shaka-player/lib/cast/cast_proxy.js

/**
 * @license
 * Copyright 2016 Google Inc.
 *
 * 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.
 */

goog.provide('shaka.cast.CastProxy');

goog.require('goog.asserts');
goog.require('shaka.cast.CastSender');
goog.require('shaka.cast.CastUtils');
goog.require('shaka.log');
goog.require('shaka.util.Error');
goog.require('shaka.util.EventManager');
goog.require('shaka.util.FakeEvent');
goog.require('shaka.util.FakeEventTarget');
goog.require('shaka.util.IDestroyable');



/**
 * A proxy to switch between local and remote playback for Chromecast in a way
 * that is transparent to the app's controls.
 *
 * @constructor
 * @struct
 * @param {!HTMLMediaElement} video The local video element associated with the
 *   local Player instance.
 * @param {!shaka.Player} player A local Player instance.
 * @param {string} receiverAppId The ID of the cast receiver application.
 * @implements {shaka.util.IDestroyable}
 * @extends {shaka.util.FakeEventTarget}
 * @export
 */
shaka.cast.CastProxy = function(video, player, receiverAppId) {
  shaka.util.FakeEventTarget.call(this);

  /** @private {HTMLMediaElement} */
  this.localVideo_ = video;

  /** @private {shaka.Player} */
  this.localPlayer_ = player;

  /** @private {Object} */
  this.videoProxy_ = null;

  /** @private {Object} */
  this.playerProxy_ = null;

  /** @private {shaka.util.FakeEventTarget} */
  this.videoEventTarget_ = null;

  /** @private {shaka.util.FakeEventTarget} */
  this.playerEventTarget_ = null;

  /** @private {shaka.util.EventManager} */
  this.eventManager_ = null;

  /** @private {shaka.cast.CastSender} */
  this.sender_ = new shaka.cast.CastSender(
      receiverAppId,
      this.onCastStatusChanged_.bind(this),
      this.onFirstCastStateUpdate_.bind(this),
      this.onRemoteEvent_.bind(this),
      this.onResumeLocal_.bind(this),
      this.getInitState_.bind(this));

  this.init_();
};
goog.inherits(shaka.cast.CastProxy, shaka.util.FakeEventTarget);


/**
 * Destroys the proxy and the underlying local Player.
 *
 * @param {boolean=} opt_forceDisconnect If true, force the receiver app to shut
 *   down by disconnecting.  Does nothing if not connected.
 * @override
 * @export
 */
shaka.cast.CastProxy.prototype.destroy = function(opt_forceDisconnect) {
  if (opt_forceDisconnect && this.sender_) {
    this.sender_.forceDisconnect();
  }

  var async = [
    this.eventManager_ ? this.eventManager_.destroy() : null,
    this.localPlayer_ ? this.localPlayer_.destroy() : null,
    this.sender_ ? this.sender_.destroy() : null
  ];

  this.localVideo_ = null;
  this.localPlayer_ = null;
  this.videoProxy_ = null;
  this.playerProxy_ = null;
  this.eventManager_ = null;
  this.sender_ = null;

  return Promise.all(async);
};


/**
 * @event shaka.cast.CastProxy.CastStatusChangedEvent
 * @description Fired when cast status changes.  The status change will be
 *   reflected in canCast() and isCasting().
 * @property {string} type
 *   'caststatuschanged'
 * @exportDoc
 */


/**
 * Get a proxy for the video element that delegates to local and remote video
 * elements as appropriate.
 *
 * @suppress {invalidCasts} to cast proxy Objects to unrelated types
 * @return {HTMLMediaElement}
 * @export
 */
shaka.cast.CastProxy.prototype.getVideo = function() {
  return /** @type {HTMLMediaElement} */(this.videoProxy_);
};


/**
 * Get a proxy for the Player that delegates to local and remote Player objects
 * as appropriate.
 *
 * @suppress {invalidCasts} to cast proxy Objects to unrelated types
 * @return {shaka.Player}
 * @export
 */
shaka.cast.CastProxy.prototype.getPlayer = function() {
  return /** @type {shaka.Player} */(this.playerProxy_);
};


