// addHTLC...
// NOTE: This MUST be called with stateMtx held.
func (lc *LightningChannel) addHTLC(ourCommitTx, theirCommitTx *wire.MsgTx,
	paymentDesc *PaymentDescriptor) error {

	// If the HTLC is going to us, then we're the sender, otherwise they
	// are.
	var senderKey, receiverKey *btcec.PublicKey
	var senderRevocation, receiverRevocation []byte
	if paymentDesc.PayToUs {
		receiverKey = lc.channelState.OurCommitKey.PubKey()
		receiverRevocation = paymentDesc.OurRevocation[:]
		senderKey = lc.channelState.TheirCommitKey
		senderRevocation = paymentDesc.TheirRevocation[:]
	} else {
		senderKey = lc.channelState.OurCommitKey.PubKey()
		senderRevocation = paymentDesc.OurRevocation[:]
		receiverKey = lc.channelState.TheirCommitKey
		receiverRevocation = paymentDesc.TheirRevocation[:]
	}

	// Generate the proper redeem scripts for the HTLC output for both the
	// sender and the receiver.
	timeout := paymentDesc.Timeout
	rHash := paymentDesc.RHash
	delay := lc.channelState.CsvDelay
	senderPKScript, err := senderHTLCScript(timeout, delay, senderKey,
		receiverKey, senderRevocation[:], rHash[:])
	if err != nil {
		return nil
	}
	receiverPKScript, err := receiverHTLCScript(timeout, delay, senderKey,
		receiverKey, receiverRevocation[:], rHash[:])
	if err != nil {
		return nil
	}

	// Now that we have the redeem scripts, create the P2SH public key
	// script for each.
	senderP2SH, err := scriptHashPkScript(senderPKScript)
	if err != nil {
		return nil
	}
	receiverP2SH, err := scriptHashPkScript(receiverPKScript)
	if err != nil {
		return nil
	}

	// Add the new HTLC outputs to the respective commitment transactions.
	amountPending := int64(paymentDesc.Value)
	if paymentDesc.PayToUs {
		ourCommitTx.AddTxOut(wire.NewTxOut(amountPending, receiverP2SH))
		theirCommitTx.AddTxOut(wire.NewTxOut(amountPending, senderP2SH))
	} else {
		ourCommitTx.AddTxOut(wire.NewTxOut(amountPending, senderP2SH))
		theirCommitTx.AddTxOut(wire.NewTxOut(amountPending, receiverP2SH))
	}

	return nil
}

// getFundingParams pulls the relevant transaction information from the json returned by blockchain.info
// To generate a new valid transaction all of the parameters of the TxOut we are
// spending from must be used.
func getFundingParams(rawtx *blockChainInfoTx, vout uint32) (*wire.TxOut, *wire.OutPoint) {
	blkChnTxOut := rawtx.Outputs[vout]

	hash, err := wire.NewShaHashFromStr(rawtx.Hash)
	if err != nil {
		log.Fatal(err)
	}

	// Then convert it to a btcutil amount
	amnt := btcutil.Amount(int64(blkChnTxOut.Value))

	if err != nil {
		log.Fatal(err)
	}

	outpoint := wire.NewOutPoint(hash, vout)

	subscript, err := hex.DecodeString(blkChnTxOut.ScriptHex)
	if err != nil {
		log.Fatal(err)
	}

	oldTxOut := wire.NewTxOut(int64(amnt), subscript)

	return oldTxOut, outpoint
}

func p2pkhOutputs(amounts ...btcutil.Amount) []*wire.TxOut {
	v := make([]*wire.TxOut, 0, len(amounts))
	for _, a := range amounts {
		outScript := make([]byte, txsizes.P2PKHOutputSize)
		v = append(v, wire.NewTxOut(int64(a), outScript))
	}
	return v
}

// createTxOut generates a TxOut that can be added to a transaction.
func createTxOut(outCoins uint64, addr btcutil.Address) *wire.TxOut {
	// Take the address and generate a PubKeyScript out of it
	script, err := txscript.PayToAddrScript(addr)
	if err != nil {
		log.Fatal(err)
	}
	txout := wire.NewTxOut(int64(outCoins), script)
	return txout
}

