using System;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}

​

record NotificationEvent(DateTime NotificationDate, string NotificationMessage);

​

class Publisher{

    //publishers name

    public string PublisherName { get; private set; }

​

    //publishers notification interval

    public int NotificationInterval { get; private set; }

​

    // declare a delegate function

    public delegate void Notify(Publisher p, NotificationEvent e);

​

    // declare an event variable of the delegate function

    public event Notify OnPublish;

​

    // class constructor

    public Publisher(string _publisherName, int _notificationInterval){

        PublisherName = _publisherName;

        NotificationInterval = _notificationInterval;

    }

​

    //publish function publishes a Notification Event

    public void Publish(){

​

        while (true){

​

            // fire event after certain interval

            Thread.Sleep(NotificationInterval);

​

            if (OnPublish != null)

            {

                NotificationEvent notificationObj = new NotificationEvent(DateTime.Now, "New Notification Arrived from");

                OnPublish(this, notificationObj);

            }

            Thread.Yield();

        }

    }

}

​

class Subscriber{

    public string SubscriberName { get; private set; }

​

    public Subscriber(string _subscriberName){

        SubscriberName = _subscriberName;

    }

​

    // This function subscribe to the events of the publisher

    public void Subscribe(Publisher p){

​

        // register OnNotificationReceived with publisher event

        p.OnPublish += OnNotificationReceived;  // multicast delegate 

​

    }

​

    // This function unsubscribe from the events of the publisher

    public void Unsubscribe(Publisher p){

​

        // unregister OnNotificationReceived from publisher

        p.OnPublish -= OnNotificationReceived;  // multicast delegate 

    }

​

    // It get executed when the event published by the Publisher

    // ***I want to make this method async here:***

    protected virtual /**/ async /**/ void OnNotificationReceived(Publisher p, NotificationEvent e){

        await Task.Delay(TimeSpan.FromSeconds(1));

        Console.WriteLine("Hey " + SubscriberName + ", " + e.NotificationMessage +" - "+ p.PublisherName + " at " + e.NotificationDate);

    }

}