package peer

import (
	"net/netip"
)

const (
	PacketTypeSyn = iota + 1
	PacketTypeSynAck
	PacketTypeAck
	PacketTypeProbe
	PacketTypeAddrDiscovery
)

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

type PacketSyn struct {
	TraceID uint64 // TraceID to match response w/ request.
	//SentAt        int64    // Unixmilli.
	//SharedKeyType byte     // Currently only 1 is supported for AES.
	SharedKey     [32]byte // Our shared key.
	Direct        bool
	PossibleAddrs [8]netip.AddrPort // Possible public addresses of the sender.
}

func (p PacketSyn) Marshal(buf []byte) []byte {
	return newBinWriter(buf).
		Byte(PacketTypeSyn).
		Uint64(p.TraceID).
		//Int64(p.SentAt).
		//Byte(p.SharedKeyType).
		SharedKey(p.SharedKey).
		Bool(p.Direct).
		AddrPort8(p.PossibleAddrs).
		Build()
}

func ParsePacketSyn(buf []byte) (p PacketSyn, err error) {
	err = newBinReader(buf[1:]).
		Uint64(&p.TraceID).
		//Int64(&p.SentAt).
		//Byte(&p.SharedKeyType).
		SharedKey(&p.SharedKey).
		Bool(&p.Direct).
		AddrPort8(&p.PossibleAddrs).
		Error()
	return
}

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

type PacketAck struct {
	TraceID       uint64
	ToAddr        netip.AddrPort
	PossibleAddrs [8]netip.AddrPort // Possible public addresses of the sender.
}

func (p PacketAck) Marshal(buf []byte) []byte {
	return newBinWriter(buf).
		Byte(PacketTypeAck).
		Uint64(p.TraceID).
		AddrPort(p.ToAddr).
		AddrPort8(p.PossibleAddrs).
		Build()
}

func ParsePacketAck(buf []byte) (p PacketAck, err error) {
	err = newBinReader(buf[1:]).
		Uint64(&p.TraceID).
		AddrPort(&p.ToAddr).
		AddrPort8(&p.PossibleAddrs).
		Error()
	return
}

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

// A probeReqPacket is sent from a client to a server to determine if direct
// UDP communication can be used.
type PacketProbe struct {
	TraceID uint64
}

func (p PacketProbe) Marshal(buf []byte) []byte {
	return newBinWriter(buf).
		Byte(PacketTypeProbe).
		Uint64(p.TraceID).
		Build()
}

func ParsePacketProbe(buf []byte) (p PacketProbe, err error) {
	err = newBinReader(buf[1:]).
		Uint64(&p.TraceID).
		Error()
	return
}

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

type PacketLocalDiscovery struct{}