using System.Collections.Generic;

using System.Linq;

using System;

public class Program

{

    public static void Main()

    {

        var products = GetProducts();

        var orders = GetOrders();

        var allProducts = from p in products 

                          select p;

        // Using extension methods

        var allProductsExt = products.Select(p => p);

        var idAndNameOnly = from p in products

                            select new { p.Id, p.Name };

        // Using extension methods

        var idAndNameOnlyExt = products.Select(p => new { p.Id, p.Name });

        var lowStock =  from p in products

                        where p.StockLevel < 5

                        select p;

        // Using extension methods

        var lowStockExt = products.Where(p => p.StockLevel < 5);

        var byPrice = from p in products

                      orderby p.Price descending

                      select p;

        // Using extension methods

        var byPriceExt = products.OrderByDescending(p => p.Price);

        var orderProducts = from o in orders

                    select new

                    {

                        Order = o,

                        Products = from p in products

                                   join pid in o.ProductIds

                                   on p.Id equals pid

                                   select p

                    };

        // Using extension methods

        var orderProductsExt = orders.Select(o => new { Order = o, Products = products.Where(p => o.ProductIds.Contains(p.Id))});

        var distinctPrices = (from p in products 

                             select p.Price).Distinct();

        // Using extension methods

        var distinctPricesExt = products.Select(p => p.Price).Distinct();

        var top3Expensive = (from p in products

                             orderby p.Price descending

                             select p).Take(3);

        // Using extension methods

        var top3ExpensiveExt = products.OrderByDescending(p => p.Price).Take(3);

        var priceSum = products.Sum(p => p.Price);      

        var productCount = products.Count();

        var minStockLevel = products.Min(p => p.StockLevel);

​

        // Modify this bit to see what the different queries produce

        foreach(var p in top3Expensive)

            Console.WriteLine(p.Id + " " + p.Name);

    }   

    public static IList<Product> GetProducts()

    {

        var products = new List<Product>();

        products.Add(new Product

        {

            Id = 1,

            Name = "Sausages",

            Description = "Succulent pork sausages, from the finest farms in the land",

            Price = 4.99M,

            StockLevel = 12         

        });

        products.Add(new Product

        {

            Id = 2,

            Name = "Bacon",

            Description = "Delicious bacon, fry it or grill it!",

            Price = 3.50M,

            StockLevel = 5

        });

​

        products.Add(new Product

        {

            Id = 3,

            Name = "Chicken Fillets",

            Description = "Our chickens are treated well, and our fillets will treat you well",

            Price = 8.99M,

            StockLevel = 4

        });

​

        products.Add(new Product

        {

            Id = 4,

            Name = "Fishcakes",

            Description = "If you love fish and you love cakes then you'll love our fish cakes",

            Price = 3.99M,

            StockLevel = 22         

        });

​

        products.Add(new Product

        {

            Id = 5,

            Name = "Lamb Chops",

            Description = "Lovely with mint sauce",

            Price = 12.00M,

            StockLevel = 0          

        });     

        return products;

    }       

    public static IList<Order> GetOrders()

    {       

        var orders = new List<Order>();

        orders.Add(new Order                   

        {

            Id = 1,

            ProductIds = new List<int>(){ 1, 4 }

        });

        orders.Add(new Order

        {

            Id = 2,

            ProductIds = new List<int>(){ 2, 3, 5 }

        });

        orders.Add(new Order

        {

            Id = 3,

            ProductIds = new List<int>(){ 3, 1 }

        });

        orders.Add(new Order

        {

            Id = 4,

            ProductIds = new List<int>(){ 4 }

        });

        orders.Add(new Order

        {

            Id = 5,

            ProductIds = new List<int>(){ 2, 4, 3, 1 }

        });

        return orders;

    }

}

​

public class Product

{       

    public int Id {get; set;}

    public string Name {get; set;}

    public string Description {get; set;}

    public decimal Price {get; set;}

    public int StockLevel {get; set;}

}

​

public class Order

{

    public int Id {get; set;}

    public IList<int> ProductIds {get; set;}

}