package domain

import "crypto/sha256"

type RequestHash [sha256.Size]byte

func HashImmutableRequest(canonical []byte) RequestHash { return sha256.Sum256(canonical) }

type ReplayDecision uint8

const (
	ReplayNew ReplayDecision = iota
	ReplayExact
	ReplayConflict
)

// ClassifyReplay compares a canonical immutable request against durable state.
// A nil stored hash means no mutation with this request UUID exists.
func ClassifyReplay(stored *RequestHash, incoming RequestHash) ReplayDecision {
	if stored == nil {
		return ReplayNew
	}
	if *stored == incoming {
		return ReplayExact
	}
	return ReplayConflict
}