git-move-dates

#!/usr/bin/env perl
use strict;
use warnings;
use Getopt::Long;
use Pod::Usage;

# process command-line options
my %option = (
    weeks     => 0,
    days      => 0,
    hours     => 0,
    minutes   => 0,
    seconds   => 0,
    author    => 0,
    committer => 0,
);

GetOptions(
    \%option,  'committer!', 'author!', 'dry-run!',
    'weeks=i', 'days=i',     'hours=i', 'minutes=i',
    'seconds=i', 'help', 'manual',
) or pod2usage();

pod2usage( -verbose => 1) if $option{help};
pod2usage( -verbose => 2) if $option{manual};

# by default, translate both
$option{author} = $option{committer} = 1
    unless $option{author} || $option{committer};

# translation into seconds
my $seconds
    = $option{seconds} + 60
    * ( $option{minutes} + 60
        * ( $option{hours} + 24
            * ( $option{days} + 7 
                * $option{weeks} )
          )
      );

# nothing to do
exit 0 if ! $seconds;

# generate the shell command
my $cmd = q{git filter-branch --commit-filter '};
$cmd .= qq{GIT_${_}_DATE=`echo "\$GIT_${_}_DATE"|perl -pe'\\''s/\\d+/\$&+$seconds/e'\\''`;}
    for map uc, grep { $option{$_} } qw( author committer );
$cmd .= q{git commit-tree "$@"' -- };
$cmd .= join ' ', map {qq{"$_"}} @ARGV;

# print it or run it
if   ( $option{'dry-run'} ) { print "$cmd\n"; }
else                        { exec $cmd; }

__END__

=head1 NAME

git-move-dates - simple translation of commit dates

=head1 SYNOPSIS

B<git-move-dates> [ B<options> ] [ I<rev-list> ]

=head1 DESCRIPTION

B<git-move-dates> uses B<git filter-branch> to rewrite commits by
translating their GIT_AUTHOR_DATE and GITy_COMMITER_DATE.

=head2 Command-line options

B<git-move-dates> accepts the following options:

=over 4

=item B<--dry-run>

Print the generated command instead of executing it.

=item B<--author>

Move the GIT_AUTHOR_DATE.

=item B<--committer>

Move the GIT_COMMITTER_DATE.

=item B<--seconds> I<seconds>

=item B<--minutes> I<minutes>

=item B<--hours> I<hours>

=item B<--days> I<days>

=item B<--weeks> I<weeks>

Add an offset of the given unit (positive or negative).

It's possible to combine them with something like:

    git-move-dates --days 1 --hours 1

=item B<--help>

Provide a short help summary.

=item B<--manual>

Show this manual page.

=back

=head1 AUTHOR

Philippe Bruhat (BooK), C<< book@cpan.org >>.

=head1 LICENSE

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

=cut