Source: lib/offline/storage.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.offline.Storage');

goog.require('goog.asserts');
goog.require('shaka.Player');
goog.require('shaka.log');
goog.require('shaka.media.DrmEngine');
goog.require('shaka.media.ManifestParser');
goog.require('shaka.offline.DBEngine');
goog.require('shaka.offline.DownloadManager');
goog.require('shaka.offline.OfflineManifestParser');
goog.require('shaka.offline.OfflineUtils');
goog.require('shaka.util.ConfigUtils');
goog.require('shaka.util.Error');
goog.require('shaka.util.Functional');
goog.require('shaka.util.IDestroyable');
goog.require('shaka.util.LanguageUtils');
goog.require('shaka.util.StreamUtils');



/**
 * This manages persistent offline data including storage, listing, and deleting
 * stored manifests.  Playback of offline manifests are done using Player
 * using the special URI (e.g. 'offline:12').
 *
 * @param {shaka.Player} player
 *   The player instance to pull configuration data from.
 *
 * @struct
 * @constructor
 * @implements {shaka.util.IDestroyable}
 * @export
 */
shaka.offline.Storage = function(player) {
  /** @private {shaka.offline.DBEngine} */
  this.dbEngine_ = new shaka.offline.DBEngine();

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

  /** @private {?shakaExtern.OfflineConfiguration} */
  this.config_ = this.defaultConfig_();

  /** @private {shaka.media.DrmEngine} */
  this.drmEngine_ = null;

  /** @private {boolean} */
  this.storeInProgress_ = false;

  /** @private {Array.<shakaExtern.Track>} */
  this.firstPeriodTracks_ = null;

  /**
   * The IDs of the segments that have been stored for an in-progress store().
   * This is used to cleanup in destroy().
   * @private {!Array.<number>}
   */
  this.inProgressSegmentIds_ = [];

  /** @private {number} */
  this.manifestId_ = -1;

  /** @private {number} */
  this.duration_ = 0;

  /** @private {?shakaExtern.Manifest} */
  this.manifest_ = null;

  var netEngine = player.getNetworkingEngine();
  goog.asserts.assert(netEngine, 'Player must not be destroyed');

  /** @private {shaka.offline.DownloadManager} */
  this.downloadManager_ = new shaka.offline.DownloadManager(
      netEngine, player.getConfiguration().streaming.retryParameters,
      this.config_);
};


/**
 * Gets whether offline storage is supported.
 *
 * @return {boolean}
 * @export
 */
shaka.offline.Storage.support = function() {
  return shaka.offline.DBEngine.isSupported();
};


/**
 * Sets the DBEngine instance to use.  This is used for testing.
 *
 * @param {!shaka.offline.DBEngine} engine
 */
shaka.offline.Storage.prototype.setDbEngine = function(engine) {
  goog.asserts.assert(!this.dbEngine_.initialized(),
                      'Should not be initialized yet');
  this.dbEngine_ = engine;
};


/**
 * @override
 * @export
 */
shaka.offline.Storage.prototype.destroy = function() {
  var segments = this.inProgressSegmentIds_;
  var dbEngine = this.dbEngine_;
  // Destroy the download manager first to ensure segments are not added while
  // we delete old ones.
  var ret = !this.downloadManager_ ?
      Promise.resolve() :
      this.downloadManager_.destroy()
          .catch(function() {})
          .then(function() {
            return Promise.all(segments.map(function(id) {
              return dbEngine.remove('segment', id);
            }));
          })
          .then(function() { return dbEngine.destroy(); });

  this.dbEngine_ = null;
  this.downloadManager_ = null;
  this.player_ = null;
  this.config_ = null;
  return ret;
};


/**
 * Sets configuration values for Storage.  This is not associated with
 * Player.configure and will not change Player.
 *
 * @param {shakaExtern.OfflineConfiguration} config
 * @export
 */
shaka.offline.Storage.prototype.configure = function(config) {
  goog.asserts.assert(this.config_, 'Must not be destroyed');
  shaka.util.ConfigUtils.mergeConfigObjects(
      this.config_, config, this.defaultConfig_(), {}, '');
};


