#!/usr/bin/perl

use strict;

unless ($ENV{GIT_DIR})
{
	$ENV{GIT_DIR} = '.git' if -f '.git/config';
}
unless ($ENV{GIT_DIR})
{
	$ENV{GIT_DIR} = shift || die "usage: $0 gitdir file...\n";
}

my %revs_by_path;
my %path_by_rev;
my %by_hash;

open(R, "git rev-list --objects --all |");
while (<R>)
{
	chomp;
	my ($sha1, $path) = split / /, $_, 2;
	next unless $path;
	push(@{$revs_by_path{$path}}, $sha1);
	$path_by_rev{$sha1}{$path} = 1;
}
close R;

sub index_pack
{
	my $idx = shift;
	my $pack = $idx;
	local *R, *V, $_;

	$pack =~ s/\.idx$/.pack/;
	$pack =~ /pack-([a-z0-9]{40})\.pack$/;
	my $cache = "cache-$1.v";
	my @objects;

	unless (open(R, $cache))
	{
		print STDERR "Caching $cache...\n";
		open(R, ">$cache");
		open(V, "git verify-pack -v $idx|");
		print R while $_ = <V>;
		close V;
		close R;
		print STDERR "Pack index cache created.\n\n";
		open(R, $cache);
	}

	while (<R>)
	{
		last if /^chain length/;
		chomp;
		my ($sha1, $type, $size, $offset, $depth, $base) = split /\s+/;
		my $o = {
			sha1 => $sha1,
			type => $type,
			uncompressed_size => $size,
			offset => $offset,
			depth => $depth,
			base => $base,
		};
		push @objects, $o;
		$by_hash{$sha1} = $o;
	}
	close R;

	my $last = undef;
	foreach my $o (sort {$a->{offset} <=> $b->{offset}} @objects)
	{
		$last->{pack_size} = $o->{offset} - $last->{offset} if $last;
		$last = $o;
	}
	$last->{pack_size} = ((-s $pack) - 20) - $last->{offset};
}

opendir(D, "$ENV{GIT_DIR}/objects/pack");
while (my $entry = readdir D)
{
	next unless $entry =~ /^pack-[a-z0-9]{40}\.idx$/;
	index_pack "$ENV{GIT_DIR}/objects/pack/$entry";
}
closedir D;

if (@ARGV)
{
	my $g_total = 0;
	my $g_revs = 0;

	foreach my $path (@ARGV)
	{
		print $path, "\n";

		my $total = 0;
		my $revs = 0;
		foreach my $sha1 (
			sort {$by_hash{$b}{depth} <=> $by_hash{$a}{depth}}
			grep {$by_hash{$_}}
			@{$revs_by_path{$path}})
		{
			my $o = $by_hash{$sha1};
			printf "%8s... %1s%2i %10i\n",
				substr($sha1, 0, 8),
				($o->{depth}
					? ($path_by_rev{$o->{base}}{$path}
						? 's'
						: 'o')
					: ''),
				$o->{depth},
				$o->{pack_size};
			$total += $o->{pack_size};
			$revs++;
		}

		$g_total += $total;
		$g_revs += $revs;

		my $units = 'bytes';
		if ($total >= 1024)
		{
			$units = 'KiB';
			$total /= 1024;

			if ($total >= 1024)
			{
				$units = 'MiB';
				$total /= 1024;
			}
		}

		print '-'x40, "\n";
		printf "%15s %10i %s\n",
			"$revs revs",
			$total, $units;
		print "\n";
	}

	my $units = 'bytes';
	if ($g_total >= 1024)
	{
		$units = 'KiB';
		$g_total /= 1024;

		if ($g_total >= 1024)
		{
			$units = 'MiB';
			$g_total /= 1024;
		}
	}

	printf "%15s %10i %s\n",
		"$g_revs revs",
		$g_total, $units;
}
else
{
	foreach my $path (sort keys %revs_by_path)
	{
		my $total = 0;
		my $revs = 0;
		foreach my $sha1 (
			sort {$by_hash{$b}{depth} <=> $by_hash{$a}{depth}}
			grep {$by_hash{$_}}
			@{$revs_by_path{$path}})
		{
			$total += $by_hash{$sha1}{pack_size};
			$revs++;
		}

		my $units = 'bytes';
		if ($total >= 1024)
		{
			$units = 'KiB';
			$total /= 1024;

			if ($total >= 1024)
			{
				$units = 'MiB';
				$total /= 1024;
			}
		}
		$total = int $total;

		printf "%3i revs %10i %-5s %s\n",
			$revs,
			$total, $units,
			$path;
	}
}