$wgDispLangNeedChanges = array (
	'zh',
	'zh-yue',
	'zh-min-nan'
);

$wgDispLangChanges = array (
	'zh-cn' 	=> 'zh-cn',	//zh-hans, for compatibility
	'zh-tw' 	=> 'zh-hant',
	'zh-hk' 	=> 'zh-hant',
	'zh-mo' 	=> 'zh-hant',
	'zh-sg' 	=> 'zh-sg',	//zh-hans, for compatibility
	'zh-min-nan' 	=> 'zh-hant',
	'zh-yue' 	=> 'zh-hant'
);


function getDisplayLangCode() {
	global $wgContLanguageCode, $wgDispLangNeedChange, $wgDispLangChanges;
	global $wgDispLangNeedChanges, $wgUser;
	$mNeeds2ChangeLangCode = 0;

	// Check is that on the change list
	//(for example while using zh interface in en sites would not affected.)
	foreach($wgDispLangNeedChanges as $i => $LanguageCode) {
		if ($wgDispLangNeedChanges[$i] == $wgContLanguageCode)
			$mNeeds2ChangeLangCode = 1;
	}

	// when a change is required do the stuffs below
	if ($mNeeds2ChangeLangCode == 1) {
		// get language interface perference from logged in users
		if ((is_object($wgUser)) && ($wgUser->isLoggedin())) {
			$getLanguageCode = $wgUser->getOption('language');
		}

		// get the HTTP_ACCEPT_LANGUAGE value for anonymous users
		else if (array_key_exists('HTTP_ACCEPT_LANGUAGE', $_SERVER)) {
			$getLanguageCode = str_replace( '_', '-', strtolower($_SERVER["HTTP_ACCEPT_LANGUAGE"]));
			$getLanguageCode = strtok($getLanguageCode,',;');
		}

		// if both two methods above failed, get the $wgContLanguageCode directly
		else {
			$getLanguageCode = $wgContLanguageCode;
		}

		// -----------------------------------------------------------

		// check if the language is in the change list
		// if found in the substitude list, change into that value
		if (array_key_exists($getLanguageCode, $wgDispLangChanges))
		{
			$mDisplayLanguageCode = $wgDispLangChanges[$getLanguageCode];
		}

		// return the wgContLanguageCode in other cases
		else
		{
			$mDisplayLanguageCode = $getLanguageCode;
		}
	}

	// when changes is not required (e.g. in en, de, fr, ja, ko, etc... sites)
	else {
		$mDisplayLanguageCode = $wgContLanguageCode;
	}

	return $mDisplayLanguageCode;
}