Contao\Environment::httpAcceptLanguage PHP Method

    protected static function httpAcceptLanguage()
    {
        $arrAccepted = array();
        $arrLanguages = array();
        // The implementation differs from the original implementation and also works with .jp browsers
        preg_match_all('/([a-z]{1,8}(-[a-z]{1,8})?)\\s*(;\\s*q\\s*=\\s*(1|0\\.[0-9]+))?/i', $_SERVER['HTTP_ACCEPT_LANGUAGE'], $arrAccepted);
        // Remove all invalid locales
        foreach ($arrAccepted[1] as $v) {
            $chunks = explode('-', $v);
            // Language plus dialect, e.g. en-US or fr-FR
            if (isset($chunks[1])) {
                $locale = $chunks[0] . '-' . strtoupper($chunks[1]);
                if (preg_match('/^[a-z]{2}(-[A-Z]{2})?$/', $locale)) {
                    $arrLanguages[] = $locale;
                }
            }
            $locale = $chunks[0];
            // Language only, e.g. en or fr (see #29)
            if (preg_match('/^[a-z]{2}$/', $locale)) {
                $arrLanguages[] = $locale;
            }
        }
        return array_slice(array_unique($arrLanguages), 0, 8);
    }