package main

import (
	"context"
	"net"
	"os"
	"os/signal"
	"serveg/common/log"
	"strconv"
	"syscall"
	"time"
)

func main() {
	os.Exit(run())
}

// main with int return value
func run() int {
	defer log.Defer()
	log.StartGoroutine()
	logger := log.LoggerContext{Name: "main"}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	//defer stop()

	conf, err := ParseOrCreateDefault()
	if err != nil {
		logger.Error(err)
		return 1
	}

	errCh := make(chan error, 1)
	go func() { errCh <- server(conf) }()
	logger.Info("server started")

	select {
	// server failed to start
	case err := <-errCh:
		logger.Error(err)
		return 1
	// got SIGINT/SIGTERM
	case <-ctx.Done():
		stop() // restore default behaviour: a second Ctrl+C kills immediately
		logger.Info("shutting down")
	}

	return 0
}

func server(conf *Config) error {
	logger := log.LoggerContext{Name: "server"}
	addr := net.JoinHostPort(conf.Ip.String(), strconv.Itoa(int(conf.Port)))

	logger.Info("listening at", addr)
	srv, err := net.Listen("tcp", addr)
	if err != nil {
		return err
	}
	defer func() { _ = srv.Close() }()

	for i := int64(0); ; i++ {
		conn, err := srv.Accept()
		if err != nil {
			logger.Warn(err)
			continue
		}
		go handleConnection(conn, i)
	}
}

func handleConnection(conn net.Conn, n int64) {
	logger := log.LoggerContext{Name: "conn-" + strconv.FormatInt(n, 10)}
	defer func() {
		if r := recover(); r != nil {
			logger.Error("panic: ", r)
		}
		_ = conn.Close()
	}()

	buf := make([]byte, 4096)

	for {
		if err := conn.SetDeadline(time.Now().Add(30 * time.Second)); err != nil {
			logger.Warn(err)
			break
		}
		n, err := conn.Read(buf)
		if err != nil {
			logger.Warn(err)
			break
		}
		msgBytes := buf[:n]
		logger.Info("msg: `", string(msgBytes), "`")
		if _, err := conn.Write(msgBytes); err != nil {
			logger.Warn(err)
			break
		}
	}
}