Как сделать рефакторинг - C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace Rifactoring
{
    class Customer
    {
        private string name = null;
        private List<Rental> rentals = new List<Rental>();
 
        public Customer(string name) 
        {
            this.name = name;
        }
 
        public string Statement() 
        {
            double totalAmount = 0;
            int frequentRenterPoints = 0;
            string result = string.Format("Учет аренды для {0}:", name);
 
            foreach (Rental rental in rentals) 
            {
                double thisAmount = 0;
                switch (rental.Movie.PriceCode) 
                {
                    case Movie.Regular:
                        thisAmount += 2;
                        if (rental.DaysRented > 2)
                            thisAmount += (rental.DaysRented - 2) * 1.5;
                        break;
 
                    case Movie.New_Release:
                        thisAmount += rental.DaysRented * 3;
                        break;
 
                    case Movie.Childrens:
                        if (rental.DaysRented > 3)
                            thisAmount += (rental.DaysRented - 3) * 1.5;
                        break;
                }
 
                frequentRenterPoints++;
                if ((rental.Movie.PriceCode == Movie.New_Release) && (rental.DaysRented>1))
                    frequentRenterPoints++;
 
                result += "\t" + rental.Movie.Title + "\t" + thisAmount;
                totalAmount += thisAmount;
            }

            result += "Сумма составляет" + totalAmount + "\n";
            result += "Вы заработали" + frequentRenterPoints + "очков за активность";
            return result;
        }
 
        //Свойства
        public Rental Rentals
        {
            set { this.rentals.Add(value); }
        }
 
        public string Name
        {
            get { return this.name; }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace Rifactoring
{
    class Movie
    {
        public const int Childrens = 2;
        public const int Regular = 0;
        public const int New_Release = 1;
 
        private string title = null;
        private int priceCode = 0;
 
        public Movie(String title, int priceCode) 
        {
            this.title = title;
            this.priceCode = priceCode;
        }
 
        //свойства
        public int PriceCode
        {
            get {return this.priceCode;}
            set { this.priceCode = value;}
        }

        public string Title 
        {
            get { return this.title; }
        }
    
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace Rifactoring
{
    class Program
    {
        static void Main()
        {
            Customer customer = new Customer("Alex");
            Movie movie = new Movie("Matrix", 1);
            Rental rental = new Rental(movie, 2);
 
            customer.Rentals = rental;
            Console.WriteLine(customer.Statement());
 
            Console.ReadKey();
 
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace Rifactoring
{
    class Rental
    {
        private Movie movie = null;
        private int daysRented = 0;
 
        public Rental(Movie movie, int daysRented) 
        {
            this.movie = movie;
            this.daysRented = daysRented;
        }
 
        public int DaysRented 
        {
            get { return daysRented; }
        }
 
        public Movie Movie 
        {
            get { return movie; }
        }
    }
}