package main

import (
	"flag"
	"fmt"
	"net"
	"os"
)

func main() {
	//180.177.2.133 TW
	//124.244.86.40 HK
	ip := flag.String("ip", "180.177.2.133:62531", "IP address to send and receive UDP packets")
	port := flag.Int("port", 8890, "Port to send and receive UDP packets")
	flag.Parse()

	if *ip == "" {
		fmt.Println("IP address is required")
		os.Exit(1)
	}

	addr := net.UDPAddr{
		IP:   net.ParseIP(*ip),
		Port: *port,
	}

	conn, err := net.DialUDP("udp", nil, &addr)
	if err != nil {
		fmt.Printf("Failed to connect to UDP server: %v\n", err)
		os.Exit(1)
	}
	defer conn.Close()

	localAddr := conn.LocalAddr().(*net.UDPAddr)
	fmt.Printf("Local address: %s\n", localAddr.String())

	message := []byte("Hello UDP Server")

	go func() {
		for {
			_, err := conn.Write(message)
			if err != nil {
				fmt.Printf("Failed to send UDP packet: %v\n", err)
				os.Exit(1)
			}
		}
	}()

	buffer := make([]byte, 1024)
	for {
		n, remoteAddr, err := conn.ReadFromUDP(buffer)
		if err != nil {
			fmt.Printf("Failed to read UDP packet: %v\n", err)
			continue
		}

		if remoteAddr.IP.String() == *ip {
			fmt.Printf("Received UDP packet from %s: %s\n", remoteAddr, string(buffer[:n]))
		}
	}
}