hestiacp/web/inc/i18n.php

<?php
// Functions for internationalization
// I18N support information here

putenv("LANGUAGE=".detect_user_language());
setlocale( LC_ALL, 'C.UTF-8' );

$domain = 'hestiacp';
$localedir = '/usr/local/hestia/web/locale';
bindtextdomain($domain, $localedir);
textdomain($domain);


/**
 * Detects user language from Accept-Language HTTP header.
 * @param string Fallback language (default: 'en')
 * @return string Language code (such as 'en' and 'ja')
 */
function detect_user_language() {
   if (!empty($_SESSION['language'])) {
        return $_SESSION['language'];   
   }elseif (!empty($_SESSION['LANGUAGE'])){
       return $_SESSION['LANGUAGE'];
   }else{
       return 'en';
   }
}
/**
 * Translate ISO2 to "Language" 
 * nl = Dutch, de = German
 * @param string iso2 code
 * @return string Language
 */
function translate_json($string){
    $json = file_get_contents($_SERVER['DOCUMENT_ROOT'].'/locale/languages.json');
    $json_a = json_decode($json, true);
    return $json_a[$string][0] .' ('.$json_a[$string.'_locale'][0].')';
}
/**
 * Detects user language .
 * @param string Fallback language (default: 'en')
 * @return string Language code (such as 'en' and 'ja')
 */

function detect_login_language(){

}