#!/usr/bin/env perl

#############################################################################

# Copyright (c) 2008,2009 Novell, Inc.

# All Rights Reserved.

#

# This program is free software; you can redistribute it and/or

# modify it under the terms of version 2 of the GNU General Public License as

# published by the Free Software Foundation.

#

# 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.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, contact Novell, Inc.

#

# To contact Novell about this file by physical or electronic mail,

# you may find current contact information at www.novell.com

#############################################################################

#

# script to merge changes done to *.changes files

#

# To install the script as a git merge driver:

#

#   git config merge.rpm-changes.name "*.changes merge driver"

#   git config merge.rpm-changes.driver "scripts/rpm-changes-merge.pl %A %O %B"

#   echo '*.changes merge=rpm-changes' >>.git/info/attributes

use strict;

use warnings;

BEGIN {

    if ($0 =~ /^(.*)\/[^\/]*/) {

        unshift @INC, "$1/lib";

    } else {

        unshift @INC,  "./lib";

    }

}

use Time::Zone;

use Getopt::Std;

use POSIX qw(mktime);

use File::Temp qw(tempfile);

my $conflicts = 0;

sub usage {

    print STDERR

"Usage:

  Three-way merge:

    $0 [-p] my.changes orig.changes their.changes

  Two-way merge:

    $0 [-p] -2 my.changes their.changes

  Fixup mode:

    $0 [-p] -1 my.changes

";

    exit 1;

}

sub main {

    $ENV{'TZ'} = "UTC";

    our ($opt_p, $opt_1, $opt_2, $opt_3) = (0, 0, 0, 0);

    my (%O, %A, %B, $out);

    if (!getopts('p123') || $opt_1 + $opt_2 + $opt_3 > 1) {

        usage();

    }

    if ($opt_1) {

        usage() if @ARGV != 1;

        loadchanges($ARGV[0], \%A);

    } elsif ($opt_2) {

        usage() if @ARGV != 2;

        loadchanges($ARGV[0], \%A);

        loadchanges($ARGV[1], \%B);

    } else {

        usage() if @ARGV != 3;

        loadchanges($ARGV[0], \%A);

        loadchanges($ARGV[1], \%O);

        loadchanges($ARGV[2], \%B);

    }

    if ($opt_p) {

        $out = \*STDOUT;

    } else {

        open($out, '>', $ARGV[0]) or die "$ARGV[0]: $!\n";

    }

    my %seen;

    for my $key (reverse(sort(keys(%A), keys(%O), keys(%B)))) {

        next if $seen{$key};

        $seen{$key} = 1;

        print $out merge($A{$key}, $O{$key}, $B{$key});

    }

    exit $conflicts;

}

sub merge {

    my ($a, $o, $b) = @_;

    $a = "" unless defined $a;

    $o = "" unless defined $o;

    $b = "" unless defined $b;

    return $a if $a eq $b;

    return $a if $o eq $b;

    return $b if $o eq $a;

    return rcs_merge($a, $o, $b);

}

my $have_rcs_merge = 1;

sub rcs_merge {

    my @texts = @_;

    my $res;

    if ($have_rcs_merge) {

        my @fh;

        my @fn;

        for my $i (0..2) {

            ($fh[$i], $fn[$i]) = tempfile();

            my $fh = $fh[$i];

            print $fh $texts[$i];

        }

        $res = `merge -p $fn[0] $fn[1] $fn[2]`;

        for my $i (0..2) {

            close($fh[$i]);

            unlink($fn[$i]);

        }

        if ($? == 0) {

            return $res;

        } elsif ($? >> 8 == 1) {

            $conflicts = 1;

            return $res;

        } else {

            print STDERR "merge(1) not found, using DumbMerge(TM) instead.\n";

            print STDERR "Install the rcs package for better merge results.\n";

            $have_rcs_merge = 0;

        }

    }

    return "<<<<<<< $ARGV[0]\n" . $texts[0] . "=======\n" . $texts[2] . ">>>>>>> $ARGV[2]\n";

}

sub loadchanges {

    my ($file, $res) = @_;

    open(my $fh, '<', $file) or die "$file: $!\n";

    my $l;

    my $date = 1<<32;

    my $email = "";

    my $expect_date = 0;

    my $text;

    while ($l = <$fh>) {

        if ($expect_date) {

            (my $dt, $email) = parse_date($l);

            if (defined $dt) {

                $date = $dt;

            } else {

                print STDERR "$file:$.: invalid date: $l";

            }

            $expect_date = 0;

        }

        if ($l =~ /^-{50}-*$/ || eof($fh)) {

            if (eof($fh)) {

                $text .= $l;

            }

            if (defined $text) {

                my $key = sprintf("%010d %s", $date, $email);

                if (defined $res->{$key}) {

                    $res->{$key} .= $text;

                } else {

                    $res->{$key} = $text

                }

            }

            undef $text;

            $date--;

            $expect_date = 1;

        }

        $text .= $l;

    }

    close($fh)

}

my %monthnum = (

    jan => 0,

    feb => 1,

    mar => 2,

    apr => 3,

    may => 4,

    jun => 5,

    jul => 6,

    aug => 7,

    sep => 8,

    oct => 9,

    nov => 10,

    dec => 11,

);

sub parse_date {

    my $l = shift;

    if ($l !~ /^(?:mon|tue|wed|thu|fri|sat|sun) +(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec) +(\d+) +(\d\d):(\d\d):(\d\d) +([A-Z]+) +(\d\d\d\d) +- +([^ ]*) *$/i) {

        return (undef, "");

    }

    my ($b, $d, $H, $M, $S, $Z, $Y, $email) = ($1, $2, $3, $4, $5, $6, $7, $8);

    my $date = mktime($S, $M, $H, $d, $monthnum{lc $b}, $Y - 1900);

    return (undef, "") unless defined $date;

    my $offset = tz_offset($Z);

    return (undef, "") unless defined $offset;

    chomp $email;

    return ($date - $offset, $email);

}

main();

# vim: sw=4:et