#!/usr/bin/env perl
use utf8;
###############################################################################
# This program generates license plates.
# 
# Copyright © 2020 Richard Lesh.  All rights reserved.
###############################################################################

use Utils;
use strict;
use warnings;

our $LETTERS = "ABCDEFGHJKLMNPQRTUVWXYZ";
our $DIGITS = "0123456789";
our $plate_count = 0;

sub get_choices {
    my ($which) = @_;
    if (index($LETTERS, $which) != -1) {
        return $LETTERS;
    } elsif (index($DIGITS, $which) != -1) {
        return $DIGITS;
    } else {
        return $which;
    }
}

sub expand_pattern {
    my ($prefix, $pattern) = @_;
    my $CHOICES = get_choices(substr($pattern, 0, 1));
    my $REMAINING_PATTERN = substr($pattern, 1);
    my $IS_LAST = Utils::isEmpty($REMAINING_PATTERN);
    foreach my $c (split('', $CHOICES)) {
        my $NEW_PREFIX = $prefix . $c;
        if ($IS_LAST) {
            print $NEW_PREFIX, "\n";
            ++$plate_count;
        } else {
            expand_pattern($NEW_PREFIX, $REMAINING_PATTERN);
        }
    }
}

MAIN:
{
    my $pattern = "ABC 123";
    if (scalar(@ARGV) == 1) {
        $pattern = $ARGV[0];
    } else {
        print Utils::messageFormat("Syntax: \{0:s\} pattern", "LicensePlates2"), "\n";
        exit 1;
    }

    expand_pattern("", $pattern);
    print "Total: ", $plate_count, "\n";
}