Fossil wrapper script to emulate git log -p

#!/usr/bin/env perl
use strict;
use warnings;

use Carp;
use File::Which;
use IO::Interactive qw(is_interactive);

die "usage: $0 <files...>\n\n" unless @ARGV;

my $out;
if (is_interactive()) {
    my $pager = $ENV{PAGER} || which('less') || which('more');
    open $out, '|-', $pager or croak "Cannot pipe to $pager: $!";
}
else {
    $out = *STDOUT;
}

open my $bcmd, '-|', 'fossil branch current'
        or die "Cannot get branch: $!\n";
my $cbranch = <$bcmd>;
chomp $cbranch;
close $bcmd;

for my $file (@ARGV) {
    my $lastckid;
    open my $finfo, '-|', "fossil finfo --brief --limit 0 '$file'"
            or die "Failed to get file info: $!\n";
    my @filines = <$finfo>;
    close $finfo;

    for my $line (@filines) {
        my ($currckid, $date, $user, $branch, @cwords) = split ' ', $line;
        next unless $branch eq $cbranch;
        if (defined $lastckid and defined $branch) {
            my $comment = join ' ', @cwords;
            open my $diff, '-|', 'fossil', 'diff', $file,
                    '--from', $currckid
                    '--to',   $lastckid,
                    or die "Failed to diff $currckid -> $lastckid: $!\n";
            my @dl = <$diff>;
            close $diff;
            my $patch = join '', @dl;

            print $out <<"OUT"
Checkin ID $currckid to $branch by $user on $date
Comment: $comment

$patch

OUT
        }

        $lastckid = $currckid;
    }
}