package paymentsdb

import (
	"crypto/rand"
	"crypto/sha256"
	"errors"
	"fmt"
	"io"
	"math"
	"reflect"
	"testing"
	"time"

	"github.com/btcsuite/btcd/btcec/v2"
	"github.com/btcsuite/btcd/chaincfg/chainhash"
	"github.com/davecgh/go-spew/spew"
	"github.com/lightningnetwork/lnd/lntypes"
	"github.com/lightningnetwork/lnd/lnwire"
	"github.com/lightningnetwork/lnd/record"
	"github.com/lightningnetwork/lnd/routing/route"
	"github.com/lightningnetwork/lnd/tlv"
	"github.com/stretchr/testify/require"
)

var (
	testHash = [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,
	}

	rev = [chainhash.HashSize]byte{
		0x51, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
		0x48, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
		0x2d, 0xe7, 0x93, 0xe4,
	}
)

var (
	priv, _ = btcec.NewPrivateKey()
	pub     = priv.PubKey()
	vertex  = route.NewVertex(pub)

	testHop1 = &route.Hop{
		PubKeyBytes:      vertex,
		ChannelID:        12345,
		OutgoingTimeLock: 111,
		AmtToForward:     555,
		CustomRecords: record.CustomSet{
			65536: []byte{},
			80001: []byte{},
		},
		MPP:      record.NewMPP(32, [32]byte{0x42}),
		Metadata: []byte{1, 2, 3},
	}

	testHop2 = &route.Hop{
		PubKeyBytes:      vertex,
		ChannelID:        12345,
		OutgoingTimeLock: 111,
		AmtToForward:     555,

		// Only tlv payloads are now supported in LND therefore we set
		// LegacyPayload to false.
		LegacyPayload: false,
	}

	testRoute = route.Route{
		TotalTimeLock: 123,
		TotalAmount:   1234567,
		SourcePubKey:  vertex,
		Hops: []*route.Hop{
			testHop2,
			testHop1,
		},
	}

	testBlindedRoute = route.Route{
		TotalTimeLock: 150,
		TotalAmount:   1000,
		SourcePubKey:  vertex,
		Hops: []*route.Hop{
			{
				PubKeyBytes:   vertex,
				EncryptedData: []byte{1, 3, 3},
				BlindingPoint: pub,
			},
			{
				PubKeyBytes:   vertex,
				EncryptedData: []byte{3, 2, 1},
			},
			{
				// Final hop must have AmtToForward,
				// OutgoingTimeLock, and TotalAmtMsat per
				// BOLT spec. We use the correct values here
				// although it is not tested in this test.
				PubKeyBytes:      vertex,
				EncryptedData:    []byte{2, 2, 2},
				AmtToForward:     1000,
				OutgoingTimeLock: 100,
				TotalAmtMsat:     1000,
			},
		},
	}
)

// htlcStatus is a helper structure used in tests to track the status of an HTLC
// attempt, including whether it was settled or failed.
type htlcStatus struct {
	*HTLCAttemptInfo
	settle     *lntypes.Preimage
	settleTime time.Time
	failure    *HTLCFailReason
	failTime   time.Time
}

// payment is a helper structure that holds basic information on a test payment,
// such as the payment id, the status and the total number of HTLCs attempted.
type payment struct {
	id     lntypes.Hash
	status PaymentStatus
	htlcs  int
}

// createTestPayments registers payments depending on the provided statuses in
// the payments slice. Each payment will receive one failed HTLC and another
// HTLC depending on the final status of the payment provided.
func createTestPayments(t *testing.T, p DB, payments []*payment) {
	t.Helper()

	ctx := t.Context()

	attemptID := uint64(0)

	for i := 0; i < len(payments); i++ {
		preimg := genPreimage(t)

		rhash := sha256.Sum256(preimg[:])
		info := genPaymentCreationInfo(t, rhash)

		// Set the payment id accordingly in the payments slice.
		payments[i].id = info.PaymentIdentifier

		attempt := genAttemptWithHash(
			t, attemptID, genSessionKey(t), rhash,
		)

		attemptID++

		// Init the payment.
		err := p.InitPayment(ctx, info.PaymentIdentifier, info)
		require.NoError(t, err, "unable to send htlc message")

		// Register and fail the first attempt for all payments.
		_, err = p.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
		require.NoError(t, err, "unable to send htlc message")

		htlcFailure := HTLCFailUnreadable
		_, err = p.FailAttempt(
			ctx, info.PaymentIdentifier, attempt.AttemptID,
			&HTLCFailInfo{
				Reason: htlcFailure,
			},
		)
		require.NoError(t, err, "unable to fail htlc")

		// Increase the HTLC counter in the payments slice for the
		// failed attempt.
		payments[i].htlcs++

		// Depending on the test case, fail or succeed the next
		// attempt.
		attempt = genAttemptWithHash(
			t, attemptID, genSessionKey(t), rhash,
		)
		attemptID++

		_, err = p.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
		require.NoError(t, err, "unable to send htlc message")

		switch payments[i].status {
		// Fail the attempt and the payment overall.
		case StatusFailed:
			htlcFailure := HTLCFailUnreadable
			_, err := p.FailAttempt(
				ctx, info.PaymentIdentifier, attempt.AttemptID,
				&HTLCFailInfo{
					Reason: htlcFailure,
				},
			)
			require.NoError(t, err, "unable to fail htlc")

			failReason := FailureReasonNoRoute
			_, err = p.Fail(
				ctx, info.PaymentIdentifier, failReason,
			)
			require.NoError(t, err, "unable to fail payment hash")

		// Settle the attempt
		case StatusSucceeded:
			_, err := p.SettleAttempt(
				ctx, info.PaymentIdentifier, attempt.AttemptID,
				&HTLCSettleInfo{
					Preimage: preimg,
				},
			)
			require.NoError(t, err, "no error should have been "+
				"received from settling a htlc attempt")

		// We leave the attempt in-flight by doing nothing.
		case StatusInFlight:
		}

		// Increase the HTLC counter in the payments slice for any
		// attempt above.
		payments[i].htlcs++
	}
}

// assertRouteEquals compares to routes for equality and returns an error if
// they are not equal.
func assertRouteEqual(t *testing.T, a, b *route.Route) error {
	t.Helper()

	if !reflect.DeepEqual(a, b) {
		return fmt.Errorf("HTLCAttemptInfos don't match: %v vs %v",
			spew.Sdump(a), spew.Sdump(b))
	}

	return nil
}

// assertPaymentInfo retrieves the payment referred to by hash and verifies the
// expected values.
func assertPaymentInfo(t *testing.T, p DB, hash lntypes.Hash,
	c *PaymentCreationInfo, f *FailureReason, a *htlcStatus) {

	t.Helper()

	payment, err := p.FetchPayment(t.Context(), hash)
	require.NoError(t, err)
	require.Equal(t, c, payment.Info, "PaymentCreationInfos don't match")

	if f != nil {
		require.NotNil(
			t, payment.FailureReason, "expected failure reason",
		)
		require.Equal(
			t, *f, *payment.FailureReason,
			"unexpected failure reason",
		)
	} else {
		require.Nil(
			t, payment.FailureReason, "expected no failure reason",
		)
	}

	if a == nil {
		require.Empty(t, payment.HTLCs, "expected no htlcs")
		return
	}

	require.GreaterOrEqual(t, len(payment.HTLCs), int(a.AttemptID)+1,
		"HTLC with attempt ID %v not found", a.AttemptID)
	htlc := payment.HTLCs[a.AttemptID]
	require.NoError(t, assertRouteEqual(t, &htlc.Route, &a.Route),
		"routes do not match")
	require.Equal(t, a.AttemptID, htlc.AttemptID, "unexpected attempt ID")

	if a.failure != nil {
		require.NotNil(t, htlc.Failure, "expected HTLC to be failed")
		require.Equal(t, *a.failure, htlc.Failure.Reason,
			"expected HTLC failure")
	} else {
		require.Nil(t, htlc.Failure, "expected no HTLC failure")
	}

	if a.settle != nil {
		require.Equal(
			t, *a.settle, htlc.Settle.Preimage,
			"expected HTLC settle preimage",
		)
	} else {
		require.Nil(t, htlc.Settle, "expected no settle info")
	}

	if !a.settleTime.IsZero() {
		// Normalize to UTC to ensure consistent timezone comparison.
		require.Equal(
			t, a.settleTime.UTC(), htlc.Settle.SettleTime.UTC(),
			"SettleTimes don't match",
		)
	}

	if !a.failTime.IsZero() {
		// Normalize to UTC to ensure consistent timezone comparison.
		require.Equal(
			t, htlc.Failure.FailTime.UTC(), a.failTime.UTC(),
			"FailTimes don't match",
		)
	}
}

// assertDBPaymentstatus retrieves the status of the payment referred to by hash
// and compares it with the expected state.
func assertDBPaymentstatus(t *testing.T, p DB, hash lntypes.Hash,
	expStatus PaymentStatus) {

	t.Helper()

	ctx := t.Context()

	payment, err := p.FetchPayment(ctx, hash)
	if errors.Is(err, ErrPaymentNotInitiated) {
		return
	}
	if err != nil {
		t.Fatal(err)
	}

	if payment.Status != expStatus {
		t.Fatalf("payment status mismatch: expected %v, got %v",
			expStatus, payment.Status)
	}
}

// assertDBPayments is a helper function that given a slice of payment and
// indices for the slice asserts that exactly the same payments in the
// slice for the provided indices exist when fetching payments from the
// database.
func assertDBPayments(t *testing.T, paymentDB DB, payments []*payment) {
	t.Helper()

	response, err := paymentDB.QueryPayments(
		t.Context(), Query{
			IndexOffset:       0,
			MaxPayments:       uint64(len(payments)),
			IncludeIncomplete: true,
		},
	)
	require.NoError(t, err, "could not fetch payments from db")

	dbPayments := response.Payments

	// Make sure that the number of fetched payments is the same
	// as expected.
	require.Len(
		t, dbPayments, len(payments), "unexpected number of payments",
	)

	// Convert fetched payments of type MPPayment to our helper structure.
	p := make([]*payment, len(dbPayments))
	for i, dbPayment := range dbPayments {
		p[i] = &payment{
			id:     dbPayment.Info.PaymentIdentifier,
			status: dbPayment.Status,
			htlcs:  len(dbPayment.HTLCs),
		}
	}

	// Check that each payment we want to assert exists in the database.
	require.Equal(t, payments, p)
}

