package main

import (
	"context"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"time"
)

type handler struct {
}

func (h *handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	w.Write([]byte("Hello World"))
}

func newServer(port int) *http.Server {
	s := &http.Server{
		Addr:           fmt.Sprintf(":%d", port),
		Handler:        &handler{},
		ReadTimeout:    100 * time.Millisecond,
		WriteTimeout:   100 * time.Millisecond,
		MaxHeaderBytes: 1 << 20,
		ErrorLog:       log.New(os.Stderr, "", log.LstdFlags),
	}
	return s
}

func send(port int) {
	conn, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", port))
	if err != nil {
		fmt.Println(err)
		return
	}

	n, e := conn.Write([]byte("GET / HTTP/1.1\r\n"))
	fmt.Println("send first line", n, e)

	n, e = conn.Write([]byte("Host: www.google.com\r\n"))
	fmt.Println("send host", n, e)

	n, e = conn.Write([]byte("Host1"))
	fmt.Println("send part header", n, e)

	// more than ReadTimeout
	time.Sleep(time.Millisecond * 110)

	buf := make([]byte, 8192)
	n, e = conn.Read(buf)
	fmt.Println("read resp", n, e)
	fmt.Println("print resp", "`"+string(buf)+"`")
	time.Sleep(time.Millisecond * 200)
	fmt.Println("conn close", conn.Close())
}

func main() {
	port := 12101
	svr := newServer(port)
	go func() {
		fmt.Println(svr.ListenAndServe())
	}()

	// wait server start
	time.Sleep(time.Second * 1)
	go send(port)

	time.Sleep(time.Second * 1)
	fmt.Println("server shutdown", svr.Shutdown(context.Background()))
	time.Sleep(time.Second * 1)
}

send first line 16 <nil>
send host 22 <nil>
send part header 5 <nil>
read resp 0 EOF
print resp ``
conn close <nil>
http: Server closed
server shutdown <nil>

send first line 16 <nil>
send host 22 <nil>
send part header 5 <nil>
read resp 103 <nil>
print resp `HTTP/1.1 400 Bad Request
Content-Type: text/plain; charset=utf-8
Connection: close

400 Bad Request`
conn close <nil>
http: Server closed
server shutdown <nil>