package discovery

import (
	"encoding/binary"

	"github.com/go-errors/errors"
	"github.com/lightningnetwork/lnd/channeldb"
	"github.com/lightningnetwork/lnd/lnwallet"
	"github.com/lightningnetwork/lnd/lnwire"
	"github.com/roasbeef/btcd/btcec"
)

// newProofKey constructs a new announcement signature message key.
func newProofKey(chanID uint64, isRemote bool) waitingProofKey {
	return waitingProofKey{
		chanID:   chanID,
		isRemote: isRemote,
	}
}

// ToBytes returns a serialized representation of the key.
func (k waitingProofKey) ToBytes() []byte {
	var key [9]byte

	var b uint8
	if k.isRemote {
		b = 0
	} else {
		b = 1
	}

	binary.BigEndian.PutUint64(key[:8], k.chanID)
	key[8] = b

	return key[:]
}

// createChanAnnouncement helper function which creates the channel announcement
// by the given channeldb objects.
func createChanAnnouncement(chanProof *channeldb.ChannelAuthProof,
	chanInfo *channeldb.ChannelEdgeInfo,
	e1, e2 *channeldb.ChannelEdgePolicy) (
	*lnwire.ChannelAnnouncement,
	*lnwire.ChannelUpdateAnnouncement,
	*lnwire.ChannelUpdateAnnouncement) {
	// First, using the parameters of the channel, along with the
	// channel authentication chanProof, we'll create re-create the
	// original authenticated channel announcement.
	chanID := lnwire.NewShortChanIDFromInt(chanInfo.ChannelID)
	chanAnn := &lnwire.ChannelAnnouncement{
		NodeSig1:       chanProof.NodeSig1,
		NodeSig2:       chanProof.NodeSig2,
		ShortChannelID: chanID,
		BitcoinSig1:    chanProof.BitcoinSig1,
		BitcoinSig2:    chanProof.BitcoinSig2,
		NodeID1:        chanInfo.NodeKey1,
		NodeID2:        chanInfo.NodeKey2,
		BitcoinKey1:    chanInfo.BitcoinKey1,
		BitcoinKey2:    chanInfo.BitcoinKey2,
	}

	// We'll unconditionally queue the channel's existence chanProof as
	// it will need to be processed before either of the channel
	// update networkMsgs.

	// Since it's up to a node's policy as to whether they
	// advertise the edge in dire direction, we don't create an
	// advertisement if the edge is nil.
	var edge1Ann, edge2Ann *lnwire.ChannelUpdateAnnouncement
	if e1 != nil {
		edge1Ann = &lnwire.ChannelUpdateAnnouncement{
			Signature:                 e1.Signature,
			ShortChannelID:            chanID,
			Timestamp:                 uint32(e1.LastUpdate.Unix()),
			Flags:                     0,
			TimeLockDelta:             e1.TimeLockDelta,
			HtlcMinimumMsat:           uint32(e1.MinHTLC),
			FeeBaseMsat:               uint32(e1.FeeBaseMSat),
			FeeProportionalMillionths: uint32(e1.FeeProportionalMillionths),
		}
	}
	if e2 != nil {
		edge2Ann = &lnwire.ChannelUpdateAnnouncement{
			Signature:                 e2.Signature,
			ShortChannelID:            chanID,
			Timestamp:                 uint32(e2.LastUpdate.Unix()),
			Flags:                     1,
			TimeLockDelta:             e2.TimeLockDelta,
			HtlcMinimumMsat:           uint32(e2.MinHTLC),
			FeeBaseMsat:               uint32(e2.FeeBaseMSat),
			FeeProportionalMillionths: uint32(e2.FeeProportionalMillionths),
		}
	}

	return chanAnn, edge1Ann, edge2Ann
}

// copyPubKey is copying the public key and setting curve.
// NOTE: At the moment of creation the function was need only because we are
// setting the curve to nil in the read message function and in order to
// properly validate the signatures we need to set the curve again.
func copyPubKey(pub *btcec.PublicKey) *btcec.PublicKey {
	return &btcec.PublicKey{
		Curve: btcec.S256(),
		X:     pub.X,
		Y:     pub.Y,
	}
}

// SignAnnouncement helper function which is used for signing the announce
// messages.
func SignAnnouncement(signer *lnwallet.MessageSigner,
	msg lnwire.Message) (*btcec.Signature, error) {
	var data []byte
	var err error
	switch m := msg.(type) {
	case *lnwire.ChannelAnnouncement:
		data, err = m.DataToSign()
	case *lnwire.ChannelUpdateAnnouncement:
		data, err = m.DataToSign()
	case *lnwire.NodeAnnouncement:
		data, err = m.DataToSign()
	default:
		return nil, errors.New("can't sign message " +
			"of this format")
	}
	if err != nil {
		return nil, errors.Errorf("can't get data to sign: %v", err)
	}

	return signer.SignData(data)
}