// genPreimage generates a random preimage.
func genPreimage(t *testing.T) lntypes.Preimage {
	t.Helper()

	var preimage [32]byte
	_, err := io.ReadFull(rand.Reader, preimage[:])
	require.NoError(t, err, "unable to generate preimage")

	return preimage
}

// genSessionKey generates a new random private key for use as a session key.
func genSessionKey(t *testing.T) *btcec.PrivateKey {
	t.Helper()

	key, err := btcec.NewPrivateKey()
	require.NoError(t, err)

	return key
}

// genPaymentCreationInfo generates a payment creation info.
func genPaymentCreationInfo(t *testing.T,
	paymentHash lntypes.Hash) *PaymentCreationInfo {

	t.Helper()

	// Add constant first hop custom records for testing for testing
	// purposes.
	firstHopCustomRecords := lnwire.CustomRecords{
		lnwire.MinCustomRecordsTlvType + 1: []byte("test_record_1"),
		lnwire.MinCustomRecordsTlvType + 2: []byte("test_record_2"),
		lnwire.MinCustomRecordsTlvType + 3: []byte{
			0x01, 0x02, 0x03, 0x04, 0x05,
		},
	}

	return &PaymentCreationInfo{
		PaymentIdentifier:     paymentHash,
		Value:                 testRoute.ReceiverAmt(),
		CreationTime:          time.Unix(time.Now().Unix(), 0),
		PaymentRequest:        []byte("hola"),
		FirstHopCustomRecords: firstHopCustomRecords,
	}
}

// genPreimageAndHash generates a random preimage and its corresponding hash.
func genPreimageAndHash(t *testing.T) (lntypes.Preimage, lntypes.Hash) {
	t.Helper()

	preimage := genPreimage(t)

	rhash := sha256.Sum256(preimage[:])
	var hash lntypes.Hash
	copy(hash[:], rhash[:])

	return preimage, hash
}

// genAttemptWithPreimage generates an HTLC attempt and returns both the
// attempt and preimage.
func genAttemptWithHash(t *testing.T, attemptID uint64,
	sessionKey *btcec.PrivateKey, hash lntypes.Hash) *HTLCAttemptInfo {

	t.Helper()

	attempt, err := NewHtlcAttempt(
		attemptID, sessionKey, *testRoute.Copy(), time.Time{},
		&hash,
	)
	require.NoError(t, err, "unable to generate htlc attempt")

	return &attempt.HTLCAttemptInfo
}

// genInfo generates a payment creation info and the corresponding preimage.
func genInfo(t *testing.T) (*PaymentCreationInfo, lntypes.Preimage) {
	t.Helper()

	preimage, _ := genPreimageAndHash(t)

	rhash := sha256.Sum256(preimage[:])
	creationInfo := genPaymentCreationInfo(t, rhash)

	return creationInfo, preimage
}

// TestDeleteFailedAttempts checks that DeleteFailedAttempts properly removes
// failed HTLCs from finished payments.
func TestDeleteFailedAttempts(t *testing.T) {
	t.Parallel()

	paymentDB, _ := NewTestDB(t)

	// Register three payments:
	// All payments will have one failed HTLC attempt and one HTLC attempt
	// according to its final status.
	// 1. A payment with two failed attempts.
	// 2. A payment with one failed and one in-flight attempt.
	// 3. A payment with one failed and one settled attempt.

	// Initiate payments, which is a slice of payment that is used as
	// template to create the corresponding test payments in the database.
	//
	// Note: The payment id and number of htlc attempts of each payment will
	// be added to this slice when creating the payments below.
	// This allows the slice to be used directly for testing purposes.
	payments := []*payment{
		{status: StatusFailed},
		{status: StatusInFlight},
		{status: StatusSucceeded},
	}

	// Use helper function to register the test payments in the data and
	// populate the data to the payments slice.
	createTestPayments(t, paymentDB, payments)

	// Check that all payments are there as we added them.
	assertDBPayments(t, paymentDB, payments)

	// Calling DeleteFailedAttempts on a failed payment should delete all
	// HTLCs.
	require.NoError(t, paymentDB.DeleteFailedAttempts(
		t.Context(), payments[0].id,
	))

	// Expect all HTLCs to be deleted.
	payments[0].htlcs = 0
	assertDBPayments(t, paymentDB, payments)

	// Calling DeleteFailedAttempts on an in-flight payment should return
	// an error.
	err := paymentDB.DeleteFailedAttempts(
		t.Context(), payments[1].id,
	)
	require.Error(t, err)

	// Since DeleteFailedAttempts returned an error, we should expect the
	// payment to be unchanged.
	assertDBPayments(t, paymentDB, payments)

	// Cleaning up a successful payment should remove failed htlcs.
	require.NoError(t, paymentDB.DeleteFailedAttempts(
		t.Context(), payments[2].id,
	))

	// Expect all HTLCs except for the settled one to be deleted.
	payments[2].htlcs = 1
	assertDBPayments(t, paymentDB, payments)

	// Attempting to cleanup a non-existent payment returns an error.
	require.Error(
		t, paymentDB.DeleteFailedAttempts(
			t.Context(), lntypes.ZeroHash,
		),
	)
}

// TestMPPRecordValidation tests MPP record validation.
func TestMPPRecordValidation(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)

	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	attemptID := uint64(0)

	attempt := genAttemptWithHash(
		t, attemptID, genSessionKey(t), rhash,
	)

	// Init the payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err, "unable to send htlc message")

	// Create three unique attempts we'll use for the test, and
	// register them with the payment control. We set each
	// attempts's value to one third of the payment amount, and
	// populate the MPP options.
	shardAmt := info.Value / 3
	attempt.Route.FinalHop().AmtToForward = shardAmt
	attempt.Route.FinalHop().MPP = record.NewMPP(
		info.Value, [32]byte{1},
	)

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err, "unable to send htlc message")

	// Now try to register a non-MPP attempt, which should fail.
	attemptID++
	attempt2 := genAttemptWithHash(
		t, attemptID, genSessionKey(t), rhash,
	)

	attempt2.Route.FinalHop().MPP = nil

	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt2,
	)
	require.ErrorIs(t, err, ErrMPPayment)

	// Try to register attempt one with a different payment address.
	attempt2.Route.FinalHop().MPP = record.NewMPP(
		info.Value, [32]byte{2},
	)
	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt2,
	)
	require.ErrorIs(t, err, ErrMPPPaymentAddrMismatch)

	// Try registering one with a different total amount.
	attempt2.Route.FinalHop().MPP = record.NewMPP(
		info.Value/2, [32]byte{1},
	)
	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt2,
	)
	require.ErrorIs(t, err, ErrMPPTotalAmountMismatch)

	// Create and init a new payment. This time we'll check that we cannot
	// register an MPP attempt if we already registered a non-MPP one.
	preimg = genPreimage(t)

	rhash = sha256.Sum256(preimg[:])
	info = genPaymentCreationInfo(t, rhash)

	attemptID++
	attempt = genAttemptWithHash(
		t, attemptID, genSessionKey(t), rhash,
	)

	err = paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err, "unable to send htlc message")

	attempt.Route.FinalHop().MPP = nil
	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt,
	)
	require.NoError(t, err, "unable to send htlc message")

	// Attempt to register an MPP attempt, which should fail.
	attemptID++
	attempt2 = genAttemptWithHash(
		t, attemptID, genSessionKey(t), rhash,
	)

	attempt2.Route.FinalHop().MPP = record.NewMPP(
		info.Value, [32]byte{1},
	)

	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt2,
	)
	require.ErrorIs(t, err, ErrNonMPPayment)
}

// TestDeleteSinglePayment tests that DeletePayment correctly
// deletes information about a completed payment from the database.
func TestDeleteSinglePayment(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	// Register four payments:
	// All payments will have one failed HTLC attempt and one HTLC attempt
	// according to its final status.
	// 1. A payment with two failed attempts.
	// 2. Another payment with two failed attempts.
	// 3. A payment with one failed and one settled attempt.
	// 4. A payment with one failed and one in-flight attempt.

	// Initiate payments, which is a slice of payment that is used as
	// template to create the corresponding test payments in the database.
	//
	// Note: The payment id and number of htlc attempts of each payment will
	// be added to this slice when creating the payments below.
	// This allows the slice to be used directly for testing purposes.
	payments := []*payment{
		{status: StatusFailed},
		{status: StatusFailed},
		{status: StatusSucceeded},
		{status: StatusInFlight},
	}

	// Use helper function to register the test payments in the data and
	// populate the data to the payments slice.
	createTestPayments(t, paymentDB, payments)

	// Check that all payments are there as we added them.
	assertDBPayments(t, paymentDB, payments)

	// Delete HTLC attempts for first payment only.
	require.NoError(t, paymentDB.DeletePayment(
		ctx, payments[0].id, true,
	))

	// The first payment is the only altered one as its failed HTLC should
	// have been removed but is still present as payment.
	payments[0].htlcs = 0
	assertDBPayments(t, paymentDB, payments)

	// Delete the first payment completely.
	require.NoError(t, paymentDB.DeletePayment(
		ctx, payments[0].id, false,
	))

	// The first payment should have been deleted.
	assertDBPayments(t, paymentDB, payments[1:])

	// Now delete the second payment completely.
	require.NoError(t, paymentDB.DeletePayment(
		ctx, payments[1].id, false,
	))

	// The Second payment should have been deleted.
	assertDBPayments(t, paymentDB, payments[2:])

	// Delete failed HTLC attempts for the third payment.
	require.NoError(t, paymentDB.DeletePayment(
		ctx, payments[2].id, true,
	))

	// Only the successful HTLC attempt should be left for the third
	// payment.
	payments[2].htlcs = 1
	assertDBPayments(t, paymentDB, payments[2:])

	// Now delete the third payment completely.
	require.NoError(t, paymentDB.DeletePayment(
		ctx, payments[2].id, false,
	))

	// Only the last payment should be left.
	assertDBPayments(t, paymentDB, payments[3:])

	// Deleting HTLC attempts from InFlight payments should not work and an
	// error returned.
	require.Error(t, paymentDB.DeletePayment(
		ctx, payments[3].id, true,
	))

	// The payment is InFlight and therefore should not have been altered.
	assertDBPayments(t, paymentDB, payments[3:])

	// Finally deleting the InFlight payment should also not work and an
	// error returned.
	require.Error(t, paymentDB.DeletePayment(
		ctx, payments[3].id, false,
	))

	// The payment is InFlight and therefore should not have been altered.
	assertDBPayments(t, paymentDB, payments[3:])
}

