package peer

import (
	"log"
	"sync/atomic"
)

type mcReader struct {
	conn  udpReader
	super controlMsgHandler
	peers [256]*atomic.Pointer[remotePeer]

	incoming []byte
	buf      []byte
}

func newMCReader(
	conn udpReader,
	super controlMsgHandler,
	peers [256]*atomic.Pointer[remotePeer],
) *mcReader {
	return &mcReader{conn, super, peers, newBuf(), newBuf()}
}

func (r *mcReader) Run() {
	for {
		r.handleNextPacket()
	}
}

func (r *mcReader) handleNextPacket() {
	incoming := r.incoming[:bufferSize]
	n, remoteAddr, err := r.conn.ReadFromUDPAddrPort(incoming)
	if err != nil {
		log.Fatalf("Failed to read from UDP multicast port: %v", err)
	}
	incoming = incoming[:n]

	h, ok := headerFromLocalDiscoveryPacket(incoming)
	if !ok {
		return
	}

	peer := r.peers[h.SourceIP].Load()
	if peer == nil || peer.PubSignKey == nil {
		return
	}

	if !verifyLocalDiscoveryPacket(incoming, r.buf, peer.PubSignKey) {
		return
	}

	r.super.HandleControlMsg(controlMsg[packetLocalDiscovery]{
		SrcIP:   h.SourceIP,
		SrcAddr: remoteAddr,
	})
}