using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    private static List<SalesRecord> salesRecords = new();

    public static void Main()

    {

        var currentServiceProvider = "AWS";

        var accManager = GetAccountManager(currentServiceProvider);

​

        Console.WriteLine("Enter User ID:");

        var userId = Console.ReadLine();

        Console.WriteLine("Enter Password:");

        var password = Console.ReadLine();

​

        // ... Authenticate user ...

        if (accManager.Authenticate(userId, password))

        {

            Random random = new Random();

            for (var i = 0; i < 10000; i++)

            {

                var item = i < 4000 ? "A" : i < 8000 ? "B" : "C";

                salesRecords.Add(new SalesRecord(item, random.Next()));

            }

        }

​

​

​

        // ... Propagate salesRecords with random quantities ...

​

        Console.WriteLine("Which item do you want to view? (A/B/C):");

        var chosenItem = Console.ReadLine();

        var chosenRecord = salesRecords.Where(x => x.Item == chosenItem).OrderByDescending(x => x.Qty);

        // ... Display items by filtering and sorting them in descending order with linq expression ...

        foreach (var chosen in chosenRecord)

        {

            Console.WriteLine(chosen.Item + " " + chosen.Qty);

​

        }

    }

​

    public static IAccountManager GetAccountManager(string serviceProvider)

    {

        if (serviceProvider == "AWS")

        {

            return new AwsService();

        }

        else

        {

            return new AzureService();

        }

        return null;

    }

}

​

public struct SalesRecord

{

    public string Item { get; set; }

​

    public int Qty { get; set; }

​

    public SalesRecord(string item)

    {

        Item = item;

        Qty = 0;

    }

    public SalesRecord(string item, int qty)

    {

        Item = item;

        Qty = qty;

    }

}

​

public interface IAccountManager

{

    public bool Authenticate(string userId, string password);

}

​

​

​

// ... Interface Implementations ...

​

public class AwsService : IAccountManager

{

    public bool Authenticate(string userId, string password)

    {

        return userId == "aws" && password == "abc123";

    }

​

    public bool DeleteUser(string userId)

    {

        return true;

    }

}

​

public class AzureService : IAccountManager

{

    public bool AuthUser(string userId, string password)

    {

        return userId == "azure" && password == "abc321";

    }

​

    public bool RemoveUser(string userId)

    {

        return true;

    }

​

    public bool Authenticate(string userId, string password)

    {

        return this.AuthUser(userId, password);

    }

}