// TestPaymentRegistrable checks the method `Registrable` behaves as expected
// for ALL possible payment statuses.
func TestPaymentRegistrable(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		status         PaymentStatus
		registryErr    error
		hasSettledHTLC bool
		paymentFailed  bool
	}{
		{
			status:      StatusInitiated,
			registryErr: nil,
		},
		{
			// Test inflight status with no settled HTLC and no
			// failed payment.
			status:      StatusInFlight,
			registryErr: nil,
		},
		{
			// Test inflight status with settled HTLC but no failed
			// payment.
			status:         StatusInFlight,
			registryErr:    ErrPaymentPendingSettled,
			hasSettledHTLC: true,
		},
		{
			// Test inflight status with no settled HTLC but failed
			// payment.
			status:        StatusInFlight,
			registryErr:   ErrPaymentPendingFailed,
			paymentFailed: true,
		},
		{
			// Test error state with settled HTLC and failed
			// payment.
			status:         0,
			registryErr:    ErrUnknownPaymentStatus,
			hasSettledHTLC: true,
			paymentFailed:  true,
		},
		{
			status:      StatusSucceeded,
			registryErr: ErrPaymentAlreadySucceeded,
		},
		{
			status:      StatusFailed,
			registryErr: ErrPaymentAlreadyFailed,
		},
		{
			status:      0,
			registryErr: ErrUnknownPaymentStatus,
		},
	}

	for i, tc := range testCases {
		i, tc := i, tc

		p := &MPPayment{
			Status: tc.status,
			State: &MPPaymentState{
				HasSettledHTLC: tc.hasSettledHTLC,
				PaymentFailed:  tc.paymentFailed,
			},
		}

		name := fmt.Sprintf("test_%d_%s", i, p.Status.String())
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			err := p.Registrable()
			require.ErrorIs(t, err, tc.registryErr,
				"registrable under state %v", tc.status)
		})
	}
}

// TestPaymentSetState checks that the method setState creates the
// MPPaymentState as expected.
func TestPaymentSetState(t *testing.T) {
	t.Parallel()

	// Create a test preimage and failure reason.
	preimage := lntypes.Preimage{1}
	failureReasonError := FailureReasonError

	testCases := []struct {
		name     string
		payment  *MPPayment
		totalAmt int

		expectedState *MPPaymentState
		errExpected   error
	}{
		{
			// Test that when the sentAmt exceeds totalAmount, the
			// error is returned.
			name: "amount exceeded error",
			// SentAmt returns 90, 10
			// TerminalInfo returns non-nil, nil
			// InFlightHTLCs returns 0
			payment: &MPPayment{
				HTLCs: []HTLCAttempt{
					makeSettledAttempt(100, 10, preimage),
				},
			},
			totalAmt:    1,
			errExpected: ErrSentExceedsTotal,
		},
		{
			// Test that when the htlc is failed, the fee is not
			// used.
			name: "fee excluded for failed htlc",
			payment: &MPPayment{
				// SentAmt returns 90, 10
				// TerminalInfo returns nil, nil
				// InFlightHTLCs returns 1
				HTLCs: []HTLCAttempt{
					makeActiveAttempt(100, 10),
					makeFailedAttempt(100, 10),
				},
			},
			totalAmt: 1000,
			expectedState: &MPPaymentState{
				NumAttemptsInFlight: 1,
				RemainingAmt:        1000 - 90,
				FeesPaid:            10,
				HasSettledHTLC:      false,
				PaymentFailed:       false,
			},
		},
		{
			// Test when the payment is settled, the state should
			// be marked as terminated.
			name: "payment settled",
			// SentAmt returns 90, 10
			// TerminalInfo returns non-nil, nil
			// InFlightHTLCs returns 0
			payment: &MPPayment{
				HTLCs: []HTLCAttempt{
					makeSettledAttempt(100, 10, preimage),
				},
			},
			totalAmt: 1000,
			expectedState: &MPPaymentState{
				NumAttemptsInFlight: 0,
				RemainingAmt:        1000 - 90,
				FeesPaid:            10,
				HasSettledHTLC:      true,
				PaymentFailed:       false,
			},
		},
		{
			// Test when the payment is failed, the state should be
			// marked as terminated.
			name: "payment failed",
			// SentAmt returns 0, 0
			// TerminalInfo returns nil, non-nil
			// InFlightHTLCs returns 0
			payment: &MPPayment{
				FailureReason: &failureReasonError,
			},
			totalAmt: 1000,
			expectedState: &MPPaymentState{
				NumAttemptsInFlight: 0,
				RemainingAmt:        1000,
				FeesPaid:            0,
				HasSettledHTLC:      false,
				PaymentFailed:       true,
			},
		},
	}

	for _, tc := range testCases {
		tc := tc

		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			// Attach the payment info.
			info := &PaymentCreationInfo{
				Value: lnwire.MilliSatoshi(tc.totalAmt),
			}
			tc.payment.Info = info

			// Call the method that updates the payment state.
			err := tc.payment.setState()
			require.ErrorIs(t, err, tc.errExpected)

			require.Equal(
				t, tc.expectedState, tc.payment.State,
				"state not updated as expected",
			)
		})
	}
}

// TestNeedWaitAttempts checks whether we need to wait for the results of the
// HTLC attempts against ALL possible payment statuses.
func TestNeedWaitAttempts(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		status           PaymentStatus
		remainingAmt     lnwire.MilliSatoshi
		hasSettledHTLC   bool
		hasFailureReason bool
		needWait         bool
		expectedErr      error
	}{
		{
			// For a newly created payment we don't need to wait
			// for results.
			status:       StatusInitiated,
			remainingAmt: 1000,
			needWait:     false,
			expectedErr:  nil,
		},
		{
			// With HTLCs inflight we don't need to wait when the
			// remainingAmt is not zero and we have no settled
			// HTLCs.
			status:       StatusInFlight,
			remainingAmt: 1000,
			needWait:     false,
			expectedErr:  nil,
		},
		{
			// With HTLCs inflight we need to wait when the
			// remainingAmt is not zero but we have settled HTLCs.
			status:         StatusInFlight,
			remainingAmt:   1000,
			hasSettledHTLC: true,
			needWait:       true,
			expectedErr:    nil,
		},
		{
			// With HTLCs inflight we need to wait when the
			// remainingAmt is not zero and the payment is failed.
			status:           StatusInFlight,
			remainingAmt:     1000,
			needWait:         true,
			hasFailureReason: true,
			expectedErr:      nil,
		},

		{
			// With the payment settled, but the remainingAmt is
			// not zero, we have an error state.
			status:       StatusSucceeded,
			remainingAmt: 1000,
			needWait:     false,
			expectedErr:  ErrPaymentInternal,
		},
		{
			// Payment is in terminal state, no need to wait.
			status:       StatusFailed,
			remainingAmt: 1000,
			needWait:     false,
			expectedErr:  nil,
		},
		{
			// A newly created payment with zero remainingAmt
			// indicates an error.
			status:       StatusInitiated,
			remainingAmt: 0,
			needWait:     false,
			expectedErr:  ErrPaymentInternal,
		},
		{
			// With zero remainingAmt we must wait for the results.
			status:       StatusInFlight,
			remainingAmt: 0,
			needWait:     true,
			expectedErr:  nil,
		},
		{
			// Payment is terminated, no need to wait for results.
			status:       StatusSucceeded,
			remainingAmt: 0,
			needWait:     false,
			expectedErr:  nil,
		},
		{
			// Payment is terminated, no need to wait for results.
			status:       StatusFailed,
			remainingAmt: 0,
			needWait:     false,
			expectedErr:  ErrPaymentInternal,
		},
		{
			// Payment is in an unknown status, return an error.
			status:       0,
			remainingAmt: 0,
			needWait:     false,
			expectedErr:  ErrUnknownPaymentStatus,
		},
		{
			// Payment is in an unknown status, return an error.
			status:       0,
			remainingAmt: 1000,
			needWait:     false,
			expectedErr:  ErrUnknownPaymentStatus,
		},
	}

	for _, tc := range testCases {
		tc := tc

		p := &MPPayment{
			Info: &PaymentCreationInfo{
				PaymentIdentifier: [32]byte{1, 2, 3},
			},
			Status: tc.status,
			State: &MPPaymentState{
				RemainingAmt:   tc.remainingAmt,
				HasSettledHTLC: tc.hasSettledHTLC,
				PaymentFailed:  tc.hasFailureReason,
			},
		}

		name := fmt.Sprintf("status=%s|remainingAmt=%v|"+
			"settledHTLC=%v|failureReason=%v", tc.status,
			tc.remainingAmt, tc.hasSettledHTLC, tc.hasFailureReason)

		t.Run(name, func(t *testing.T) {
			t.Parallel()

			result, err := p.NeedWaitAttempts()
			require.ErrorIs(t, err, tc.expectedErr)
			require.Equalf(t, tc.needWait, result, "status=%v, "+
				"remainingAmt=%v", tc.status, tc.remainingAmt)
		})
	}
}

