using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace AsyncTaskMethodBuilderDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            var info = Hello();
            Console.WriteLine("我去： " + info.Result);
            Console.Read();
        }
        static Task<string> Hello()
        {
            MyStateMachine machine = new MyStateMachine();
            machine.t_builder = AsyncTaskMethodBuilder<string>.Create();
            //TaskCompletionSource
            machine.state = -1;
            machine.t_builder.Start(ref machine);
            return machine.t_builder.Task;
        }
    }

    public class MyStateMachine : IAsyncStateMachine
    {
        public AsyncTaskMethodBuilder<string> t_builder;
        public int state;
        private MyStateMachine machine = null;
        private TaskAwaiter<string> myawaiter;
        string result = string.Empty;
        public MyStateMachine()
        {
        }
        public void MoveNext()
        {
            try
            {
                switch (state)
                {
                    case -1:
                        Console.WriteLine("hello world");
                        var waiter = Task.Run(() =>
                        {
                            Console.WriteLine("i'm middle");

                            return "i'm ok";
                        }).GetAwaiter();
                        state = 0;  //设置下一个状态
                        myawaiter = waiter;
                        machine = this;
                        //丢给线程池执行
                        t_builder.AwaitUnsafeOnCompleted(ref waiter, ref machine);
                        break;
                    case 0:
                        var j = myawaiter.GetResult();
                        Console.WriteLine("我是结尾哦:{0}", j);
                        t_builder.SetResult(j);
                        break;
                }
            }
            catch (Exception ex)
            {
                t_builder.SetException(ex);  //设置t_builder的异常
            }
        }
        public void SetStateMachine(IAsyncStateMachine stateMachine)
        {
        }
    }
}