/**
 * @return {boolean} True if the cast API is available and there are receivers.
 * @export
 */
shaka.cast.CastProxy.prototype.canCast = function() {
  return this.sender_ ?
      this.sender_.apiReady() && this.sender_.hasReceivers() :
      false;
};


/**
 * @return {boolean} True if we are currently casting.
 * @export
 */
shaka.cast.CastProxy.prototype.isCasting = function() {
  return this.sender_ ? this.sender_.isCasting() : false;
};


/**
 * @return {string} The name of the Cast receiver device, if isCasting().
 * @export
 */
shaka.cast.CastProxy.prototype.receiverName = function() {
  return this.sender_ ? this.sender_.receiverName() : '';
};


/**
 * @return {!Promise} Resolved when connected to a receiver.  Rejected if the
 *   connection fails or is canceled by the user.
 * @export
 */
shaka.cast.CastProxy.prototype.cast = function() {
  var initState = this.getInitState_();

  // TODO: transfer manually-selected tracks?
  // TODO: transfer side-loaded text tracks?

  return this.sender_.cast(initState).then(function() {
    // Unload the local manifest when casting succeeds.
    return this.localPlayer_.unload();
  }.bind(this));
};


/**
 * Set application-specific data.
 *
 * @param {Object} appData Application-specific data to relay to the receiver.
 * @export
 */
shaka.cast.CastProxy.prototype.setAppData = function(appData) {
  this.sender_.setAppData(appData);
};


/**
 * Show a dialog where user can choose to disconnect from the cast connection.
 * @export
 */
shaka.cast.CastProxy.prototype.suggestDisconnect = function() {
  this.sender_.showDisconnectDialog();
};


/**
 * Force the receiver app to shut down by disconnecting.
 * @export
 */
shaka.cast.CastProxy.prototype.forceDisconnect = function() {
  this.sender_.forceDisconnect();
};


/**
 * Initialize the Proxies and the Cast sender.
 * @private
 */
shaka.cast.CastProxy.prototype.init_ = function() {
  this.sender_.init();

  this.eventManager_ = new shaka.util.EventManager();

  shaka.cast.CastUtils.VideoEvents.forEach(function(name) {
    this.eventManager_.listen(this.localVideo_, name,
        this.videoProxyLocalEvent_.bind(this));
  }.bind(this));

  shaka.cast.CastUtils.PlayerEvents.forEach(function(name) {
    this.eventManager_.listen(this.localPlayer_, name,
        this.playerProxyLocalEvent_.bind(this));
  }.bind(this));

  // We would like to use Proxy here, but it is not supported on IE11 or Safari.
  this.videoProxy_ = {};
  for (var k in this.localVideo_) {
    Object.defineProperty(this.videoProxy_, k, {
      configurable: false,
      enumerable: true,
      get: this.videoProxyGet_.bind(this, k),
      set: this.videoProxySet_.bind(this, k)
    });
  }

  this.playerProxy_ = {};
  for (var k in /** @type {Object} */(this.localPlayer_)) {
    Object.defineProperty(this.playerProxy_, k, {
      configurable: false,
      enumerable: true,
      get: this.playerProxyGet_.bind(this, k)
    });
  }

  this.videoEventTarget_ = new shaka.util.FakeEventTarget();
  this.videoEventTarget_.dispatchTarget =
      /** @type {EventTarget} */(this.videoProxy_);

  this.playerEventTarget_ = new shaka.util.FakeEventTarget();
  this.playerEventTarget_.dispatchTarget =
      /** @type {EventTarget} */(this.playerProxy_);
};


/**
 * @return {shaka.cast.CastUtils.InitStateType} initState Video and player state
 *   to be sent to the receiver.
 * @private
 */
shaka.cast.CastProxy.prototype.getInitState_ = function() {
  var initState = {
    'video': {},
    'player': {},
    'playerAfterLoad': {},
    'manifest': this.localPlayer_.getManifestUri(),
    'startTime': null
  };

  // Pause local playback before capturing state.
  this.localVideo_.pause();

  shaka.cast.CastUtils.VideoInitStateAttributes.forEach(function(name) {
    initState['video'][name] = this.localVideo_[name];
  }.bind(this));

