#!/usr/bin/perl -w
use strict;

open O, '<', $ARGV[0] or die $!;
open N, '<', "lib/survex-$ARGV[0]" or die $!;

my $fuzzy = 0;
my $diff = 0;
my ($o, $n);
while (1) {
    $o //= <O>;
    $n //= <N>;
    if (!defined $n) {
	last unless defined $o;
	print '-' if $diff;
	print $o;
	$o = undef;
	next;
    }
    if (!defined $o) {
	print '+' if $diff;
	print $n;
	$n = undef;
	next;
    }

    if ($o eq '' || $n eq '') {
	$fuzzy = 0;
    }

    if ($o eq $n) {
	print ' ' if $diff;
	print $n;
	$n = $o = undef;
	next;
    }

    if ($o eq "#~ $n") {
	print ' ' if $diff;
	print $o;
	$n = $o = undef;
	next;
    }

    if ($o =~ /^("PO(?:-Revision|T-Creation)-Date: \d+-\d+-\d+ \d+:\d+):\d\d (.*\n)$/ &&
	$n eq "$1:00 $2") {
	print ' ' if $diff;
	print $o;
	$n = $o = undef;
	next;
    }

    if ($o =~ /^"PO-Revision-Date:/ && $n =~ /^"PO-Revision-Date:/) {
	print ' ' if $diff;
	print $o;
	$n = $o = undef;
	next;
    }

    if ($o eq "#, fuzzy\n") {
	print ' ' if $diff;
	print $o;
	$o = undef;
	$fuzzy = 1;
	next;
    }

    my $tmp = $o;
    if ($tmp =~ s/, fuzzy// && $n eq $tmp) {
	print ' ' if $diff;
	print $o;
	$n = $o = undef;
	$fuzzy = 1;
	next;
    }

    if ($fuzzy && $o =~ /^(?:#~ )?msgstr / && $n eq "msgstr \"\"\n") {
	print ' ' if $diff;
	print $o;
	$n = $o = undef;
	$fuzzy = 0;
	next;
    }

    print "-$o" if $diff;
    print '+' if $diff;
    print $n;
    $n = $o = undef;
}