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

	requestAmount := coinutil.Amount(5)
	bigInput := int64(3)
	smallInput := int64(2)
	request := TstNewOutputRequest(
		t, 1, "34eVkREKgvvGASZW7hkgE2uNc1yycntMK6", requestAmount, pool.Manager().ChainParams())
	seriesID, eligible := TstCreateCreditsOnNewSeries(t, pool, []int64{smallInput, bigInput})
	changeStart := TstNewChangeAddress(t, pool, seriesID, 0)
	w := newWithdrawal(0, []OutputRequest{request}, eligible, *changeStart)
	w.txOptions = func(tx *withdrawalTx) {
		tx.calculateFee = TstConstantFee(0)
		tx.calculateSize = func() int {
			// Trigger an output split right after the second input is added.
			if len(tx.inputs) == 2 {
				return txMaxSize + 1
			}
			return txMaxSize - 1
		}
	}

	if err := w.fulfillRequests(); err != nil {
		t.Fatal(err)
	}

	if len(w.transactions) != 2 {
		t.Fatalf("Wrong number of finalized transactions; got %d, want 2", len(w.transactions))
	}

	tx1 := w.transactions[0]
	if len(tx1.outputs) != 1 {
		t.Fatalf("Wrong number of outputs on tx1; got %d, want 1", len(tx1.outputs))
	}
	if tx1.outputs[0].amount != coinutil.Amount(bigInput) {
		t.Fatalf("Wrong amount for output in tx1; got %d, want %d", tx1.outputs[0].amount,
			bigInput)
	}

	tx2 := w.transactions[1]
	if len(tx2.outputs) != 1 {
		t.Fatalf("Wrong number of outputs on tx2; got %d, want 1", len(tx2.outputs))
	}
	if tx2.outputs[0].amount != coinutil.Amount(smallInput) {
		t.Fatalf("Wrong amount for output in tx2; got %d, want %d", tx2.outputs[0].amount,
			smallInput)
	}

	if len(w.status.outputs) != 1 {
		t.Fatalf("Wrong number of output statuses; got %d, want 1", len(w.status.outputs))
	}
	status := w.status.outputs[request.outBailmentID()].status
	if status != statusSplit {
		t.Fatalf("Wrong output status; got '%s', want '%s'", status, statusSplit)
	}
}

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

	tx := createWithdrawalTx(t, pool, []int64{5}, []int64{})

	if tx.inputTotal() != coinutil.Amount(5) {
		t.Fatalf("Wrong total output; got %v, want %v", tx.outputTotal(), coinutil.Amount(5))
	}
}

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

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

// TestRollbackLastOutputWhenNewOutputAdded checks that we roll back the last
// output if a tx becomes too big right after we add a new output to it.
func TestRollbackLastOutputWhenNewOutputAdded(t *testing.T) {
	tearDown, pool, _ := TstCreatePoolAndTxStore(t)
	defer tearDown()

	net := pool.Manager().ChainParams()
	series, eligible := TstCreateCreditsOnNewSeries(t, pool, []int64{5, 5})
	requests := []OutputRequest{
		// This is ordered by bailment ID
		TstNewOutputRequest(t, 1, "34eVkREKgvvGASZW7hkgE2uNc1yycntMK6", 1, net),
		TstNewOutputRequest(t, 2, "3PbExiaztsSYgh6zeMswC49hLUwhTQ86XG", 2, net),
	}
	changeStart := TstNewChangeAddress(t, pool, series, 0)

	w := newWithdrawal(0, requests, eligible, *changeStart)
	w.txOptions = func(tx *withdrawalTx) {
		tx.calculateFee = TstConstantFee(0)
		tx.calculateSize = func() int {
			// Trigger an output split right after the second output is added.
			if len(tx.outputs) > 1 {
				return txMaxSize + 1
			}
			return txMaxSize - 1
		}
	}

	if err := w.fulfillRequests(); err != nil {
		t.Fatal("Unexpected error:", err)
	}

	// At this point we should have two finalized transactions.
	if len(w.transactions) != 2 {
		t.Fatalf("Wrong number of finalized transactions; got %d, want 2", len(w.transactions))
	}

