using System;

using System.Collections.Generic;

using System.Collections.ObjectModel;

using System.Linq;

​

public class OrderItem

{

    public readonly int PartNumber;

    public readonly string Description;

    public readonly double UnitPrice;

    private int _quantity = 0;

    public OrderItem(int partNumber, string description, int quantity, double unitPrice)

    {

        this.PartNumber = partNumber;

        this.Description = description;

        this.Quantity = quantity;

        this.UnitPrice = unitPrice;

    } 

    public int Quantity    

    {

        get

        {

            return _quantity;

        }

        set

        {

            if (value < 0)

            {

                throw new ArgumentException("Quantity cannot be negative.");

            }

​

            _quantity = value;

        }

    }

    public override string ToString()

    {

        return String.Format("{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}", 

            PartNumber, _quantity, Description, UnitPrice, UnitPrice * _quantity);

    }

}

​

public class Order

{

    private readonly List<OrderItem> _orderItems = new List<OrderItem>();

    // TODO Add dictionaries to search for an order item using part number and description.

    private Dictionary<int, OrderItem> dictionatyPartNumber = new Dictionary<int, OrderItem>();

    private Dictionary<string, List<OrderItem>> dictionatyDescription = new Dictionary<string, List<OrderItem>>();

    public IReadOnlyList<OrderItem> OrderItems

    {

        get

        {

            return new ReadOnlyCollection<OrderItem>(_orderItems);

        }

    }

    public void AddRange(IEnumerable<OrderItem> orderItems)

    {

        _orderItems.AddRange(orderItems);

        // TODO Add values to dictionaries.

        foreach(var item in orderItems) 

        {

            dictionatyPartNumber.Add(item.PartNumber, item);

            if (dictionatyDescription.ContainsKey(item.Description)) 

            {

                dictionatyDescription[item.Description].Add(item);

            }

            else 

            {

                dictionatyDescription[item.Description] = new List<OrderItem>() { item };

            }           

        }

    }

    public OrderItem FindByPartNumber(int partNumber)

    {

        // TODO Implement FindByPartNumber method for searching for OrderItem using part number.

        if (dictionatyPartNumber.ContainsKey(partNumber)) 

        {

            return dictionatyPartNumber[partNumber];

        }

        return null;

    }

    public IList<OrderItem> FindByDescription(string description)

    {

        // TODO Implement FindByDescription method for searching for OrderItem using description.

        if (dictionatyDescription.ContainsKey(description)) 

        {

            return dictionatyDescription[description];

        }

        return null;

    }

}

​

public class Program

{

    public static void Main()

    {

        var order = new Order();

        order.AddRange(new OrderItem[]

        {

            new OrderItem(110072674, "Widget", 400, 45.17),

            new OrderItem(110072675, "Sprocket", 27, 5.3),

            new OrderItem(101030411, "Motor", 10, 237.5),

            new OrderItem(110072684, "Gear", 175, 5.17)

        });

        Display("Order #1", order);

        if (order.FindByPartNumber(111033401) == null)

        {

            Console.WriteLine("Order #1 doesn't have #111033401 item.\n");

        }

        order.AddRange(new OrderItem[]

        {

            new OrderItem(111033401, "Nut", 10, .5),

            new OrderItem(127700026, "Crank", 27, 5.98)

        });

        Display("Order #2", order);

​

        var list = order.FindByDescription("Crank");

        if (list.Count > 0)

        {

            // TODO Calculate an order item price, and write it to the console using the same format as in Display method.

            double itemPrice = list[0].Quantity * list[0].UnitPrice;

            Console.WriteLine("Order #2 has \"Crunk\" item - price is {0:###,###.00}$.", itemPrice);

        }

    }

    private static void Display(string title, Order order)

    {

        Console.WriteLine(title);

        foreach (OrderItem item in order.OrderItems)

        {

            Console.WriteLine(item);

        }

        Console.WriteLine();

    }

}