using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var firms = FirmRepository.Get();

        var pricesPerWeek = firms

            .Where(firm => firm.Id == 1)

            .SelectMany(firm => firm.Prices)

            .Where(

                productPrice => productPrice.Year == DateTime.Now.Year && 

                productPrice.ProductId == 1)

            .Select(productPrice => new {productPrice.Week, productPrice.Price})

            .ToList();

        pricesPerWeek.ForEach(x => Console.WriteLine("Week {0}: {1}",x.Week,x.Price));

    }

}

​

​

public class Firm

{

    public Firm() 

    {

        Prices = new List<ProductPrice>();

    }

    public int Id {get;set;}

    public String Name {get;set;}

    public List<ProductPrice> Prices {get; private set;}

}

​

public class ProductPrice

{

    public int FirmId {get;set;}

    public int ProductId {get;set;}

    public int Year {get;set;}

    public int Week {get;set;}

    public decimal Price {get;set;}

}

​

public class Product

{

    public int Id {get;set;}

    public String Description {get;set;}

}

​

public class FirmRepository

{

    public static IEnumerable<Firm> Get()

    {

        var firms = new List<Firm>();

        var firm = new Firm {Id = 1, Name = "ABC" };

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 1, Year = 2015, Week = 52, Price = 1.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 1, Year = 2016, Week = 1, Price = 1.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 1, Year = 2016, Week = 2, Price = 1.68m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 1, Year = 2016, Week = 3, Price = 1.75m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 1, Year = 2016, Week = 4, Price = 1.99m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 2, Year = 2015, Week = 52, Price = 11.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 2, Year = 2016, Week = 1, Price = 12.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 2, Year = 2016, Week = 2, Price = 13.68m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 2, Year = 2016, Week = 3, Price = 14.75m});

        firm.Prices.Add(new ProductPrice {FirmId = 1, ProductId = 2, Year = 2016, Week = 4, Price = 15.99m});

        firms.Add(firm);

        firm = new Firm {Id = 2, Name = "DEF" };

        firm.Prices.Add(new ProductPrice {FirmId = 2, Year = 2016, Week = 1, Price = 2.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 2, Year = 2016, Week = 2, Price = 2.68m});

        firm.Prices.Add(new ProductPrice {FirmId = 2, Year = 2016, Week = 3, Price = 2.75m});

        firm.Prices.Add(new ProductPrice {FirmId = 2, Year = 2016, Week = 4, Price = 2.99m});

        firms.Add(firm);

        firm = new Firm {Id = 3, Name = "GHI" };

        firm.Prices.Add(new ProductPrice {FirmId = 3, Year = 2016, Week = 1, Price = 3.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 3, Year = 2016, Week = 2, Price = 3.68m});

        firm.Prices.Add(new ProductPrice {FirmId = 3, Year = 2016, Week = 3, Price = 3.75m});

        firm.Prices.Add(new ProductPrice {FirmId = 3, Year = 2016, Week = 4, Price = 3.99m});

        firms.Add(firm);

        firm = new Firm {Id = 4, Name = "JKL" };

        firm.Prices.Add(new ProductPrice {FirmId = 4, Year = 2016, Week = 1, Price = 4.65m});

        firm.Prices.Add(new ProductPrice {FirmId = 4, Year = 2016, Week = 2, Price = 4.68m});

        firm.Prices.Add(new ProductPrice {FirmId = 4, Year = 2016, Week = 3, Price = 4.75m});

        firm.Prices.Add(new ProductPrice {FirmId = 4, Year = 2016, Week = 4, Price = 4.99m});

        firms.Add(firm);

        return firms;

    }

}