using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var customer1 = new Customer("Steve");

        // Customers expose a method for adding an Order

        customer1.AddOrder("123");

        customer1.AddOrder("234");

        customer1.AddOrder("345");

        customer1.AddOrder("345");

        customer1.AddOrder("");

        var customer2 = new Customer("Eric");

        customer2.AddOrder("100");

        customer2.AddOrder("200");

        customer2.AddOrder("300");

        var customers = new List<Customer>() {customer1, customer2};

        foreach (var customer in customers)

        {

            customer.PrintMyOrderOverview();

        }

        //Customers have a property exposing their historic Orders

        foreach (Order order in customer1.MyHistoricOrders)

        {

            Console.WriteLine(order.OrderNumber);

        }

        //customer1.myOrders.Add(new Order("addmanually")); //Exception protection level!

    }

}

​

public class Customer

{

    public string Name {get;private set;}

​

    public List<Order> MyHistoricOrders 

    {   

        get 

        {

            return _myOrders;

        }

    }

    private List<Order> _myOrders = new List<Order>();

​

    public Customer(string name)

    {

        Name = name;

        //var myOrders = new List<Order>();

        //MyOrders = myOrders;

    }

​

    public void AddOrder(string addedOrder)

    {

        //Trying to add a null Order should do nothing

        //Trying to add an Order with an existing OrderNumber should replace the existing Order (not add a duplicate)

        if ((!String.IsNullOrEmpty(addedOrder)) || (ExistsOrderNumber(addedOrder, this._myOrders)))

​

        {_myOrders.Add(new Order(addedOrder));}

        return;

    }

    private bool ExistsOrderNumber(string checkNumber, List<Order> list)

    {

        foreach (Order order in list)

        {

            if (checkNumber == order.OrderNumber)

            return true;

        }

        return false;

    }

​

    private void PrintListOfMyOrders()

    {

        foreach (Order order in _myOrders)

        {

            Console.WriteLine(order.OrderNumber);

        }

    }

​

    public void PrintMyOrderOverview()

    {

        Console.WriteLine(Name + "'s orders:");

        PrintListOfMyOrders();

        Console.WriteLine("Customer's Order Total: {0}", _myOrders.Count);

        Console.WriteLine();

    }

}

​

public class Order

{

    public string OrderNumber {get;private set;}

​

    public Order(string orderNumber)

    {

        OrderNumber = orderNumber;

    }

}