	// First tx should have one output with 1 and one change output with 4
	// satoshis.
	firstTx := w.transactions[0]
	req1 := requests[0]
	checkTxOutputs(t, firstTx,
		[]*withdrawalTxOut{&withdrawalTxOut{request: req1, amount: req1.Amount}})
	checkTxChangeAmount(t, firstTx, coinutil.Amount(4))

	// Second tx should have one output with 2 and one changeoutput with 3 satoshis.
	secondTx := w.transactions[1]
	req2 := requests[1]
	checkTxOutputs(t, secondTx,
		[]*withdrawalTxOut{&withdrawalTxOut{request: req2, amount: req2.Amount}})
	checkTxChangeAmount(t, secondTx, coinutil.Amount(3))
}

func TestCreateTx(t *testing.T) {
	bs := &waddrmgr.BlockStamp{Height: 11111}
	mgr := newManager(t, txInfo.privKeys, bs)
	account := uint32(0)
	changeAddr, _ := coinutil.DecodeAddress("muqW4gcixv58tVbSKRC5q6CRKy8RmyLgZ5", &chaincfg.TestNet3Params)
	var tstChangeAddress = func(account uint32) (coinutil.Address, error) {
		return changeAddr, nil
	}

	// Pick all utxos from txInfo as eligible input.
	eligible := mockCredits(t, txInfo.hex, []uint32{1, 2, 3, 4, 5})
	// Now create a new TX sending 25e6 satoshis to the following addresses:
	outputs := map[string]coinutil.Amount{outAddr1: 15e6, outAddr2: 10e6}
	tx, err := createTx(eligible, outputs, bs, defaultFeeIncrement, mgr, account, tstChangeAddress, &chaincfg.TestNet3Params, false)
	if err != nil {
		t.Fatal(err)
	}

	if tx.ChangeAddr.String() != changeAddr.String() {
		t.Fatalf("Unexpected change address; got %v, want %v",
			tx.ChangeAddr.String(), changeAddr.String())
	}

	msgTx := tx.MsgTx
	if len(msgTx.TxOut) != 3 {
		t.Fatalf("Unexpected number of outputs; got %d, want 3", len(msgTx.TxOut))
	}

	// The outputs in our new TX amount to 25e6 satoshis, so to fulfil that
	// createTx should have picked the utxos with indices 4, 3 and 5, which
	// total 25.1e6.
	if len(msgTx.TxIn) != 3 {
		t.Fatalf("Unexpected number of inputs; got %d, want 3", len(msgTx.TxIn))
	}

	// Given the input (15e6 + 10e6 + 1e7) and requested output (15e6 + 10e6)
	// amounts in the new TX, we should have a change output with 8.99e6, which
	// implies a fee of 1e3 satoshis.
	expectedChange := coinutil.Amount(8.999e6)

	outputs[changeAddr.String()] = expectedChange
	checkOutputsMatch(t, msgTx, outputs)

	minFee := feeForSize(defaultFeeIncrement, msgTx.SerializeSize())
	actualFee := coinutil.Amount(1e3)
	if minFee > actualFee {
		t.Fatalf("Requested fee (%v) for tx size higher than actual fee (%v)", minFee, actualFee)
	}
}

func ExampleAmount() {

	a := coinutil.Amount(0)
	fmt.Println("Zero Satoshi:", a)

	a = coinutil.Amount(1e8)
	fmt.Println("100,000,000 Satoshis:", a)

	a = coinutil.Amount(1e5)
	fmt.Println("100,000 Satoshis:", a)
	// Output:
	// Zero Satoshi: 0 BTC
	// 100,000,000 Satoshis: 1 BTC
	// 100,000 Satoshis: 0.001 BTC
}

// Check that some requested outputs are not fulfilled when we don't have credits for all
// of them.
func TestFulfillRequestsNotEnoughCreditsForAllRequests(t *testing.T) {
	tearDown, pool, _ := TstCreatePoolAndTxStore(t)
	defer tearDown()
	net := pool.Manager().ChainParams()

