package ping

import (
	"fmt"
	"net"
	"os/exec"
	"regexp"
	"sync"
)

func PingLocal255() int {
	localIP, err := getLocalIP()
	if err != nil {
		fmt.Println("Error getting local IP:", err)
		return 0
	}

	network := getNetworkPrefix(localIP)

	var wg sync.WaitGroup
	deviceCount := 0
	mu := &sync.Mutex{}

	for i := 2; i < 255; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			addr := fmt.Sprintf("%s.%d", network[:len(network)-2], i)

			if addr == localIP.String() {
				return
			}

			if ping(addr) {
				mu.Lock()
				deviceCount++
				mu.Unlock()
			}
		}(i)
	}

	wg.Wait()
	return deviceCount
}

func getLocalIP() (net.IP, error) {
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return nil, err
	}
	for _, addr := range addrs {
		if ipnet, ok := addr.(*net.IPNet); ok && ipnet.IP.IsGlobalUnicast() {
			return ipnet.IP, nil
		}
	}
	return nil, fmt.Errorf("local IP not found")
}

func getNetworkPrefix(ip net.IP) string {
	ip = ip.To4()
	return fmt.Sprintf("%d.%d.%d.0", ip[0], ip[1], ip[2])
}

func isValidIPv4(ip string) bool {
	ipv4Regex := `^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$`
	re := regexp.MustCompile(ipv4Regex)
	return re.MatchString(ip)
}

func ping(ip string) bool {
	if !isValidIPv4(ip) {
		return false
	}
	output, err := exec.Command("ping", "-c", "1", "-W", "1", ip).CombinedOutput()

	if err != nil {
		return false
	}
	_ = output
	return true
}