  // If the video is still playing, set the startTime.
  // Has no effect if nothing is loaded.
  if (!this.localVideo_.ended) {
    initState['startTime'] = this.localVideo_.currentTime;
  }

  shaka.cast.CastUtils.PlayerInitState.forEach(function(pair) {
    var getter = pair[0];
    var setter = pair[1];
    var value = /** @type {Object} */(this.localPlayer_)[getter]();

    initState['player'][setter] = value;
  }.bind(this));

  shaka.cast.CastUtils.PlayerInitAfterLoadState.forEach(function(pair) {
    var getter = pair[0];
    var setter = pair[1];
    var value = /** @type {Object} */(this.localPlayer_)[getter]();

    initState['playerAfterLoad'][setter] = value;
  }.bind(this));

  return initState;
};


/**
 * Dispatch an event to notify the app that the status has changed.
 * @private
 */
shaka.cast.CastProxy.prototype.onCastStatusChanged_ = function() {
  var event = new shaka.util.FakeEvent('caststatuschanged');
  this.dispatchEvent(event);
};


/**
 * Dispatch a synthetic play or pause event to ensure that the app correctly
 * knows that the player is playing, if joining an existing receiver.
 * @private
 */
shaka.cast.CastProxy.prototype.onFirstCastStateUpdate_ = function() {
  var type = this.videoProxy_.paused ? 'pause' : 'play';
  var fakeEvent = new shaka.util.FakeEvent(type);
  this.videoEventTarget_.dispatchEvent(fakeEvent);
};


/**
 * Transfer remote state back and resume local playback.
 * @private
 */
shaka.cast.CastProxy.prototype.onResumeLocal_ = function() {
  // Transfer back the player state.
  shaka.cast.CastUtils.PlayerInitState.forEach(function(pair) {
    var getter = pair[0];
    var setter = pair[1];
    var value = this.sender_.get('player', getter)();
    /** @type {Object} */(this.localPlayer_)[setter](value);
  }.bind(this));

  // Get the most recent manifest URI and ended state.
  var manifestUri = this.sender_.get('player', 'getManifestUri')();
  var ended = this.sender_.get('video', 'ended');

  var manifestReady = Promise.resolve();
  var autoplay = this.localVideo_.autoplay;

  var startTime = null;

  // If the video is still playing, set the startTime.
  // Has no effect if nothing is loaded.
  if (!ended) {
    startTime = this.sender_.get('video', 'currentTime');
  }

  // Now load the manifest, if present.
  if (manifestUri) {
    // Don't autoplay the content until we finish setting up initial state.
    this.localVideo_.autoplay = false;
    manifestReady = this.localPlayer_.load(manifestUri, startTime);
    // Pass any errors through to the app.
    manifestReady.catch(function(error) {
      goog.asserts.assert(error instanceof shaka.util.Error,
                          'Wrong error type!');
      var event = new shaka.util.FakeEvent('error', { 'detail': error });
      this.localPlayer_.dispatchEvent(event);
    }.bind(this));
  }

  // Get the video state into a temp variable since we will apply it async.
  var videoState = {};
  shaka.cast.CastUtils.VideoInitStateAttributes.forEach(function(name) {
    videoState[name] = this.sender_.get('video', name);
  }.bind(this));

  // Finally, take on video state and player's "after load" state.
  manifestReady.then(function() {
    shaka.cast.CastUtils.VideoInitStateAttributes.forEach(function(name) {
      this.localVideo_[name] = videoState[name];
    }.bind(this));

    shaka.cast.CastUtils.PlayerInitAfterLoadState.forEach(function(pair) {
      var getter = pair[0];
      var setter = pair[1];
      var value = this.sender_.get('player', getter)();
      /** @type {Object} */(this.localPlayer_)[setter](value);
    }.bind(this));

    // Restore original autoplay setting.
    this.localVideo_.autoplay = autoplay;
    if (manifestUri) {
      // Resume playback with transferred state.
      this.localVideo_.play();
    }
  }.bind(this));
};


/**
 * @param {string} name
 * @return {?}
 * @private
 */
shaka.cast.CastProxy.prototype.videoProxyGet_ = function(name) {
  if (name == 'addEventListener') {
    return this.videoEventTarget_.addEventListener.bind(
        this.videoEventTarget_);
  }
  if (name == 'removeEventListener') {
    return this.videoEventTarget_.removeEventListener.bind(
        this.videoEventTarget_);
  }

