/*
   Copyright 2024 Josh Deprez

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package main

import (
	"fmt"
	"log"

	"gitea.drjosh.dev/josh/jrouter/atalk/nbp"
	"github.com/google/gopacket/pcap"
	"github.com/sfiera/multitalk/pkg/ddp"
	"github.com/sfiera/multitalk/pkg/ethernet"
	"github.com/sfiera/multitalk/pkg/ethertalk"
)

func handleNBPInAURP(pcapHandle *pcap.Handle, myHWAddr ethernet.Addr, ddpkt *ddp.ExtPacket) error {
	if ddpkt.Proto != ddp.ProtoNBP {
		return fmt.Errorf("invalid DDP type %d on socket 2", ddpkt.Proto)
	}
	nbpkt, err := nbp.Unmarshal(ddpkt.Data)
	if err != nil {
		return fmt.Errorf("invalid NBP packet: %v", err)
	}
	if nbpkt.Function != nbp.FunctionFwdReq {
		// It's something else??
		return fmt.Errorf("can't handle %v", nbpkt.Function)
	}

	if len(nbpkt.Tuples) < 1 {
		return fmt.Errorf("no tuples in NBP packet")
	}

	log.Printf("NBP/DDP/AURP: Converting FwdReq to LkUp (%v)", nbpkt.Tuples[0])

	// Convert it to a LkUp and broadcast on EtherTalk
	// TODO: use zone-specific multicast
	nbpkt.Function = nbp.FunctionLkUp
	nbpRaw, err := nbpkt.Marshal()
	if err != nil {
		return fmt.Errorf("couldn't marshal LkUp: %v", err)
	}

	// "If the destination network is extended, however, the router must also
	// change the destination network number to $0000, so that the packet is
	// received by all nodes on the network (within the correct zone multicast
	// address)."
	ddpkt.DstNet = 0x0000
	ddpkt.DstNode = 0xFF // Broadcast node address within the dest network
	ddpkt.Data = nbpRaw

	outFrame, err := ethertalk.AppleTalk(myHWAddr, *ddpkt)
	if err != nil {
		return err
	}
	// TODO: outFrame.Dst = zone-specific multicast address
	outFrameRaw, err := ethertalk.Marshal(*outFrame)
	if err != nil {
		return err
	}
	return pcapHandle.WritePacketData(outFrameRaw)
}