06. Vending Machine

using System;

namespace vendingMachine
{
    class Program
    {
        static void Main(string[] args)
        {
            string input;
            double coinsInserted;
            bool coins;
            double sumCoins = 0.0;
            double costSum = 0.0;
            double change = 0.0;

            do
            {
                input = Console.ReadLine();
                coins = double.TryParse(input, out coinsInserted);
                if (coins)
                {
                    switch (coinsInserted)
                    {
                        case 0.1:
                        case 0.2:
                        case 0.5:
                        case 1:
                        case 2:
                            break;
                        default:
                            Console.WriteLine("Cannot accept {0}", coinsInserted);
                            continue;
                    }
                    sumCoins += coinsInserted;
                }
            } while (coins);

            if (input == "Start")
            {
                bool end = false;
                do
                {
                    input = Console.ReadLine();
                    double productPrice = 0.0;
                    switch (input)
                    {
                        case "Nuts":
                            productPrice = 2.0;
                            break;
                        case "Water":
                            productPrice = 0.7;
                            break;
                        case "Crisps":
                            productPrice = 1.5;
                            break;
                        case "Soda":
                            productPrice = 0.8;
                            break;
                        case "Coke":
                            productPrice = 1.0;
                            break;
                        case "End":
                            end = true;
                            break;
                        default:
                            Console.WriteLine("Invalid product");
                            continue;
                    }
                    if (end)
                    {
                        continue;
                    }
                    costSum += productPrice;
                    if (costSum > sumCoins)
                    {
                        Console.WriteLine("Sorry, not enough money");
                        costSum -= productPrice;
                        continue;
                    }
                    Console.WriteLine($"Purchased {input.ToLower()}");

                } while (!end);
                change = sumCoins - costSum;
                Console.WriteLine($"Change: {change:F2}");


            }
        }
    }
}