	// Create eligible inputs and the list of outputs we need to fulfil.
	seriesID, eligible := TstCreateCreditsOnNewSeries(t, pool, []int64{2e6, 4e6})
	out1 := TstNewOutputRequest(
		t, 1, "34eVkREKgvvGASZW7hkgE2uNc1yycntMK6", coinutil.Amount(3e6), net)
	out2 := TstNewOutputRequest(
		t, 2, "3PbExiaztsSYgh6zeMswC49hLUwhTQ86XG", coinutil.Amount(2e6), net)
	out3 := TstNewOutputRequest(
		t, 3, "3Qt1EaKRD9g9FeL2DGkLLswhK1AKmmXFSe", coinutil.Amount(5e6), net)
	outputs := []OutputRequest{out1, out2, out3}
	changeStart := TstNewChangeAddress(t, pool, seriesID, 0)

	w := newWithdrawal(0, outputs, eligible, *changeStart)
	if err := w.fulfillRequests(); err != nil {
		t.Fatal(err)
	}

	tx := w.transactions[0]
	// The created tx should spend both eligible credits, so we expect it to have
	// an input amount of 2e6+4e6 satoshis.
	inputAmount := eligible[0].Amount + eligible[1].Amount
	// We expect it to include outputs for requests 1 and 2, plus a change output, but
	// output request #3 should not be there because we don't have enough credits.
	change := inputAmount - (out1.Amount + out2.Amount + tx.calculateFee())
	expectedOutputs := []OutputRequest{out1, out2}
	sort.Sort(byOutBailmentID(expectedOutputs))
	expectedOutputs = append(
		expectedOutputs, TstNewOutputRequest(t, 4, changeStart.addr.String(), change, net))
	msgtx := tx.toMsgTx()
	checkMsgTxOutputs(t, msgtx, expectedOutputs)

	// withdrawal.status should state that outputs 1 and 2 were successfully fulfilled,
	// and that output 3 was not.
	expectedStatuses := map[OutBailmentID]outputStatus{
		out1.outBailmentID(): statusSuccess,
		out2.outBailmentID(): statusSuccess,
		out3.outBailmentID(): statusPartial}
	for _, wOutput := range w.status.outputs {
		if wOutput.status != expectedStatuses[wOutput.request.outBailmentID()] {
			t.Fatalf("Unexpected status for %v; got '%s', want '%s'", wOutput.request,
				wOutput.status, expectedStatuses[wOutput.request.outBailmentID()])
		}
	}
}

func compareMsgTxAndWithdrawalTxOutputs(t *testing.T, msgtx *wire.MsgTx, tx *withdrawalTx) {
	nOutputs := len(tx.outputs)

	if tx.changeOutput != nil {
		nOutputs++
	}

	if len(msgtx.TxOut) != nOutputs {
		t.Fatalf("Unexpected number of TxOuts; got %d, want %d", len(msgtx.TxOut), nOutputs)
	}

	for i, output := range tx.outputs {
		outputRequest := output.request
		txOut := msgtx.TxOut[i]
		if !bytes.Equal(txOut.PkScript, outputRequest.PkScript) {
			t.Fatalf(
				"Unexpected pkScript for outputRequest %d; got %x, want %x",
				i, txOut.PkScript, outputRequest.PkScript)
		}
		gotAmount := coinutil.Amount(txOut.Value)
		if gotAmount != outputRequest.Amount {
			t.Fatalf(
				"Unexpected amount for outputRequest %d; got %v, want %v",
				i, gotAmount, outputRequest.Amount)
		}
	}

	// Finally check the change output if it exists
	if tx.changeOutput != nil {
		msgTxChange := msgtx.TxOut[len(msgtx.TxOut)-1]
		if msgTxChange != tx.changeOutput {
			t.Fatalf("wrong TxOut in msgtx; got %v, want %v", msgTxChange, tx.changeOutput)
		}
	}
}