/**
 * Stores the given manifest.
 *
 * @param {string} manifestUri
 * @param {!Object} appMetadata
 * @param {!shakaExtern.ManifestParser.Factory=} opt_manifestParserFactory
 * @return {!Promise.<shakaExtern.StoredContent>}
 * @export
 */
shaka.offline.Storage.prototype.store = function(
    manifestUri, appMetadata, opt_manifestParserFactory) {
  if (this.storeInProgress_) {
    return Promise.reject(new shaka.util.Error(
        shaka.util.Error.Category.STORAGE,
        shaka.util.Error.Code.STORE_ALREADY_IN_PROGRESS));
  }
  this.storeInProgress_ = true;

  /** @type {shakaExtern.ManifestDB} */
  var manifestDb;

  var error = null;
  var onError = function(e) { error = e; };
  return this.initIfNeeded_()
      .then(function() {
        this.checkDestroyed_();
        return this.loadInternal(
            manifestUri, onError, opt_manifestParserFactory);
      }.bind(this)).then((
          /**
           * @param {{manifest: shakaExtern.Manifest,
           *          drmEngine: !shaka.media.DrmEngine}} data
           * @return {!Promise}
           */
          function(data) {
            this.checkDestroyed_();
            this.manifest_ = data.manifest;
            this.drmEngine_ = data.drmEngine;

            if (this.manifest_.presentationTimeline.isLive()) {
              throw new shaka.util.Error(
                  shaka.util.Error.Category.STORAGE,
                  shaka.util.Error.Code.CANNOT_STORE_LIVE_OFFLINE, manifestUri);
            }

            // Re-filter now that DrmEngine is initialized.
            this.manifest_.periods.forEach(this.filterPeriod_.bind(this));

            this.manifestId_ = this.dbEngine_.reserveId('manifest');
            this.duration_ = 0;
            manifestDb = this.createOfflineManifest_(manifestUri, appMetadata);
            return this.downloadManager_.download(manifestDb);
          })
      .bind(this))
      .then(function() {
        this.checkDestroyed_();
        // Throw any errors from the manifest parser or DrmEngine.
        if (error)
          throw error;

        return this.dbEngine_.insert('manifest', manifestDb);
      }.bind(this))
      .then(function() {
        return this.cleanup_();
      }.bind(this))
      .then(function() {
        return shaka.offline.OfflineUtils.getStoredContent(manifestDb);
      }.bind(this))
      .catch(function(err) {
        var Functional = shaka.util.Functional;
        return this.cleanup_().catch(Functional.noop).then(function() {
          throw err;
        });
      }.bind(this));
};


/**
 * Removes the given stored content.
 *
 * @param {shakaExtern.StoredContent} content
 * @return {!Promise}
 * @export
 */
shaka.offline.Storage.prototype.remove = function(content) {
  var uri = content.offlineUri;
  var parts = /^offline:([0-9]+)$/.exec(uri);
  if (!parts) {
    return Promise.reject(new shaka.util.Error(
        shaka.util.Error.Category.STORAGE,
        shaka.util.Error.Code.MALFORMED_OFFLINE_URI, uri));
  }

  var error = null;
  var onError = function(e) {
    // Ignore errors if the session was already removed.
    if (e.code != shaka.util.Error.Code.OFFLINE_SESSION_REMOVED)
      error = e;
  };

