#!/usr/bin/perl

#--------------------------------------------------------------------#
# Simple Directory Mirror
#       Date Written:   29-Aug-2001 04:35:58 PM
#       Last Modified:  31-Aug-2001 12:36:17 PM
#       Author:         Kurt Kincaid (sifukurt@yahoo.com)
#
# Makes backups of all files in a directory, and only copies the
# file again if it has changed. It does not go through subdirectories.
# This specifically was a feature I did not want. However, it
# shouldn't be too difficult to add that feature if you are so
# inclined.
#
# This is free software and may be redistributed and/or modified
# under the same terms as Perl itself.
#--------------------------------------------------------------------#

use Digest::MD5 qw(md5_hex);
use File::Copy;
use strict;

our ( $work_dir, $bu_dir, $file, $digest, $sleep_time );
our ( @files, @new_files, @deleted, %File );

#--------------------------------------------------------------------#
# Configuration options
#--------------------------------------------------------------------#
$sleep_time = 300; # seconds
$work_dir = '/kurt/work';
$bu_dir = '/kurt/perl/backup';

Files( $work_dir, \@files );
foreach $file ( @files ) {
    if ( -d $file ) { next }
    open (FILE, "$work_dir\/$file");
    binmode(FILE);
    $File{$file} = Digest::MD5->new->addfile(*FILE)->hexdigest();
    close (FILE);
    copy( "$work_dir\/$file", "$bu_dir\/$file" );
}

for (;;) {
    sleep( $sleep_time );
    Files( $work_dir, \@new_files );
    @deleted = Compare( \@files, \@new_files );
    foreach $file ( @deleted ) {
        unlink "$bu_dir\/$file";
        delete $File{$file};
        @files = keys %File;
    }
    foreach $file ( @new_files ) {
        if ( -d $file ) { next }
        open (FILE, "$work_dir\/$file");
        binmode(FILE);
        $digest = Digest::MD5->new->addfile(*FILE)->hexdigest();
        close (FILE);
        unless ( $digest eq $File{$file} ) {
            $File{$file} = $digest;
            copy( "$work_dir\/$file", "$bu_dir\/$file" );
        }
    }
}

sub Files {
    my ( $file, $array ) = @_;
    opendir ITEMS, $file;
    @$array = grep !/^\./, readdir ITEMS;
    closedir ITEMS;
    chomp @$array;
    return @$array;
}

sub Compare {
    my ( $arrayref1, $arrayref2 ) = @_;
    unless ( defined $arrayref1 && defined $arrayref2 && @$arrayref1 > 0 && @$arrayref2 > 0 ) {
        return undef;
    }
    my %seen;
    my @aonly;
    my $item;
    foreach $item (@$arrayref2) { $seen{$item} = 1 }
    foreach $item (@$arrayref1) {
        unless ( $seen{$item} ) {
            push ( @aonly, $item );
        }
    }
    return @aonly;
}