// TestAllowMoreAttempts checks whether more attempts can be created against
// ALL possible payment statuses.
func TestAllowMoreAttempts(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		status         PaymentStatus
		remainingAmt   lnwire.MilliSatoshi
		hasSettledHTLC bool
		paymentFailed  bool
		allowMore      bool
		expectedErr    error
	}{
		{
			// A newly created payment with zero remainingAmt
			// indicates an error.
			status:       StatusInitiated,
			remainingAmt: 0,
			allowMore:    false,
			expectedErr:  ErrPaymentInternal,
		},
		{
			// With zero remainingAmt we don't allow more HTLC
			// attempts.
			status:       StatusInFlight,
			remainingAmt: 0,
			allowMore:    false,
			expectedErr:  nil,
		},
		{
			// With zero remainingAmt we don't allow more HTLC
			// attempts.
			status:       StatusSucceeded,
			remainingAmt: 0,
			allowMore:    false,
			expectedErr:  nil,
		},
		{
			// With zero remainingAmt we don't allow more HTLC
			// attempts.
			status:       StatusFailed,
			remainingAmt: 0,
			allowMore:    false,
			expectedErr:  nil,
		},
		{
			// With zero remainingAmt and settled HTLCs we don't
			// allow more HTLC attempts.
			status:         StatusInFlight,
			remainingAmt:   0,
			hasSettledHTLC: true,
			allowMore:      false,
			expectedErr:    nil,
		},
		{
			// With zero remainingAmt and failed payment we don't
			// allow more HTLC attempts.
			status:        StatusInFlight,
			remainingAmt:  0,
			paymentFailed: true,
			allowMore:     false,
			expectedErr:   nil,
		},
		{
			// With zero remainingAmt and both settled HTLCs and
			// failed payment, we don't allow more HTLC attempts.
			status:         StatusInFlight,
			remainingAmt:   0,
			hasSettledHTLC: true,
			paymentFailed:  true,
			allowMore:      false,
			expectedErr:    nil,
		},
		{
			// A newly created payment can have more attempts.
			status:       StatusInitiated,
			remainingAmt: 1000,
			allowMore:    true,
			expectedErr:  nil,
		},
		{
			// With HTLCs inflight we can have more attempts when
			// the remainingAmt is not zero and we have neither
			// failed payment or settled HTLCs.
			status:       StatusInFlight,
			remainingAmt: 1000,
			allowMore:    true,
			expectedErr:  nil,
		},
		{
			// With HTLCs inflight we cannot have more attempts
			// though the remainingAmt is not zero but we have
			// settled HTLCs.
			status:         StatusInFlight,
			remainingAmt:   1000,
			hasSettledHTLC: true,
			allowMore:      false,
			expectedErr:    nil,
		},
		{
			// With HTLCs inflight we cannot have more attempts
			// though the remainingAmt is not zero but we have
			// failed payment.
			status:        StatusInFlight,
			remainingAmt:  1000,
			paymentFailed: true,
			allowMore:     false,
			expectedErr:   nil,
		},
		{
			// With HTLCs inflight we cannot have more attempts
			// though the remainingAmt is not zero but we have
			// settled HTLCs and failed payment.
			status:         StatusInFlight,
			remainingAmt:   1000,
			hasSettledHTLC: true,
			paymentFailed:  true,
			allowMore:      false,
			expectedErr:    nil,
		},
		{
			// With the payment settled, but the remainingAmt is
			// not zero, we have an error state.
			status:         StatusSucceeded,
			remainingAmt:   1000,
			hasSettledHTLC: true,
			allowMore:      false,
			expectedErr:    ErrPaymentInternal,
		},
		{
			// With the payment failed with no inflight HTLCs, we
			// don't allow more attempts to be made.
			status:        StatusFailed,
			remainingAmt:  1000,
			paymentFailed: true,
			allowMore:     false,
			expectedErr:   nil,
		},
		{
			// With the payment in an unknown state, we don't allow
			// more attempts to be made.
			status:       0,
			remainingAmt: 1000,
			allowMore:    false,
			expectedErr:  nil,
		},
	}

	for i, tc := range testCases {
		tc := tc

		p := &MPPayment{
			Info: &PaymentCreationInfo{
				PaymentIdentifier: [32]byte{1, 2, 3},
			},
			Status: tc.status,
			State: &MPPaymentState{
				RemainingAmt:   tc.remainingAmt,
				HasSettledHTLC: tc.hasSettledHTLC,
				PaymentFailed:  tc.paymentFailed,
			},
		}

		name := fmt.Sprintf("test_%d|status=%s|remainingAmt=%v", i,
			tc.status, tc.remainingAmt)

		t.Run(name, func(t *testing.T) {
			t.Parallel()

			result, err := p.AllowMoreAttempts()
			require.ErrorIs(t, err, tc.expectedErr)
			require.Equalf(t, tc.allowMore, result, "status=%v, "+
				"remainingAmt=%v", tc.status, tc.remainingAmt)
		})
	}
}

func makeActiveAttempt(total, fee int) HTLCAttempt {
	return HTLCAttempt{
		HTLCAttemptInfo: makeAttemptInfo(total, total-fee),
	}
}

func makeSettledAttempt(total, fee int,
	preimage lntypes.Preimage) HTLCAttempt {

	return HTLCAttempt{
		HTLCAttemptInfo: makeAttemptInfo(total, total-fee),
		Settle:          &HTLCSettleInfo{Preimage: preimage},
	}
}

func makeFailedAttempt(total, fee int) HTLCAttempt {
	return HTLCAttempt{
		HTLCAttemptInfo: makeAttemptInfo(total, total-fee),
		Failure: &HTLCFailInfo{
			Reason: HTLCFailInternal,
		},
	}
}

func makeAttemptInfo(total, amtForwarded int) HTLCAttemptInfo {
	hop := &route.Hop{AmtToForward: lnwire.MilliSatoshi(amtForwarded)}
	return HTLCAttemptInfo{
		Route: route.Route{
			TotalAmount: lnwire.MilliSatoshi(total),
			Hops:        []*route.Hop{hop},
		},
	}
}

// lastHopArgs is a helper struct that holds the arguments for the last hop
// when creating an attempt with a route with a single hop (last hop).
type lastHopArgs struct {
	amt       lnwire.MilliSatoshi
	total     lnwire.MilliSatoshi
	mpp       *record.MPP
	encrypted []byte
}

// makeLastHopAttemptInfo creates an HTLCAttemptInfo with a route with a single
// hop (last hop).
func makeLastHopAttemptInfo(id uint64, args lastHopArgs) HTLCAttemptInfo {
	lastHop := &route.Hop{
		PubKeyBytes:   vertex,
		ChannelID:     1,
		AmtToForward:  args.amt,
		MPP:           args.mpp,
		EncryptedData: args.encrypted,
		TotalAmtMsat:  args.total,
	}

	return HTLCAttemptInfo{
		AttemptID: id,
		Route: route.Route{
			SourcePubKey: vertex,
			TotalAmount:  args.amt,
			Hops:         []*route.Hop{lastHop},
		},
	}
}

// makePayment creates an MPPayment with set of attempts.
func makePayment(total lnwire.MilliSatoshi,
	attempts ...HTLCAttempt) *MPPayment {

	return &MPPayment{
		Info: &PaymentCreationInfo{
			Value: total,
		},
		HTLCs: attempts,
	}
}

// TestVerifyAttemptNonMPPAmountMismatch tests that we return an error if the
// attempted amount doesn't match the payment amount.
func TestVerifyAttemptNonMPPAmountMismatch(t *testing.T) {
	t.Parallel()

	payment := makePayment(1000)
	attempt := makeLastHopAttemptInfo(1, lastHopArgs{amt: 900})

	require.ErrorIs(t, verifyAttempt(payment, &attempt), ErrValueMismatch)
}

// TestVerifyAttemptNonMPPSuccess tests that we don't return an error if the
// attempted amount matches the payment amount.
func TestVerifyAttemptNonMPPSuccess(t *testing.T) {
	t.Parallel()

	payment := makePayment(1200)
	attempt := makeLastHopAttemptInfo(1, lastHopArgs{amt: 1200})

	require.NoError(t, verifyAttempt(payment, &attempt))
}

// TestVerifyAttemptMPPTransitionErrors tests cases where we cannot transition
// from a non-MPP payment to an MPP payment or vice versa.
func TestVerifyAttemptMPPTransitionErrors(t *testing.T) {
	t.Parallel()

	total := lnwire.MilliSatoshi(2000)
	mpp := record.NewMPP(total, testHash)

	paymentWithMPP := makePayment(
		total,
		HTLCAttempt{
			HTLCAttemptInfo: makeLastHopAttemptInfo(
				1,
				lastHopArgs{amt: 1000, mpp: mpp},
			),
		},
	)
	nonMPP := makeLastHopAttemptInfo(2, lastHopArgs{amt: 1000})
	require.ErrorIs(t, verifyAttempt(paymentWithMPP, &nonMPP), ErrMPPayment)

	paymentWithNonMPP := makePayment(
		total,
		HTLCAttempt{
			HTLCAttemptInfo: makeLastHopAttemptInfo(
				1,
				lastHopArgs{amt: total},
			),
		},
	)
	mppAttempt := makeLastHopAttemptInfo(
		2, lastHopArgs{amt: 1000, mpp: mpp},
	)
	require.ErrorIs(
		t,
		verifyAttempt(paymentWithNonMPP, &mppAttempt),
		ErrNonMPPayment,
	)
}

// TestVerifyAttemptMPPOptionMismatch tests that we return an error if the
// MPP options don't match the payment options.
func TestVerifyAttemptMPPOptionMismatch(t *testing.T) {
	t.Parallel()

	total := lnwire.MilliSatoshi(3000)
	goodMPP := record.NewMPP(total, testHash)
	payment := makePayment(
		total,
		HTLCAttempt{
			HTLCAttemptInfo: makeLastHopAttemptInfo(
				1,
				lastHopArgs{amt: 1500, mpp: goodMPP},
			),
		},
	)

	badAddr := record.NewMPP(total, rev)
	attemptBadAddr := makeLastHopAttemptInfo(
		2,
		lastHopArgs{amt: 1500, mpp: badAddr},
	)
	require.ErrorIs(
		t,
		verifyAttempt(payment, &attemptBadAddr),
		ErrMPPPaymentAddrMismatch,
	)

	badTotal := record.NewMPP(total-1, testHash)
	attemptBadTotal := makeLastHopAttemptInfo(
		3,
		lastHopArgs{amt: 1500, mpp: badTotal},
	)
	require.ErrorIs(
		t,
		verifyAttempt(payment, &attemptBadTotal),
		ErrMPPTotalAmountMismatch,
	)

	matching := makeLastHopAttemptInfo(
		4,
		lastHopArgs{amt: 1500, mpp: record.NewMPP(total, testHash)},
	)
	require.NoError(t, verifyAttempt(payment, &matching))
}

// TestVerifyAttemptBlindedValidation tests that we return an error if we try
// to register an MPP attempt for a blinded payment.
func TestVerifyAttemptBlindedValidation(t *testing.T) {
	t.Parallel()

	total := lnwire.MilliSatoshi(5000)

	// Payment with a blinded attempt.
	existing := makeLastHopAttemptInfo(
		1,
		lastHopArgs{amt: 2500, total: total, encrypted: []byte{1}},
	)
	payment := makePayment(
		total,
		HTLCAttempt{HTLCAttemptInfo: existing},
	)

	// Attempt with a normal MPP record should fail because a payment
	// cannot have a mix of blinded and non-blinded attempts.
	goodMPP := makeLastHopAttemptInfo(
		2,
		lastHopArgs{amt: 2500, mpp: record.NewMPP(total, testHash)},
	)
	require.ErrorIs(
		t, verifyAttempt(payment, &goodMPP),
		ErrMixedBlindedAndNonBlindedPayments,
	)

	blindedMPP := makeLastHopAttemptInfo(
		2,
		lastHopArgs{
			amt:       2500,
			total:     total,
			mpp:       record.NewMPP(total, testHash),
			encrypted: []byte{2},
		},
	)
	require.ErrorIs(
		t,
		verifyAttempt(payment, &blindedMPP),
		ErrMPPRecordInBlindedPayment,
	)

	mismatchedTotal := makeLastHopAttemptInfo(
		3,
		lastHopArgs{amt: 2500, total: total + 1, encrypted: []byte{3}},
	)
	require.ErrorIs(
		t,
		verifyAttempt(payment, &mismatchedTotal),
		ErrBlindedPaymentTotalAmountMismatch,
	)

	matching := makeLastHopAttemptInfo(
		4,
		lastHopArgs{amt: 2500, total: total, encrypted: []byte{4}},
	)
	require.NoError(t, verifyAttempt(payment, &matching))
}

