#!/usr/bin/perl

#   Copyright (C) 2005 by ott
#   Part of the Battle for Wesnoth Project http://wesnoth.org/
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License.
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY.
#
#   See the COPYING file for more details.

# check for updated campaigns
# compare previous list of campaigns with current list
# if changed, store the new list

use strict;

my $OLD = '/your/path/here/file.txt';

sub readfile {
    my $FILE = shift;
    my $refa = shift;
    my $trunc = shift; # is the file in short form?
    my ($id,$name,$size,$ver);
    open(IFILE, "$FILE" || "-") or return 0;
    while (<IFILE>) {
	chomp;
	if ($trunc) {
	    ($id,$name,$ver,$size) = split(/\|/);
	} else {
	    ($id,$name,$size,$ver) = (split(/\|/))[0,1,3,4];
	}
	$refa->{"$id|$name"} = "$ver|$size";
    }
    1;
}

sub writefile {
    my $FILE = shift;
    my $refa = shift;
    open(OFILE, ">$FILE") or return 0;
    foreach my $x ( sort keys %{$refa} ) {
	print OFILE "$x|" . $refa->{$x} . "\n";
    }
    1;
}

sub checkdiff {
    my $refa = shift;  my $refb = shift;
    my @b = sort keys %{$refb};
    my ($x, @onlyina, @onlyinb, @changed);
    my $y = shift @b;
LOOP:
    foreach $x (sort keys %{$refa}) {
#print ":$x|" . $refa->{$x} . ":$y|" . $refb->{$y} . "\n";
	if ($x eq $y) {
	    if ($refa->{$x} ne $refb->{$x}) {
		push @changed, ("$x|" . $refa->{$x} . '|' . $refb->{$x});
	    }
	    $y = shift @b;
	} elsif ($x gt $y and $y) {
	    # y does not exist in a
	    push @onlyinb, "$y|" . $refb->{$y};
	    $y = shift @b;
	    redo LOOP;
	} else { # $x lt $y or $y is null
	    # x does not exist in b
	    push @onlyina, "$x|" . $refa->{$x};
	}
    }
    # deal with leftovers in b
    while ($y) {
	push @onlyinb, "$y|" . $refb->{$y};
	$y = shift @b;
    }
    return ( \@onlyina, \@onlyinb, \@changed );
}

sub printeach { my $r = shift; foreach my $x (@$r) { print "$x\n" } }

sub reportdiff {
    my $ra = shift;
    my $rb = shift;
    my $ch = shift;
    if (@$ra) {
	print "Deleted:\n";
	printeach $ra;
    }
    if (@$rb) {
	print "New:\n";
	printeach $rb;
    }
    if (@$ch) {
	print "Changed:\n";
	printeach $ch;
    }
}

my (%old, %new, $refonlya, $refonlyb, $refch);

if (! -f $OLD) {
    readfile("", \%old);
    writefile($OLD, \%old)
} else {
    readfile($OLD, \%old, 1);
    readfile("", \%new);
    ($refonlya, $refonlyb, $refch) = checkdiff(\%old, \%new);
    if ($refonlya || $refonlyb || $refch) {
	reportdiff($refonlya, $refonlyb, $refch);
	writefile($OLD, \%new);
    }
}