  /** @type {shakaExtern.ManifestDB} */
  var manifestDb;
  /** @type {!shaka.media.DrmEngine} */
  var drmEngine;
  var manifestId = Number(parts[1]);
  return this.initIfNeeded_().then(function() {
    this.checkDestroyed_();
    return this.dbEngine_.get('manifest', manifestId);
  }.bind(this)).then((
      /**
       * @param {?shakaExtern.ManifestDB} data
       * @return {!Promise}
       */
      function(data) {
        this.checkDestroyed_();
        if (!data) {
          throw new shaka.util.Error(
              shaka.util.Error.Category.STORAGE,
              shaka.util.Error.Code.REQUESTED_ITEM_NOT_FOUND, uri);
        }
        manifestDb = data;
        var manifest =
            shaka.offline.OfflineManifestParser.reconstructManifest(manifestDb);
        var netEngine = this.player_.getNetworkingEngine();
        goog.asserts.assert(netEngine, 'Player must not be destroyed');
        drmEngine =
            new shaka.media.DrmEngine(netEngine, onError, function() {});
        drmEngine.configure(this.player_.getConfiguration().drm);
        return drmEngine.init(manifest, true /* isOffline */);
      })
  .bind(this)).then(function() {
    return drmEngine.removeSessions(manifestDb.sessionIds);
  }.bind(this)).then(function() {
    return drmEngine.destroy();
  }.bind(this)).then(function() {
    this.checkDestroyed_();
    if (error) throw error;
    var Functional = shaka.util.Functional;
    // Get every segment for every stream in the manifest.
    /** @type {!Array.<number>} */
    var segments = manifestDb.periods.map(function(period) {
      return period.streams.map(function(stream) {
        var segments = stream.segments.map(function(segment) {
          var parts = /^offline:[0-9]+\/[0-9]+\/([0-9]+)$/.exec(segment.uri);
          goog.asserts.assert(parts, 'Invalid offline URI');
          return Number(parts[1]);
        });
        if (stream.initSegmentUri) {
          var parts = /^offline:[0-9]+\/[0-9]+\/([0-9]+)$/.exec(
              stream.initSegmentUri);
          goog.asserts.assert(parts, 'Invalid offline URI');
          segments.push(Number(parts[1]));
        }
        return segments;
      }).reduce(Functional.collapseArrays, []);
    }).reduce(Functional.collapseArrays, []);

    // Delete all the segments.
    var deleteCount = 0;
    var segmentCount = segments.length;
    var callback = this.config_.progressCallback;
    return this.dbEngine_.removeWhere('segment', function(segment) {
      var i = segments.indexOf(segment.key);
      if (i >= 0) {
        callback(content, deleteCount / segmentCount);
        deleteCount++;
      }
      return i >= 0;
    }.bind(this));
  }.bind(this)).then(function() {
    this.checkDestroyed_();
    this.config_.progressCallback(content, 1);
    return this.dbEngine_.remove('manifest', manifestId);
  }.bind(this));
};


/**
 * Lists all the stored content available.
 *
 * @return {!Promise.<!Array.<shakaExtern.StoredContent>>}
 * @export
 */
shaka.offline.Storage.prototype.list = function() {
  /** @type {!Array.<shakaExtern.StoredContent>} */
  var storedContents = [];
  return this.initIfNeeded_()
      .then(function() {
        this.checkDestroyed_();
        return this.dbEngine_.forEach(
            'manifest', function(/** shakaExtern.ManifestDB */ manifest) {
              storedContents.push(
                  shaka.offline.OfflineUtils.getStoredContent(manifest));
            });
      }.bind(this))
      .then(function() { return storedContents; });
};


/**
 * Loads the given manifest, parses it, and constructs the DrmEngine.  This
 * stops the manifest parser.  This may be replaced by tests.
 *
 * @param {string} manifestUri
 * @param {function(*)} onError
 * @param {!shakaExtern.ManifestParser.Factory=} opt_manifestParserFactory
 * @return {!Promise.<{
 *   manifest: shakaExtern.Manifest,
 *   drmEngine: !shaka.media.DrmEngine
 * }>}
 */
shaka.offline.Storage.prototype.loadInternal = function(
    manifestUri, onError, opt_manifestParserFactory) {

  var netEngine = /** @type {!shaka.net.NetworkingEngine} */ (
      this.player_.getNetworkingEngine());
  var config = this.player_.getConfiguration();

  /** @type {shakaExtern.Manifest} */
  var manifest;
  /** @type {!shaka.media.DrmEngine} */
  var drmEngine;
  /** @type {!shakaExtern.ManifestParser} */
  var manifestParser;

  var onKeyStatusChange = function() {};
  return shaka.media.ManifestParser
      .getFactory(
          manifestUri, netEngine, config.manifest.retryParameters,
          opt_manifestParserFactory)
      .then(function(factory) {
        this.checkDestroyed_();
        manifestParser = new factory();
        manifestParser.configure(config.manifest);
        return manifestParser.start(
            manifestUri, netEngine, this.filterPeriod_.bind(this), onError);
      }.bind(this))
      .then(function(data) {
        this.checkDestroyed_();
        manifest = data;
        drmEngine =
            new shaka.media.DrmEngine(netEngine, onError, onKeyStatusChange);
        drmEngine.configure(config.drm);
        return drmEngine.init(manifest, true /* isOffline */);
      }.bind(this))
      .then(function() {
        this.checkDestroyed_();
        return this.createSegmentIndex_(manifest);
      }.bind(this))
      .then(function() {
        this.checkDestroyed_();
        return drmEngine.createOrLoad();
      }.bind(this))
      .then(function() {
        this.checkDestroyed_();
        return manifestParser.stop();
      }.bind(this))
      .then(function() {
        this.checkDestroyed_();
        return {manifest: manifest, drmEngine: drmEngine};
      }.bind(this))
      .catch(function(error) {
        if (manifestParser)
          return manifestParser.stop().then(function() { throw error; });
        else
          throw error;
      });
};


