#!/usr/bin/perl

use strict;
use warnings;
use CGI qw(:standard :html3);
use Algorithm::Diff qw(traverse_sequences);
use Text::Tabs;

my $old = '1,2,3,4';
my $new = '5,6,7,8';

my @old = split( /\s+/, $old );
my @new = split( /\s+/, $new );

my $style = <<EOS;
        PRE {
            margin-left: 24pt;
            font-size: 12pt;
            font-family: Courier, monospaced;
            white-space:pre
    }
        PRE.onlynew { color: red  }
        PRE.onlyold { color: blue }
EOS

print start_html(
    {
        -title => "$old vs $new",
        -style => { -code => $style }
    }
  ),
  h1(
    { -style => 'margin-left: 24pt' },
    span( { -style => 'color: red' }, $old ),
    span(" <i>vs.<i> "), span( { -style => 'color: blue' }, $new )
  ),
  "\n";

traverse_sequences(
    \@old,
    \@new,
    {
        MATCH     => \&match,
        DISCARD_A => \&only_old,
        DISCARD_B => \&only_new,
    }
);
print end_html;

sub match {
    print @old, "\n";
}

sub only_old {
    print "<strong><font color=red>" . shift(@old) . "</font></strong>\n";
}

sub only_new {
    print "<strong><font color=blue>" . shift(@new) . "(</font></strong>\n";
}