protected function getLanguageSuffix()
{
$currentAppLanguage = Yii::$app->language;
$langsExceptions = ['zh-CN', 'zh-TW', 'zh-TW'];
if (strpos($currentAppLanguage, '-') === false) {
return $currentAppLanguage;
}
if (in_array($currentAppLanguage, $langsExceptions)) {
return $currentAppLanguage;
} else {
return substr($currentAppLanguage, 0, strpos($currentAppLanguage, '-'));
}
}