FormFacebook::getLocaleByLanguageId

protected function getLocaleByLanguageId($languageId = null): string
{
	switch ($languageId = $languageId ?? Context::getCurrent()->getLanguage())
	{
		case 'ru':
		case 'kz':
		case 'ua':
		case 'by':
			return 'ru_RU';
		case 'pl':
		case 'fr':
		case 'it':
		case 'tr':
		case 'de':
		case 'es':
			return mb_strtolower($languageId).'_'.mb_strtoupper($languageId);
		case 'la':
			return 'es_LA';
		case 'br': // Brazilian
			return 'pt_BR';
		case 'sc': // simplified Chinese
			return 'zh_CN';
		case 'tc': // traditional Chinese
			return 'zh_TW';
		default:
			return'en_US';
	}
}