package main

import (
	"flag"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"os"
	"syscall"
)

type HelloServer struct {
}

func (HelloServer) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
	data, err := ioutil.ReadAll(req.Body)
	if err != nil {
		log.Printf("%v", err)
	}
	log.Printf("request from %s, %s: %s, body %s", req.RemoteAddr, req.Method, req.RequestURI, string(data))
	resp.WriteHeader(http.StatusOK)
	resp.Write([]byte("Hello server"))
}

func startUnixSocketServer(addr string) error {
	var l net.Listener
	var err error
	if addr != "" {
		log.Printf("listen on %s", addr)
		l, err = net.Listen("tcp", addr)
	} else {
		socket := "/run/test.sock"
		log.Printf("listen on %s", socket)
		l, err = newUnixSocket(socket)
	}
	if err != nil {
		return err
	}
	httpServer := &http.Server{Addr: addr}
	httpServer.Handler = HelloServer{}
	return httpServer.Serve(l)
}

func newUnixSocket(path string) (net.Listener, error) {
	if err := syscall.Unlink(path); err != nil && !os.IsNotExist(err) {
		return nil, err
	}
	mask := syscall.Umask(0777)
	defer syscall.Umask(mask)
	l, err := net.Listen("unix", path)
	if err != nil {
		return nil, err
	}
	return l, nil
}

// ./server # serve unix socket
// ./server -address :80 # serve tcp 80
func main() {
	address := flag.String("address", "", "the address to listen")
	flag.Parse()
	log.Fatal(startUnixSocketServer(*address))
}