package nonce

import (
	"crypto/rand"

	"github.com/indra-labs/indra/pkg/crypto/sha256"
)

const IDLen = 8

// ID is a value generated by a hash chain that renews at first use and every
// time it generates 65536 new ID's.
type ID [IDLen]byte

var seed sha256.Hash
var counter uint16

func reseed() {
	if c, e := rand.Read(seed[:]); check(e) && c != IDLen {
	}
	counter++
}

// NewID returns a random 8 byte nonce to be used as identifiers.
func NewID() (t ID) {
	if counter == 0 {
		reseed()
	}
	s := sha256.Single(seed[:])
	copy(seed[:], s[:])
	copy(t[:], seed[:IDLen])
	return
}