mpare.
   * @param {string} rhsLangTag - The right-hand-side language tag to compare.
   *
   * @returns {boolean}
   *  `true`  if the language tags match, either directly or after normalization.
   *  `false` if either tag is invalid or empty, or if they do not match.
   *
   * @see https://datatracker.ietf.org/doc/html/rfc5646#appendix-A
   */
  static langTagsMatch(lhsLangTag, rhsLangTag) {
    if (!lhsLangTag || !rhsLangTag) {
      return false;
    }

    if (lhsLangTag === rhsLangTag) {
      // A simple direct match.
      return true;
    }

    if (lhsLangTag.split("-")[0] !== rhsLangTag.split("-")[0]) {
      // The language components of the tags do not match so there is no need to normalize them and compare.
      return false;
    }

    try {
      return (
        TranslationsUtils.#normalizeLangTag(lhsLangTag) ===
        TranslationsUtils.#normalizeLangTag(rhsLangTag)
      );
    } catch {
      // One of the locales is not valid, just continue on to return false.
    }

    return false;
  }

  /**
   * Serializes a language pair into a unique key that is human readable. This is useful
   * for caching, deduplicating, and logging.
   *
   * e.g.
   *   "en -> fr"
   *   "en -> fr,base"
   *   "zh-Hans,tiny -> fr,base"
   *
   * @param {LanguagePair} languagePair
   */
  static serializeLanguagePair({
    sourceLanguage,
    targetLanguage,
    sourceVariant,
    targetVariant,
  }) {
    let key = sourceLanguage;
    if (sourceVariant) {
      key += `,${sourceVariant}`;
    }
    key += ` -> ${targetLanguage}`;
    if (targetVariant) {
      key += `,${targetVariant}`;
    }
    return key;
  }

  /**
   * Deletes all translations language model files.
   *
   * @returns {Promise<string[]>} - A list of record IDs.
   */
  static async deleteAllLanguageFiles() {
    const { RemoteSettings } = ChromeUtils.importESModule(
      "resource://services-settings/remote-settings.sys.mjs"
    );
    const client = RemoteSettings(
      TranslationsUtils.translationsModelsCollectionName
    );

    try {
      await client.attachments.deleteAll();
    } catch (error) {
      if (!(error instanceof lazy.RemoteSettingsClient.EmptyDatabaseError)) {
        lazy.console.error(
          "Failed to delete Translations language files.",
          error
        );
      }
    }

    try {
      const records = await client.get({
        syncIfEmpty: false,
        loadDumpIfNewer: false,
      });
      return records.map(record => record.id);
    } catch (error) {
      lazy.console.error("Failed to list Translations model records.", error);
      return [];
    }
  }
}
PK