#!perl

HELP "+<N>" => "Add N more items of the previous thing";

my $limit = 200;
my $err_limit = "Repetition is limited at $limit items.";
my $err_pfand = "Plugins 'pfand' and 'repeat' cannot be combined.";

sub command($self, $cart, $command, @) {
    return ABORT, $err_pfand if $cart->entries('is_pfand');

    my ($post) = $command =~ /^\+(\d+)?$/
        or return NEXT;

    return ABORT, "Can't modify an empty transaction." if not $cart->size;

    my $last = ($cart->entries)[-1];

    return REJECT, "Addition only works on products." if not $last->has_attribute('product_id');

    if ($post) {
        return REJECT, $err_limit if $last->quantity + $post > $limit;

        $last->quantity($last->quantity + $post);
        return ACCEPT;
    }

    return "Add to previous product", \&add;
}

sub add($self, $cart, $arg, @) {
    $arg =~ /^\d+$/ and $arg > 0
        or return REJECT, "Invalid value.";

    my $last = ($cart->entries)[-1];
    return REJECT, $err_limit if $last->quantity + $arg > $limit;

    $last->quantity($last->quantity + $arg);
    return ACCEPT;
}