package tendrils

import (
	"context"
	"log"
	"net"
	"time"
)

func (t *Tendrils) listenDante(ctx context.Context, iface net.Interface) {
	go t.listenPTP(ctx, iface)
}

func (t *Tendrils) listenPTP(ctx context.Context, iface net.Interface) {
	addr, err := net.ResolveUDPAddr("udp4", "224.0.1.129:319")
	if err != nil {
		return
	}

	conn, err := net.ListenMulticastUDP("udp4", &iface, addr)
	if err != nil {
		if t.DebugDante {
			log.Printf("[dante] %s: failed to listen ptp: %v", iface.Name, err)
		}
		return
	}
	defer conn.Close()

	buf := make([]byte, 1500)
	for {
		select {
		case <-ctx.Done():
			return
		default:
		}

		conn.SetReadDeadline(time.Now().Add(1 * time.Second))
		n, src, err := conn.ReadFromUDP(buf)
		if err != nil {
			if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
				continue
			}
			continue
		}

		t.handlePTPPacket(iface.Name, src.IP, buf[:n])
	}
}

func (t *Tendrils) handlePTPPacket(ifaceName string, srcIP net.IP, data []byte) {
	if len(data) < 34 {
		return
	}

	messageType := data[0] & 0x0f

	if messageType != 0x0b {
		return
	}

	if len(data) < 64 {
		return
	}

	clockClass := data[48]
	clockAccuracy := data[49]
	priority1 := data[47]
	priority2 := data[51]

	if t.DebugDante {
		log.Printf("[dante] %s: ptp announce from %s class=%d accuracy=%d p1=%d p2=%d",
			ifaceName, srcIP, clockClass, clockAccuracy, priority1, priority2)
	}

	t.nodes.SetDanteClockMaster(srcIP)
}

func (n *Nodes) UpdateDanteTxChannels(name string, ip net.IP, channels string) {
	n.mu.Lock()
	defer n.mu.Unlock()

	node := n.getNodeByIPLocked(ip)
	if node == nil {
		return
	}
	node.DanteTxChannels = channels
}

func (n *Nodes) GetDanteTxDeviceInGroup(groupIP net.IP) string {
	n.mu.RLock()
	defer n.mu.RUnlock()

	groupKey := groupIP.String()
	gm := n.multicastGroups[groupKey]
	if gm == nil {
		return ""
	}

	for _, membership := range gm.Members {
		if membership.Node != nil && membership.Node.DanteTxChannels != "" {
			return membership.Node.DisplayName()
		}
	}
	return ""
}