/**
 * Replace the old apple-style `avc1.<dd>.<dd>` codec string with the standard
 * `avc1.<hhhhhh>`
 *
 * @param {string} codec
 *        Codec string to translate
 * @return {string}
 *         The translated codec string
 */
export const translateLegacyCodec = function(codec) {
  if (!codec) {
    return codec;
  }

  return codec.replace(/avc1\.(\d+)\.(\d+)/i, function(orig, profile, avcLevel) {
    const profileHex = ('00' + Number(profile).toString(16)).slice(-2);
    const avcLevelHex = ('00' + Number(avcLevel).toString(16)).slice(-2);

    return 'avc1.' + profileHex + '00' + avcLevelHex;
  });
};

/**
 * Replace the old apple-style `avc1.<dd>.<dd>` codec strings with the standard
 * `avc1.<hhhhhh>`
 *
 * @param {string[]} codecs
 *        An array of codec strings to translate
 * @return {string[]}
 *         The translated array of codec strings
 */
export const translateLegacyCodecs = function(codecs) {
  return codecs.map(translateLegacyCodec);
};

/**
 * Replace codecs in the codec string with the old apple-style `avc1.<dd>.<dd>` to the
 * standard `avc1.<hhhhhh>`.
 *
 * @param {string} codecString
 *        The codec string
 * @return {string}
 *         The codec string with old apple-style codecs replaced
 *
 * @private
 */
export const mapLegacyAvcCodecs = function(codecString) {
  return codecString.replace(/avc1\.(\d+)\.(\d+)/i, (match) => {
    return translateLegacyCodecs([match])[0];
  });
};

/**
 * @typedef {Object} ParsedCodecInfo
 * @property {number} codecCount
 *           Number of codecs parsed
 * @property {string} [videoCodec]
 *           Parsed video codec (if found)
 * @property {string} [videoObjectTypeIndicator]
 *           Video object type indicator (if found)
 * @property {string|null} audioProfile
 *           Audio profile
 */

/**
 * Parses a codec string to retrieve the number of codecs specified, the video codec and
 * object type indicator, and the audio profile.
 *
 * @param {string} [codecs]
 *        The codec string to parse
 * @return {ParsedCodecInfo}
 *         Parsed codec info
 */
export const parseCodecs = function(codecs = '') {
  const result = {
    codecCount: 0
  };

  result.codecCount = codecs.split(',').length;
  result.codecCount = result.codecCount || 2;

  // parse the video codec
  const parsed = (/(^|\s|,)+(avc[13])([^ ,]*)/i).exec(codecs);

  if (parsed) {
    result.videoCodec = parsed[2];
    result.videoObjectTypeIndicator = parsed[3];
  }

  // parse the last field of the audio codec
  result.audioProfile =
    (/(^|\s|,)+mp4a.[0-9A-Fa-f]+\.([0-9A-Fa-f]+)/i).exec(codecs);
  result.audioProfile = result.audioProfile && result.audioProfile[2];

  return result;
};

/**
 * Returns a ParsedCodecInfo object for the default alternate audio playlist if there is
 * a default alternate audio playlist for the provided audio group.
 *
 * @param {Object} master
 *        The master playlist
 * @param {string} audioGroupId
 *        ID of the audio group for which to find the default codec info
 * @return {ParsedCodecInfo}
 *         Parsed codec info
 */
export const audioProfileFromDefault = (master, audioGroupId) => {
  if (!master.mediaGroups.AUDIO || !audioGroupId) {
    return null;
  }

  const audioGroup = master.mediaGroups.AUDIO[audioGroupId];

  if (!audioGroup) {
    return null;
  }

  for (const name in audioGroup) {
    const audioType = audioGroup[name];

    if (audioType.default && audioType.playlists) {
      // codec should be the same for all playlists within the audio type
      return parseCodecs(audioType.playlists[0].attributes.CODECS).audioProfile;
    }
  }

  return null;
};