/**
 * The default track selection function.
 *
 * @param {!Array.<shakaExtern.Track>} tracks
 * @return {!Array.<shakaExtern.Track>}
 * @private
 */
shaka.offline.Storage.prototype.defaultTrackSelect_ = function(tracks) {
  var LanguageUtils = shaka.util.LanguageUtils;

  var selectedTracks = [];

  // Select the highest bandwidth video track with height <= 480.
  var videoTracks = tracks.filter(function(t) {
    return t.type == 'video' && t.height <= 480;
  });
  videoTracks.sort(function(a, b) { return b.bandwidth - a.bandwidth; });
  if (videoTracks.length)
    selectedTracks.push(videoTracks[0]);

  // Select middle bandwidth audio track with best audio pref language match.
  var audioLangPref = LanguageUtils.normalize(
      this.player_.getConfiguration().preferredAudioLanguage);
  var matchTypes = [
    LanguageUtils.MatchType.EXACT,
    LanguageUtils.MatchType.BASE_LANGUAGE_OKAY,
    LanguageUtils.MatchType.OTHER_SUB_LANGUAGE_OKAY
  ];
  var allAudioTracks =
      tracks.filter(function(t) { return t.type == 'audio'; });
  // For each match type, get the tracks that match the audio preference for
  // that match type.
  var tracksByMatchType = matchTypes.map(function(match) {
    return allAudioTracks.filter(function(track) {
      var lang = LanguageUtils.normalize(track.language);
      return LanguageUtils.match(match, audioLangPref, lang);
    });
  });
  // Find the best match type that has any matches, defaulting to all tracks.
  var audioTracks = allAudioTracks;
  for (var i = 0; i < tracksByMatchType.length; i++) {
    if (tracksByMatchType[i].length) {
      audioTracks = tracksByMatchType[i];
    }
  }
  audioTracks.sort(function(a, b) { return a.bandwidth - b.bandwidth; });
  if (audioTracks.length)
    selectedTracks.push(audioTracks[Math.floor(audioTracks.length / 2)]);

  // Select all text tracks with any text pref language match.
  var textLangPref = LanguageUtils.normalize(
      this.player_.getConfiguration().preferredTextLanguage);
  var matchesTextPref = LanguageUtils.match.bind(
      null, LanguageUtils.MatchType.OTHER_SUB_LANGUAGE_OKAY, textLangPref);
  selectedTracks.push.apply(selectedTracks, tracks.filter(function(t) {
    var language = LanguageUtils.normalize(t.language);
    return t.type == 'text' && matchesTextPref(language);
  }));

  return selectedTracks;
};


/**
 * @return {shakaExtern.OfflineConfiguration}
 * @private
 */
shaka.offline.Storage.prototype.defaultConfig_ = function() {
  return {
    trackSelectionCallback: this.defaultTrackSelect_.bind(this),
    progressCallback: new Function('storedContent', 'percent', '')
  };
};


/**
 * Initializes the DBEngine if it is not already.
 *
 * @return {!Promise}
 * @private
 */
shaka.offline.Storage.prototype.initIfNeeded_ = function() {
  var scheme = shaka.offline.OfflineUtils.DB_SCHEME;
  return this.dbEngine_.initialized() ? Promise.resolve() :
                                        this.dbEngine_.init(scheme);
};


