package peer

import (
	"bytes"
	crand "crypto/rand"
	"encoding/binary"
	"io"
	"io/ioutil"
	"math/rand"
	"net"
	"os"
	"time"

	"github.com/btcsuite/btcd/btcec"
	"github.com/btcsuite/btcd/chaincfg/chainhash"
	"github.com/btcsuite/btcd/wire"
	"github.com/btcsuite/btcutil"
	"github.com/lightningnetwork/lnd/chainntnfs"
	"github.com/lightningnetwork/lnd/channeldb"
	"github.com/lightningnetwork/lnd/htlcswitch"
	"github.com/lightningnetwork/lnd/input"
	"github.com/lightningnetwork/lnd/keychain"
	"github.com/lightningnetwork/lnd/lntest/mock"
	"github.com/lightningnetwork/lnd/lnwallet"
	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
	"github.com/lightningnetwork/lnd/lnwire"
	"github.com/lightningnetwork/lnd/netann"
	"github.com/lightningnetwork/lnd/queue"
	"github.com/lightningnetwork/lnd/shachain"
	"github.com/lightningnetwork/lnd/ticker"
)

const (
	broadcastHeight = 100
)

var (
	alicesPrivKey = []byte{
		0x2b, 0xd8, 0x06, 0xc9, 0x7f, 0x0e, 0x00, 0xaf,
		0x1a, 0x1f, 0xc3, 0x32, 0x8f, 0xa7, 0x63, 0xa9,
		0x26, 0x97, 0x23, 0xc8, 0xdb, 0x8f, 0xac, 0x4f,
		0x93, 0xaf, 0x71, 0xdb, 0x18, 0x6d, 0x6e, 0x90,
	}

	bobsPrivKey = []byte{
		0x81, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
		0x63, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
		0xd, 0xe7, 0x95, 0xe4, 0xb7, 0x25, 0xb8, 0x4d,
		0x1e, 0xb, 0x4c, 0xfd, 0x9e, 0xc5, 0x8c, 0xe9,
	}

	// Use a hard-coded HD seed.
	testHdSeed = [32]byte{
		0xb7, 0x94, 0x38, 0x5f, 0x2d, 0x1e, 0xf7, 0xab,
		0x4d, 0x92, 0x73, 0xd1, 0x90, 0x63, 0x81, 0xb4,
		0x4f, 0x2f, 0x6f, 0x25, 0x88, 0xa3, 0xef, 0xb9,
		0x6a, 0x49, 0x18, 0x83, 0x31, 0x98, 0x47, 0x53,
	}

	// Just use some arbitrary bytes as delivery script.
	dummyDeliveryScript = alicesPrivKey

	// testTx is used as the default funding txn for single-funder channels.
	testTx = &wire.MsgTx{
		Version: 1,
		TxIn: []*wire.TxIn{
			{
				PreviousOutPoint: wire.OutPoint{
					Hash:  chainhash.Hash{},
					Index: 0xffffffff,
				},
				SignatureScript: []byte{0x04, 0x31, 0xdc, 0x00, 0x1b, 0x01, 0x62},
				Sequence:        0xffffffff,
			},
		},
		TxOut: []*wire.TxOut{
			{
				Value: 5000000000,
				PkScript: []byte{
					0x41, // OP_DATA_65
					0x04, 0xd6, 0x4b, 0xdf, 0xd0, 0x9e, 0xb1, 0xc5,
					0xfe, 0x29, 0x5a, 0xbd, 0xeb, 0x1d, 0xca, 0x42,
					0x81, 0xbe, 0x98, 0x8e, 0x2d, 0xa0, 0xb6, 0xc1,
					0xc6, 0xa5, 0x9d, 0xc2, 0x26, 0xc2, 0x86, 0x24,
					0xe1, 0x81, 0x75, 0xe8, 0x51, 0xc9, 0x6b, 0x97,
					0x3d, 0x81, 0xb0, 0x1c, 0xc3, 0x1f, 0x04, 0x78,
					0x34, 0xbc, 0x06, 0xd6, 0xd6, 0xed, 0xf6, 0x20,
					0xd1, 0x84, 0x24, 0x1a, 0x6a, 0xed, 0x8b, 0x63,
					0xa6, // 65-byte signature
					0xac, // OP_CHECKSIG
				},
			},
		},
		LockTime: 5,
	}
)

// noUpdate is a function which can be used as a parameter in createTestPeer to
// call the setup code with no custom values on the channels set up.
var noUpdate = func(a, b *channeldb.OpenChannel) {}

