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src/browser/main/carrier.js

  1. /**
  2.  * A class in charge of building the payload expected by the native app
  3.  * the payload must be a {@link Payload}
  4.  */
  5. class Carrier {
  6.     /**
  7.      * Generate a new {@link Carrier}
  8.      */
  9.     constructor () {
  10.         /**
  11.          *
  12.          * @type {Payload}
  13.          */
  14.         this.last = {};
  15.     }
  16.  
  17.     /**
  18.      * Clear the last payload sent
  19.      */
  20.     clear () {
  21.         this.last = {};
  22.     }
  23.  
  24.     /**
  25.      * Store the last payload sent
  26.      * @param {Payload} payload
  27.      */
  28.     store (payload) {
  29.         this.last = payload;
  30.     }
  31.  
  32.     /**
  33.      *
  34.      * @param {Playback} playback
  35.      * @returns {Payload}
  36.      */
  37.     payloadFrom (playback) {
  38.         return {
  39.             PlaybackStatus: playback.getStatus(),
  40.             LoopStatus: playback.getLoopStatus(),
  41.             Shuffle: playback.isShuffle(),
  42.             Volume: playback.getVolume(),
  43.             CanGoNext: playback.canGoNext(),
  44.             CanGoPrevious: playback.canGoPrevious(),
  45.             Identity: playback.getIdentity(),
  46.             Rate: playback.getRate(),
  47.             Metadata: {
  48.                 'mpris:trackid': playback.activePlayer.getId(),
  49.                 'mpris:length': playback.activePlayer.getLength(),
  50.                 'mpris:artUrl': playback.activePlayer.getCover(),
  51.                 'xesam:url': playback.activePlayer.getUrl(),
  52.                 'xesam:title': playback.activePlayer.getTitle(),
  53.                 'xesam:artist': playback.activePlayer.getArtists(),
  54.             }
  55.         };
  56.     }
  57.  
  58.     /**
  59.      *
  60.      * @param {Payload} payload
  61.      * @return {Payload}
  62.      */
  63.     onlyUpdated (payload) {
  64.         let diffs = {
  65.             Metadata: {}
  66.         };
  67.         for (let prop in payload) {
  68.             if (prop === 'Metadata') {
  69.                 let changed = false;
  70.                 for (let meta in payload.Metadata) {
  71.                     if (JSON.stringify(payload.Metadata[meta]) !== (this.last.Metadata && JSON.stringify(this.last.Metadata[meta]))) {
  72.                         changed = true;
  73.                     }
  74.                 }
  75.                 if (changed)
  76.                     diffs.Metadata = payload.Metadata;
  77.             } else if (payload[prop] !== this.last[prop])
  78.                 diffs[prop] = payload[prop];
  79.         }
  80.         if (Object.keys(diffs.Metadata).length === 0)
  81.             delete diffs.Metadata;
  82.         // noinspection JSValidateTypes
  83.         return diffs;
  84.     }
  85.  
  86.     /**
  87.      *
  88.      * @param {Playback} playback
  89.      * @returns {Payload}
  90.      */
  91.     requestPayload (playback) {
  92.         let payload = this.payloadFrom(playback);
  93.         let diffs = this.onlyUpdated(payload);
  94.         this.store(payload);
  95.         return diffs;
  96.     }
  97. }