/* global AudioMetadata, ForwardLock, LazyLoader */
/* exported ForwardLockMetadata */
'use strict';

/**
 * Parse metadata for ForwardLocked files. Generally, this will forward on to
 * the metadata parser for the underlying format.
 */
var ForwardLockMetadata = (function() {

  /**
   * Parse a file and return a Promise with the metadata.
   *
   * @param {BlobView} locked The audio file to parse.
   * @return {Promise} A Promise returning the parsed metadata object.
   */
  function parse(locked) {
    return new Promise(function(resolve, reject) {
      LazyLoader.load('/shared/js/omadrm/fl.js').then(() => {
        ForwardLock.getKey(function(secret) {
          ForwardLock.unlockBlob(secret, locked.blob, callback, reject);

          function callback(unlocked, unlockedMetadata) {
            // Now that we have the unlocked content of the locked file, pass it
            // back to AudioMetadata.parse to get the metadata. When we're done,
            // add some extra metadata to indicate that this is locked content
            // (so it isn't shared) and to specify the vendor that locked it.
            resolve(AudioMetadata.parse(unlocked).then(function(metadata) {
              metadata.locked = true;
              if (unlockedMetadata.vendor) {
                metadata.vendor = unlockedMetadata.vendor;
              }
              if (!metadata.title) {
                metadata.title = unlockedMetadata.name;
              }
              if (metadata.picture && metadata.picture.flavor === 'embedded') {
                // Grab the slice for the embedded album art while we still have
                // the decrypted blob to look at!
                metadata.picture = {
                  flavor: 'unsynced',
                  blob: unlocked.slice(metadata.picture.start,
                                       metadata.picture.end,
                                       metadata.picture.type)
                };
              }
              return metadata;
            }));
          }
        });
      });
    });
  }

  return {
    parse: parse
  };

})();