package node

import (
	"encoding/binary"
	"log"
	"net"
	"net/netip"
	"time"
)

func localBroadcaster() {
	var (
		buf1 = make([]byte, bufferSize)
		buf2 = make([]byte, bufferSize)
	)
	time.Sleep(4 * time.Second)
	doBroadcast(buf1, buf2)
	for range time.Tick(32 * time.Second) {
		doBroadcast(buf1, buf2)
	}
}

func doBroadcast(buf1, buf2 []byte) {
	ifaces, err := net.Interfaces()
	if err != nil {
		log.Printf("Failed to list interfaces: %v", err)
		return
	}

	for _, iface := range ifaces {
		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagRunning == 0 {
			continue
		}
		if iface.Flags&net.FlagPointToPoint != 0 {
			continue
		}
		if iface.Flags&net.FlagBroadcast == 0 {
			continue
		}

		addrs, err := iface.Addrs()
		if err != nil {
			log.Printf("Failed to get interface addresses: %v", err)
			continue
		}

		for _, addr := range addrs {
			ipNet, ok := addr.(*net.IPNet)
			if !ok {
				continue
			}
			ip4 := ipNet.IP.To4()
			if ip4 == nil {
				continue
			}

			ip, ok := lastAddr(ipNet)
			if !ok {
				log.Printf("Failed to find broadcast address: %v", ipNet)
				continue
			}

			log.Printf("Broadcasting on address: %v", ip)
			//addr := netip.AddrPortFrom(ip, 456)
		}
	}
}

// works when the n is a prefix, otherwise...
func lastAddr(n *net.IPNet) (netip.Addr, bool) {
	ip := make(net.IP, len(n.IP.To4()))
	binary.BigEndian.PutUint32(ip, binary.BigEndian.Uint32(n.IP.To4())|
		^binary.BigEndian.Uint32(net.IP(n.Mask).To4()))
	return netip.AddrFromSlice(ip)
}