// TestVerifyAttemptBlindedMissingTotalAmount tests that we return an error if
// we try to register a blinded payment attempt where the final hop doesn't set
// the total amount.
func TestVerifyAttemptBlindedMissingTotalAmount(t *testing.T) {
	t.Parallel()

	total := lnwire.MilliSatoshi(5000)

	// Payment with no existing attempts.
	payment := makePayment(total)

	// Attempt with encrypted data (blinded payment) but missing total
	// amount.
	attemptMissingTotal := makeLastHopAttemptInfo(
		1,
		lastHopArgs{
			amt:       2500,
			total:     0,
			encrypted: []byte{1, 2, 3},
		},
	)
	require.ErrorIs(
		t,
		verifyAttempt(payment, &attemptMissingTotal),
		ErrBlindedPaymentMissingTotalAmount,
	)

	// Attempt with encrypted data and valid total amount should succeed.
	attemptWithTotal := makeLastHopAttemptInfo(
		2,
		lastHopArgs{
			amt:       2500,
			total:     total,
			encrypted: []byte{4, 5, 6},
		},
	)
	require.NoError(t, verifyAttempt(payment, &attemptWithTotal))
}

// TestVerifyAttemptBlindedMixedWithNonBlinded tests that we return an error if
// we try to register a non-MPP attempt for a blinded payment.
func TestVerifyAttemptBlindedMixedWithNonBlinded(t *testing.T) {
	t.Parallel()

	total := lnwire.MilliSatoshi(4000)

	// Payment with a blinded attempt.
	existing := makeLastHopAttemptInfo(
		1,
		lastHopArgs{amt: 2000, total: total, encrypted: []byte{1}},
	)
	payment := makePayment(
		total,
		HTLCAttempt{HTLCAttemptInfo: existing},
	)

	partial := makeLastHopAttemptInfo(2, lastHopArgs{amt: 2000})
	require.ErrorIs(
		t,
		verifyAttempt(payment, &partial),
		ErrMixedBlindedAndNonBlindedPayments,
	)

	full := makeLastHopAttemptInfo(3, lastHopArgs{amt: total})
	require.ErrorIs(
		t,
		verifyAttempt(payment, &full),
		ErrMixedBlindedAndNonBlindedPayments,
	)
}

// TestVerifyAttemptAmountExceedsTotal tests that we return an error if the
// attempted amount exceeds the payment amount.
func TestVerifyAttemptAmountExceedsTotal(t *testing.T) {
	t.Parallel()

	total := lnwire.MilliSatoshi(1000)
	mpp := record.NewMPP(total, testHash)
	existing := makeLastHopAttemptInfo(1, lastHopArgs{amt: 800, mpp: mpp})
	payment := makePayment(
		total,
		HTLCAttempt{HTLCAttemptInfo: existing},
	)

	attempt := makeLastHopAttemptInfo(2, lastHopArgs{amt: 300, mpp: mpp})
	require.ErrorIs(t, verifyAttempt(payment, &attempt), ErrValueExceedsAmt)
}

// TestEmptyRoutesGenerateSphinxPacket tests that the generateSphinxPacket
// function is able to gracefully handle being passed a nil set of hops for the
// route by the caller.
func TestEmptyRoutesGenerateSphinxPacket(t *testing.T) {
	t.Parallel()

	sessionKey, _ := btcec.NewPrivateKey()
	emptyRoute := &route.Route{}
	_, _, err := generateSphinxPacket(emptyRoute, testHash[:], sessionKey)
	require.ErrorIs(t, err, route.ErrNoRouteHopsProvided)
}

// TestSuccessesWithoutInFlight tests that the payment control will disallow
// calls to Success when no payment is in flight.
func TestSuccessesWithoutInFlight(t *testing.T) {
	t.Parallel()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)

	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Attempt to complete the payment should fail.
	_, err := paymentDB.SettleAttempt(
		t.Context(),
		info.PaymentIdentifier, 0,
		&HTLCSettleInfo{
			Preimage: preimg,
		},
	)
	require.ErrorIs(t, err, ErrPaymentNotInitiated)
}

// TestFailsWithoutInFlight checks that a strict payment control will disallow
// calls to Fail when no payment is in flight.
func TestFailsWithoutInFlight(t *testing.T) {
	t.Parallel()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)

	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Calling Fail should return an error.
	_, err := paymentDB.Fail(
		t.Context(), info.PaymentIdentifier, FailureReasonNoRoute,
	)
	require.ErrorIs(t, err, ErrPaymentNotInitiated)
}

// TestDeletePayments tests that DeletePayments correctly deletes information
// about completed payments from the database.
func TestDeletePayments(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	// Register three payments:
	// 1. A payment with two failed attempts.
	// 2. A payment with one failed and one settled attempt.
	// 3. A payment with one failed and one in-flight attempt.
	payments := []*payment{
		{status: StatusFailed},
		{status: StatusSucceeded},
		{status: StatusInFlight},
	}

	// Use helper function to register the test payments in the data and
	// populate the data to the payments slice.
	createTestPayments(t, paymentDB, payments)

	// Check that all payments are there as we added them.
	assertDBPayments(t, paymentDB, payments)

	// Delete HTLC attempts for failed payments only.
	numPayments, err := paymentDB.DeletePayments(ctx, true, true)
	require.NoError(t, err)
	require.EqualValues(t, 0, numPayments)

	// The failed payment is the only altered one.
	payments[0].htlcs = 0
	assertDBPayments(t, paymentDB, payments)

	// Delete failed attempts for all payments.
	numPayments, err = paymentDB.DeletePayments(ctx, false, true)
	require.NoError(t, err)
	require.EqualValues(t, 0, numPayments)

	// The failed attempts should be deleted, except for the in-flight
	// payment, that shouldn't be altered until it has completed.
	payments[1].htlcs = 1
	assertDBPayments(t, paymentDB, payments)

	// Now delete all failed payments.
	numPayments, err = paymentDB.DeletePayments(ctx, true, false)
	require.NoError(t, err)
	require.EqualValues(t, 1, numPayments)

	assertDBPayments(t, paymentDB, payments[1:])

	// Finally delete all completed payments.
	numPayments, err = paymentDB.DeletePayments(ctx, false, false)
	require.NoError(t, err)
	require.EqualValues(t, 1, numPayments)

	assertDBPayments(t, paymentDB, payments[2:])
}

// TestDeleteNonInFlight checks that calling DeletePayments only deletes
// payments from the database that are not in-flight.
func TestDeleteNonInFlight(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	var (
		numSuccess, numInflight int
		attemptID               uint64 = 0
	)

	// Create payments with different statuses: failed, success, inflight,
	// and another success.
	payments := []struct {
		failed  bool
		success bool
	}{
		// Payment 0: failed.
		{failed: true, success: false},
		// Payment 1: success.
		{failed: false, success: true},
		// Payment 2: inflight.
		{failed: false, success: false},
		// Payment 3: success.
		{failed: false, success: true},
	}

	for _, p := range payments {
		preimg := genPreimage(t)

		rhash := sha256.Sum256(preimg[:])
		info := genPaymentCreationInfo(t, rhash)
		attempt := genAttemptWithHash(
			t, attemptID, genSessionKey(t), rhash,
		)

		// After generating the attempt, increment the attempt ID to
		// have unique attempt IDs for each attempt otherwise the unique
		// constraint on the attempt ID will be violated.
		attemptID++

		// Init payment which initiates StatusInFlight.
		err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
		require.NoError(t, err, "unable to init payment")

		_, err = paymentDB.RegisterAttempt(
			ctx, info.PaymentIdentifier, attempt,
		)
		require.NoError(t, err, "unable to register attempt")

		switch {
		case p.failed:
			// Fail the payment attempt.
			htlcFailure := HTLCFailUnreadable
			_, err := paymentDB.FailAttempt(
				ctx, info.PaymentIdentifier, attempt.AttemptID,
				&HTLCFailInfo{
					Reason: htlcFailure,
				},
			)
			require.NoError(t, err, "unable to fail htlc")

			// Fail the payment, which should move it to Failed.
			failReason := FailureReasonNoRoute
			_, err = paymentDB.Fail(
				ctx, info.PaymentIdentifier, failReason,
			)
			require.NoError(t, err, "unable to fail payment")

			// Verify the status is indeed Failed.
			assertDBPaymentstatus(
				t, paymentDB, info.PaymentIdentifier,
				StatusFailed,
			)

		case p.success:
			// Settle the attempt.
			_, err := paymentDB.SettleAttempt(
				ctx, info.PaymentIdentifier, attempt.AttemptID,
				&HTLCSettleInfo{
					Preimage: preimg,
				},
			)
			require.NoError(t, err, "unable to settle attempt")

			assertDBPaymentstatus(
				t, paymentDB, info.PaymentIdentifier,
				StatusSucceeded,
			)

			numSuccess++

		default:
			// Leave as inflight.
			assertDBPaymentstatus(
				t, paymentDB, info.PaymentIdentifier,
				StatusInFlight,
			)

			numInflight++
		}
	}

	// Delete all failed payments.
	numPayments, err := paymentDB.DeletePayments(ctx, true, false)
	require.NoError(t, err)
	require.EqualValues(t, 1, numPayments)

	// This should leave the succeeded and in-flight payments.
	resp, err := paymentDB.QueryPayments(ctx, Query{
		IndexOffset:       0,
		MaxPayments:       math.MaxUint64,
		IncludeIncomplete: true,
	})
	require.NoError(t, err)

	require.Equal(t, numSuccess+numInflight, len(resp.Payments),
		"expected %d payments, got %d", numSuccess+numInflight,
		len(resp.Payments))

	var s, i int
	for _, p := range resp.Payments {
		switch p.Status {
		case StatusSucceeded:
			s++
		case StatusInFlight:
			i++
		}
	}

	require.Equal(t, numSuccess, s,
		"expected %d succeeded payments, got %d", numSuccess, s)
	require.Equal(t, numInflight, i,
		"expected %d in-flight payments, got %d", numInflight, i)

	// Now delete all payments except in-flight.
	numPayments, err = paymentDB.DeletePayments(ctx, false, false)
	require.NoError(t, err)
	require.EqualValues(t, 2, numPayments)

