#!/usr/bin/perl -Tw
use strict;
use Storable qw/lock_store lock_retrieve/;
use CGI qw/:standard/;

#########################
# Begin Config

# File to store 'rotate' data in.
# CGI instance must have read/write access
my $data_file = '/var/www/images.dat';

# Image to show if there's an error
# ie: "Error", "404 Not Found" image
my $err_img = '/var/www/images/err.jpg';

# Catagories for 'rotate' and 'random'
# Keys are the catagory names to pass as 'c' argument,
# arrays are the directories for that catagory.
my $cat = {
 'banners' =>
   ['/home/user/imgs/banners', '/home/user/imgs/banners2'],
 'logos'   =>
   ['/home/user/imgs/logos', '/home/user/imgs/logos2']
};

#########################
# End Config

# Automatically generate an 'all' catagory
@{$cat->{'all'}} = map{@{$cat->{$_}}}keys %{$cat};

# Rotate the image number for a catagory
sub rotate_img {
 my $q = shift;

 my @imgs = get_imgs(@{$cat->{$q}});
 my $data = -e $data_file ? lock_retrieve($data_file) : {};
 $data->{$q} = 0 if $data->{$q}++ == $#imgs;
 lock_store $data, $data_file;
 return $imgs[$data->{$q}];
}

# Get list of images from directories
sub get_imgs {
 sort grep {-f && /(?:\.gif|jpe?g|png)$/i }
  map{ glob("$_/*") } @_
}

# Output an image to the browser
sub show_img {
 my $img = shift;
 my ($mime) = $img =~ /\.(gif|jpe?g|png)$/;
 $mime = 'jpeg' if $mime eq 'jpg';
 open my $fh, '<', $img
  or die "Could not open $img for read: $!";
 binmode $fh;
 my $img_data = do { local $/; <$fh> };
 close $fh;
 print header('image/' . $mime), $img_data;
 exit;
}

my $m = param('m') || ''; # Mode
my $c = param('c') || ''; # Catagory

# Rotated image
if ($m eq 'rotate') {
 show_img( $cat->{$c} ? rotate_img($c) : $err_img );
}

# Random image
elsif ($m eq 'random') {
 show_img($err_img) unless $cat->{$c};
 my @imgs = get_imgs(@{$cat->{$c}});
 show_img($imgs[rand @imgs]);
}

# Specific Image
elsif ($m eq 'image') {
 ($m,$c) = split(/\//, $c, 2);
 show_img($err_img) unless
  $cat->{$m} && $c;
 for ( get_imgs(@{$cat->{$m}}) ) {
  show_img($_) if m#/\Q$c\E\.(?:gif|jpe?g|png)$#;
 }
 show_img($err_img);
}

# Invalid Call
else {
 show_img($err_img);
}