#!/usr/bin/perl -w
use strict;

use Getopt::Long;
use Cwd qw(abs_path cwd);
use Digest::MD4;
use Digest::MD5;

our $SUMS_FILE = '.rsyncsums';

&Getopt::Long::Configure('bundling');
&usage if !&GetOptions(
    'recurse|r' => \( my $recurse_opt ),
    'mode|m=s' => \( my $cmp_mode = 'strict' ),
    'check|c' => \( my $check_opt ),
    'verbose|v+' => \( my $verbosity = 0 ),
    'help|h' => \( my $help_opt ),
);
&usage if $help_opt || $cmp_mode !~ /^(lax|strict)$/;

my $ignore_ctime_and_inode = $cmp_mode eq 'lax' ? 0 : 1;

my $start_dir = cwd();

my @dirs = @ARGV;
@dirs = '.' unless @dirs;
foreach (@dirs) {
    $_ = abs_path($_);
}

$| = 1;

my $exit_code = 0;

my $md4 = Digest::MD4->new;
my $md5 = Digest::MD5->new;

while (@dirs) {
    my $dir = shift @dirs;

    if (!chdir($dir)) {
	warn "Unable to chdir to $dir: $!\n";
	next;
    }
    if (!opendir(DP, '.')) {
	warn "Unable to opendir $dir: $!\n";
	next;
    }

    my $reldir = $dir;
    $reldir =~ s#^$start_dir(/|$)# $1 ? '' : '.' #eo;
    if ($verbosity) {
	print "$reldir ... ";
	print "\n" if $check_opt;
    }

    my %cache;
    my $f_cnt = 0;
    if (open(FP, '<', $SUMS_FILE)) {
	while (<FP>) {
	    chomp;
	    my($sum4, $sum5, $size, $mtime, $ctime, $inode, $fn) = split(' ', $_, 7);
	    $cache{$fn} = [ 0, $sum4, $sum5, $size, $mtime, $ctime & 0xFFFFFFFF, $inode & 0xFFFFFFFF ];
	    $f_cnt++;
	}
	close FP;
    }

    my @subdirs;
    my $d_cnt = 0;
    my $update_cnt = 0;
    while (defined(my $fn = readdir(DP))) {
	next if $fn =~ /^\.\.?$/ || $fn =~ /^\Q$SUMS_FILE\E$/o || -l $fn;
	if (-d _) {
	    push(@subdirs, "$dir/$fn") unless $fn =~ /^(CVS|\.svn|\.git|\.bzr)$/;
	    next;
	}
	next unless -f _;

	my($size,$mtime,$ctime,$inode) = (stat(_))[7,9,10,1];
	$ctime &= 0xFFFFFFFF;
	$inode &= 0xFFFFFFFF;
	my $ref = $cache{$fn};
	$d_cnt++;

	if (!$check_opt) {
	    if (defined $ref) {
		$$ref[0] = 1;
		if ($$ref[3] == $size
		 && $$ref[4] == $mtime
		 && ($ignore_ctime_and_inode || ($$ref[5] == $ctime && $$ref[6] == $inode))
		 && $$ref[1] !~ /=/ && $$ref[2] !~ /=/) {
		    next;
		}
	    }
	    if (!$update_cnt++) {
		print "UPDATING\n" if $verbosity;
	    }
	}

	if (!open(IN, $fn)) {
	    print STDERR "Unable to read $fn: $!\n";
	    if (defined $ref) {
		delete $cache{$fn};
		$f_cnt--;
	    }
	    next;
	}

	my($sum4, $sum5);
	while (1) {
	    while (sysread(IN, $_, 64*1024)) {
		$md4->add($_);
		$md5->add($_);
	    }
	    $sum4 = $md4->hexdigest;
	    $sum5 = $md5->hexdigest;
	    print " $sum4 $sum5" if $verbosity > 2;
	    print " $fn" if $verbosity > 1;
	    my($size2,$mtime2,$ctime2,$inode2) = (stat(IN))[7,9,10,1];
	    $ctime2 &= 0xFFFFFFFF;
	    $inode2 &= 0xFFFFFFFF;
	    last if $size == $size2 && $mtime == $mtime2
	     && ($ignore_ctime_and_inode || ($ctime == $ctime2 && $inode == $inode2));
	    $size = $size2;
	    $mtime = $mtime2;
	    $ctime = $ctime2;
	    $inode = $inode2;
	    sysseek(IN, 0, 0);
	    print " REREADING\n" if $verbosity > 1;
	}

	close IN;

	if ($check_opt) {
	    my $dif;
	    if (!defined $ref) {
		$dif = 'MISSING';
	    } elsif ($sum4 ne $$ref[1] || $sum5 ne $$ref[2]) {
		$dif = 'FAILED';
	    } else {
		print " OK\n" if $verbosity > 1;
		next;
	    }
	    if ($verbosity < 2) {
		print $verbosity ? ' ' : "$reldir/";
		print $fn;
	    }
	    print " $dif\n";
	    $exit_code = 1;
	} else {
	    print "\n" if $verbosity > 1;
	    $cache{$fn} = [ 1, $sum4, $sum5, $size, $mtime, $ctime, $inode ];
	}
    }

    closedir DP;

    unshift(@dirs, sort @subdirs) if $recurse_opt;

    if ($check_opt) {
	;
    } elsif ($d_cnt == 0) {
	if ($f_cnt) {
	    print "(removed $SUMS_FILE) " if $verbosity;
	    unlink($SUMS_FILE);
	}
	print "empty\n" if $verbosity;
    } elsif ($update_cnt || $d_cnt != $f_cnt) {
	print "UPDATING\n" if $verbosity && !$update_cnt;
	open(FP, '>', $SUMS_FILE) or die "Unable to write $dir/$SUMS_FILE: $!\n";

	foreach my $fn (sort keys %cache) {
	    my $ref = $cache{$fn};
	    my($found, $sum4, $sum5, $size, $mtime, $ctime, $inode) = @$ref;
	    next unless $found;
	    printf FP '%s %s %10d %10d %10d %10d %s' . "\n", $sum4, $sum5, $size, $mtime, $ctime, $inode, $fn;
	}
	close FP;
    } else {
	print "ok\n" if $verbosity;
    }
}

exit $exit_code;

sub usage
{
    die <<EOT;
Usage: rsyncsums [OPTIONS] [DIRS]

Options:
 -r, --recurse     Update $SUMS_FILE files in subdirectories too.
 -m, --mode=MODE   Compare entries in either "lax" or "strict" mode.  Using
                   "lax" compares size and mtime, while "strict" additionally
                   compares ctime and inode.  Default:  strict.
 -c, --check       Check if the checksums are right (doesn't update).
 -v, --verbose     Mention what we're doing.  Repeat for more info.
 -h, --help        Display this help message.
EOT
}