Method isEnabled

/**
 * Method to determine if the language filter plugin is enabled.
 * This works for both site and administrator.
 *
 * @param   CMSApplication     $app  The application
 * @param   DatabaseInterface  $db   The database
 *
 * @return  boolean  True if site is supporting multiple languages; false otherwise.
 *
 * @since   2.5.4
 */
public static function isEnabled(CMSApplication $app = null, DatabaseInterface $db = null)
{
    // Flag to avoid doing multiple database queries.
    static $tested = false;
    // Do not proceed with testing if the flag is true
    if (static::$enabled) {
        return true;
    }
    // Get application object.
    $app = $app ?: Factory::getApplication();
    // If being called from the frontend, we can avoid the database query.
    if ($app->isClient('site')) {
        static::$enabled = $app->getLanguageFilter();
        return static::$enabled;
    }
    // If already tested, don't test again.
    if (!$tested) {
        // Determine status of language filter plugin.
        $db = $db ?: Factory::getDbo();
        $query = $db->getQuery(true)->select($db->quoteName('enabled'))->from($db->quoteName('#__extensions'))->where([$db->quoteName('type') . ' = ' . $db->quote('plugin'), $db->quoteName('folder') . ' = ' . $db->quote('system'), $db->quoteName('element') . ' = ' . $db->quote('languagefilter')]);
        $db->setQuery($query);
        static::$enabled = (bool) $db->loadResult();
        $tested = true;
    }
    return static::$enabled;
}