#!/usr/bin/perl -w
# Copyright 2018 The Linux Foundation
# License: AGPL-3.0+ <http://www.gnu.org/licenses/agpl-3.0.txt>
use strict;
use warnings;
use Email::MIME;
use Digest::MD5 qw(md5_hex);

$| = 0;
my $h = '[0-9a-f]';
my $state = '';
my $blob;
my $suff; # 16 bytes for git hashing
while (<STDIN>) {
	if ($_ eq "blob\n") {
		$state = 'blob';
	} elsif (/^commit /) {
		$state = 'commit';
	} elsif ($state eq 'commit') {
		if (m{^(M 100644 :\d+) (${h}{2})/(${h}{2})(${h}{2})(${h}{34})}o) {
			my ($pfx, $x2, $x4, $x6, $x34) = ($1, $2, $3, $4, $5);
			print "$pfx $x2/$x4/$x6/$x34.$suff\n";
			next;
		}
		if (/^data (\d+)/) {
			print $_;
			my $len = $1;
			if ($len) {
				my $tmp;
				read(STDIN, $tmp, $len) or die "read: $!\n";
				print $tmp;
			}
			next;
		}
	} elsif ($state eq 'blob') {
		if (/^data (\d+)/) {
			my $len = $1;
			print $_;
			next unless $len;

			read(STDIN, $blob, $len) or die "read: $!\n";
			print $blob;
			my $mime = Email::MIME->new($blob);
			$suff = $mime->header('Subject');
			utf8::encode($suff);
			# git uses the last 16 bytes for deltas
			$suff = substr(md5_hex(substr($suff, -16)), -16);
			next;
		}
	}
	print $_;
}