// NewUnsignedTransaction creates an unsigned transaction paying to one or more
// non-change outputs.  An appropriate transaction fee is included based on the
// transaction size.
//
// Transaction inputs are chosen from repeated calls to fetchInputs with
// increasing targets amounts.
//
// If any remaining output value can be returned to the wallet via a change
// output without violating mempool dust rules, a P2PKH change output is
// appended to the transaction outputs.  Since the change output may not be
// necessary, fetchChange is called zero or one times to generate this script.
// This function must return a P2PKH script or smaller, otherwise fee estimation
// will be incorrect.
//
// If successful, the transaction, total input value spent, and all previous
// output scripts are returned.  If the input source was unable to provide
// enough input value to pay for every output any any necessary fees, an
// InputSourceError is returned.
//
// BUGS: Fee estimation may be off when redeeming non-compressed P2PKH outputs.
func NewUnsignedTransaction(outputs []*wire.TxOut, relayFeePerKb btcutil.Amount,
	fetchInputs InputSource, fetchChange ChangeSource) (*AuthoredTx, error) {

	targetAmount := h.SumOutputValues(outputs)
	estimatedSize := txsizes.EstimateSerializeSize(1, outputs, true)
	targetFee := txrules.FeeForSerializeSize(relayFeePerKb, estimatedSize)

	for {
		inputAmount, inputs, scripts, err := fetchInputs(targetAmount + targetFee)
		if err != nil {
			return nil, err
		}
		if inputAmount < targetAmount+targetFee {
			return nil, insufficientFundsError{}
		}

		maxSignedSize := txsizes.EstimateSerializeSize(len(inputs), outputs, true)
		maxRequiredFee := txrules.FeeForSerializeSize(relayFeePerKb, maxSignedSize)
		remainingAmount := inputAmount - targetAmount
		if remainingAmount < maxRequiredFee {
			targetFee = maxRequiredFee
			continue
		}

		unsignedTransaction := &wire.MsgTx{
			Version:  wire.TxVersion,
			TxIn:     inputs,
			TxOut:    outputs,
			LockTime: 0,
		}
		changeIndex := -1
		changeAmount := inputAmount - targetAmount - maxRequiredFee
		if changeAmount != 0 && !txrules.IsDustAmount(changeAmount,
			txsizes.P2PKHPkScriptSize, relayFeePerKb) {
			changeScript, err := fetchChange()
			if err != nil {
				return nil, err
			}
			if len(changeScript) > txsizes.P2PKHPkScriptSize {
				return nil, errors.New("fee estimation requires change " +
					"scripts no larger than P2PKH output scripts")
			}
			change := wire.NewTxOut(int64(changeAmount), changeScript)
			l := len(outputs)
			unsignedTransaction.TxOut = append(outputs[:l:l], change)
			changeIndex = l
		}

		return &AuthoredTx{
			Tx:          unsignedTransaction,
			PrevScripts: scripts,
			TotalInput:  inputAmount,
			ChangeIndex: changeIndex,
		}, nil
	}
}

// createTxOut generates a TxOut that can be added to a transaction.
func createTxOut(inCoin int64, addr btcutil.Address) *wire.TxOut {
	// Pay the minimum network fee so that nodes will broadcast the tx.
	outCoin := inCoin - TX_FEE
	// Take the address and generate a PubKeyScript out of it
	script, err := txscript.PayToAddrScript(addr)
	if err != nil {
		log.Fatal(err)
	}
	txout := wire.NewTxOut(outCoin, script)
	return txout
}

func TestStoreTransactionsWithChangeOutput(t *testing.T) {
	tearDown, pool, store := TstCreatePoolAndTxStore(t)
	defer tearDown()

	wtx := createWithdrawalTxWithStoreCredits(t, store, pool, []int64{5e6}, []int64{1e6, 1e6})
	wtx.changeOutput = wire.NewTxOut(int64(3e6), []byte{})
	msgtx := wtx.toMsgTx()
	tx := &changeAwareTx{MsgTx: msgtx, changeIdx: int32(len(msgtx.TxOut) - 1)}

	if err := storeTransactions(store, []*changeAwareTx{tx}); err != nil {
		t.Fatal(err)
	}

	sha := msgtx.TxSha()
	txDetails, err := store.TxDetails(&sha)
	if err != nil {
		t.Fatal(err)
	}
	if txDetails == nil {
		t.Fatal("The new tx doesn't seem to have been stored")
	}

	storedTx := txDetails.TxRecord.MsgTx
	outputTotal := int64(0)
	for i, txOut := range storedTx.TxOut {
		if int32(i) != tx.changeIdx {
			outputTotal += txOut.Value
		}
	}
	if outputTotal != int64(2e6) {
		t.Fatalf("Unexpected output amount; got %v, want %v", outputTotal, int64(2e6))
	}

