#! /usr/local/bin/perl
#                                                         -*- Perl -*-
# Copyright (C) 2000  Motoyuki Kasahara
#
# 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, 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.

use FileHandle;

if (@ARGV != 2) {
    die "Usage: $0 old-po-file new-po-file\n";
}
$old_file_name = $ARGV[0];
$new_file_name = $ARGV[1];

#
# Read the old PO file.
#
if (!open(OLD_FILE, $old_file_name)) {
    die "$0: failed to open the file, $!: $old_file_name\n";
}

$msgid = '';
while (<OLD_FILE>) {
    next if /^\#/;
    chop if /\n/;
    if (/^msgid:(.*)/) {
	$msgid = $1;
	if ($msgid eq '') {
	    warn "$old_file_name:$.: msgid is empty\n";
	    next;
	} elsif (defined($old_messages{$msgid})) {
	    warn "$old_file_name:$.: msgid redefined: $msgid";
	    next;
	}
	$old_messages{$msgid} = '';

    } elsif (/^msgstr:(.*)/) {
	$msgstr = $1;
	if ($msgid eq '') {
	    warn "$old_file_name:$.: msgid is empty\n";
	    next;
	} elsif ($msgstr eq '') {
	    warn "$old_file_name:$.: msgstr is empty\n";
	    next;
	}
	$old_messages{$msgid} = $msgstr;
    }
}
close(OLD_FILE);

#
# Read the current PO file.
#
if (!open(NEW_FILE, $new_file_name)) {
    die "$0: failed to open the file, $!: $new_file_name\n";
}

$msgid = '';
while (<NEW_FILE>) {
    next if /^\#/;
    chop if /\n/;
    if (/^msgid:(.*)/) {
	$msgid = $1;
	if ($msgid eq '') {
	    warn "$new_file_name:$.: msgid is empty\n";
	    next;
	} elsif (defined($new_messages{$msgid})) {
	    warn "$new_file_name:$.: msgid redefined: $msgid";
	    next;
	}
	$new_messages{$msgid} = '';

    } elsif (/^msgstr:(.*)/) {
	$msgstr = $1;
	if ($msgid eq '') {
	    warn "$new_file_name:$.: msgid is empty\n";
	    next;
	} elsif ($msgstr ne '') {
	    warn "$new_file_name:$.: msgstr is not empty\n";
	    next;
	}
	if (defined($old_messages{$msgid})) {
	    $new_messages{$msgid} = $old_messages{$msgid};
	} else {
	    warn "$new_file_name:$.: no such msgid in $old_file_name: $msgid\n";
	    $new_messages{$msgid} = '';
	}
	print "msgid:", $msgid, "\n";
	print "msgstr:", $new_messages{$msgid}, "\n\n";
    }
}
close(NEW_FILE);

#
# Output removed entries as comment.
#
foreach $msgid (keys(%old_messages)) {
    if (!defined($new_messages{$msgid})) {
	print "#msgid:", $msgid, "\n";
	print "#msgstr:", $old_messages{$msgid}, "\n\n";
    }
}