<?php
header('Content-type: image/jpeg');
define('IMAGES_PATH', './thumbs');
define('TMP_PATH', './tmp');

define('MAX_WIDTH', 150);
define('MAX_HEIGHT', 150);

if(empty($_GET['image'])) die('no image specified');

$outputname = IMAGES_PATH . '/' . md5($_GET['image']);
if(file_exists($outputname))
{
    readfile($outputname);
    die();
}

$tmpname = TMP_PATH . '/' . uniqid();

$ch = curl_init(str_replace(" ", "%20", $_GET['image']));
$fp = fopen($tmpname, 'wb');
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_exec($ch);
fclose($fp);
if(curl_errno($ch)) die();

$imagesize = @getimagesize($tmpname);
if(!$imagesize) die('invalid image specified');

$source = null;
$thumb = null;
$thumb_width = MAX_WIDTH;
$thumb_height = MAX_HEIGHT;

$source_width = $source_height = -1;
$dest_x = $dest_y = 0;
$source_x = $source_y = 0;

if($imagesize[0] <= MAX_WIDTH)
{
    $thumb_width = $source_width = $imagesize[0];
    $thumb_height = $source_height = min($imagesize[1], MAX_HEIGHT);
    $source_y = max($imagesize[1] - $source_height, 0) / 2;
}
else if($imagesize[1] <= MAX_HEIGHT)
{
    $thumb_height = $source_height = $imagesize[1];
    $thumb_width = $source_width = min($imagesize[0], MAX_WIDTH);
    $source_x = max($imagesize[0] - $source_width, 0) / 2;
}

if($source_width <= 0)
{
    if($imagesize[0] >= $imagesize[1])
    {
        $source_height = $imagesize[1];
        $source_width = (MAX_WIDTH/MAX_HEIGHT)*($source_height);
        $source_x = max($imagesize[0] - $source_width, 0) / 2;
    }
    else
    {
        $source_width = $imagesize[0];
        $source_height = (MAX_HEIGHT/MAX_WIDTH)*($source_width);
        $source_y = max($imagesize[1] - $source_height, 0) / 2;
    }
}

switch($imagesize['mime'])
{
    case 'image/jpg':
    case 'image/jpeg':
        $source = imagecreatefromjpeg($tmpname);
    break;

    case 'image/png':
        $source = imagecreatefrompng($tmpname);
    break;

    default: break;
}

if(!$source) die('invalid image specified (mime type not supported)');

$thumb = imagecreatetruecolor($thumb_width, $thumb_height);
imagecopyresampled($thumb, $source, $dest_x, $dest_y, $source_x, $source_y, $thumb_width, $thumb_height, $source_width, $source_height);

imagejpeg($thumb, null, 100);
imagejpeg($thumb, $outputname, 100);
unlink($tmpname);