# A draft of program to convert rexgen rule into John the Ripper rules

use strict;
use warnings;

my $rule = "\\0([123]|[oO]ne|[tT](wo|hree))";
# $rule = "\\0(1|[oO]no|ONE)(2|[tT]wo|TWO)(3|[tT]hree|THREE)";
# $rule = "\\0(1|[oO]no\\0|ONE)(2|[tT]wo|TWO)(3|[tT]hree|THREE\\0)";
# $rule = "(A|B)(1|2)";
# $rule = "asdf\\0qwer";
# TODO: \0 is evaluated as from input. Bad.
# $rule = "b(\\|a)(0|1)e";

sub to_tokens {
    # TODO: Handle \ and things in [] .
    $_[0] =~ /([(|)]|[^(|)]+)/g
}

# Usage: mul(["a", "b"], ["1", "2"]) -> qw/a1 a2 b1 b2/
# The first list could be empty, the second list could not be empty.
sub combine {
    # warn "combine 0: @{$_[0]}\n";
    # warn "combine 1: @{$_[1]}\n";
    my @a = @{shift()};
    my @b = @{shift()};
    if (@a) {
        map {
            my $a = $_;
            map {
                $a . $_
            } @b;
        } @a
    } else {
        @b
    }
}

# Rename combine into combine_i to use this
# sub combine {
#     my @r = combine_i @_;
#     warn "combine r: @r\n";
#     @r
# }

sub parse_part;

sub parse_group {
    # warn "parse_group: @{$_[0]}\n";
    my @all;
    my @current_branch;
    while (@{$_[0]} && $_[0][0] ne ')') {
        while (@{$_[0]} && $_[0][0] ne '|' && $_[0][0] ne ')') {
            my @p = parse_part($_[0]);
            @current_branch = combine [@current_branch], [@p];
        }
        if (@{$_[0]} && $_[0][0] eq '|') {
            shift @{$_[0]};
        }
        push @all, @current_branch;
        @current_branch = ();
    }
    shift @{$_[0]};
    @all
}

sub parse_part {
    # warn "parse_part: @{$_[0]}\n";
    die unless @_;
    my $p = shift @{$_[0]};
    $p eq '(' ? parse_group($_[0]) : $p
}

sub expand_braces {
    my @a;
    while (@_) {
        my @b = parse_part \@_;
        # warn "top\n";
        @a = combine [@a], [@b];
    }
    @a
}

# Expand \0
sub expand_0 {
    map {
        my @l = split /\\0/;
        if (/\\0$/) {
            push @l, "";
        }
        my $f = shift @l;
        # TODO: Don't screw current memorized value.
        local $_ = qq/M A0"$f" /;
        $_ .= join " X0zz ", map { 'Az"' . $_ . '"' } @l;
        s/^M A0"" /M /;
        s/ Az""$//;
        # Don't use M if there is only one \0.
        s/^M // if $#l < 1;
        $_
    } @_
}

print "$_\n" for expand_0 expand_braces to_tokens $rule;