use warnings;
use strict;
use myconfig qw/read_config/;

my $d2s_original = read_config();
#'C:\Users\user1\AppData\Local\VirtualStore\Program Files (x86)\Diablo II\Save\my_d.d2s';
#'revert.d2s';
my $d2s_loaded = 'loaded.d2s';

if(! -f $d2s_original){
  die 'wtf the character file does not exist.';
}
if(! -f $d2s_loaded){
  die 'The d2s file is not loaded!!';
}

#if different sizes, abort.
my (@s1, @s2);
@s1 = stat($d2s_original);
@s2 = stat($d2s_loaded);
if(scalar(@s1) == 0){
  die('unable to stat original d2s file.');
}
if(scalar(@s2) == 0){
  die('unable to stat loaded d2s file.');
}
if($s1[7] != $s2[7]){
  die 'Files are different sizes, cannot compare.';
}

#detect changes in the files.
my (${f1}, ${f2});
open(${f1}, '<', $d2s_original);
open(${f2}, '<', $d2s_loaded);
my ($b1, $b2);
my $address = -1;
my $changes = 0;
while(sysread(${f1}, $b1, 1) == 1){
  $address++;
  sysread(${f2}, $b2, 1) or die 'Cannot read the loaded d2s file.';
  #ignore the checksum changes.
  #if($address >= 13 && $address <= 15){
  #  next;
  #}
  if(ord($b1) != ord($b2)){
    print('@ ', $address, ': ', ord($b2), '/', ord($b1), ' ');
    print('B8:', (unpack('B8', $b2))[0], '/', (unpack('B8', $b1))[0], ' ');
    print('H2:0x', (unpack('H2', $b2))[0], '/0x', (unpack('H2', $b1))[0], ' ');
    print('b8:', (unpack('b8', $b2))[0], '/', (unpack('b8', $b1))[0], ' ');
    print('h2:0x', (unpack('h2', $b2))[0], '/0x', (unpack('h2', $b1))[0], ' ');
    print "\n";
    $changes++;
  }
}

if($changes == 0){
  die 'The files are the same...dummy.';
}
else{
  CORE::say "Total of #$changes byte changes.";
}