using System.Collections.Generic;
using NSpec;

class describe_VendingMachine : nspec
{
    void given_an_empty_VendingMachine()
    {
        before = () => machine = new VendingMachine();

        should_not_be_in_stock("A1");

        context["doritos are stocked in A1, with a price of $1"] = () =>
        {
            stock("doritos", "A1", 1m);

            should_be_in_stock("A1");

            context["mountain dew is stocked in A2, with a price of $1"] = () =>
            {
                stock("mountain dew", "A2", 1m);

                should_be_in_stock("A2");

                should_be_in_stock("A1");
            };

            context["doritos are vended"] = () =>
            {
                before = () => machine.VendItem("A1");

                should_not_be_in_stock("A1");
            };

            specify = () => machine.CanVend("A1").should_be_false();

            new[] { 1m, 5m }.Do(amount =>
            {
                context["{0} dollar is put in the machine".With(amount)] = () =>
                {
                    insert_money(amount);

                    specify = () => machine.CanVend("A1").should_be_true();
                };
            });
        };
    }

    void insert_money(decimal amount)
    {
        before = () => machine.Insert(amount);
    }

    void should_be_in_stock(string slot)
    {
        specify = () => machine.InStock(slot).should_be_true();
    }

    void should_not_be_in_stock(string slot)
    {
        specify = () => machine.InStock(slot).should_be_false();
    }

    void stock(string name, string slot, decimal price)
    {
        before = () => machine.StockItem(name, slot, price);
    }

    VendingMachine machine;
}

public class VendingMachine
{
    public void StockItem(string name, string slot, decimal price)
    {
        stocked.Add(slot);

        this.price = price;
    }

    public bool InStock(string slot)
    {
        return stocked.Contains(slot);
    }

    public VendingMachine()
    {
        stocked = new List<string>();
    }

    public void VendItem(string slot)
    {
        stocked.Remove(slot);
    }

    public void Insert(decimal money)
    {
        this.money = money;
    }

    public bool CanVend(string slot)
    {
        return money >= price;
    }
    IList<string> stocked;
    decimal money;
    private decimal price;
}