use String::CRC32;

my $ref = "repository-201119";
my $reflen = length($ref) + 1;  # allow for trailing /

my %refs;
my %crcs;
my %new;
my %changed;
my %moved;

sub dir_walk {
    my ($top, $filefunc, $dirfunc) = @_;
    my $DIR;
    if (-d $top) {
        my $file;
        unless (opendir $DIR, $top) {
            warn "Couldn’t open directory $top: $!; skipping.\n";
            return;
        }

        my @results;
        while ($file = readdir $DIR) {
            next if $file eq '.' || $file eq '..';
            push@results,dir_walk("$top/$file", $filefunc, $dirfunc);
        }
        return $dirfunc ? $dirfunc->($top, @results) : () ;
    } else {
        return $filefunc ? $filefunc->($top): () ;
    }
}

sub filecrc32 {
    open my $fh, "<:raw", $_[0] or die $!;
    return crc32($fh);
}

sub addRefFile {
    $refs{substr($_[0], $reflen)} = filecrc32($_[0]);
}

sub cmpFile {
    my $file = $_[0];
    my $crc = filecrc32($file);
    if (!defined($refs{$file})) {
        $new{$file} = $crc;
    } elsif ($crc != $refs{$file}) {
        $changed{$file} = $crc;
    } else {
        delete $refs{$file};
    }
}

sub mvdir {
    $moved{$_[1]} = $_[0];
    opendir my $newDir, $_[1];
    while (my $f = readdir $newDir) {
        if (defined($refs{"$_[0]/$f"})) {
            delete $refs{"$_[0]/$f"};
            delete $new{"$_[1]/$f"};
        }
    }

}

# build up the old file list
dir_walk($ref, \&addRefFile);

# check each subtree in the old against the new
# and top level files
opendir my $DIR, $ref or die $!;

while (my $f = readdir $DIR) {
    if (-d $f) {
        dir_walk($f, \&cmpFile) unless $f eq "." || $f eq "..";
    } elsif (-f "$ref/$f") {
        cmpFile($f);
    }
}
closedir $DIR;


for my $k (keys %refs) {
    push @{$crcs{$refs{$k}}}, $k;
}

for my $f (keys %new) {
    if (defined $new{$f} && defined($crcs{$new{$f}})) { # move dir will impact %new
        my $first = ${$crcs{$new{$f}}}[0];
        my $second = ${$crcs{$new{$f}}}[1];
        if ($second eq "") {
            my $ndir = $f =~ s/\/[^\/]*$//r;
            my $odir = $first =~ s/\/[^\/]*$/\1/r;
            if (!-d "$ref/$ndir" && !-d "$odir") {
                mvdir($odir, $ndir);
            } else {
                $moved{$f} = $first;
                delete $refs{$first};
                delete $new{$f};
            }
        } else {
            print "fix  \"", join(":", @{$crcs{$new{$f}}}), "\" \"$f\"\n";
        }
    }
}

for my $f (keys %changed) {
    delete $refs{$f} if defined($refs{$f});
}

print "delete \"", join("\"\ndelete \"", sort(keys %refs)), "\"\n";
for my $k (sort keys %moved) {
    print "move \"$moved{$k}\" \"$k\"\n";
}
print "replace \"", join("\"\nreplace \"", sort(keys %changed)), "\"\n";

print "add \"", join("\"\nadd \"", sort(keys %new)), "\n";