using System;
using System.Threading.Tasks;

namespace RxVsTplSample
{
    public class TplAsyncOperation<TArg, TResult>
    {
        Func<TArg, Task<TResult>> operation;

        public TplAsyncOperation(Func<TArg, Task<TResult>> operation)
        {
            this.operation = operation;
        }

        public IAsyncResult BeginInvoke(TArg arg, AsyncCallback callback, object state)
        {
            var task = operation(arg);
            task.ContinueWith(_ => callback(task));
            return task;
        }

        public TResult EndInvoke(IAsyncResult result)
        {
            return ((Task<TResult>)result).Result;
        }
    }
}