package main

import (
	"encoding/binary"

	"github.com/meshnet-gophers/meshtastic-go"
	pb "github.com/meshnet-gophers/meshtastic-go/meshtastic"
	"google.golang.org/protobuf/proto"
)

const (
	FlagViaMQTT = (1 << 4)
	FlagWantACK = (1 << 3)
)

var (
	broadcastID = meshtastic.BroadcastNodeID.Uint32()
)

var pkcChan = &pb.ChannelSettings{
	ChannelNum: 0xFFFFFFFF,
	Name:       "[PKC]",
	Psk:        nil,
}

type MeshIf interface {
	Open() error
	ReadMeshPacket() (*pb.MeshPacket, uint64, error)
	WriteMeshPacket(*pb.MeshPacket) error
	Close() error
}

type RadioHeaderFlag uint8

func (r RadioHeaderFlag) WantACK() uint8 {
	return uint8(r>>3) & 1
}

func (r RadioHeaderFlag) MQTT() uint8 {
	return uint8(r>>4) & 1
}

func (r RadioHeaderFlag) HopStart() uint8 {
	return uint8(r>>5) & 0b111
}

func (r RadioHeaderFlag) HopLimit() uint8 {
	return uint8(r & 0b111)
}

type PacketTruncated struct {
	To   uint32
	From uint32
	ID   uint32
}

func buildRoutingReply(p *pb.MeshPacket, err pb.Routing_Error) *pb.MeshPacket {
	cb, _ := proto.Marshal(&pb.Routing{
		Variant: &pb.Routing_ErrorReason{ErrorReason: err},
	})
	return &pb.MeshPacket{
		// Reversed
		To:   p.From,
		From: p.To,

		PkiEncrypted: p.PkiEncrypted,
		PublicKey:    p.PublicKey,

		// (N)ACK
		Priority: pb.MeshPacket_ACK,
		HopLimit: p.HopStart,
		Channel:  p.Channel,
		PayloadVariant: &pb.MeshPacket_Decoded{
			Decoded: &pb.Data{
				Portnum:   pb.PortNum_ROUTING_APP,
				RequestId: p.Id,
				Payload:   cb,
			},
		},
	}
}

func buildPkcNonce(id uint32, extra uint32, from uint32) []byte {
	var buf [13]byte // zero-init
	binary.LittleEndian.PutUint32(buf[0:4], id)
	binary.LittleEndian.PutUint32(buf[4:8], extra)
	binary.LittleEndian.PutUint32(buf[8:12], from)
	buf[12] = 0 // last byte is zero
	return buf[:]
}