	inputTotal := btcutil.Amount(0)
	for _, debit := range txDetails.Debits {
		inputTotal += debit.Amount
	}
	if inputTotal != btcutil.Amount(5e6) {
		t.Fatalf("Unexpected input amount; got %v, want %v", inputTotal, btcutil.Amount(5e6))
	}

	credits, err := store.UnspentOutputs()
	if err != nil {
		t.Fatal(err)
	}
	if len(credits) != 1 {
		t.Fatalf("Unexpected number of credits in txstore; got %d, want 1", len(credits))
	}
	changeOutpoint := wire.OutPoint{Hash: sha, Index: uint32(tx.changeIdx)}
	if credits[0].OutPoint != changeOutpoint {
		t.Fatalf("Credit's outpoint (%v) doesn't match the one from change output (%v)",
			credits[0].OutPoint, changeOutpoint)
	}
}

// addChange adds a change output if there are any satoshis left after paying
// all the outputs and network fees. It returns true if a change output was
// added.
//
// This method must be called only once, and no extra inputs/outputs should be
// added after it's called. Also, callsites must make sure adding a change
// output won't cause the tx to exceed the size limit.
func (tx *withdrawalTx) addChange(pkScript []byte) bool {
	tx.fee = tx.calculateFee()
	change := tx.inputTotal() - tx.outputTotal() - tx.fee
	log.Debugf("addChange: input total %v, output total %v, fee %v", tx.inputTotal(),
		tx.outputTotal(), tx.fee)
	if change > 0 {
		tx.changeOutput = wire.NewTxOut(int64(change), pkScript)
		log.Debugf("Added change output with amount %v", change)
	}
	return tx.hasChange()
}

// createSpendTx generates a basic spending transaction given the passed
// signature and public key scripts.
func createSpendingTx(sigScript, pkScript []byte) *wire.MsgTx {
	coinbaseTx := wire.NewMsgTx()

	outPoint := wire.NewOutPoint(&wire.ShaHash{}, ^uint32(0))
	txIn := wire.NewTxIn(outPoint, []byte{OP_0, OP_0})
	txOut := wire.NewTxOut(0, pkScript)
	coinbaseTx.AddTxIn(txIn)
	coinbaseTx.AddTxOut(txOut)

	spendingTx := wire.NewMsgTx()
	coinbaseTxSha := coinbaseTx.TxSha()
	outPoint = wire.NewOutPoint(&coinbaseTxSha, 0)
	txIn = wire.NewTxIn(outPoint, sigScript)
	txOut = wire.NewTxOut(0, nil)

	spendingTx.AddTxIn(txIn)
	spendingTx.AddTxOut(txOut)

	return spendingTx
}

// createSpendTx generates a basic spending transaction given the passed
// signature and public key scripts.
func createSpendingTx(sigScript, pkScript []byte) *wire.MsgTx {
	coinbaseTx := wire.NewMsgTx(wire.TxVersion)

	outPoint := wire.NewOutPoint(&chainhash.Hash{}, ^uint32(0))
	txIn := wire.NewTxIn(outPoint, []byte{OP_0, OP_0})
	txOut := wire.NewTxOut(0, pkScript)
	coinbaseTx.AddTxIn(txIn)
	coinbaseTx.AddTxOut(txOut)

	spendingTx := wire.NewMsgTx(wire.TxVersion)
	coinbaseTxHash := coinbaseTx.TxHash()
	outPoint = wire.NewOutPoint(&coinbaseTxHash, 0)
	txIn = wire.NewTxIn(outPoint, sigScript)
	txOut = wire.NewTxOut(0, nil)

	spendingTx.AddTxIn(txIn)
	spendingTx.AddTxOut(txOut)

	return spendingTx
}

func TestWithdrawalTxOutputTotal(t *testing.T) {
	tearDown, pool, _ := TstCreatePoolAndTxStore(t)
	defer tearDown()

	tx := createWithdrawalTx(t, pool, []int64{}, []int64{4})
	tx.changeOutput = wire.NewTxOut(int64(1), []byte{})

	if tx.outputTotal() != btcutil.Amount(4) {
		t.Fatalf("Wrong total output; got %v, want %v", tx.outputTotal(), btcutil.Amount(4))
	}
}

func TestWithdrawalTxToMsgTxWithInputButNoOutputsWithChange(t *testing.T) {
	tearDown, pool, _ := TstCreatePoolAndTxStore(t)
	defer tearDown()

	tx := createWithdrawalTx(t, pool, []int64{1}, []int64{})
	tx.changeOutput = wire.NewTxOut(int64(1), []byte{})

	msgtx := tx.toMsgTx()

	compareMsgTxAndWithdrawalTxOutputs(t, msgtx, tx)
	compareMsgTxAndWithdrawalTxInputs(t, msgtx, tx)
}

