perl-menu-loop

use v5.22.0;   # sub routine signatures requires perl >= 5.22
use feature qw(say);
use strict;
use warnings;
use experimental qw(signatures);

my @category_prices = (
   "Office Visit" => 75.0,
   "Vaccination" => 50.0,
   "Hospitalization" => 300.5,
   "Heartworm Treatment" => 150.5,
   "Overnight Stay" => 450.0,
   "Dentistry" => 200.5,
   "X-Ray" => 275.0,
   "Lab Work" => 45.0,
   "Prescription" => 15.5,
);

sub calculate_total($cost, $total) { $cost+$total }

sub amount_due($total) {
    my $sales_tax = 0.07 * $total;
    $total += $sales_tax;

    say "Amount Due (inc. of sales tax)  ", $total;
    say "Thank you for your visit bark bark! (❍ᴥ❍ʋ)~ Clearing for next customer.";
}

sub print_menu($total) {
    say "Welcome to 'Lions Tigers and Bears' Pet Clinic! ฅ^•ﻌ•^ฅ  ~(=^‥^)";
    say "Press the adjacent number to add the the service to your bill! meow~";
    say "SERVICE              PRICE";

    my $num_categories = ($#category_prices+1)/2;
    my @categories = map { $category_prices[$_*2] } 0..($num_categories-1);
    my @prices = map { $category_prices[$_*2 +1] } 0..($num_categories-1);
    my %prices = map { $categories[$_] => $prices[$_] } 0..($num_categories-1);
    my %choices = map { ($_+ 1 ) => $categories[$_] } 0..($num_categories-1);
    for my $i (0..$#categories) {
        my $idx = $i+1;
        my $price = format_price($prices[$i]);
        say "$idx: $categories[$i]\t$price";
    }
    say <<'END';
0: Check Out        0
Type 30 to Terminate  0
END

    my $choice = -1;
    my $cost = 0.0;
    my @bill;
    prompt();
    while (my $choice = <>) {
        next if !defined $choice;
        if ( $choice !~ /^\d+$/) {
            say "\tPlease type an integer.";
            prompt();
            next;
        }
        $choice = int $choice;
        exit if $choice == 30;
        last if $choice == 0;
        if (!exists $choices{$choice}) {
            say "\tIgnoring unrecognized command '$choice'";
            prompt();
            next;
        }
        my $category = $choices{$choice};
        my $price = $prices{$category};
        push @bill, [$category, $price];
        $total = calculate_total($price, $total);
        say "";
        say "Items on your bill";
        for my $item ( @bill ) {
            my ( $category, $price ) = @$item;
            $price = format_price($price);
            say "$category \t\$$price";
        }
        say "";
        say "Total       \$$total";
        prompt();
    }
    amount_due($total);
    return $total;
}

sub format_price($price) { sprintf "%.1f", $price }

sub prompt { print "> " }

my $total = 0;
while (1) {
    $total = print_menu($total);
}