package shared

import "encoding/binary"

const PROTO_VERSION uint16 = 1

const (
	_ uint16 = iota
	// (client -> server) requests an IP
	// [ pubkey - 1216 bytes ]
	REQ_REGISTER
	// (server -> client) returns the assigned IP and encapsulated multicast key
	// [ ip - 16 bytes ] [ ciphertext - 1168 bytes ]
	RESP_REGISTER
	// (client -> server -> client2) relays an encrypted packet to a specified peer
	// [ destIP - 16 bytes ] [ srcIP - 16 bytes ] [ encrypted pkt ]
	ENC_PKT
	// (client -> server -> *) broadcasts an encrypted packet
	// [ encrypted pkt ]
	BROADCAST_PKT
	// (client -> server) requests peer's pubkey from the server for encapsulation
	// [ ip - 16 bytes ]
	REQ_GET_PUBKEY
	// (server -> client) provides requested pubkey
	// [ ip - 16 bytes ] [ pubkey - 1216 bytes ]
	RESP_GET_PUBKEY
	// (client -> server -> client2) establishes a session key with another peer
	// [ destIP - 16 bytes ] [ srcIP - 16 bytes ] [ ciphertext - 1120 bytes ]
	REQ_ESTABLISH
	// (client2 -> server -> client) acknowledges the session key was established
	// [ destIP - 16 bytes ] [ srcIP - 16 bytes ]
	RESP_ESTABLISH
)

func BuildPkt(pktType uint16, data []byte) []byte {
	out := make([]byte, 4+len(data))
	binary.LittleEndian.PutUint16(out[0:], PROTO_VERSION)
	binary.LittleEndian.PutUint16(out[2:], pktType)
	copy(out[4:], data)
	return out
}