package node

import "unsafe"

const (
	headerSize    = 24
	streamData    = 1
	streamRouting = 2
)

type header struct {
	Counter  uint64 // Init with fasttime.Now() << 30 to ensure monotonic.
	SourceIP byte
	DestIP   byte
	Forward  byte
	Stream   byte   // See stream* constants.
	DataSize uint16 // Data size following associated data.
}

func (hdr *header) Parse(nb []byte) {
	hdr.Counter = *(*uint64)(unsafe.Pointer(&nb[0]))
	hdr.SourceIP = nb[8]
	hdr.DestIP = nb[9]
	hdr.Forward = nb[10]
	hdr.Stream = nb[11]
	hdr.DataSize = *(*uint16)(unsafe.Pointer(&nb[12]))
}

func (hdr header) Marshal(buf []byte) {
	*(*uint64)(unsafe.Pointer(&buf[0])) = hdr.Counter
	buf[8] = hdr.SourceIP
	buf[9] = hdr.DestIP
	buf[10] = hdr.Forward
	buf[11] = hdr.Stream
	*(*uint16)(unsafe.Pointer(&buf[12])) = hdr.DataSize
}