<?php
    require_once "common.php";

    if (ini_get("memory_limit") < 48)
        ini_set("memory_limit", "48M");

    if (!function_exists("gd_info"))
        exit("GD not installed; image cannot be resized.");

    $gd_info = gd_info();
    $gd_version = (substr_count(strtolower($gd_info["GD Version"]), "2.")) ? 2 : 1 ;

    $quality = fallback($_GET["quality"], 80);
    $filename = rtrim(fallback($_GET['file']));
    $extension = pathinfo($filename, PATHINFO_EXTENSION);

    if (!file_exists($filename))
        display_error("Image Not Found");

    function display_error($string) {
        $thumbnail = imagecreatetruecolor(oneof(@$_GET['max_width'], 100), 18);
        imagestring($thumbnail, 1, 5, 5, $string, imagecolorallocate($thumbnail, 255, 255, 255));
        header("Content-type: image/png");
        header("Content-Disposition: inline; filename=error.png");
        imagepng($thumbnail);
        exit;
    }

    list($original_width, $original_height, $type, $attr) = getimagesize($filename);

    $new_width = (int) fallback($_GET["max_width"], 0);
    $new_height = (int) fallback($_GET["max_height"], 0);

    $crop_x = 0;
    $crop_y = 0;

    function resize(&$crop_x, &$crop_y, &$new_width, &$new_height, $original_width, $original_height) {
        $xscale = ($new_width / $original_width);
        $yscale = $new_height / $original_height;

        if ($new_width <= $original_width and $new_height <= $original_height and $xscale == $yscale)
            return;

        if ( isset($_GET['square']) ) {
            if ( $new_width === 0 )
                $new_width = $new_height;

            if ( $new_height === 0 )
                $new_height = $new_width;

            if($original_width > $original_height) {
                # portrait
                $crop_x = ceil( ($original_width - $original_height) / 2 );
            } else if ($original_height > $original_width) {
                # landscape
                $crop_y = ceil( ($original_height - $original_width) / 2 );
            }

            return;

        } else {
    
            if ($new_width and !$new_height)
                return $new_height = ($new_width / $original_width) * $original_height;
            elseif (!$new_width and $new_height)
                return $new_width = ($new_height / $original_height) * $original_width;
    
            if ($xscale != $yscale) {
                if ($original_width * $yscale <= $new_width)
                    $new_width = $original_width * $yscale;
    
                if ($original_height * $xscale <= $new_height)
                    $new_height = $original_height * $xscale;
            }
    
            $xscale = ($new_width / $original_width);
            $yscale = $new_height / $original_height;
    
            if (round($xscale, 3) == round($yscale, 3))
                return;
    
            resize($crop_x, $crop_y, $new_width, $new_height, $original_width, $original_height);
        }
    }

    # Determine the final scale of the thumbnail.
    resize($crop_x, $crop_y, $new_width, $new_height, $original_width, $original_height);

    # If it's already below the maximum, just redirect to it.
    if ($original_width <= $new_width and $original_height <= $new_height)
        header("Location: ".$filename);

    $cache_filename = md5($filename.$new_width.$new_height.$quality).".".$extension;
    $cache_file = INCLUDES_DIR."/caches/thumb_".$cache_filename;

    if (isset($_GET['no_cache']) and $_GET['no_cache'] == "true" and file_exists($cache_file))
        unlink($cache_file);

    # Serve a cache if it exists and the original image has not changed.
    if (file_exists($cache_file) and filemtime($cache_file) > filemtime($filename)) {
        header("Last-Modified: ".gmdate('D, d M Y H:i:s', filemtime($cache_file)).' GMT');
        header("Content-type: image/".($extension == "jpg" ? "jpeg" : $extension));
        header("Cache-Control: public");
        header("Expires: ".date("r", strtotime("+30 days")));
        header("Content-Disposition: inline; filename=".$cache_filename);
        readfile($cache_file);
        exit;
    }

    # Verify that the image is able to be thumbnailed, and prepare variables used later in the script.
    switch ($type) {
        case IMAGETYPE_GIF:
            $image = imagecreatefromgif($filename);
            $done = (function_exists("imagegif")) ? "imagegif" : "imagejpeg" ;
            $mime = (function_exists("imagegif")) ? "image/gif" : "image/jpeg" ;
            break;

        case IMAGETYPE_JPEG:
            $image = imagecreatefromjpeg($filename);
            $done = "imagejpeg";
            $mime = "image/jpeg";
            break;

        case IMAGETYPE_PNG:
            $image = imagecreatefrompng($filename);
            $done = "imagepng";
            $mime = "image/png";
            break;

        case IMAGETYPE_BMP:
            $image = imagecreatefromwbmp($filename);
            $done = "imagewbmp";
            $mime = "image/bmp";
            break;

        default:
            display_error("Unsupported image type.");
            break;
    }

    if (!$image)
        display_error("Image could not be created.");

    # Decide what functions to use.
    $create = ($gd_version == 2) ? "imagecreatetruecolor" : "imagecreate" ;
    $copy = ($gd_version == 2 and $original_width < 4096) ? "imagecopyresampled" : "imagecopyresized" ;

    # Create the final resized image.
    $thumbnail = $create($new_width, $new_height);

    if ($done == "imagepng")
        imagealphablending($thumbnail, false);

    # if square crop is desired, original dimensions need to be set to square ratio
    if ( isset($_GET['square']) ) {
        if ($original_width > $original_height) {
            $original_width = $original_height;
        } else if ($original_height > $original_width) {
            $original_height = $original_width;
        }
    }

    $copy($thumbnail, $image, 0, 0, $crop_x, $crop_y, $new_width, $new_height, $original_width, $original_height);

    header("Last-Modified: ".gmdate("D, d M Y H:i:s", filemtime($filename))." GMT");
    header("Content-type: ".$mime);
    header("Content-Disposition: inline; filename=".$cache_filename.".".$extension);

    if ($done == "imagepng")
        imagesavealpha($thumbnail, true);

    # Generate the cache image.
    if (!isset($_GET['no_cache']) or $_GET['no_cache'] == "false")
        if ($done == "imagejpeg")
            $done($thumbnail, $cache_file, $quality);
        else
            $done($thumbnail, $cache_file);

    # Serve the image.
    if ($done == "imagejpeg")
        $done($thumbnail, "", $quality);
    else
        $done($thumbnail);

    # Clear memory.
    imagedestroy($image);
    imagedestroy($thumbnail);