  // If we are casting, but the first update has not come in yet, use local
  // values, but not local methods.
  if (this.sender_.isCasting() && !this.sender_.hasRemoteProperties()) {
    var value = this.localVideo_[name];
    if (typeof value != 'function') {
      return value;
    }
  }

  // Use local values and methods if we are not casting.
  if (!this.sender_.isCasting()) {
    var value = this.localVideo_[name];
    if (typeof value == 'function') {
      value = value.bind(this.localVideo_);
    }
    return value;
  }

  return this.sender_.get('video', name);
};


/**
 * @param {string} name
 * @param {?} value
 * @private
 */
shaka.cast.CastProxy.prototype.videoProxySet_ = function(name, value) {
  if (!this.sender_.isCasting()) {
    this.localVideo_[name] = value;
    return;
  }

  this.sender_.set('video', name, value);
};


/**
 * @param {!Event} event
 * @private
 */
shaka.cast.CastProxy.prototype.videoProxyLocalEvent_ = function(event) {
  if (this.sender_.isCasting()) {
    // Ignore any unexpected local events while casting.  Events can still be
    // fired by the local video and Player when we unload() after the Cast
    // connection is complete.
    return;
  }

  // Convert this real Event into a FakeEvent for dispatch from our
  // FakeEventListener.
  var fakeEvent = new shaka.util.FakeEvent(event.type, event);
  this.videoEventTarget_.dispatchEvent(fakeEvent);
};


/**
 * @param {string} name
 * @return {?}
 * @private
 */
shaka.cast.CastProxy.prototype.playerProxyGet_ = function(name) {
  if (name == 'addEventListener') {
    return this.playerEventTarget_.addEventListener.bind(
        this.playerEventTarget_);
  }
  if (name == 'removeEventListener') {
    return this.playerEventTarget_.removeEventListener.bind(
        this.playerEventTarget_);
  }

  if (name == 'getMediaElement') {
    return function() { return this.videoProxy_; }.bind(this);
  }

  if (name == 'getNetworkingEngine') {
    // Always returns a local instance, in case you need to make a request.
    // Issues a warning, in case you think you are making a remote request
    // or affecting remote filters.
    if (this.sender_.isCasting()) {
      shaka.log.warning('NOTE: getNetworkingEngine() is always local!');
    }
    return this.localPlayer_.getNetworkingEngine.bind(this.localPlayer_);
  }

  // If we are casting, but the first update has not come in yet, use local
  // getters, but not local methods.
  if (this.sender_.isCasting() && !this.sender_.hasRemoteProperties()) {
    if (shaka.cast.CastUtils.PlayerGetterMethods.indexOf(name) >= 0) {
      var value = /** @type {Object} */(this.localPlayer_)[name];
      goog.asserts.assert(typeof value == 'function', 'only methods on Player');
      return value.bind(this.localPlayer_);
    }
  }

  // Use local getters and methods if we are not casting.
  if (!this.sender_.isCasting()) {
    var value = /** @type {Object} */(this.localPlayer_)[name];
    goog.asserts.assert(typeof value == 'function', 'only methods on Player');
    return value.bind(this.localPlayer_);
  }

  return this.sender_.get('player', name);
};


/**
 * @param {!Event} event
 * @private
 */
shaka.cast.CastProxy.prototype.playerProxyLocalEvent_ = function(event) {
  if (this.sender_.isCasting()) {
    // Ignore any unexpected local events while casting.
    return;
  }

  this.playerEventTarget_.dispatchEvent(event);
};


/**
 * @param {string} targetName
 * @param {!shaka.util.FakeEvent} event
 * @private
 */
shaka.cast.CastProxy.prototype.onRemoteEvent_ = function(targetName, event) {
  goog.asserts.assert(this.sender_.isCasting(),
                      'Should only receive remote events while casting');
  if (!this.sender_.isCasting()) {
    // Ignore any unexpected remote events.
    return;
  }

  if (targetName == 'video') {
    this.videoEventTarget_.dispatchEvent(event);
  } else if (targetName == 'player') {
    this.playerEventTarget_.dispatchEvent(event);
  }
};