class AsyncTest{
    //simple example
    async run(){
        //按照顺序等待后输出
        let one = await this.output("one", 1000);
        console.log(''output:'' + one);
        let two = await this.output("two", 3000);
        console.log(two);
        console.log(''run.....'');
    }
    //await and Promise.all difference
    async runDiff(){ 
        let one = this.output(''diff one'', 2000);
        let two = this.output(''diff two'', 2000);
        console.log(  await two + await one );  //在2秒之后，两个都输出了，而不是各自都等待两秒
        console.log(''runDiff.....'');
    }

    //Promise.all realize
    runAll(){
        let nowTime = new Date();
        console.log(''b:'' + nowTime.toTimeString());
        let array = ["a", "b", "c"];
        let that = this;
        array.forEach(async function(item){
            console.log( await that.output(item, 2000) );//2秒后同时输出
        });
        let fn = async ()=>{
            for(let item of array){
                let v = await this.output(item, 2000);
                console.log(v ); //分步骤两秒执行
            }
        }
        fn.call(this);
    }

    premosFn(){
        let nowTime = new Date();
        console.log(''b:'' + nowTime.toTimeString());
        let array = ["a", "b", "c"];
        let that = this;
        //promise.all
        let preFn = async function(){
            let promises = array.map(function(item){
                return that.output(item,2000); //同时开启多个定时器
            });
            let r = await Promise.all(promises);
            console.log(r.join('',''));
        }
        preFn();
    }

    reject(){
        let rejectFn = function(){
            return new Promise((resolve, reject)=>{
                setTimeout(()=>{
                    reject();
                },2000);
            });
        }
        let asyncReject = async function(){
            try{
                await rejectFn();
            }catch( e) {
                console.log(''reject.....'');
            }
        }
        asyncReject();
    }

    output(log, time){
        return new Promise(resolve=>{
            setTimeout(()=>{
                var nowTime = new Date();
                resolve( nowTime.toTimeString() + ":" + log + "\r\n");
            }, time);
        });
    }
}

public class AsyncDemo
{
    private Task<string> Output(string val, int time)
    {
        return System.Threading.Tasks.Task.Run(() =>
        {
            System.Threading.Thread.Sleep(time * 1000);
            return (DateTime.Now.ToLongTimeString()) + ": " + val + "\r\n";
        });
    }

    public async System.Threading.Tasks.Task Run()
    {
        string oneVal = await Output("One", 2);
        string twoVal = await Output("Two", 2);
        System.Console.WriteLine("Run \r\n" + oneVal + " " + twoVal);
    }

    public async System.Threading.Tasks.Task RunDiff()
    {
        Task<string> oneTask = Output("one", 2);
        Task<string> twoTask = Output("two", 2);
        string val = await oneTask + await twoTask; 
        System.Console.WriteLine("RunDiff \r\n" + val);

    }

    public async System.Threading.Tasks.Task RunAll()
    {
        System.Console.WriteLine("b:" + (DateTime.Now.ToLongTimeString()));

        string[] array = new string[3] { "a", "b", "c" };
        foreach(var item in array)
        {
            string v = await Output(item, 2);
            System.Console.WriteLine(v);
        }
    }

    public async System.Threading.Tasks.Task PromiseFn()
    {
        System.Console.WriteLine("b:" + (DateTime.Now.ToLongTimeString()));

        string[] array = new string[3] { "a", "b", "c" };
        List<System.Threading.Tasks.Task<string>> tasks = new List<System.Threading.Tasks.Task<string>>();
        foreach (var item in array)
        {
            tasks.Add(Output(item, 2));
        }
        //waitAll返回值不能获取，他返回为void，而WhenAll则返回为一个Task（这个Task就有其列表值）
        string[] r = await System.Threading.Tasks.Task.WhenAll(tasks.ToArray());
        System.Console.WriteLine(string.Join(",",r));
    }

    public async System.Threading.Tasks.Task Reject()
    {
        Func<System.Threading.Tasks.Task> func = async () =>
        {
            throw new Exception("custom...");
            await Output("reject", 2);
        };
        await func();
    }
}

AsyncDemo asyncDemo = new AsyncDemo();
asyncDemo.Run().Wait();
asyncDemo.RunDiff().Wait();
asyncDemo.RunAll().Wait();
asyncDemo.PromiseFn().Wait();
try
{
    asyncDemo.Reject().Wait();
}catch(Exception e)
{
    System.Console.WriteLine("reject ex");
}

System.Console.WriteLine("b:" + (DateTime.Now.ToLongTimeString()));

string[] array = new string[3] { "a", "b", "c" };

var r = await this.Output(array.First(), 2).ContinueWith((tsc) =>
{
    string v = tsc.GetAwaiter().GetResult();
    return this.Output(v + "02", 2);
});
System.Console.WriteLine(r.Result);