Generate Minecraft Online-Status-Images

<?php
/**
* --------------------------------------------------------------------------------
* - Generate Minecraft Online-Status-Image
* --------------------------------------------------------------------------------
* This code is based on Revi's initial idea and work
* http://forums.bukkit.org/threads/web-beautiful-monitoring.122457/#post-1519585
*
* Features
* - supports png, jpg and gif
* - per image cache files
* - keep the cache clean (30)
*/


/**
* --------------------------------------------------------------------------------
* - Configuration Section
* --------------------------------------------------------------------------------
*/
error_reporting(0); # set to E_ALL when debugging otherwise you can leave this alone

$host = 'localhost';            # IP or hostname
$port = 25565;                  # port
$folder_name = 'cache';         # folder used for caching; Make sure the folder is created and has the correct access rights
$time_update_cache = 5;         # update cache every x second, decrease this value if you want a faster response time
$offline_message = 'offline';   # this message will be shown, when the server is offline or in case of connection problems
$file_type = @$_GET['t'];       # supported file_types (png|jpg|gif)
$keep_files = 30;               # if we spam the refresh button we may loose the old cache file and leave an unused image behind.
                                # to prevent this we only keep 30 files (10 per file_type) at max. This can also be doubled safely.

/**
* You normally don't have to edit below this line.
* Only edit below this line if you know what you are doing.
*/
$file_type = (is_supported_filetype($file_type)) ? $file_type : 'png'; # always fallback to png
header("Content-type: image/" . $file_type);

$folder = escapeshellcmd($folder_name);
$new_cache_time = time();
$file_list = glob('./' . $folder . '/*.' . $file_type); # get all image files in $folder_name

if (count($file_list) >= $keep_files)
    clear_cache($file_list);

$image_path = '';
$old_cache_time = str_replace('.' . $file_type,'',str_replace('./' . $folder . '/','', $file_list[0])); # get the oldest cache file time from filename

function monitoring_view($online = 1, $max_online = 21, $img) {
    global $offline_message;

    $x_start = 0;
    $y_start = 0;
    $y_end = 20;
    $height = 20;
    $width = 200;

    //$img = imagecreatetruecolor($width, $height);
    $d = imagecolorexact($img ,0, 0, 0 );

    if ($online != 'f'){
        $x_end = $online * ($width / $max_online);
        imagefill($img, 0, 0, imagecolorallocate($img, 230, 220, 230));
        $s=0; # saturation (increase red and blue)
        $red = imagecolorallocate($img, 200-$s, 255, 150-$s); # allocate the imagecolor

        // set pixels for y and x
        for ($i = $y_start; $i < $y_end; $i++){ // y
            for ($j = $x_start; $j < $x_end; $j++){ // x
                imagesetpixel($img, $j, $i, $red);
                $red = imagecolorallocate($img, 180-$s, 255, 150-$s);
                $s = $s + 0.03;
            }
        }

        imagestring($img, 5, 80, 2, $online . '/' . $max_online, $d);
    } else {
        imagefill($img, 0, 0, ($blue = imagecolorallocate($img, 255, 0, 0)));
        imagestring($img, 5, 70, 2, $offline_message, $d);
    }

    return $img;
}

function clear_cache($file_list) {
    foreach ($file_list as $file) {
        unlink($file);
    }
}

function get_image_path() {
    global $image_path;

    return $image_path;
}

function set_image_path($path) {
    global $image_path;

    $image_path = $path;
}

function is_supported_filetype($file_type) {
    switch ($file_type) {
        case 'png':
        case 'jpg':
        case 'gif':
            return true;
    }

    return false;
}

function get_image($img) {
    global $file_type;

    switch ($file_type) {
        case 'jpg':
            return imagejpeg($img);
        case 'gif':
            return imagegif($img);
    }

    return imagepng($img);
}


function set_image($img, $path) {
    global $file_type;

    switch ($file_type) {
        case 'jpg':
            return imagejpeg($img, $path);
        case 'gif':
            return imagegif($img, $path);
    }

    return imagepng($img, $path);
}

function create_image() {
    global $file_type;

    $path = get_image_path();

    switch ($file_type) {
        case 'jpg':
            return imagecreatefromjpeg($path);
        case 'gif':
            return imagecreatefromgif($path);
    }

    return imagecreatefrompng($path);
}

 /**
 * extract online informations from connection packet
 */
function online($host, $port) {
    global $offline_message;

    $socket = @fsockopen($host, $port);

    if ($socket !== false) {
        @fwrite($socket, "\xFE");
        $data = "";
        $data = @fread($socket, 1024);
        @fclose($socket);

        if ($data !== false && substr($data, 0, 1) == "\xFF") {
            $info = explode("\xA7", mb_convert_encoding(substr($data, 1), "iso-8859-1", "utf-16be"));
            return $info;
        }
    }

    return $offline_message;
}

/**
* Handle cache files
*/
if (!@file_exists($folder)) {
    @mkdir($folder);
}

if ($file_list[0] != '') {
    if ($new_cache_time - $old_cache_time >= $time_update_cache) {
        $online = online($host, $port);
        $img = monitoring_view($online[1], $online[2], imagecreatetruecolor(200, 20));

        set_image($img, './' . $folder . '/' . $new_cache_time . '.' . $file_type);
        get_image($img);
        imagedestroy($img);

        // unlink old file after the new one has been created
        unlink('./' . $folder . '/' . $old_cache_time . '.' . $file_type);
    } else {
        set_image_path('./' . $folder . '/' . $old_cache_time . '.' . $file_type);
        $img = create_image(get_image_path());
        get_image($img);
        imagedestroy($img);
    }
} else {
    $online = online($host, $port);
    $img = monitoring_view($online[1], $online[2], imagecreatetruecolor(200, 20));
    set_image($img, './' . $folder . '/' . $new_cache_time . '.' . $file_type);
    get_image($img);
    imagedestroy($img);
}
?>