idioma php

function idioma() {
    $http_accept = getenv('HTTP_ACCEPT_LANGUAGE');

    if (isset($http_accept) && strlen($http_accept) > 1) {
        $x = explode(",", $http_accept);
        foreach ($x as $val) {
            if (preg_match("/(.*);q=([0-1]{0,1}.d{0,4})/i", $val, $matches))
            $lang[$matches[1]] = (float) $matches[2];
            else
                $lang[$val] = 1.0;
        }

        $qval = 0.0;
        foreach ($lang as $key => $value) {
            if ($value > $qval) {
                $qval = (float) $value;
                return $key;
            }
        }
    }
    return self::$tag_default;
}

switch (idioma()) {
    case "pt-BR":
    case "pt": header('Location: http://pt.dominio.com');
    break;
    case 'en-us': header('Location: index.php');
    break;
    case 'es': header('Location: http://es.dominio.com');
    break;
}