// createTestPeer creates a channel between two nodes, and returns a peer for
// one of the nodes, together with the channel seen from both nodes. It takes
// an updateChan function which can be used to modify the default values on
// the channel states for each peer.
func createTestPeer(notifier chainntnfs.ChainNotifier,
	publTx chan *wire.MsgTx, updateChan func(a, b *channeldb.OpenChannel)) (
	*Brontide, *lnwallet.LightningChannel, func(), error) {

	aliceKeyPriv, aliceKeyPub := btcec.PrivKeyFromBytes(
		btcec.S256(), alicesPrivKey,
	)
	aliceKeySigner := &keychain.PrivKeyDigestSigner{PrivKey: aliceKeyPriv}
	bobKeyPriv, bobKeyPub := btcec.PrivKeyFromBytes(
		btcec.S256(), bobsPrivKey,
	)

	channelCapacity := btcutil.Amount(10 * 1e8)
	channelBal := channelCapacity / 2
	aliceDustLimit := btcutil.Amount(200)
	bobDustLimit := btcutil.Amount(1300)
	csvTimeoutAlice := uint32(5)
	csvTimeoutBob := uint32(4)

	prevOut := &wire.OutPoint{
		Hash:  chainhash.Hash(testHdSeed),
		Index: 0,
	}
	fundingTxIn := wire.NewTxIn(prevOut, nil, nil)

	aliceCfg := channeldb.ChannelConfig{
		ChannelConstraints: channeldb.ChannelConstraints{
			DustLimit:        aliceDustLimit,
			MaxPendingAmount: lnwire.MilliSatoshi(rand.Int63()),
			ChanReserve:      btcutil.Amount(rand.Int63()),
			MinHTLC:          lnwire.MilliSatoshi(rand.Int63()),
			MaxAcceptedHtlcs: uint16(rand.Int31()),
			CsvDelay:         uint16(csvTimeoutAlice),
		},
		MultiSigKey: keychain.KeyDescriptor{
			PubKey: aliceKeyPub,
		},
		RevocationBasePoint: keychain.KeyDescriptor{
			PubKey: aliceKeyPub,
		},
		PaymentBasePoint: keychain.KeyDescriptor{
			PubKey: aliceKeyPub,
		},
		DelayBasePoint: keychain.KeyDescriptor{
			PubKey: aliceKeyPub,
		},
		HtlcBasePoint: keychain.KeyDescriptor{
			PubKey: aliceKeyPub,
		},
	}
	bobCfg := channeldb.ChannelConfig{
		ChannelConstraints: channeldb.ChannelConstraints{
			DustLimit:        bobDustLimit,
			MaxPendingAmount: lnwire.MilliSatoshi(rand.Int63()),
			ChanReserve:      btcutil.Amount(rand.Int63()),
			MinHTLC:          lnwire.MilliSatoshi(rand.Int63()),
			MaxAcceptedHtlcs: uint16(rand.Int31()),
			CsvDelay:         uint16(csvTimeoutBob),
		},
		MultiSigKey: keychain.KeyDescriptor{
			PubKey: bobKeyPub,
		},
		RevocationBasePoint: keychain.KeyDescriptor{
			PubKey: bobKeyPub,
		},
		PaymentBasePoint: keychain.KeyDescriptor{
			PubKey: bobKeyPub,
		},
		DelayBasePoint: keychain.KeyDescriptor{
			PubKey: bobKeyPub,
		},
		HtlcBasePoint: keychain.KeyDescriptor{
			PubKey: bobKeyPub,
		},
	}

	bobRoot, err := chainhash.NewHash(bobKeyPriv.Serialize())
	if err != nil {
		return nil, nil, nil, err
	}
	bobPreimageProducer := shachain.NewRevocationProducer(*bobRoot)
	bobFirstRevoke, err := bobPreimageProducer.AtIndex(0)
	if err != nil {
		return nil, nil, nil, err
	}
	bobCommitPoint := input.ComputeCommitmentPoint(bobFirstRevoke[:])

	aliceRoot, err := chainhash.NewHash(aliceKeyPriv.Serialize())
	if err != nil {
		return nil, nil, nil, err
	}
	alicePreimageProducer := shachain.NewRevocationProducer(*aliceRoot)
	aliceFirstRevoke, err := alicePreimageProducer.AtIndex(0)
	if err != nil {
		return nil, nil, nil, err
	}
	aliceCommitPoint := input.ComputeCommitmentPoint(aliceFirstRevoke[:])

