#!/usr/bin/perl

use strict;
use warnings 'all';
use locale;

use Data::Dumper;
use FindBin;
use Getopt::Std;


my %opts;
getopts('hkn', \%opts);

&usage if $opts{h} || $#ARGV!=1 || ! -d $ARGV[0] || ! -f $ARGV[1];
$ARGV[0]=~s/\/+$/\//;

my $md5;
if ($opts{m}) {
	$md5 = (`which md5`=~/(.*)/)[0] || (`which md5sum`=~/(.*)/)[0] || die "No md5 binary found\n";
	$md5 .= ($md5=~/md5$/ ? ' -r ' : '');
}

my %snap;
open SNAP, "<$ARGV[1]" or die $!;
$_ = <SNAP>;
/^STATE=(MD5|MTIME)$/ or die "Unknown STATE line: $_\n";
my $stype = $1;
for (map {chomp; $_} <SNAP>) {
	next unless /^(.+?)(\s+STATE=(.+))?$/;
	if ($2) {
		$snap{$1} = $3;
	} else {
		$snap{$1} = undef;
	}
}
close SNAP;

for (grep {$snap{$_}} keys %snap) {
	next unless -f "$ARGV[0]/$_";

	my $state;
	if ($stype eq 'MD5') {
 		$state = (`$md5 $ARGV[0]/$_ | awk '{print \$1}'`=~/(.*)/)[0];
	} else {
 		$state = join(':', (stat("$ARGV[0]/$_"))[1,9]) or die $!;
	}

	if ($snap{$_} eq $state) {
		unlink "$ARGV[0]/$_" unless $opts{n};
		print "    removing old file: $_\n";
	} else {
		print "    skipping modified file: $_\n";
	}
}

for (sort {(length($b)<=>length($a))||($a cmp $b)} grep {!$snap{$_}} keys %snap) {
	opendir DIR, "$ARGV[0]/$_" or die $!;
	my @cont = readdir DIR;
	if ($#cont==1) {
		rmdir "$ARGV[0]/$_";
		print "    removing empty dir: $_\n";
	} else {
		print "    skipping non-empty dir: $_\n";
	}
	closedir DIR;
}

unlink $ARGV[1] unless $opts{k} || $opts{n};


sub usage {
	print <<EOM;
Usage: $FindBin::RealScript [options] prefix file

Options:
    -h             Print this message
    -k             Keep file
    -n             Dry-run mode

EOM
	exit;
}