function user_browser($agent) {
    preg_match("/(MSIE|Opera|Firefox|Chrome|Version|Opera Mini|Netscape|Konqueror|SeaMonkey|Camino|Minefield|Iceweasel|K-Meleon|Maxthon)(?:\/| )([0-9.]+)/", $agent, $browser_info);
    list(, $browser, $version) = $browser_info;
    if (preg_match("/Opera ([0-9.]+)/i", $agent, $opera))
        return 'Opera|' . $opera[1];
    if ($browser == 'MSIE') {
        preg_match("/(Maxthon|Avant Browser|MyIE2)/i", $agent, $ie);
        if ($ie)
            return $ie[1] . ' based on IE|' . $version;
        return 'IE|' . $version;
    }
    if ($browser == 'Firefox') {
        preg_match("/(Flock|Navigator|Epiphany)\/([0-9.]+)/", $agent, $ff);
        if ($ff)
            return $ff[1] . '|' . $ff[2];
    }
    if ($browser == 'Opera' && $version == '9.80')
        return 'Opera|' . substr($agent, -5);
    if ($browser == 'Version')
        return 'Safari|' . $version;
    if (!$browser && strpos($agent, 'Gecko'))
        return 'Browser based on Gecko';
    return $browser . '|' . $version;
}