// mockCredits decodes the given txHex and returns the outputs with
// the given indices as eligible inputs.
func mockCredits(t *testing.T, txHex string, indices []uint32) []wtxmgr.Credit {
	serialized, err := hex.DecodeString(txHex)
	if err != nil {
		t.Fatal(err)
	}
	utx, err := coinutil.NewTxFromBytes(serialized)
	if err != nil {
		t.Fatal(err)
	}
	tx := utx.MsgTx()

	isCB := blockchain.IsCoinBaseTx(tx)
	now := time.Now()

	eligible := make([]wtxmgr.Credit, len(indices))
	c := wtxmgr.Credit{
		OutPoint: wire.OutPoint{Hash: *utx.Sha()},
		BlockMeta: wtxmgr.BlockMeta{
			Block: wtxmgr.Block{Height: -1},
		},
	}
	for i, idx := range indices {
		c.OutPoint.Index = idx
		c.Amount = coinutil.Amount(tx.TxOut[idx].Value)
		c.PkScript = tx.TxOut[idx].PkScript
		c.Received = now
		c.FromCoinBase = isCB
		eligible[i] = c
	}
	return eligible
}

// TstCreateCreditsOnStore inserts a new credit in the given store for
// every item in the amounts slice.
func TstCreateCreditsOnStore(t *testing.T, s *wtxmgr.Store, pkScript []byte,
	amounts []int64) []wtxmgr.Credit {
	msgTx := createMsgTx(pkScript, amounts)
	meta := &wtxmgr.BlockMeta{
		Block: wtxmgr.Block{Height: TstInputsBlock},
	}

	rec, err := wtxmgr.NewTxRecordFromMsgTx(msgTx, time.Now())
	if err != nil {
		t.Fatal(err)
	}

	if err := s.InsertTx(rec, meta); err != nil {
		t.Fatal("Failed to create inputs: ", err)
	}

	credits := make([]wtxmgr.Credit, len(msgTx.TxOut))
	for i := range msgTx.TxOut {
		if err := s.AddCredit(rec, meta, uint32(i), false); err != nil {
			t.Fatal("Failed to create inputs: ", err)
		}
		credits[i] = wtxmgr.Credit{
			OutPoint: wire.OutPoint{
				Hash:  rec.Hash,
				Index: uint32(i),
			},
			BlockMeta: *meta,
			Amount:    coinutil.Amount(msgTx.TxOut[i].Value),
			PkScript:  msgTx.TxOut[i].PkScript,
		}
	}
	return credits
}

func createAndFulfillWithdrawalRequests(t *testing.T, pool *Pool, roundID uint32) withdrawalInfo {

	params := pool.Manager().ChainParams()
	seriesID, eligible := TstCreateCreditsOnNewSeries(t, pool, []int64{2e6, 4e6})
	requests := []OutputRequest{
		TstNewOutputRequest(t, 1, "34eVkREKgvvGASZW7hkgE2uNc1yycntMK6", 3e6, params),
		TstNewOutputRequest(t, 2, "3PbExiaztsSYgh6zeMswC49hLUwhTQ86XG", 2e6, params),
	}
	changeStart := TstNewChangeAddress(t, pool, seriesID, 0)
	dustThreshold := coinutil.Amount(1e4)
	startAddr := TstNewWithdrawalAddress(t, pool, seriesID, 1, 0)
	lastSeriesID := seriesID
	w := newWithdrawal(roundID, requests, eligible, *changeStart)
	if err := w.fulfillRequests(); err != nil {
		t.Fatal(err)
	}
	return withdrawalInfo{
		requests:      requests,
		startAddress:  *startAddr,
		changeStart:   *changeStart,
		lastSeriesID:  lastSeriesID,
		dustThreshold: dustThreshold,
		status:        *w.status,
	}
}

// Check that withdrawal.status correctly states that no outputs were fulfilled when we
// don't have enough eligible credits for any of them.
func TestFulfillRequestsNoSatisfiableOutputs(t *testing.T) {
	tearDown, pool, _ := TstCreatePoolAndTxStore(t)
	defer tearDown()

	seriesID, eligible := TstCreateCreditsOnNewSeries(t, pool, []int64{1e6})
	request := TstNewOutputRequest(
		t, 1, "3Qt1EaKRD9g9FeL2DGkLLswhK1AKmmXFSe", coinutil.Amount(3e6), pool.Manager().ChainParams())
	changeStart := TstNewChangeAddress(t, pool, seriesID, 0)

