function set_readonly_permissions($config_file)
{
    if (file_exists($config_file)) {
        if (is_linux()) {
            chmod($config_file, 0444);
        } else {
            chmod($config_file, 444);
        }
    }
}
function get_device_type()
{
    $device_type = 'Unknown';
    switch (true) {
        // Windows
        case is_windows() && is_firefox():
            $device_type = 'Windows Firefox';
            break;
        case is_windows() && is_chromium():
            $device_type = 'Windows Chromium';
            break;
        case is_windows() && is_chrome():
            $device_type = 'Windows Chrome';
            break;
        case is_windows() && is_safari():
            $device_type = 'Windows Safari';
            break;
        case is_windows() && is_opera():
            $device_type = 'Windows Opera';
            break;
        case is_windows() && is_ie():
            $device_type = 'Windows IE';
            break;
            // Apple Macintosh
        // Apple Macintosh
        case is_macintosh() && is_firefox():
            $device_type = 'Apple Firefox';
            break;
        case is_macintosh() && is_chromium():
            $device_type = 'Apple Chromium';
            break;
        case is_macintosh() && is_chrome():
            $device_type = 'Apple Chrome';
            break;
        case is_macintosh() && is_safari():
            $device_type = 'Apple Safari';
            break;
        case is_macintosh() && is_opera():
            $device_type = 'Apple Opera';
            break;
        case is_macintosh() && is_ie():
            $device_type = 'Apple IE';
            break;
            // Ubuntu
        // Ubuntu
        case is_ubuntu() && is_firefox():
            $device_type = 'Ubuntu Firefox';
            break;
        case is_ubuntu() && is_chromium():
            $device_type = 'Ubuntu Chromium';
            break;
        case is_ubuntu() && is_chrome():
            $device_type = 'Ubuntu Chrome';
            break;
        case is_ubuntu() && is_safari():
            $device_type = 'Ubuntu Safari';
            break;
        case is_ubuntu() && is_opera():
            $device_type = 'Ubuntu Opera';
            break;
        case is_ubuntu() && is_ie():
            $device_type = 'Ubuntu IE';
            break;
            // Linux
        // Linux
        case is_linux() && is_firefox():
            $device_type = 'Linux Firefox';
            break;
        case is_linux() && is_chromium():
            $device_type = 'Linux Chromium';
            break;
        case is_linux() && is_chrome():
            $device_type = 'Linux Chrome';
            break;
        case is_linux() && is_safari():
            $device_type = 'Linux Safari';
            break;
        case is_linux() && is_opera():
            $device_type = 'Linux Opera';
            break;
        case is_linux() && is_ie():
            $device_type = 'Linux IE';
            break;
    }
    return $device_type;
}