	aliceCommitTx, bobCommitTx, err := lnwallet.CreateCommitmentTxns(
		channelBal, channelBal, &aliceCfg, &bobCfg, aliceCommitPoint,
		bobCommitPoint, *fundingTxIn, channeldb.SingleFunderTweaklessBit,
	)
	if err != nil {
		return nil, nil, nil, err
	}

	alicePath, err := ioutil.TempDir("", "alicedb")
	if err != nil {
		return nil, nil, nil, err
	}

	dbAlice, err := channeldb.Open(alicePath)
	if err != nil {
		return nil, nil, nil, err
	}

	bobPath, err := ioutil.TempDir("", "bobdb")
	if err != nil {
		return nil, nil, nil, err
	}

	dbBob, err := channeldb.Open(bobPath)
	if err != nil {
		return nil, nil, nil, err
	}

	estimator := chainfee.NewStaticEstimator(12500, 0)
	feePerKw, err := estimator.EstimateFeePerKW(1)
	if err != nil {
		return nil, nil, nil, err
	}

	// TODO(roasbeef): need to factor in commit fee?
	aliceCommit := channeldb.ChannelCommitment{
		CommitHeight:  0,
		LocalBalance:  lnwire.NewMSatFromSatoshis(channelBal),
		RemoteBalance: lnwire.NewMSatFromSatoshis(channelBal),
		FeePerKw:      btcutil.Amount(feePerKw),
		CommitFee:     feePerKw.FeeForWeight(input.CommitWeight),
		CommitTx:      aliceCommitTx,
		CommitSig:     bytes.Repeat([]byte{1}, 71),
	}
	bobCommit := channeldb.ChannelCommitment{
		CommitHeight:  0,
		LocalBalance:  lnwire.NewMSatFromSatoshis(channelBal),
		RemoteBalance: lnwire.NewMSatFromSatoshis(channelBal),
		FeePerKw:      btcutil.Amount(feePerKw),
		CommitFee:     feePerKw.FeeForWeight(input.CommitWeight),
		CommitTx:      bobCommitTx,
		CommitSig:     bytes.Repeat([]byte{1}, 71),
	}

	var chanIDBytes [8]byte
	if _, err := io.ReadFull(crand.Reader, chanIDBytes[:]); err != nil {
		return nil, nil, nil, err
	}

	shortChanID := lnwire.NewShortChanIDFromInt(
		binary.BigEndian.Uint64(chanIDBytes[:]),
	)

	aliceChannelState := &channeldb.OpenChannel{
		LocalChanCfg:            aliceCfg,
		RemoteChanCfg:           bobCfg,
		IdentityPub:             aliceKeyPub,
		FundingOutpoint:         *prevOut,
		ShortChannelID:          shortChanID,
		ChanType:                channeldb.SingleFunderTweaklessBit,
		IsInitiator:             true,
		Capacity:                channelCapacity,
		RemoteCurrentRevocation: bobCommitPoint,
		RevocationProducer:      alicePreimageProducer,
		RevocationStore:         shachain.NewRevocationStore(),
		LocalCommitment:         aliceCommit,
		RemoteCommitment:        aliceCommit,
		Db:                      dbAlice,
		Packager:                channeldb.NewChannelPackager(shortChanID),
		FundingTxn:              testTx,
	}
	bobChannelState := &channeldb.OpenChannel{
		LocalChanCfg:            bobCfg,
		RemoteChanCfg:           aliceCfg,
		IdentityPub:             bobKeyPub,
		FundingOutpoint:         *prevOut,
		ChanType:                channeldb.SingleFunderTweaklessBit,
		IsInitiator:             false,
		Capacity:                channelCapacity,
		RemoteCurrentRevocation: aliceCommitPoint,
		RevocationProducer:      bobPreimageProducer,
		RevocationStore:         shachain.NewRevocationStore(),
		LocalCommitment:         bobCommit,
		RemoteCommitment:        bobCommit,
		Db:                      dbBob,
		Packager:                channeldb.NewChannelPackager(shortChanID),
	}

