using System;
using System.Threading.Tasks;
using Polly;

namespace AsyncDelegateGotcha
{
    public class Program
    {
        static async Task Main(string[] args)
        {
            var toTestSync = new PollySyncAsyncTest();
            var toTestAsync = new PollySyncAsyncTest();

            await toTestSync.TestSync();
            await toTestAsync.TestAsync();

            Console.ReadLine();
        }
    }

    class PollySyncAsyncTest
    {
        private int _counter = 0;

        public async Task TestAsync()
        {
            var policy = Policy
                .Handle<Exception>()
                .RetryAsync(3);

            await policy.ExecuteAsync(async () =>
            {
                var something = await DoSomethingAsync();
                if (something != true) throw new Exception("Assert fail");
            });
        }

        public async Task TestSync()
        {
            var policy = Policy
                .Handle<Exception>()
                .Retry(3);

            await policy.Execute( // Executing a Func<Task> delegate through a sync policy.
                async () => // Providing the compiler an async delegate where it expects a sync delegate.
                {
                    var something = await DoSomethingAsync();
                    if (something != true) throw new Exception("Assert fail");
                });
        }

        private async Task<bool> DoSomethingAsync()
        {
            await Task.Delay(TimeSpan.FromSeconds(1));

            if (++_counter <= 2) throw new Exception("Fault which we might expect the policy to handle");

            return true;
        }
    }
}