#!perl

HELP "3dprint <gram>" => "3D-print filament afrekenen";

use Scalar::Util qw(looks_like_number);

sub command :Tab(3dprint) ($self, $cart, $command, @) {
    return NEXT if $command ne '3dprint';

    return "Gewicht in gram, inclusief supports en purges", \&gram;
}

sub gram($self, $cart, $input, @) {
    looks_like_number($input) and $input == int($input) or return REJECT, "Invalid number!";
    my $gram = int($input);
    return REJECT, "$input: Invalid amount." if $gram <= 0;

    my $beneficiary = "3dprinter";
    my $amount = 0.10 + $gram * 0.03;

    $cart
        ->add(-$amount, "Given to $beneficiary ($gram g)")
        ->add_contra($beneficiary, +$amount, "Received from \$you (${gram} g)");

    return ACCEPT;
}