// newManagedAddress returns a new managed address based on the passed account,
// private key, and whether or not the public key is compressed.  The managed
// address will have access to the private and public keys.
func newManagedAddress(m *Manager, account uint32, privKey *btcec.PrivateKey, compressed bool) (*managedAddress, error) {
	// Encrypt the private key.
	//
	// NOTE: The privKeyBytes here are set into the managed address which
	// are cleared when locked, so they aren't cleared here.
	privKeyBytes := privKey.Serialize()
	privKeyEncrypted, err := m.cryptoKeyPriv.Encrypt(privKeyBytes)
	if err != nil {
		str := "failed to encrypt private key"
		return nil, managerError(ErrCrypto, str, err)
	}

	// Leverage the code to create a managed address without a private key
	// and then add the private key to it.
	ecPubKey := (*btcec.PublicKey)(&privKey.PublicKey)
	managedAddr, err := newManagedAddressWithoutPrivKey(m, account,
		ecPubKey, compressed)
	if err != nil {
		return nil, err
	}
	managedAddr.privKeyEncrypted = privKeyEncrypted
	managedAddr.privKeyCT = privKeyBytes

	return managedAddr, nil
}

func generateSinFromKey(key *btcec.PrivateKey) string {
	pub := key.PubKey()
	comp := pub.SerializeCompressed()
	hexb := hex.EncodeToString(comp)
	stx := generateSinFromPublicKey(hexb)
	return stx
}

// keyToAddr maps the passed private to corresponding p2pkh address.
func keyToAddr(key *btcec.PrivateKey, net *chaincfg.Params) (btcutil.Address, error) {
	serializedKey := key.PubKey().SerializeCompressed()
	pubKeyAddr, err := btcutil.NewAddressPubKey(serializedKey, net)
	if err != nil {
		return nil, err
	}
	return pubKeyAddr.AddressPubKeyHash(), nil
}

// authPKH...
func (c *LNDConn) authPKH(
	myId *btcec.PrivateKey, theirPKH, localEphPubBytes []byte) error {
	if c.Authed {
		return fmt.Errorf("%s already authed", c.RemotePub)
	}
	if len(theirPKH) != 20 {
		return fmt.Errorf("remote PKH must be 20 bytes, got %d",
			len(theirPKH))
	}

	// Send 53 bytes: our pubkey, and the remote's pubkey hash.
	var greetingMsg [53]byte
	copy(greetingMsg[:33], myId.PubKey().SerializeCompressed())
	copy(greetingMsg[:33], theirPKH)
	if _, err := c.Conn.Write(greetingMsg[:]); err != nil {
		return err
	}

	// Wait for their response.
	// TODO(tadge): add timeout here
	//  * NOTE(roasbeef): read timeout should be set on the underlying
	//    net.Conn.
	resp := make([]byte, 53)
	if _, err := c.Conn.Read(resp); err != nil {
		return err
	}

	// Parse their long-term public key, and generate the DH proof.
	theirPub, err := btcec.ParsePubKey(resp[:33], btcec.S256())
	if err != nil {
		return err
	}
	idDH := fastsha256.Sum256(btcec.GenerateSharedSecret(myId, theirPub))
	fmt.Printf("made idDH %x\n", idDH)
	theirDHproof := btcutil.Hash160(append(localEphPubBytes, idDH[:]...))

	// Verify that their DH proof matches the one we just generated.
	if bytes.Equal(resp[33:], theirDHproof) == false {
		return fmt.Errorf("Invalid DH proof %x", theirDHproof)
	}

	// If their DH proof checks out, then send our own.
	myDHproof := btcutil.Hash160(append(c.RemotePub.SerializeCompressed(), idDH[:]...))
	if _, err = c.Conn.Write(myDHproof); err != nil {
		return err
	}