// createCommitTx...
// TODO(roasbeef): fix inconsistency of 32 vs 20 byte revocation hashes everywhere...
func createCommitTx(fundingOutput *wire.TxIn, selfKey, theirKey *btcec.PublicKey,
	revokeHash []byte, csvTimeout uint32, amountToSelf,
	amountToThem btcutil.Amount) (*wire.MsgTx, error) {

	// First, we create the script for the delayed "pay-to-self" output.
	ourRedeemScript, err := commitScriptToSelf(csvTimeout, selfKey, theirKey,
		revokeHash)
	if err != nil {
		return nil, err
	}
	payToUsScriptHash, err := scriptHashPkScript(ourRedeemScript)
	if err != nil {
		return nil, err
	}

	// Next, we create the script paying to them. This is just a regular
	// P2PKH-like output, without any added CSV delay. However, we instead
	// use P2SH.
	theirRedeemScript, err := commitScriptUnencumbered(theirKey)
	if err != nil {
		return nil, err
	}
	payToThemScriptHash, err := scriptHashPkScript(theirRedeemScript)
	if err != nil {
		return nil, err
	}

	// Now that both output scripts have been created, we can finally create
	// the transaction itself.
	commitTx := wire.NewMsgTx()
	commitTx.AddTxIn(fundingOutput)
	// TODO(roasbeef): we default to blocks, make configurable as part of
	// channel reservation.
	commitTx.TxIn[0].Sequence = lockTimeToSequence(false, csvTimeout)
	commitTx.AddTxOut(wire.NewTxOut(int64(amountToSelf), payToUsScriptHash))
	commitTx.AddTxOut(wire.NewTxOut(int64(amountToThem), payToThemScriptHash))

	return commitTx, nil
}

// createCommitTx...
// TODO(roasbeef): fix inconsistency of 32 vs 20 byte revocation hashes everywhere...
func createCommitTx(fundingOutput *wire.TxIn, selfKey, theirKey *btcec.PublicKey,
	revokeHash []byte, csvTimeout uint32, amountToSelf,
	amountToThem btcutil.Amount) (*wire.MsgTx, error) {

	// First, we create the script for the delayed "pay-to-self" output.
	ourRedeemScript, err := commitScriptToSelf(csvTimeout, selfKey, theirKey,
		revokeHash)
	if err != nil {
		return nil, err
	}
	payToUsScriptHash, err := scriptHashPkScript(ourRedeemScript)
	if err != nil {
		return nil, err
	}

	// Next, we create the script paying to them. This is just a regular
	// P2PKH-like output, without any added CSV delay. However, we instead
	// use P2SH.
	theirRedeemScript, err := commitScriptUnencumbered(theirKey)
	if err != nil {
		return nil, err
	}
	payToThemScriptHash, err := scriptHashPkScript(theirRedeemScript)
	if err != nil {
		return nil, err
	}

	// Now that both output scripts have been created, we can finally create
	// the transaction itself. We use a transaction version of 2 since CSV
	// will fail unless the tx version is >= 2.
	commitTx := wire.NewMsgTx()
	commitTx.Version = 2
	commitTx.AddTxIn(fundingOutput)
	commitTx.AddTxOut(wire.NewTxOut(int64(amountToSelf), payToUsScriptHash))
	commitTx.AddTxOut(wire.NewTxOut(int64(amountToThem), payToThemScriptHash))

	return commitTx, nil
}

// addChange adds a new output with the given amount and address, and
// randomizes the index (and returns it) of the newly added output.
func addChange(msgtx *wire.MsgTx, change btcutil.Amount, changeAddr btcutil.Address) (int, error) {
	pkScript, err := txscript.PayToAddrScript(changeAddr)
	if err != nil {
		return 0, fmt.Errorf("cannot create txout script: %s", err)
	}
	msgtx.AddTxOut(wire.NewTxOut(int64(change), pkScript))

	// Randomize index of the change output.
	rng := badrand.New(badrand.NewSource(time.Now().UnixNano()))
	r := rng.Int31n(int32(len(msgtx.TxOut))) // random index
	c := len(msgtx.TxOut) - 1                // change index
	msgtx.TxOut[r], msgtx.TxOut[c] = msgtx.TxOut[c], msgtx.TxOut[r]
	return int(r), nil
}

