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#!/usr/bin/env perl
use strict;
use warnings;
# Autor: Boris Däppen, 2018
# No guarantee given, use at own risk and will

# PODNAME: backup-hanoi
# ABSTRACT: predict on which device to put next backup

use v5.6.0;
use Backup::Hanoi;

# we fake say, to support older perl
sub say {
    print "$_[0]\n";
}

my $help = <<'END_MESSAGE';

  backup-hanoi tells you where to write your next backup

  You need to list your devices in a text file, separated by newline

  example usages:

    # list repeatable pattern
    backup-hanoi device-list.txt

    # list which device should be used for backup number 40
    backup-hanoi device-list.txt 40

    # create a device-list for the backups 40 up to 60
    backup-hanoi device-list.txt 40 60

    # first initialise all backups (fifo), then replace 40 times (hanoi)
    backup-hanoi device-list.txt init 40

END_MESSAGE
unless (@ARGV) {
    say $help;
    exit 0;
}


my $devices_file = shift @ARGV;
my $cycle        = shift @ARGV;
my $cycle_top    = shift @ARGV;

open my $file_handle, '<', $devices_file;
chomp(my @devices = <$file_handle>);
close $file_handle;

my $backup = Backup::Hanoi->new(\@devices);

if (defined $cycle_top and ($cycle_top or $cycle_top == 0)) {

    # start with negative number for FIFO
    $cycle = 1 - (scalar @devices) if ($cycle eq 'init');

	for ($cycle .. $cycle_top) {
		say $backup->get_device_for_cycle($_);
	}
}
elsif (defined $cycle and ($cycle or $cycle == 0)) {
	say $backup->get_device_for_cycle($cycle);
}
else {
	for (0 .. ((2**(scalar @devices))/2)-1)  {
		say $backup->get_device_for_cycle($_);
	}
}

__END__

=pod

=encoding UTF-8

=head1 NAME

backup-hanoi - predict on which device to put next backup

=head1 VERSION

version 0.005

=head1 SYNOPSIS

This is an early release.
This code is currently not used in production by the author.
Use it with care!

L<backup-hanoi> tells you where to write your next backup.
You need to list your devices in a text file, separated by newline.

 # list repeatable pattern
 backup-hanoi device-list.txt

 # list which device should be used for backup number 40
 backup-hanoi device-list.txt 40

 # create a device-list for the backups 40 up to 60
 backup-hanoi device-list.txt 40 60

 # if you have 5 devices in the list
 # create a plan for initilisation and overwriting
 # for one year of daily backups
 backup-hanoi device-list.txt -4 360

 # same, but easier
 backup-hanoi device-list.txt init 360

=head1 AUTHOR

Boris Däppen <bdaeppen.perl@gmail.com>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2018 by Boris Däppen.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut