using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    //This is a class which defines the parts of the complex object

    //which are to be generated by the proxy pattern.

    public class Person

    {

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public string CubeAddress { get; set; }

        public string PhoneExtention { get; set; }

        public string MobilePhone { get; set; }

    }

    public interface IPerson

    {

        void Add(Person person);

        Person Find(string firstName, string lastName);

    }

    private static readonly List<Person> StaffList = new List<Person>();

​

    // Concrete implementation of the IPerson

    // The ManagementDepartment is private and cannot be instantiated by a client.

    // The client creates an instance of the ProxyDepartment class which controls its access to the more complex and expensive to create ManagementDepartment class.

    private class ManagementDepartment : IPerson

    {

        public ManagementDepartment()

        {

            Console.WriteLine("ManagementDepartment: Initialized");

        }

        public void Add(Person person)

        {

            StaffList.Add(person);

        }

        public Person Find(string firstName, string lastName)

        {

            return StaffList.FirstOrDefault(_ => _.FirstName == firstName && _.LastName == lastName);

        }

    }

    public class ProxyDepartment : IPerson

    {

        private ManagementDepartment _department;

        public ProxyDepartment() 

        {

            Console.WriteLine("ProxyDepartment: Initialized");

        }

        public void Add(Person person)

        {

            // A Virtual Proxy creates the object only on its first method call

            if (_department == null)

            {

                _department = new ManagementDepartment();

                _department.Add(person);

            }

            else

            {

                _department.Add(person);

            }

            Console.WriteLine("Data Added from Proxy Client = {0} {1}", person.FirstName, person.LastName);

        }

        public Person Find(string firstName, string lastName)

        {

            if (_department != null) 

                return _department.Find(firstName, lastName);

            _department = new ManagementDepartment();

            return _department.Find(firstName, lastName);

        }

    }

    public static void Main()

    {

        // Creates the class instance

        ProxyDepartment proxy = new ProxyDepartment();

        // When adding the new person it will use the instance that is saved in the _department Class

        proxy.Add(new Person

                  {

                      FirstName = "FirstName 1",

                      LastName = "LastName 1"

                  });

        proxy.Add(new Person

                  {

                      FirstName = "FirstName 2",

                      LastName = "LastName 2"

                  });

    }

}