : "Sintel is an independently produced short film, initiated by the Blender Foundation as a means to further improve and validate the free/open source 3D creation suite Blender. With initial funding provided by 1000s of donations via the internet community, it has again proven to be a viable development model for both open 3D technology as for independent animation film.\nThis 15 minute film has been realized in the studio of the Amsterdam Blender Institute, by an international team of artists and developers. In addition to that, several crucial technical and creative targets have been realized online, by developers and artists and teams all over the world.\nwww.sintel.org",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/Sintel.mp4" ],
              "subtitle" : "By Blender Foundation",
              "thumb" : "images/Sintel.jpg",
              "title" : "Sintel"
            },
			{ "description" : "Smoking Tire takes the all-new Subaru Outback to the highest point we can find in hopes our customer-appreciation Balloon Launch will get some free T-shirts into the hands of our viewers.",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/SubaruOutbackOnStreetAndDirt.mp4" ],
              "subtitle" : "By Garage419",
              "thumb" : "images/SubaruOutbackOnStreetAndDirt.jpg",
              "title" : "Subaru Outback On Street And Dirt"
            },
			{ "description" : "Tears of Steel was realized with crowd-funding by users of the open source 3D creation tool Blender. Target was to improve and test a complete open and free pipeline for visual effects in film - and to make a compelling sci-fi film in Amsterdam, the Netherlands.  The film itself, and all raw material used for making it, have been released under the Creatieve Commons 3.0 Attribution license. Visit the tearsofsteel.org website to find out more about this, or to purchase the 4-DVD box with a lot of extras.  (CC) Blender Foundation - http://www.tearsofsteel.org", 
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/TearsOfSteel.mp4" ],
              "subtitle" : "By Blender Foundation",
              "thumb" : "images/TearsOfSteel.jpg",
              "title" : "Tears of Steel"
            },
			{ "description" : "The Smoking Tire heads out to Adams Motorsports Park in Riverside, CA to test the most requested car of 2010, the Volkswagen GTI. Will it beat the Mazdaspeed3's standard-setting lap time? Watch and see...",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/VolkswagenGTIReview.mp4" ],
              "subtitle" : "By Garage419",
              "thumb" : "images/VolkswagenGTIReview.jpg",
              "title" : "Volkswagen GTI Review"
            },
			{ "description" : "The Smoking Tire is going on the 2010 Bullrun Live Rally in a 2011 Shelby GT500, and posting a video from the road every single day! The only place to watch them is by subscribing to The Smoking Tire or watching at BlackMagicShine.com",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/WeAreGoingOnBullrun.mp4" ],
              "subtitle" : "By Garage419",
              "thumb" : "images/WeAreGoingOnBullrun.jpg",
              "title" : "We Are Going On Bullrun"
            },
			{ "description" : "The Smoking Tire meets up with Chris and Jorge from CarsForAGrand.com to see just how far $1,000 can go when looking for a car. The Smoking Tire meets up with Chris and Jorge from CarsForAGrand.com to see just how far $1,000 can go when looking for a car.",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/WhatCarCanYouGetForAGrand.mp4" ],
              "subtitle" : "By Garage419",
              "thumb" : "images/WhatCarCanYouGetForAGrand.jpg",
              "title" : "What care can you get for a grand?"
            }
    ]}]};

 window.CastPlayer = CastPlayer;
})();