#!/usr/local/bin/perl -wT
##---------------------------------------------------------------------------##
##  Author:
##      Pradeep Padala, ppadala@cise.ufl.edu
##  Description:
##      Program to create a graphical counter
##---------------------------------------------------------------------------##
##    Copyright (C) 2002 Pradeep Padala, ppadala@cise.ufl.edu
##
##    This program is free software; you can redistribute it and/or modify
##    it under the terms of the GNU General Public License as published by
##    the Free Software Foundation; either version 2 of the License, or
##    (at your option) any later version.
##
##    This program is distributed in the hope that it will be useful,
##    but WITHOUT ANY WARRANTY; without even the implied warranty of
##    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##    GNU General Public License for more details.
##
##    You should have received a copy of the GNU General Public License
##    along with this program; if not, write to the Free Software
##    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
##    02111-1307, USA
##---------------------------------------------------------------------------##

use CGI ':standard';
use GD;
use strict;

my($LOCK_SH, $LOCK_EX, $LOCK_NB, $LOCK_UN);

$LOCK_SH = 1;
$LOCK_EX = 2;
$LOCK_NB = 4;
$LOCK_UN = 8;

select(STDOUT);
$| = 1;

&main;

sub main {
    my($id, $iformat, $show);

    $id = param("id");
    $iformat = param("iformat");
    
    my($counter_value);
    $counter_value = &update_counter_value($id);

    chomp($counter_value);
    if($iformat eq "jpg" || $iformat eq "png") {
        &print_counter($iformat, $counter_value);
    }
    else {
        &print_error_image("Image format $iformat not supported");
    }
}

sub print_counter {
    my($iformat, $counter_value) = @_;
    my($COUNTER_SIZE) = 4;

    my($im) = GD::Image->new("${iformat}s/0.${iformat}");
    if(!defined($im)) {
        &print_error_image("\$im couldn't be initialized");
        exit;
    }

    my($w, $h) = $im->getBounds();
    undef $im;
    
    my($printim) = GD::Image->new($w * $COUNTER_SIZE, $h);
    $printim->colorAllocate(255, 255, 255);

    my($pos, $l, $temp, $digit, $x, $srcim);
    $x = 0;
    for($pos = $COUNTER_SIZE - 1; $pos >= 0; $pos--) {
        if($pos > length($counter_value) - 1) {
            $digit = 0;
        }
        else {
            $l = length($counter_value);
            $temp = $l - $pos - 1;
            $digit = substr($counter_value, $temp, 1);
        }
        $srcim = GD::Image->new("${iformat}s/${digit}.${iformat}");
        $printim->copy($srcim, $x, 0, 0, 0, $w, $h);
        $x += $w;
        undef $srcim;
    }
    if($iformat eq "jpg") {
        print "Content-type: image/jpeg\n\n";
        print $printim->jpeg(100);
    }
    else {
        print "Content-type: image/png\n\n";
        print $printim->png;
    }
}

sub print_error_image {

    my $error_string = $_[0];
    my $im = new GD::Image(
    gdMediumBoldFont->width * length($error_string), 
    gdMediumBoldFont->height);

    $im->colorAllocate(255, 255, 255);
    my $red = $im->colorAllocate(255, 0, 0);
    $im->string(gdMediumBoldFont, 0, 0, $error_string, $red);
    print "Content-type: image/jpeg\n\n";
    print $im->jpeg(100); 
    exit;
}

sub update_counter_value {
    my($file_name, $counter_value);

    $file_name = "$_[0].counter"; 
    if ($file_name =~ /^([-\@\w.]+)$/) {   # For the tainting stuff
        $file_name = $1;
    }
    else {
        exit; # Should never happen
    }
    if(open(COUNTERFILE, "+<$file_name") == 0) {
        # Getting accessed for the first time
        open(COUNTERFILE, ">$file_name");
        print COUNTERFILE "1";
        close(COUNTERFILE);
        return 1;
    }
    
    flock(COUNTERFILE, $LOCK_EX);
    $counter_value = <COUNTERFILE>;
    seek(COUNTERFILE, 0, 0);
    ++$counter_value;
    print COUNTERFILE $counter_value;
    flock(COUNTERFILE, $LOCK_UN);

    close(COUNTERFILE);
    return($counter_value - 1);
}