	// Proof sent, auth complete.
	c.RemotePub = theirPub
	theirAdr := btcutil.Hash160(theirPub.SerializeCompressed())
	copy(c.RemoteLNId[:], theirAdr[:16])
	c.Authed = true

	return nil
}

// RawTxInSignature returns the serialized ECDSA signature for the input idx of
// the given transaction, with hashType appended to it.
func RawTxInSignature(tx *wire.MsgTx, idx int, subScript []byte,
	hashType SigHashType, key *btcec.PrivateKey) ([]byte, error) {

	parsedScript, err := parseScript(subScript)
	if err != nil {
		return nil, fmt.Errorf("cannot parse output script: %v", err)
	}
	hash := calcSignatureHash(parsedScript, hashType, tx, idx)
	signature, err := key.Sign(hash)
	if err != nil {
		return nil, fmt.Errorf("cannot sign tx input: %s", err)
	}

	return append(signature.Serialize(), byte(hashType)), nil
}

func GeneratePemFromKey(priv *btcec.PrivateKey) string {
	pub := priv.PubKey()
	ecd := pub.ToECDSA()
	oid := asn1.ObjectIdentifier{1, 3, 132, 0, 10}
	curve := btcec.S256()
	der, _ := asn1.Marshal(ecPrivateKey{
		Version:       1,
		PrivateKey:    priv.D.Bytes(),
		NamedCurveOID: oid,
		PublicKey:     asn1.BitString{Bytes: elliptic.Marshal(curve, ecd.X, ecd.Y)},
	})
	blck := pem.Block{Type: "EC PRIVATE KEY", Bytes: der}
	pm := pem.EncodeToMemory(&blck)
	return string(pm)
}

// NewSphinxNode...
func NewSphinxNode(nodeKey *btcec.PrivateKey, net *chaincfg.Params) *SphinxNode {
	var nodeID [securityParameter]byte
	copy(nodeID[:], btcutil.Hash160(nodeKey.PubKey().SerializeCompressed()))

	// Safe to ignore the error here, nodeID is 20 bytes.
	nodeAddr, _ := btcutil.NewAddressPubKeyHash(nodeID[:], net)

	return &SphinxNode{
		nodeID:   nodeID,
		nodeAddr: nodeAddr,
		lnKey:    nodeKey,
		// TODO(roasbeef): replace instead with bloom filter?
		// * https://moderncrypto.org/mail-archive/messaging/2015/001911.html
		seenSecrets: make(map[[sharedSecretSize]byte]struct{}),
	}
}

// authPubKey...
func (c *LNDConn) authPubKey(
	myId *btcec.PrivateKey, remotePubBytes, localEphPubBytes []byte) error {
	if c.Authed {
		return fmt.Errorf("%s already authed", c.RemotePub)
	}

	// Since we already know their public key, we can immediately generate
	// the DH proof without an additional round-trip.
	theirPub, err := btcec.ParsePubKey(remotePubBytes, btcec.S256())
	if err != nil {
		return err
	}
	theirPKH := btcutil.Hash160(remotePubBytes)
	idDH := fastsha256.Sum256(btcec.GenerateSharedSecret(myId, theirPub))
	myDHproof := btcutil.Hash160(append(c.RemotePub.SerializeCompressed(), idDH[:]...))

	// Send over the 73 byte authentication message: my pubkey, their
	// pubkey hash, DH proof.
	var authMsg [73]byte
	copy(authMsg[:33], myId.PubKey().SerializeCompressed())
	copy(authMsg[33:], theirPKH)
	copy(authMsg[53:], myDHproof)
	if _, err = c.Conn.Write(authMsg[:]); err != nil {
		return nil
	}

	// Await, their response. They should send only the 20-byte DH proof.
	resp := make([]byte, 20)
	_, err = c.Conn.Read(resp)
	if err != nil {
		return err
	}

	// Verify that their proof matches our locally computed version.
	theirDHproof := btcutil.Hash160(append(localEphPubBytes, idDH[:]...))
	if bytes.Equal(resp, theirDHproof) == false {
		return fmt.Errorf("invalid DH proof %x", theirDHproof)
	}

	// Proof checks out, auth complete.
	c.RemotePub = theirPub
	theirAdr := btcutil.Hash160(theirPub.SerializeCompressed())
	copy(c.RemoteLNId[:], theirAdr[:16])
	c.Authed = true

	return nil
}