	w := newWithdrawal(0, []OutputRequest{request}, eligible, *changeStart)
	if err := w.fulfillRequests(); err != nil {
		t.Fatal(err)
	}

	if len(w.transactions) != 0 {
		t.Fatalf("Unexpected number of transactions; got %d, want 0", len(w.transactions))
	}

	if len(w.status.outputs) != 1 {
		t.Fatalf("Unexpected number of outputs in WithdrawalStatus; got %d, want 1",
			len(w.status.outputs))
	}

	status := w.status.outputs[request.outBailmentID()].status
	if status != statusPartial {
		t.Fatalf("Unexpected status for requested outputs; got '%s', want '%s'",
			status, statusPartial)
	}
}

// TstCreateSeriesCredits creates a new credit for every item in the amounts
// slice, locked to the given series' address with branch==1 and index==0.
func TstCreateSeriesCredits(t *testing.T, pool *Pool, seriesID uint32, amounts []int64) []credit {
	addr := TstNewWithdrawalAddress(t, pool, seriesID, Branch(1), Index(0))
	pkScript, err := txscript.PayToAddrScript(addr.addr)
	if err != nil {
		t.Fatal(err)
	}
	msgTx := createMsgTx(pkScript, amounts)
	txSha := msgTx.TxSha()
	credits := make([]credit, len(amounts))
	for i := range msgTx.TxOut {
		c := wtxmgr.Credit{
			OutPoint: wire.OutPoint{
				Hash:  txSha,
				Index: uint32(i),
			},
			BlockMeta: wtxmgr.BlockMeta{
				Block: wtxmgr.Block{Height: TstInputsBlock},
			},
			Amount:   coinutil.Amount(msgTx.TxOut[i].Value),
			PkScript: msgTx.TxOut[i].PkScript,
		}
		credits[i] = newCredit(c, *addr)
	}
	return credits
}

func fetchRawUnminedCreditAmount(v []byte) (coinutil.Amount, error) {
	if len(v) < 9 {
		str := "short unmined credit value"
		return 0, storeError(ErrData, str, nil)
	}
	return coinutil.Amount(byteOrder.Uint64(v)), nil
}

// TestOutputSplittingNotEnoughInputs checks that an output will get split if we
// don't have enough inputs to fulfil it.
func TestOutputSplittingNotEnoughInputs(t *testing.T) {
	tearDown, pool, _ := TstCreatePoolAndTxStore(t)
	defer tearDown()

	net := pool.Manager().ChainParams()
	output1Amount := coinutil.Amount(2)
	output2Amount := coinutil.Amount(3)
	requests := []OutputRequest{
		// These output requests will have the same server ID, so we know
		// they'll be fulfilled in the order they're defined here, which is
		// important for this test.
		TstNewOutputRequest(t, 1, "34eVkREKgvvGASZW7hkgE2uNc1yycntMK6", output1Amount, net),
		TstNewOutputRequest(t, 2, "34eVkREKgvvGASZW7hkgE2uNc1yycntMK6", output2Amount, net),
	}
	seriesID, eligible := TstCreateCreditsOnNewSeries(t, pool, []int64{7})
	w := newWithdrawal(0, requests, eligible, *TstNewChangeAddress(t, pool, seriesID, 0))
	w.txOptions = func(tx *withdrawalTx) {
		// Trigger an output split because of lack of inputs by forcing a high fee.
		// If we just started with not enough inputs for the requested outputs,
		// fulfillRequests() would drop outputs until we had enough.
		tx.calculateFee = TstConstantFee(3)
	}

	if err := w.fulfillRequests(); err != nil {
		t.Fatal(err)
	}

	if len(w.transactions) != 1 {
		t.Fatalf("Wrong number of finalized transactions; got %d, want 1", len(w.transactions))
	}

	tx := w.transactions[0]
	if len(tx.outputs) != 2 {
		t.Fatalf("Wrong number of outputs; got %d, want 2", len(tx.outputs))
	}

	// The first output should've been left untouched.
	if tx.outputs[0].amount != output1Amount {
		t.Fatalf("Wrong amount for first tx output; got %v, want %v",
			tx.outputs[0].amount, output1Amount)
	}

