#!/usr/bin/perl

use strict;
use warnings;
use Test::More 'no_plan';

use integer;

sub b {@_[1 .. @_ - 1, 0]}
sub o {
    @_[map({$_, $_ + @_ / 2 + @_ % 2} 0 .. @_ / 2 - 1), @_ % 2 ? @_ / 2 : ()]
}
sub i {
    @_[map({$_ + @_ / 2, $_} 0 .. @_ / 2 - 1), @_ % 2 ? @_ + 1 : ()]
}

my $bal;
   $bal = qr /\( [^()]* (?: (??{$bal}) [^()]* )* \)/x;

sub shuffle {
    my ($str, @deck) = @_;
    1 while $str =~ s/([0-9]+)(?:([bio])|($bal))/($2 || $3) x $1/eg;
    $str =~ s/[^bio]+//g;
    foreach my $c (split //, $str) {
        no strict 'refs';
        @deck = &$c(@deck)
    }
    @deck;
}

my @deck = 1 .. 8;

is_deeply([shuffle ("i2o",            @deck)], [5, 6, 7, 8, 1, 2, 3, 4]);
is_deeply([shuffle ("3(b2(oi))",      @deck)], [1, 6, 3, 2, 4, 5, 7, 8]);
is_deeply([shuffle ("b",              @deck)], [2, 3, 4, 5, 6, 7, 8, 1]);
is_deeply([shuffle ("i",              @deck)], [5, 1, 6, 2, 7, 3, 8, 4]);
is_deeply([shuffle ("o",              @deck)], [1, 5, 2, 6, 3, 7, 4, 8]);
is_deeply([shuffle ("bioib",          @deck)], [6, 1, 8, 3, 2, 5, 4, 7]);
is_deeply([shuffle ("3i",             @deck)], [8, 7, 6, 5, 4, 3, 2, 1]);
is_deeply([shuffle ("2io",            @deck)], [7, 8, 5, 6, 3, 4, 1, 2]);
is_deeply([shuffle ("8b",             @deck)], [1, 2, 3, 4, 5, 6, 7, 8]);
is_deeply([shuffle ("b3oi",           @deck)], [6, 2, 7, 3, 8, 4, 1, 5]);
is_deeply([shuffle ("2(io)",          @deck)], [6, 2, 5, 1, 8, 4, 7, 3]);
is_deeply([shuffle ("b2(ib)o",        @deck)], [2, 3, 1, 6, 7, 8, 5, 4]);
is_deeply([shuffle ("3(i2(io)o)",     @deck)], [3, 4, 1, 2, 7, 8, 5, 6]);
is_deeply([shuffle ("4(4(io)2b)",     @deck)], [5, 4, 3, 6, 8, 1, 2, 7]);
is_deeply([shuffle ("5(6(bi)7(io))",  @deck)], [1, 2, 8, 4, 5, 3, 7, 6]);
is_deeply([shuffle ("2(3(4(io)b)b)b", @deck)], [1, 6, 4, 3, 5, 2, 8, 7]);

__END__
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