package gnarlring

import (
	"errors"

	"git.smesh.lol/gnarl-hamadryad/crypto"
)

// Wire message types for gnarlring frames transported over GnarlWire.
const (
	MsgTypeCommitment  = 0xE0 // child commitment frame (63 bytes)
	MsgTypeEpochFull   = 0xE1 // full epoch broadcast (1787 bytes)
	MsgTypeEpochCheck  = 0xE2 // compact epoch check (113 bytes)
	MsgTypeVote        = 0xE3 // encrypted vote
)

// SealCommitment encrypts and authenticates a child commitment frame.
func SealCommitment(secret crypto.Hamadryad, identity crypto.GnarlMid,
	nonce [crypto.GnarlNonceLen]byte, cc *ChildCommitment) *crypto.GnarlPacket {
	payload := append([]byte{MsgTypeCommitment}, MarshalCommitmentFrame(cc)...)
	return crypto.GnarlSeal(secret, identity, nonce, payload)
}

// OpenCommitment verifies and decrypts a commitment frame.
func OpenCommitment(secret crypto.Hamadryad, pkt *crypto.GnarlPacket) (*ChildCommitment, error) {
	plain, err := crypto.GnarlOpen(secret, pkt)
	if err != nil {
		return nil, err
	}
	if len(plain) < 1 || plain[0] != MsgTypeCommitment {
		return nil, errors.New("gnarlring: wrong message type for commitment")
	}
	return UnmarshalCommitmentFrame(plain[1:]), nil
}

// SealEpoch encrypts and authenticates a full epoch frame.
func SealEpoch(secret crypto.Hamadryad, identity crypto.GnarlMid,
	nonce [crypto.GnarlNonceLen]byte, es *EpochState) *crypto.GnarlPacket {
	payload := append([]byte{MsgTypeEpochFull}, MarshalEpochFrame(es)...)
	return crypto.GnarlSeal(secret, identity, nonce, payload)
}

// OpenEpoch verifies and decrypts a full epoch frame.
func OpenEpoch(secret crypto.Hamadryad, pkt *crypto.GnarlPacket) (*EpochState, error) {
	plain, err := crypto.GnarlOpen(secret, pkt)
	if err != nil {
		return nil, err
	}
	if len(plain) < 1 || plain[0] != MsgTypeEpochFull {
		return nil, errors.New("gnarlring: wrong message type for epoch")
	}
	return UnmarshalEpochFrame(plain[1:]), nil
}

// SealEpochCheck encrypts and authenticates a compact epoch check frame.
func SealEpochCheck(secret crypto.Hamadryad, identity crypto.GnarlMid,
	nonce [crypto.GnarlNonceLen]byte, es *EpochState) *crypto.GnarlPacket {
	payload := append([]byte{MsgTypeEpochCheck}, MarshalEpochCheckFrame(es)...)
	return crypto.GnarlSeal(secret, identity, nonce, payload)
}

// OpenEpochCheck verifies and decrypts a compact epoch check frame.
func OpenEpochCheck(secret crypto.Hamadryad, pkt *crypto.GnarlPacket) (*EpochCheckFrame, error) {
	plain, err := crypto.GnarlOpen(secret, pkt)
	if err != nil {
		return nil, err
	}
	if len(plain) < 1 || plain[0] != MsgTypeEpochCheck {
		return nil, errors.New("gnarlring: wrong message type for epoch check")
	}
	return UnmarshalEpochCheckFrame(plain[1:])
}