	// Set custom values on the channel states.
	updateChan(aliceChannelState, bobChannelState)

	aliceAddr := &net.TCPAddr{
		IP:   net.ParseIP("127.0.0.1"),
		Port: 18555,
	}

	if err := aliceChannelState.SyncPending(aliceAddr, 0); err != nil {
		return nil, nil, nil, err
	}

	bobAddr := &net.TCPAddr{
		IP:   net.ParseIP("127.0.0.1"),
		Port: 18556,
	}

	if err := bobChannelState.SyncPending(bobAddr, 0); err != nil {
		return nil, nil, nil, err
	}

	cleanUpFunc := func() {
		os.RemoveAll(bobPath)
		os.RemoveAll(alicePath)
	}

	aliceSigner := &mock.SingleSigner{Privkey: aliceKeyPriv}
	bobSigner := &mock.SingleSigner{Privkey: bobKeyPriv}

	alicePool := lnwallet.NewSigPool(1, aliceSigner)
	channelAlice, err := lnwallet.NewLightningChannel(
		aliceSigner, aliceChannelState, alicePool,
	)
	if err != nil {
		return nil, nil, nil, err
	}
	_ = alicePool.Start()

	bobPool := lnwallet.NewSigPool(1, bobSigner)
	channelBob, err := lnwallet.NewLightningChannel(
		bobSigner, bobChannelState, bobPool,
	)
	if err != nil {
		return nil, nil, nil, err
	}
	_ = bobPool.Start()

	chainIO := &mock.ChainIO{
		BestHeight: broadcastHeight,
	}
	wallet := &lnwallet.LightningWallet{
		WalletController: &mock.WalletController{
			RootKey:               aliceKeyPriv,
			PublishedTransactions: publTx,
		},
	}

	_, currentHeight, err := chainIO.GetBestBlock()
	if err != nil {
		return nil, nil, nil, err
	}

	htlcSwitch, err := htlcswitch.New(htlcswitch.Config{
		DB:             dbAlice,
		SwitchPackager: channeldb.NewSwitchPackager(),
		Notifier:       notifier,
		FwdEventTicker: ticker.New(
			htlcswitch.DefaultFwdEventInterval),
		LogEventTicker: ticker.New(
			htlcswitch.DefaultLogInterval),
		AckEventTicker: ticker.New(
			htlcswitch.DefaultAckInterval),
	}, uint32(currentHeight))
	if err != nil {
		return nil, nil, nil, err
	}
	if err = htlcSwitch.Start(); err != nil {
		return nil, nil, nil, err
	}

	nodeSignerAlice := netann.NewNodeSigner(aliceKeySigner)

	const chanActiveTimeout = time.Minute

	chanStatusMgr, err := netann.NewChanStatusManager(&netann.ChanStatusConfig{
		ChanStatusSampleInterval: 30 * time.Second,
		ChanEnableTimeout:        chanActiveTimeout,
		ChanDisableTimeout:       2 * time.Minute,
		DB:                       dbAlice,
		Graph:                    dbAlice.ChannelGraph(),
		MessageSigner:            nodeSignerAlice,
		OurPubKey:                aliceKeyPub,
		IsChannelActive:          htlcSwitch.HasActiveLink,
		ApplyChannelUpdate:       func(*lnwire.ChannelUpdate) error { return nil },
	})
	if err != nil {
		return nil, nil, nil, err
	}
	if err = chanStatusMgr.Start(); err != nil {
		return nil, nil, nil, err
	}

	errBuffer, err := queue.NewCircularBuffer(ErrorBufferSize)
	if err != nil {
		return nil, nil, nil, err
	}

	var pubKey [33]byte
	copy(pubKey[:], aliceKeyPub.SerializeCompressed())

	cfgAddr := &lnwire.NetAddress{
		IdentityKey: aliceKeyPub,
		Address:     aliceAddr,
		ChainNet:    wire.SimNet,
	}

	cfg := &Config{
		Addr:        cfgAddr,
		PubKeyBytes: pubKey,
		ErrorBuffer: errBuffer,
		ChainIO:     chainIO,
		Switch:      htlcSwitch,

		ChanActiveTimeout: chanActiveTimeout,
		InterceptSwitch:   htlcswitch.NewInterceptableSwitch(htlcSwitch),

		ChannelDB:      dbAlice,
		FeeEstimator:   estimator,
		Wallet:         wallet,
		ChainNotifier:  notifier,
		ChanStatusMgr:  chanStatusMgr,
		DisconnectPeer: func(b *btcec.PublicKey) error { return nil },
	}

	alicePeer := NewBrontide(*cfg)

	chanID := lnwire.NewChanIDFromOutPoint(channelAlice.ChannelPoint())
	alicePeer.activeChannels[chanID] = channelAlice

	alicePeer.wg.Add(1)
	go alicePeer.channelManager()

	return alicePeer, channelBob, cleanUpFunc, nil
}