package main

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"flag"
	"fmt"
	"math/rand"
	"net"
	"sync"
	"time"
)

var (
	address    = flag.String("a", "127.0.0.1:4242", "address (host and port)")
	numClients = flag.Int("c", 10, "number of clients")
	sleepTime  = flag.Duration("s", time.Second, "sleep time for each client")
	message    = []byte{1, 0}
)

func main() {
	flag.Parse()
	wg := sync.WaitGroup{}

	for i := 0; i < *numClients; i++ {
		wg.Add(1)
		go udpClient(&wg, i)
	}

	wg.Wait()
}

func udpClient(wg *sync.WaitGroup, id int) {
	defer wg.Done()

	clientAddr, err := net.ResolveUDPAddr("udp", *address)

	if err != nil {
		fmt.Println("Error resolving UDP address:", err)
		return
	}

	conn, err := net.DialUDP("udp", nil, clientAddr)

	if err != nil {
		fmt.Println("Error connecting to UDP server:", err)
		return
	}

	defer conn.Close()

	username := fmt.Sprintf("user%d", id+1)
	loginRequest := [2]string{username, sha256Text("password")}
	data, err := json.Marshal(loginRequest)

	if err != nil {
		fmt.Println("Error creating JSON:", err)
		return
	}

	request := append([]byte{2}, data...)
	fmt.Println(string(request))
	conn.Write(request)

	for {
		_, err := conn.Write(message)

		if err != nil {
			fmt.Println("Error sending message:", err)
			return
		}

		if rand.Float32() > 0.5 {
			conn.Write([]byte{13})
		}

		time.Sleep(*sleepTime)
	}
}

func sha256Text(password string) string {
	sum := sha256.Sum256([]byte(password))
	return hex.EncodeToString(sum[:])
}