	// This should leave the in-flight payment.
	resp, err = paymentDB.QueryPayments(ctx, Query{
		IndexOffset:       0,
		MaxPayments:       math.MaxUint64,
		IncludeIncomplete: true,
	})
	require.NoError(t, err)

	require.Equal(t, numInflight, len(resp.Payments),
		"expected %d payments, got %d", numInflight, len(resp.Payments))

	for _, p := range resp.Payments {
		require.Equal(t, StatusInFlight, p.Status,
			"expected in-flight status, got %v", p.Status)
	}
}

// TestSwitchDoubleSend checks the ability of payment control to
// prevent double sending of htlc message, when message is in StatusInFlight.
func TestSwitchDoubleSend(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, harness := NewTestDB(t)

	preimg := genPreimage(t)

	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	// Sends base htlc message which initiate base status and move it to
	// StatusInFlight and verifies that it was changed.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err, "unable to send htlc message")

	harness.AssertPaymentIndex(t, info.PaymentIdentifier)
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusInitiated,
	)
	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, nil,
	)

	// Try to initiate double sending of htlc message with the same
	// payment hash, should result in error indicating that payment has
	// already been sent.
	err = paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.ErrorIs(t, err, ErrPaymentExists)

	// Record an attempt.
	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err, "unable to send htlc message")
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusInFlight,
	)

	htlc := &htlcStatus{
		HTLCAttemptInfo: attempt,
	}
	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, htlc,
	)

	// Sends base htlc message which initiate StatusInFlight.
	err = paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	if !errors.Is(err, ErrPaymentInFlight) {
		t.Fatalf("payment control wrong behaviour: " +
			"double sending must trigger ErrPaymentInFlight error")
	}

	// After settling, the error should be ErrAlreadyPaid.
	_, err = paymentDB.SettleAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID,
		&HTLCSettleInfo{
			Preimage: preimg,
		},
	)
	require.NoError(t, err, "error shouldn't have been received, got")
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusSucceeded,
	)

	htlc.settle = &preimg
	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, htlc,
	)

	err = paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	if !errors.Is(err, ErrAlreadyPaid) {
		t.Fatalf("unable to send htlc message: %v", err)
	}
}

// TestSwitchFail checks that payment status returns to Failed status after
// failing, and that InitPayment allows another HTLC for the same payment hash.
func TestSwitchFail(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, harness := NewTestDB(t)

	preimg := genPreimage(t)

	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	// Sends base htlc message which initiate StatusInFlight.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err, "unable to send htlc message")

	harness.AssertPaymentIndex(t, info.PaymentIdentifier)
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusInitiated,
	)
	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, nil,
	)

	// Fail the payment, which should moved it to Failed.
	failReason := FailureReasonNoRoute
	_, err = paymentDB.Fail(ctx, info.PaymentIdentifier, failReason)
	require.NoError(t, err, "unable to fail payment hash")

	// Verify the status is indeed Failed.
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusFailed,
	)

	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, &failReason, nil,
	)

	// Lookup the payment so we can get its old sequence number before it is
	// overwritten.
	payment, err := paymentDB.FetchPayment(ctx, info.PaymentIdentifier)
	require.NoError(t, err)

	// Sends the htlc again, which should succeed since the prior payment
	// failed.
	err = paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err, "unable to send htlc message")

	// Check that our index has been updated, and the old index has been
	// removed.
	harness.AssertPaymentIndex(t, info.PaymentIdentifier)
	harness.AssertNoIndex(t, payment.SequenceNum)

	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusInitiated,
	)
	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, nil,
	)

	// Record a new attempt. In this test scenario, the attempt fails.
	// However, this is not communicated to control tower in the current
	// implementation. It only registers the initiation of the attempt.
	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err, "unable to register attempt")

	htlcReason := HTLCFailUnreadable
	htlcFailTime := time.Unix(5000, 0)
	_, err = paymentDB.FailAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID,
		&HTLCFailInfo{
			Reason:   htlcReason,
			FailTime: htlcFailTime,
		},
	)
	if err != nil {
		t.Fatal(err)
	}
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusInFlight,
	)

	htlc := &htlcStatus{
		HTLCAttemptInfo: attempt,
		failure:         &htlcReason,
		failTime:        htlcFailTime,
	}

	assertPaymentInfo(t, paymentDB, info.PaymentIdentifier, info, nil, htlc)

	// Record another attempt.
	attempt = genAttemptWithHash(
		t, 1, genSessionKey(t), rhash,
	)
	require.NoError(t, err)

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err, "unable to send htlc message")
	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusInFlight,
	)

	htlc = &htlcStatus{
		HTLCAttemptInfo: attempt,
	}

	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, htlc,
	)

	// Settle the attempt and verify that status was changed to
	// StatusSucceeded.
	payment, err = paymentDB.SettleAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID,
		&HTLCSettleInfo{
			Preimage: preimg,
		},
	)
	require.NoError(t, err, "error shouldn't have been received, got")

	if len(payment.HTLCs) != 2 {
		t.Fatalf("payment should have two htlcs, got: %d",
			len(payment.HTLCs))
	}

	err = assertRouteEqual(t, &payment.HTLCs[0].Route, &attempt.Route)
	if err != nil {
		t.Fatalf("unexpected route returned: %v vs %v: %v",
			spew.Sdump(attempt.Route),
			spew.Sdump(payment.HTLCs[0].Route), err)
	}

	assertDBPaymentstatus(
		t, paymentDB, info.PaymentIdentifier, StatusSucceeded,
	)

	htlc.settle = &preimg
	assertPaymentInfo(
		t, paymentDB, info.PaymentIdentifier, info, nil, htlc,
	)

	// Attempt a final payment, which should now fail since the prior
	// payment succeed.
	err = paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	if !errors.Is(err, ErrAlreadyPaid) {
		t.Fatalf("unable to send htlc message: %v", err)
	}
}

// TestMultiShard checks the ability of payment control to have multiple in-
// flight HTLCs for a single payment.
func TestMultiShard(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	// We will register three HTLC attempts, and always fail the second
	// one. We'll generate all combinations of settling/failing the first
	// and third HTLC, and assert that the payment status end up as we
	// expect.
	type testCase struct {
		settleFirst bool
		settleLast  bool
	}

	var tests []testCase
	for _, f := range []bool{true, false} {
		for _, l := range []bool{true, false} {
			tests = append(tests, testCase{f, l})
		}
	}

	runSubTest := func(t *testing.T, test testCase) {
		paymentDB, harness := NewTestDB(t)

		preimg := genPreimage(t)

		rhash := sha256.Sum256(preimg[:])
		info := genPaymentCreationInfo(t, rhash)

		// Init the payment, moving it to the StatusInFlight state.
		err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
		require.NoError(t, err)

		harness.AssertPaymentIndex(t, info.PaymentIdentifier)
		assertDBPaymentstatus(
			t, paymentDB, info.PaymentIdentifier, StatusInitiated,
		)
		assertPaymentInfo(
			t, paymentDB, info.PaymentIdentifier, info, nil, nil,
		)

		// Create three unique attempts we'll use for the test, and
		// register them with the payment control. We set each
		// attempts's value to one third of the payment amount, and
		// populate the MPP options.
		shardAmt := info.Value / 3

		var attempts []*HTLCAttemptInfo
		for i := uint64(0); i < 3; i++ {
			a := genAttemptWithHash(
				t, i, genSessionKey(t), rhash,
			)

			a.Route.FinalHop().AmtToForward = shardAmt
			a.Route.FinalHop().MPP = record.NewMPP(
				info.Value, [32]byte{1},
			)

			attempts = append(attempts, a)

			_, err = paymentDB.RegisterAttempt(
				ctx, info.PaymentIdentifier, a,
			)
			if err != nil {
				t.Fatalf("unable to send htlc message: %v", err)
			}
			assertDBPaymentstatus(
				t, paymentDB, info.PaymentIdentifier,
				StatusInFlight,
			)

			htlc := &htlcStatus{
				HTLCAttemptInfo: a,
			}
			assertPaymentInfo(
				t, paymentDB, info.PaymentIdentifier, info, nil,
				htlc,
			)
		}

		// For a fourth attempt, check that attempting to
		// register it will fail since the total sent amount
		// will be too large.
		b := genAttemptWithHash(
			t, 3, genSessionKey(t), rhash,
		)

		b.Route.FinalHop().AmtToForward = shardAmt
		b.Route.FinalHop().MPP = record.NewMPP(
			info.Value, [32]byte{1},
		)

		_, err = paymentDB.RegisterAttempt(
			ctx, info.PaymentIdentifier, b,
		)
		require.ErrorIs(t, err, ErrValueExceedsAmt)

		// Fail the second attempt.
		a := attempts[1]
		htlcFail := HTLCFailUnreadable
		secondFailTime := time.Unix(6000, 0)
		_, err = paymentDB.FailAttempt(
			ctx, info.PaymentIdentifier, a.AttemptID,
			&HTLCFailInfo{
				Reason:   htlcFail,
				FailTime: secondFailTime,
			},
		)
		if err != nil {
			t.Fatal(err)
		}

		htlc := &htlcStatus{
			HTLCAttemptInfo: a,
			failure:         &htlcFail,
			failTime:        secondFailTime,
		}
		assertPaymentInfo(
			t, paymentDB, info.PaymentIdentifier, info, nil, htlc,
		)

		// Payment should still be in-flight.
		assertDBPaymentstatus(
			t, paymentDB, info.PaymentIdentifier, StatusInFlight,
		)

		// Depending on the test case, settle or fail the first attempt.
		a = attempts[0]
		htlc = &htlcStatus{
			HTLCAttemptInfo: a,
		}

		var firstFailReason *FailureReason
		if test.settleFirst {
			firstSettleTime := time.Unix(1000, 0)
			_, err := paymentDB.SettleAttempt(
				ctx, info.PaymentIdentifier, a.AttemptID,
				&HTLCSettleInfo{
					Preimage:   preimg,
					SettleTime: firstSettleTime,
				},
			)
			if err != nil {
				t.Fatalf("error shouldn't have been "+
					"received, got: %v", err)
			}

			// Assert that the HTLC has had the preimage and
			// settle time recorded.
			htlc.settle = &preimg
			htlc.settleTime = firstSettleTime
			assertPaymentInfo(
				t, paymentDB, info.PaymentIdentifier, info, nil,
				htlc,
			)
		} else {
			firstFailTime := time.Unix(2000, 0)
			_, err := paymentDB.FailAttempt(
				ctx, info.PaymentIdentifier, a.AttemptID,
				&HTLCFailInfo{
					Reason:   htlcFail,
					FailTime: firstFailTime,
				},
			)
			if err != nil {
				t.Fatalf("error shouldn't have been "+
					"received, got: %v", err)
			}