	// The last output should have had its amount updated to whatever we had
	// left after satisfying all previous outputs.
	newAmount := tx.inputTotal() - output1Amount - tx.calculateFee()
	checkLastOutputWasSplit(t, w, tx, output2Amount, newAmount)
}

func TestFindingSpentCredits(t *testing.T) {
	t.Parallel()

	s, teardown, err := testStore()
	defer teardown()
	if err != nil {
		t.Fatal(err)
	}

	// Insert transaction and credit which will be spent.
	recvRec, err := NewTxRecord(TstRecvSerializedTx, time.Now())
	if err != nil {
		t.Fatal(err)
	}

	err = s.InsertTx(recvRec, TstRecvTxBlockDetails)
	if err != nil {
		t.Fatal(err)
	}
	err = s.AddCredit(recvRec, TstRecvTxBlockDetails, 0, false)
	if err != nil {
		t.Fatal(err)
	}

	// Insert confirmed transaction which spends the above credit.
	spendingRec, err := NewTxRecord(TstSpendingSerializedTx, time.Now())
	if err != nil {
		t.Fatal(err)
	}

	err = s.InsertTx(spendingRec, TstSignedTxBlockDetails)
	if err != nil {
		t.Fatal(err)
	}
	err = s.AddCredit(spendingRec, TstSignedTxBlockDetails, 0, false)
	if err != nil {
		t.Fatal(err)
	}

	bal, err := s.Balance(1, TstSignedTxBlockDetails.Height)
	if err != nil {
		t.Fatal(err)
	}
	expectedBal := coinutil.Amount(TstSpendingTx.MsgTx().TxOut[0].Value)
	if bal != expectedBal {
		t.Fatalf("bad balance: %v != %v", bal, expectedBal)
	}
	unspents, err := s.UnspentOutputs()
	if err != nil {
		t.Fatal(err)
	}
	op := wire.NewOutPoint(TstSpendingTx.Sha(), 0)
	if unspents[0].OutPoint != *op {
		t.Fatal("unspent outpoint doesn't match expected")
	}
	if len(unspents) > 1 {
		t.Fatal("has more than one unspent credit")
	}
}

// fetchRawCreditAmountChange returns the amount of the credit and whether the
// credit is marked as change.
func fetchRawCreditAmountChange(v []byte) (coinutil.Amount, bool, error) {
	if len(v) < 9 {
		str := fmt.Sprintf("%s: short read (expected %d bytes, read %d)",
			bucketCredits, 9, len(v))
		return 0, false, storeError(ErrData, str, nil)
	}
	return coinutil.Amount(byteOrder.Uint64(v)), v[8]&(1<<1) != 0, nil
}

// maybeDropRequests will check the total amount we have in eligible inputs and drop
// requested outputs (in descending amount order) if we don't have enough to
// fulfill them all. For every dropped output request we update its entry in
// w.status.outputs with the status string set to statusPartial.
func (w *withdrawal) maybeDropRequests() {
	inputAmount := coinutil.Amount(0)
	for _, input := range w.eligibleInputs {
		inputAmount += input.Amount
	}
	outputAmount := coinutil.Amount(0)
	for _, request := range w.pendingRequests {
		outputAmount += request.Amount
	}
	sort.Sort(sort.Reverse(byAmount(w.pendingRequests)))
	for inputAmount < outputAmount {
		request := w.popRequest()
		log.Infof("Not fulfilling request to send %v to %v; not enough credits.",
			request.Amount, request.Address)
		outputAmount -= request.Amount
		w.status.outputs[request.outBailmentID()].status = statusPartial
	}
}

// newWithdrawalTx creates a new withdrawalTx and calls setOptions()
// passing the newly created tx.
func newWithdrawalTx(setOptions func(tx *withdrawalTx)) *withdrawalTx {
	tx := &withdrawalTx{}
	tx.calculateSize = func() int { return calculateTxSize(tx) }
	tx.calculateFee = func() coinutil.Amount {
		return coinutil.Amount(1+tx.calculateSize()/1000) * feeIncrement
	}
	setOptions(tx)
	return tx
}