package Pm_11110263_FilenameGen;

use strict;
use warnings;

use Exporter 'import';
our @EXPORT_OK = qw{gen_filename};

my %dispatch = (
    'DATE DMY' => sub {
        my ($d, $m, $y) = (localtime)[3..5];
        return join '', $d, $m+1, $y+1900;
    },
    'DATE MY' => sub {
        my ($m, $y) = (localtime)[4,5];
        return join '', $m+1, $y+1900;
    },
    'DATE Y' => sub {
        return (localtime)[5] + 1900;
    },
);

sub _perform_substitution {
    my ($token) = @_;

    die "FATAL! '$token' is invalid" unless exists $dispatch{$token};

    return $dispatch{$token}->();
}

sub gen_filename {
    my ($template) = @_;

    $template =~ s/~([^~]+)~/_perform_substitution($1)/eg;

    return $template;
}

1;