// toMsgTx generates a btcwire.MsgTx with this tx's inputs and outputs.
func (tx *withdrawalTx) toMsgTx() *wire.MsgTx {
	msgtx := wire.NewMsgTx(wire.TxVersion)
	for _, o := range tx.outputs {
		msgtx.AddTxOut(wire.NewTxOut(int64(o.amount), o.pkScript()))
	}

	if tx.hasChange() {
		msgtx.AddTxOut(tx.changeOutput)
	}

	for _, i := range tx.inputs {
		msgtx.AddTxIn(wire.NewTxIn(&i.OutPoint, []byte{}))
	}
	return msgtx
}

// fundMultiSigOut create the redeemScript for the funding transaction, and
// also a TxOut paying to the p2sh of the multi-sig redeemScript. Give it the
// two pubkeys and it'll give you the p2sh'd txout. You don't have to remember
// the p2sh preimage, as long as you remember the pubkeys involved.
func fundMultiSigOut(aPub, bPub []byte, amt int64) ([]byte, *wire.TxOut, error) {
	if amt < 0 {
		return nil, nil, fmt.Errorf("can't create FundTx script with " +
			"negative coins")
	}

	// p2shify
	redeemScript, err := genFundingPkScript(aPub, bPub)
	if err != nil {
		return nil, nil, err
	}
	pkScript, err := scriptHashPkScript(redeemScript)
	if err != nil {
		return nil, nil, err
	}

	return redeemScript, wire.NewTxOut(amt, pkScript), nil
}

// createTxOut generates a TxOut that can be added to a transaction.
func createTxOut(inCoin int64, addr btcutil.Address) *wire.TxOut {
	// Pay the minimum network fee so that nodes will broadcast the tx.
	outCoin := *amount
	if outCoin == 0 {
		log.Fatal("You probably don't want to transfer 0 satoshis")
	}
	if outCoin > inCoin-TX_FEE {
		log.Fatal("Can't complete transaction--the request amount" +
			" is larger than available funds after transaction fee")
	}
	// Take the address and generate a PubKeyScript out of it
	script, err := txscript.PayToAddrScript(addr)
	if err != nil {
		log.Fatal(err)
	}
	txout := wire.NewTxOut(outCoin, script)
	return txout
}

// newBobNode generates a test "ln node" to interact with Alice (us). For the
// funding transaction, bob has a single output totaling 7BTC. For our basic
// test, he'll fund the channel with 5BTC, leaving 2BTC to the change output.
// TODO(roasbeef): proper handling of change etc.
func newBobNode() (*bobNode, error) {
	// First, parse Bob's priv key in order to obtain a key he'll use for the
	// multi-sig funding transaction.
	privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), bobsPrivKey)

	// Next, generate an output redeemable by bob.
	bobAddr, err := btcutil.NewAddressPubKey(privKey.PubKey().SerializeCompressed(),
		ActiveNetParams)
	if err != nil {
		return nil, err
	}
	bobAddrScript, err := txscript.PayToAddrScript(bobAddr.AddressPubKeyHash())
	if err != nil {
		return nil, err
	}
	prevOut := wire.NewOutPoint(&wire.ShaHash{}, ^uint32(0))
	// TODO(roasbeef): When the chain rpc is hooked in, assert bob's output
	// actually exists and it unspent in the chain.
	bobTxIn := wire.NewTxIn(prevOut, nil)

	// Using bobs priv key above, create a change address he can spend.
	bobChangeOutput := wire.NewTxOut(2*1e8, bobAddrScript)

	// Bob's initial revocation hash is just his private key with the first
	// byte changed...
	var revocation [20]byte
	copy(revocation[:], bobsPrivKey)
	revocation[0] = 0xff

	// His ID is just as creative...
	var id [wire.HashSize]byte
	id[0] = 0xff

	return &bobNode{
		id:               id,
		privKey:          privKey,
		channelKey:       pubKey,
		deliveryAddress:  bobAddr,
		revocation:       revocation,
		delay:            5,
		availableOutputs: []*wire.TxIn{bobTxIn},
		changeOutputs:    []*wire.TxOut{bobChangeOutput},
	}, nil
}

func createTxRemainder(inCoin int64) *wire.TxOut {
	remainder := inCoin - *amount - TX_FEE

	// Put the remainder back in our wallet
	pkBytes, err := hex.DecodeString(*privkey)
	if err != nil {
		log.Fatal(err)
	}
	// Get pubkey object
	_, pubkey := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)

	// Get an address object from WIF string
	changeAddress := generateAddr(pubkey)

	script, err := txscript.PayToAddrScript(changeAddress)
	if err != nil {
		log.Fatal(err)
	}
	remtx := wire.NewTxOut(remainder, script)
	return remtx
}