/**
 * @param {shakaExtern.Period} period
 * @private
 */
shaka.offline.Storage.prototype.filterPeriod_ = function(period) {
  function getFirstStreamOfType(period, tracks, contentType) {
    var tracksOfType =
        tracks.filter(function(track) { return track.type == contentType; });
    if (tracksOfType.length == 0)
      return null;
    var data =
        shaka.util.StreamUtils.findStreamForTrack(period, tracksOfType[0]);
    goog.asserts.assert(
        data, 'Could not find stream with id ' + tracksOfType[0].id);
    return data.stream;
  }

  var StreamUtils = shaka.util.StreamUtils;
  var activeStreams = {};
  if (this.firstPeriodTracks_) {
    // Use the first stream of each content type as the "active stream".  This
    // is then used to filter out the streams that are not compatible with it.
    // This ensures that in multi-Period content, all Periods have streams
    // with compatible MIME types.
    activeStreams = {
      'video': getFirstStreamOfType(
          this.manifest_.periods[0], this.firstPeriodTracks_, 'video'),
      'audio': getFirstStreamOfType(
          this.manifest_.periods[0], this.firstPeriodTracks_, 'audio')
    };
  }
  StreamUtils.filterPeriod(this.drmEngine_, activeStreams, period);
  StreamUtils.applyRestrictions(
      period, this.player_.getConfiguration().restrictions,
      /* maxHwRes */ { width: Infinity, height: Infinity });
};


/**
 * Cleans up the current store and destroys any objects.  This object is still
 * usable after this.
 *
 * @return {!Promise}
 * @private
 */
shaka.offline.Storage.prototype.cleanup_ = function() {
  var ret = this.drmEngine_ ? this.drmEngine_.destroy() : Promise.resolve();
  this.drmEngine_ = null;
  this.manifest_ = null;
  this.storeInProgress_ = false;
  this.firstPeriodTracks_ = null;
  this.inProgressSegmentIds_ = [];
  this.manifestId_ = -1;
  return ret;
};


/**
 * Calls createSegmentIndex for all streams in the manifest.
 *
 * @param {shakaExtern.Manifest} manifest
 * @return {!Promise}
 * @private
 */
shaka.offline.Storage.prototype.createSegmentIndex_ = function(manifest) {
  var Functional = shaka.util.Functional;
  var streams = manifest.periods
      .map(function(period) { return period.streamSets; })
      .reduce(Functional.collapseArrays, [])
      .map(function(streamSet) { return streamSet.streams; })
      .reduce(Functional.collapseArrays, []);
  return Promise.all(
      streams.map(function(stream) { return stream.createSegmentIndex(); }));
};


/**
 * Creates an offline 'manifest' for the real manifest.  This does not store
 * the segments yet, only adds them to the download manager through
 * createPeriod_.
 *
 * @param {string} originalManifestUri
 * @param {!Object} appMetadata
 * @return {shakaExtern.ManifestDB}
 * @private
 */
shaka.offline.Storage.prototype.createOfflineManifest_ = function(
    originalManifestUri, appMetadata) {
  var periods = this.manifest_.periods.map(this.createPeriod_.bind(this));
  var drmInfo = this.drmEngine_.getDrmInfo();
  var sessions = this.drmEngine_.getSessionIds();
  if (drmInfo) {
    if (!sessions.length) {
      throw new shaka.util.Error(
          shaka.util.Error.Category.STORAGE,
          shaka.util.Error.Code.NO_INIT_DATA_FOR_OFFLINE, originalManifestUri);
    }
    // Don't store init data since we have stored sessions.
    drmInfo.initData = [];
  }

  return {
    key: this.manifestId_,
    originalManifestUri: originalManifestUri,
    duration: this.duration_,
    size: 0,
    periods: periods,
    sessionIds: sessions,
    drmInfo: drmInfo,
    appMetadata: appMetadata
  };
};


/**
 * Converts a manifest Period to a database Period.  This will use the current
 * configuration to get the tracks to use, then it will search each segment
 * index and add all the segments to the download manager through createStream_.
 *
 * @param {shakaExtern.Period} period
 * @return {shakaExtern.PeriodDB}
 * @private
 */
shaka.offline.Storage.prototype.createPeriod_ = function(period) {
  var allTracks = shaka.util.StreamUtils.getTracks(period, null);
  var tracks = this.config_.trackSelectionCallback(allTracks);
  if (this.firstPeriodTracks_ == null) {
    this.firstPeriodTracks_ = tracks;
    // Now that the first tracks are chosen, filter again.  This ensures all
    // Periods have compatible content types.
    this.manifest_.periods.forEach(this.filterPeriod_.bind(this));
  }

