#!/usr/bin/perl

use strict;

use Image::Magick;
use IO::File;
use CGI;
use DB_File;
use Fcntl ':flock'; # import LOCK_* constants

my $q = new CGI();

my $base_directory = "/usr/local/web_customers/www.0xdeadbeef.com/images/";
my $filename;
my $scale;
my $width;
my $height;
my $aspect;
my $old_width;
my $old_height;
my $ext;
my $image;
my $info_cache;
my %info_cache;
my $info_cache_fd;
my $cached_size;

$filename = $q->param("filename");
$scale = $q->param("scale");
$width = $q->param("width");
$height = $q->param("height");
$aspect = $q->param("aspect");

if (!$filename) {
    print_error("Sorry, you need to include a filename.");
}

if (($filename =~ /^\//) || ($filename =~ /\.\./)) {
    print_error("You don't have a get out of jail free card.");
}

($ext) = $filename =~ /\.(...)$/;

if ($ext != 'jpg' && $ext != 'gif' && $ext != 'png') {
    print_error("unsupported type\n");
}

$filename = $base_directory . $filename;

if (! -f $filename) {
    print_error("Can't read that file.");
}

if ((!$scale || $scale == 1) && !$width && !$height) {
    # just dump the file to stdout
    dump_file($filename, $ext);
    exit 0;
}

# check to see if that info is in our info cache
$info_cache = tie %info_cache, "DB_File", "/home/blizzard/cache/info_cache", O_RDWR|O_CREAT, 0666, $DB_HASH
    or die("Can't open database.");
$info_cache_fd = $info_cache->fd;
open(INFO_CACHE_FH, "+<&=$info_cache_fd") ||
    die ("failed to dup info cache fd");
flock(INFO_CACHE_FH, LOCK_EX) || die("failed to lock info cache fd");

if ($info_cache->get($filename, $cached_size) == 1) {
    print STDERR "not found in info cache\n";
    # it wasn't found so cache it
    $image = new Image::Magick;
    $image->Read($filename);
    $old_width = $image->Get('width');
    $old_height = $image->Get('height');
    $info_cache->put($filename, $old_width."x".$old_height);
}
else {
    print STDERR "found in info cache\n";
    ($old_width, $old_height) = split("x", $cached_size);
}

print STDERR "old size is $old_width $old_height\n";

flock(INFO_CACHE_FH, LOCK_UN);
undef $info_cache;
untie %info_cache;
close(INFO_CACHE_FH);

# try to scale first
if ($scale) {

    if ($scale > 3 || $scale < 0.1) {
	print_error("Sorry, can't scale to $scale");
    }

    $width = int($old_width * $scale);
    $height = int($old_height * $scale);
}

elsif ($aspect) {
    if ($width) {
	$height = int($old_height * ($width / $old_width));
    }
    else {
	$width = int($old_width * ($height / $old_height));
    }
}

else {
    if (!$width) {
	$width = $old_width;
    }
    if (!$height) {
	$height = $old_height;
    }
}

# now that we know the height and width, try and look it up in the cache
my $cache;
my %cache;
my $cache_fd;
my $cache_name;
my $cache_value;

# we know what our cache key would look like
$cache_name = $filename.$width."x".$height;

print STDERR "cache name is $cache_name\n";

$cache = tie %cache, "DB_File", "/home/blizzard/cache/cache", O_RDWR|O_CREAT, 0666, $DB_HASH
    or die("Can't open database.");
$cache_fd = $cache->fd;
open(CACHE_FH, "+<&=$cache_fd") ||
    die("failed to dup info cache fd");
flock(CACHE_FH, LOCK_EX) || die("failed to lock cache fd");

# blast it out of the cache
if ($cache->get($cache_name, $cache_value) != 1) {
    print STDERR "got out of cache! $cache_name\n";
    dump_file ("/home/blizzard/cache/$cache_value");
}
else {
    print STDERR "not in the cache\n";
    my $name = get_next_file();
    # in case it wasn't opened above...
    if (!$image) {
	$image = new Image::Magick;
	$image->Read($filename);
    }
    $image->Scale(width=>$width,
		  height=>$height);
    $image->Set(magick=>'jpg');
    $image->Write("/home/blizzard/cache/$name");
    dump_file ("/home/blizzard/cache/$name");
    $cache->put($cache_name, $name);
}

flock(CACHE_FH, LOCK_UN);
undef $cache;
untie %cache;
close(CACHE_FH);

print STDERR "done\n";

sub print_error {
    my $message = shift;
    print "Content-type: text/plain\n\n";
    print $message;
    exit 1;
}

sub dump_file {
    my $filename = shift;
    my $ext = shift;
    my $buf;
    my $fh = new IO::File;
    $fh->open($filename) || print_error("Failed to open file");

    dump_header($ext);

    while (read($fh, $buf, 1024)) {
	print $buf;
    }
}

sub dump_header {
    my $ext = shift;

    if ($ext == 'jpg') {
	print "Content-type: image/jpeg\n\n";
    }
    elsif ($ext == 'gif') {
	print "Content-type: image/gif\n\n";
    }
    elsif ($ext == 'png') {
	print "Content-type: image/png\n\n";
    }
    else {
	print_error("unsupported media type\n");
    }
}

sub get_next_file {
    my $i;

    for ($i=0; $i < 255; $i++) {
	if ( ! -f "/home/blizzard/cache/$i") {
	    return $i;
	}
    }

    die("Can't create more than 255 files!\n");
}