Oop Fizz Buzz

OopFizzBuzz.cs

namespace OopFizzBuzz
{
    class Program
    {
        static void Main(string[] args)
        {
            const int lastNumber = 17;

            var app = new Program();

            app.Run(lastNumber);
        }

        private bool _isDone;

        void Run(int lastNumber)
        {
            System.Console.WriteLine($"Playing Fizz Buzz counting to {lastNumber}...");

            var counter = new FizzBuzzCounter(lastNumber);
            counter.FizzBuzzCount += OnFizzBuzzCount;
            counter.FizzBuzzComplete += OnFizzBuzzComplete;

            do
            {
                counter.Count();
            } while (!_isDone);

            System.Console.ReadLine();
        }

        private void OnFizzBuzzComplete(object sender, System.EventArgs e)
        {
            System.Console.WriteLine("Done!");
        }

        private void OnFizzBuzzCount(object sender, FizzBuzzCountEventArgs e)
        {
            _isDone = true;
            System.Console.WriteLine(e.Output);
        }
    }


    public class FizzBuzzCounter
    {
        private readonly int _lastNumber;

        public FizzBuzzCounter(int lastNumber = 17)
        {
            _lastNumber = lastNumber;
        }

        public void Count()
        {
            for (var i = 1; i < _lastNumber; ++i)
            {
                var s = string.Empty;

                var r = i % 3;

                if (r == 0)
                {
                    s = "Fizz";
                }

                r = i % 5;

                if (r == 0)
                {
                    s += "Buzz";
                }

                if (s == string.Empty)
                {
                    s = i.ToString();
                }

                RaiseFizzBuzzCount(s);
            }

            RaiseFizzBuzzComplete();
        }

        public event System.EventHandler<FizzBuzzCountEventArgs> FizzBuzzCount;

        public event System.EventHandler FizzBuzzComplete;

        public void RaiseFizzBuzzCount(string count)
        {
            var handler = FizzBuzzCount;
            handler?.Invoke(this, new FizzBuzzCountEventArgs(count));
        }

        public void RaiseFizzBuzzComplete()
        {
            var handler = FizzBuzzComplete;
            handler?.Invoke(this, System.EventArgs.Empty);
        }
        
    }

    public class FizzBuzzCountEventArgs : System.EventArgs
    {
        public FizzBuzzCountEventArgs(string output)
        {
            Output = output;
        }

        public string Output { get; }
    }

}