			// Assert the failure was recorded.
			htlc.failure = &htlcFail
			htlc.failTime = firstFailTime
			assertPaymentInfo(
				t, paymentDB, info.PaymentIdentifier, info, nil,
				htlc,
			)

			// We also record a payment level fail, to move it into
			// a terminal state.
			failReason := FailureReasonNoRoute
			_, err = paymentDB.Fail(
				ctx, info.PaymentIdentifier, failReason,
			)
			if err != nil {
				t.Fatalf("unable to fail payment hash: %v", err)
			}

			// Record the reason we failed the payment, such that
			// we can assert this later in the test.
			firstFailReason = &failReason

			// The payment is now considered pending fail, since
			// there is still an active HTLC.
			assertDBPaymentstatus(
				t, paymentDB, info.PaymentIdentifier,
				StatusInFlight,
			)
		}

		// Try to register yet another attempt. This should fail now
		// that the payment has reached a terminal condition.
		b = genAttemptWithHash(
			t, 3, genSessionKey(t), rhash,
		)

		b.Route.FinalHop().AmtToForward = shardAmt
		b.Route.FinalHop().MPP = record.NewMPP(
			info.Value, [32]byte{1},
		)

		_, err = paymentDB.RegisterAttempt(
			ctx, info.PaymentIdentifier, b,
		)
		if test.settleFirst {
			require.ErrorIs(
				t, err, ErrPaymentPendingSettled,
			)
		} else {
			require.ErrorIs(
				t, err, ErrPaymentPendingFailed,
			)
		}

		assertDBPaymentstatus(
			t, paymentDB, info.PaymentIdentifier, StatusInFlight,
		)

		// Settle or fail the remaining attempt based on the testcase.
		a = attempts[2]
		htlc = &htlcStatus{
			HTLCAttemptInfo: a,
		}
		if test.settleLast {
			// Settle the last outstanding attempt.
			lastSettleTime := time.Unix(3000, 0)
			_, err = paymentDB.SettleAttempt(
				ctx, info.PaymentIdentifier, a.AttemptID,
				&HTLCSettleInfo{
					Preimage:   preimg,
					SettleTime: lastSettleTime,
				},
			)
			require.NoError(t, err, "unable to settle")

			htlc.settle = &preimg
			htlc.settleTime = lastSettleTime
			assertPaymentInfo(
				t, paymentDB, info.PaymentIdentifier,
				info, firstFailReason, htlc,
			)
		} else {
			// Fail the attempt.
			lastFailTime := time.Unix(4000, 0)
			_, err := paymentDB.FailAttempt(
				ctx, info.PaymentIdentifier, a.AttemptID,
				&HTLCFailInfo{
					Reason:   htlcFail,
					FailTime: lastFailTime,
				},
			)
			if err != nil {
				t.Fatalf("error shouldn't have been "+
					"received, got: %v", err)
			}

			// Assert the failure was recorded.
			htlc.failure = &htlcFail
			htlc.failTime = lastFailTime
			assertPaymentInfo(
				t, paymentDB, info.PaymentIdentifier, info,
				firstFailReason, htlc,
			)

			// Check that we can override any perevious terminal
			// failure. This is to allow multiple concurrent shard
			// write a terminal failure to the database without
			// syncing.
			failReason := FailureReasonPaymentDetails
			_, err = paymentDB.Fail(
				ctx, info.PaymentIdentifier, failReason,
			)
			require.NoError(t, err, "unable to fail")
		}

		var (
			finalStatus PaymentStatus
			registerErr error
		)

		switch {
		// If one of the attempts settled but the other failed with
		// terminal error, we would still consider the payment is
		// settled.
		case test.settleFirst && !test.settleLast:
			finalStatus = StatusSucceeded
			registerErr = ErrPaymentAlreadySucceeded

		case !test.settleFirst && test.settleLast:
			finalStatus = StatusSucceeded
			registerErr = ErrPaymentAlreadySucceeded

		// If both failed, we end up in a failed status.
		case !test.settleFirst && !test.settleLast:
			finalStatus = StatusFailed
			registerErr = ErrPaymentAlreadyFailed

		// Otherwise, the payment has a succeed status.
		case test.settleFirst && test.settleLast:
			finalStatus = StatusSucceeded
			registerErr = ErrPaymentAlreadySucceeded
		}

		assertDBPaymentstatus(
			t, paymentDB, info.PaymentIdentifier, finalStatus,
		)

		// Finally assert we cannot register more attempts.
		_, err = paymentDB.RegisterAttempt(
			ctx, info.PaymentIdentifier, b,
		)
		require.ErrorIs(t, err, registerErr)
	}

	for _, test := range tests {
		subTest := fmt.Sprintf("first=%v, second=%v",
			test.settleFirst, test.settleLast)

		t.Run(subTest, func(t *testing.T) {
			runSubTest(t, test)
		})
	}
}

// TestQueryPayments tests retrieval of payments with forwards and reversed
// queries.
func TestQueryPayments(t *testing.T) {
	// Define table driven test for QueryPayments.
	// Test payments have sequence indices [1, 3, 4, 5, 6].
	// Note that payment with index 2 is deleted to create a gap in the
	// sequence numbers.
	tests := []struct {
		name       string
		query      Query
		firstIndex uint64
		lastIndex  uint64

		// expectedSeqNrs contains the set of sequence numbers we expect
		// our query to return.
		expectedSeqNrs []uint64
	}{
		{
			name: "IndexOffset at the end of the payments range",
			query: Query{
				IndexOffset:       6,
				MaxPayments:       7,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     0,
			lastIndex:      0,
			expectedSeqNrs: nil,
		},
		{
			name: "query in forwards order, start at beginning",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     1,
			lastIndex:      3,
			expectedSeqNrs: []uint64{1, 3},
		},
		{
			name: "query in forwards order, start at end, overflow",
			query: Query{
				IndexOffset:       5,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     6,
			lastIndex:      6,
			expectedSeqNrs: []uint64{6},
		},
		{
			name: "start at offset index outside of payments",
			query: Query{
				IndexOffset:       20,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     0,
			lastIndex:      0,
			expectedSeqNrs: nil,
		},
		{
			name: "overflow in forwards order",
			query: Query{
				IndexOffset:       4,
				MaxPayments:       math.MaxUint64,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     5,
			lastIndex:      6,
			expectedSeqNrs: []uint64{5, 6},
		},
		{
			name: "start at offset index outside of payments, " +
				"reversed order",
			query: Query{
				IndexOffset:       9,
				MaxPayments:       2,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     5,
			lastIndex:      6,
			expectedSeqNrs: []uint64{5, 6},
		},
		{
			name: "query in reverse order, start at end",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       2,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     5,
			lastIndex:      6,
			expectedSeqNrs: []uint64{5, 6},
		},
		{
			name: "query in reverse order, starting in middle",
			query: Query{
				IndexOffset:       4,
				MaxPayments:       2,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     1,
			lastIndex:      3,
			expectedSeqNrs: []uint64{1, 3},
		},
		{
			name: "query in reverse order, starting in middle, " +
				"with underflow",
			query: Query{
				IndexOffset:       4,
				MaxPayments:       5,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     1,
			lastIndex:      3,
			expectedSeqNrs: []uint64{1, 3},
		},
		{
			name: "all payments in reverse, order maintained",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       7,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     1,
			lastIndex:      6,
			expectedSeqNrs: []uint64{1, 3, 4, 5, 6},
		},
		{
			name: "exclude incomplete payments",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       7,
				Reversed:          false,
				IncludeIncomplete: false,
			},
			firstIndex:     6,
			lastIndex:      6,
			expectedSeqNrs: []uint64{6},
		},
		{
			name: "query payments at index gap",
			query: Query{
				IndexOffset:       1,
				MaxPayments:       7,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     3,
			lastIndex:      6,
			expectedSeqNrs: []uint64{3, 4, 5, 6},
		},
		{
			name: "query payments reverse before index gap",
			query: Query{
				IndexOffset:       3,
				MaxPayments:       7,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     1,
			lastIndex:      1,
			expectedSeqNrs: []uint64{1},
		},
		{
			name: "query payments reverse on index gap",
			query: Query{
				IndexOffset:       2,
				MaxPayments:       7,
				Reversed:          true,
				IncludeIncomplete: true,
			},
			firstIndex:     1,
			lastIndex:      1,
			expectedSeqNrs: []uint64{1},
		},
		{
			name: "query payments forward on index gap",
			query: Query{
				IndexOffset:       2,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
			},
			firstIndex:     3,
			lastIndex:      4,
			expectedSeqNrs: []uint64{3, 4},
		},
		{
			name: "query in forwards order, with start creation " +
				"time",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
				CreationDateStart: 5,
			},
			firstIndex:     5,
			lastIndex:      6,
			expectedSeqNrs: []uint64{5, 6},
		},
		{
			name: "query in forwards order, with start creation " +
				"time at end, overflow",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
				CreationDateStart: 6,
			},
			firstIndex:     6,
			lastIndex:      6,
			expectedSeqNrs: []uint64{6},
		},
		{
			name: "query with start and end creation time",
			query: Query{
				IndexOffset:       9,
				MaxPayments:       math.MaxUint64,
				Reversed:          true,
				IncludeIncomplete: true,
				CreationDateStart: 3,
				CreationDateEnd:   5,
			},
			firstIndex:     3,
			lastIndex:      5,
			expectedSeqNrs: []uint64{3, 4, 5},
		},
		{
			name: "query with only end creation time",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       math.MaxUint64,
				Reversed:          false,
				IncludeIncomplete: true,
				CreationDateEnd:   4,
			},
			firstIndex:     1,
			lastIndex:      4,
			expectedSeqNrs: []uint64{1, 3, 4},
		},
		{
			name: "query reversed with creation date start",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       3,
				Reversed:          true,
				IncludeIncomplete: true,
				CreationDateStart: 3,
			},
			firstIndex:     4,
			lastIndex:      6,
			expectedSeqNrs: []uint64{4, 5, 6},
		},
		{
			name: "count total with forward pagination",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       2,
				Reversed:          false,
				IncludeIncomplete: true,
				CountTotal:        true,
			},
			firstIndex:     1,
			lastIndex:      3,
			expectedSeqNrs: []uint64{1, 3},
		},
		{
			name: "count total with reverse pagination",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       2,
				Reversed:          true,
				IncludeIncomplete: true,
				CountTotal:        true,
			},
			firstIndex:     5,
			lastIndex:      6,
			expectedSeqNrs: []uint64{5, 6},
		},
		{
			name: "count total with filters",
			query: Query{
				IndexOffset:       0,
				MaxPayments:       math.MaxUint64,
				Reversed:          false,
				IncludeIncomplete: false,
				CountTotal:        true,
			},
			firstIndex:     6,
			lastIndex:      6,
			expectedSeqNrs: []uint64{6},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			ctx := t.Context()

			paymentDB, harness := NewTestDB(t)

