package wtdb

import (
	"io"

	"github.com/lightningnetwork/lnd/watchtower/blob"
)

// SessionStateUpdate holds a state update sent by a client along with its
// SessionID.
type SessionStateUpdate struct {
	// ID the session id of the client who sent the state update.
	ID SessionID

	// SeqNum the sequence number of the update within the session.
	SeqNum uint16

	// LastApplied the highest index that client has acknowledged is
	// committed
	LastApplied uint16

	// Hint is the 16-byte prefix of the revoked commitment transaction.
	Hint blob.BreachHint

	// EncryptedBlob is a ciphertext containing the sweep information for
	// exacting justice if the commitment transaction matching the breach
	// hint is broadcast.
	EncryptedBlob []byte
}

// Encode serializes the state update into the provided io.Writer.
func (u *SessionStateUpdate) Encode(w io.Writer) error {
	return WriteElements(w,
		u.ID,
		u.SeqNum,
		u.LastApplied,
		u.Hint,
		u.EncryptedBlob,
	)
}

// Decode deserializes the target state update from the provided io.Reader.
func (u *SessionStateUpdate) Decode(r io.Reader) error {
	return ReadElements(r,
		&u.ID,
		&u.SeqNum,
		&u.LastApplied,
		&u.Hint,
		&u.EncryptedBlob,
	)
}