package node

import (
	"io"
	"log"
	"net"
	"net/netip"
	"sync"
)

// ----------------------------------------------------------------------------

type connWriter struct {
	lock sync.Mutex
	conn *net.UDPConn
}

func newConnWriter(conn *net.UDPConn) *connWriter {
	return &connWriter{conn: conn}
}

func (w *connWriter) WriteTo(packet []byte, addr netip.AddrPort) {
	// Even though a conn is safe for concurrent use, it turns out that a mutex
	// in Go is more fair when there's contention. Without this lock, control
	// packets may fail to be sent in a timely manner causing timeouts.
	w.lock.Lock()
	if _, err := w.conn.WriteToUDPAddrPort(packet, addr); err != nil {
		log.Fatalf("Failed to write to UDP port: %v", err)
	}
	w.lock.Unlock()
}

// ----------------------------------------------------------------------------

type ifWriter struct {
	lock  sync.Mutex
	iface io.ReadWriteCloser
}

func newIFWriter(iface io.ReadWriteCloser) *ifWriter {
	return &ifWriter{iface: iface}
}

func (w *ifWriter) Write(packet []byte) {
	w.lock.Lock()
	if _, err := w.iface.Write(packet); err != nil {
		log.Fatalf("Failed to write to interface: %v", err)
	}
	w.lock.Unlock()
}