  for (var i = tracks.length - 1; i > 0; --i) {
    var found = false;
    for (var j = i - 1; j >= 0; --j) {
      if (tracks[i].type == tracks[j].type &&
          tracks[i].kind == tracks[j].kind &&
          tracks[i].language == tracks[j].language) {
        shaka.log.warning(
            'Multiple tracks of the same type/kind/language given.');
        found = true;
        break;
      }
    }
    if (found) break;
  }

  var streams = tracks.map(function(track) {
    var data = shaka.util.StreamUtils.findStreamForTrack(period, track);
    goog.asserts.assert(data, 'Could not find track with id ' + track.id);
    return this.createStream_(period, data.streamSet, data.stream);
  }.bind(this));

  return {
    startTime: period.startTime,
    streams: streams
  };
};


/**
 * Converts a manifest stream to a database stream.  This will search the
 * segment index and add all the segments to the download manager.
 *
 * @param {shakaExtern.Period} period
 * @param {shakaExtern.StreamSet} streamSet
 * @param {shakaExtern.Stream} stream
 * @return {shakaExtern.StreamDB}
 * @private
 */
shaka.offline.Storage.prototype.createStream_ = function(
    period, streamSet, stream) {
  /** @type {!Array.<shakaExtern.SegmentDB>} */
  var segmentsDb = [];
  var startTime = this.manifest_.presentationTimeline.getEarliestStart();
  var endTime = startTime;
  var i = stream.findSegmentPosition(startTime);
  var ref = (i != null ? stream.getSegmentReference(i) : null);
  while (ref) {
    var id = this.dbEngine_.reserveId('segment');
    var bandwidthSize = (ref.endTime - ref.startTime) * stream.bandwidth / 8;
    this.downloadManager_.addSegment(
        streamSet.type, ref, bandwidthSize, function(id, pos, streamId, data) {
          /** @type {shakaExtern.SegmentDataDB} */
          var dataDb = {
            key: id,
            data: data,
            manifestKey: this.manifestId_,
            streamNumber: streamId,
            segmentNumber: pos
          };
          this.inProgressSegmentIds_.push(id);
          return this.dbEngine_.insert('segment', dataDb);
        }.bind(this, id, ref.position, stream.id));

    segmentsDb.push({
      startTime: ref.startTime,
      endTime: ref.endTime,
      uri: 'offline:' + this.manifestId_ + '/' + stream.id + '/' + id
    });

    endTime = ref.endTime + period.startTime;
    ref = stream.getSegmentReference(++i);
  }

  this.duration_ = Math.max(this.duration_, (endTime - startTime));
  var initUri = null;
  if (stream.initSegmentReference) {
    var id = this.dbEngine_.reserveId('segment');
    initUri = 'offline:' + this.manifestId_ + '/' + stream.id + '/' + id;
    this.downloadManager_.addSegment(streamSet.type,
        stream.initSegmentReference, 0,
        function(streamId, data) {
          /** @type {shakaExtern.SegmentDataDB} */
          var dataDb = {
            key: id,
            data: data,
            manifestKey: this.manifestId_,
            streamNumber: streamId,
            segmentNumber: -1
          };
          this.inProgressSegmentIds_.push(id);
          return this.dbEngine_.insert('segment', dataDb);
        }.bind(this, stream.id));
  }

  return {
    id: stream.id,
    primary: streamSet.primary,
    presentationTimeOffset: stream.presentationTimeOffset || 0,
    contentType: streamSet.type,
    mimeType: stream.mimeType,
    codecs: stream.codecs,
    kind: stream.kind,
    language: streamSet.language,
    width: stream.width || null,
    height: stream.height || null,
    initSegmentUri: initUri,
    encrypted: stream.encrypted,
    keyId: stream.keyId,
    segments: segmentsDb
  };
};


/**
 * Throws an error if the object is destroyed.
 * @private
 */
shaka.offline.Storage.prototype.checkDestroyed_ = function() {
  if (!this.player_) {
    throw new shaka.util.Error(
        shaka.util.Error.Category.STORAGE,
        shaka.util.Error.Code.OPERATION_ABORTED);
  }
};


shaka.Player.registerSupportPlugin('offline', shaka.offline.Storage.support);