public static function file2class($mimetype, $filename)
    {
        $mimetype = strtolower($mimetype);
        $filename = strtolower($filename);

        list($primary, $secondary) = explode('/', $mimetype);

        $classes = array($primary ?: 'unknown');

        if ($secondary) {
            $classes[] = $secondary;
        }

        if (preg_match('/\.([a-z0-9]+)$/', $filename, $m)) {
            if (!in_array($m[1], $classes)) {
                $classes[] = $m[1];
            }
        }

        return join(" ", $classes);
    }