designPattern/DesignPattern/State-VendingMachineExample/HasMoneyState.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace State_VendingMachineExample
{
    internal class HasMoneyState : VMState
    {
        public HasMoneyState(VendingMachine context)
        {
            vendingMachine = context;
        }

        public override void AddMoney(decimal money)
        {
            vendingMachine.Money += money;
            Console.WriteLine($"Add ${money}, Balance: {vendingMachine.Money}");
        }

        public override void ReturnChange(decimal money)
        {
            throw new ApplicationException();
        }

        public override void SelectItem(int itemId)
        {
            decimal? price = vendingMachine.GetPrice(itemId).Value;
            if (!price.HasValue)
            {
                Console.WriteLine($"{itemId} not found");
                return;
            }

            if (vendingMachine.Money < price.Value)
            {
                Console.WriteLine("Insufficient money");
                return;
            }

            vendingMachine.State = vendingMachine.DispenseItemState;
            vendingMachine.State.SelectItem(itemId);
        }
    }
}