			// Make a preliminary query to make sure it's ok to
			// query when we have no payments.
			resp, err := paymentDB.QueryPayments(ctx, tt.query)
			require.NoError(t, err)
			require.Len(t, resp.Payments, 0)

			// Populate the database with a set of test payments.
			// We create 6 payments, deleting the payment at index
			// 2 so that we cover the case where sequence numbers
			// are missing.
			numberOfPayments := 6

			// Store payment info for all payments so we can delete
			// one after all are created.
			var paymentInfos []*PaymentCreationInfo

			// First, create all payments.
			for i := range numberOfPayments {
				// Generate a test payment.
				info, _ := genInfo(t)

				// Override creation time to allow for testing
				// of CreationDateStart and CreationDateEnd.
				info.CreationTime = time.Unix(int64(i+1), 0)

				paymentInfos = append(paymentInfos, info)

				// Create a new payment entry in the database.
				err = paymentDB.InitPayment(
					ctx, info.PaymentIdentifier, info,
				)
				require.NoError(t, err)
			}

			// Now delete the payment at index 1 (the second
			// payment).
			pmt, err := paymentDB.FetchPayment(
				ctx, paymentInfos[1].PaymentIdentifier,
			)
			require.NoError(t, err)

			// We delete the whole payment.
			err = paymentDB.DeletePayment(
				ctx, paymentInfos[1].PaymentIdentifier, false,
			)
			require.NoError(t, err)

			// Verify the payment is deleted.
			_, err = paymentDB.FetchPayment(
				ctx, paymentInfos[1].PaymentIdentifier,
			)
			require.ErrorIs(
				t, err, ErrPaymentNotInitiated,
			)

			// Verify the index is removed (KV store only).
			harness.AssertNoIndex(
				t, pmt.SequenceNum,
			)

			// For the last payment, settle it so we have at least
			// one completed payment for the "exclude incomplete"
			// test case.
			lastPaymentInfo := paymentInfos[numberOfPayments-1]
			attempt, err := NewHtlcAttempt(
				1, priv, testRoute,
				time.Unix(100, 0),
				&lastPaymentInfo.PaymentIdentifier,
			)
			require.NoError(t, err)

			_, err = paymentDB.RegisterAttempt(
				ctx, lastPaymentInfo.PaymentIdentifier,
				&attempt.HTLCAttemptInfo,
			)
			require.NoError(t, err)

			var preimg lntypes.Preimage
			copy(preimg[:], rev[:])

			_, err = paymentDB.SettleAttempt(
				ctx, lastPaymentInfo.PaymentIdentifier,
				attempt.AttemptID,
				&HTLCSettleInfo{
					Preimage: preimg,
				},
			)
			require.NoError(t, err)

			// Fetch all payments in the database.
			resp, err = paymentDB.QueryPayments(
				ctx, Query{
					IndexOffset:       0,
					MaxPayments:       math.MaxUint64,
					IncludeIncomplete: true,
				},
			)
			require.NoError(t, err)

			allPayments := resp.Payments

			if len(allPayments) != 5 {
				t.Fatalf("Number of payments received does "+
					"not match expected one. Got %v, "+
					"want %v.", len(allPayments), 5)
			}

			querySlice, err := paymentDB.QueryPayments(
				ctx, tt.query,
			)
			require.NoError(t, err)

			if tt.firstIndex != querySlice.FirstIndexOffset ||
				tt.lastIndex != querySlice.LastIndexOffset {

				t.Errorf("First or last index does not match "+
					"expected index. Want (%d, %d), "+
					"got (%d, %d).",
					tt.firstIndex, tt.lastIndex,
					querySlice.FirstIndexOffset,
					querySlice.LastIndexOffset)
			}

			if len(querySlice.Payments) != len(tt.expectedSeqNrs) {
				t.Errorf("expected: %v payments, got: %v",
					len(tt.expectedSeqNrs),
					len(querySlice.Payments))
			}

			for i, seqNr := range tt.expectedSeqNrs {
				q := querySlice.Payments[i]
				if seqNr != q.SequenceNum {
					t.Errorf("sequence numbers do not "+
						"match, got %v, want %v",
						q.SequenceNum, seqNr)
				}
			}

			// Verify CountTotal is set correctly when requested.
			if tt.query.CountTotal {
				// We should have 5 total payments
				// (6 created - 1 deleted).
				expectedTotal := uint64(5)
				require.Equal(
					t, expectedTotal, querySlice.TotalCount,
					"expected total count %v, got %v",
					expectedTotal, querySlice.TotalCount)
			} else {
				require.Equal(
					t, uint64(0), querySlice.TotalCount,
					"expected total count 0 when "+
						"CountTotal=false")
			}
		})
	}
}

// TestFetchInFlightPayments tests that FetchInFlightPayments correctly returns
// only payments that are in-flight.
func TestFetchInFlightPayments(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	// Register payments with different statuses:
	// 1. A payment with two failed attempts (StatusFailed).
	// 2. A payment with one failed and one settled attempt
	//    (StatusSucceeded).
	// 3. A payment with one failed and one in-flight attempt
	//    (StatusInFlight).
	// 4. Another payment with one failed and one in-flight attempt
	//    (StatusInFlight).
	payments := []*payment{
		{status: StatusFailed},
		{status: StatusSucceeded},
		{status: StatusInFlight},
		{status: StatusInFlight},
	}

	// Use helper function to register the test payments in the database and
	// populate the data to the payments slice.
	createTestPayments(t, paymentDB, payments)

	// Check that all payments are there as we added them.
	assertDBPayments(t, paymentDB, payments)

	// Fetch in-flight payments.
	inFlightPayments, err := paymentDB.FetchInFlightPayments(ctx)
	require.NoError(t, err)

	// We should only get the two in-flight payments.
	require.Len(t, inFlightPayments, 2)

	// Verify that the returned payments are the in-flight ones.
	inFlightHashes := make(map[lntypes.Hash]struct{})
	for _, p := range inFlightPayments {
		require.Equal(t, StatusInFlight, p.Status)
		inFlightHashes[p.Info.PaymentIdentifier] = struct{}{}
	}

	// Check that the in-flight payments match the expected ones.
	require.Contains(t, inFlightHashes, payments[2].id)
	require.Contains(t, inFlightHashes, payments[3].id)

	// Now settle one of the in-flight payments.
	preimg := genPreimage(t)

	_, err = paymentDB.SettleAttempt(
		ctx, payments[2].id, 5,
		&HTLCSettleInfo{
			Preimage: preimg,
		},
	)
	require.NoError(t, err)

	// Fetch in-flight payments again.
	inFlightPayments, err = paymentDB.FetchInFlightPayments(ctx)
	require.NoError(t, err)

	// We should now only get one in-flight payment.
	require.Len(t, inFlightPayments, 1)
	require.Equal(
		t, payments[3].id,
		inFlightPayments[0].Info.PaymentIdentifier,
	)
	require.Equal(t, StatusInFlight, inFlightPayments[0].Status)
}

// TestFetchInFlightPaymentsMultipleAttempts tests that when fetching in-flight
// payments, a payment with multiple in-flight attempts is only returned once.
func TestFetchInFlightPaymentsMultipleAttempts(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)

	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Init payment with double the amount to allow two attempts.
	info.Value *= 2
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Register two attempts for the same payment.
	attempt1 := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt1,
	)
	require.NoError(t, err)

	attempt2 := genAttemptWithHash(t, 1, genSessionKey(t), rhash)

	_, err = paymentDB.RegisterAttempt(
		ctx, info.PaymentIdentifier, attempt2,
	)
	require.NoError(t, err)

	// Both attempts are in-flight. Fetch in-flight payments.
	inFlightPayments, err := paymentDB.FetchInFlightPayments(ctx)
	require.NoError(t, err)

	// We should only get one payment even though it has 2 in-flight
	// attempts.
	require.Len(t, inFlightPayments, 1)
	require.Equal(
		t, info.PaymentIdentifier,
		inFlightPayments[0].Info.PaymentIdentifier,
	)
	require.Equal(t, StatusInFlight, inFlightPayments[0].Status)

	// Verify the payment has both attempts.
	require.Len(t, inFlightPayments[0].HTLCs, 2)
}

// TestRouteFirstHopData tests that Route.FirstHopAmount and
// Route.FirstHopWireCustomRecords are correctly stored and retrieved.
func TestRouteFirstHopData(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)
	firstHopAmount := lnwire.MilliSatoshi(1234)

	// Init payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Create an attempt with both FirstHopAmount and
	// FirstHopWireCustomRecords set on the route.
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)
	attempt.Route.FirstHopAmount = tlv.NewRecordT[tlv.TlvType0](
		tlv.NewBigSizeT(firstHopAmount),
	)
	typeIdx1 := uint64(lnwire.MinCustomRecordsTlvType + 10)
	typeIdx2 := uint64(lnwire.MinCustomRecordsTlvType + 20)
	attempt.Route.FirstHopWireCustomRecords = lnwire.CustomRecords{
		typeIdx1: []byte("wire_record_1"),
		typeIdx2: []byte("wire_record_2"),
	}

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err)

	// Fetch the payment and verify first hop data was stored.
	payment, err := paymentDB.FetchPayment(ctx, info.PaymentIdentifier)
	require.NoError(t, err)

	require.Len(t, payment.HTLCs, 1)
	htlc := payment.HTLCs[0]

	// Verify the FirstHopAmount matches what we set.
	require.NotNil(t, htlc.Route.FirstHopAmount)
	require.Equal(
		t, firstHopAmount,
		htlc.Route.FirstHopAmount.Val.Int(),
	)

	// Verify the FirstHopWireCustomRecords match what we set.
	require.NotEmpty(t, htlc.Route.FirstHopWireCustomRecords)
	require.Len(t, htlc.Route.FirstHopWireCustomRecords, 2)
	require.Equal(
		t, []byte("wire_record_1"),
		htlc.Route.FirstHopWireCustomRecords[typeIdx1],
	)
	require.Equal(
		t, []byte("wire_record_2"),
		htlc.Route.FirstHopWireCustomRecords[typeIdx2],
	)
}

// TestRegisterAttemptWithAMP tests that AMP data is correctly stored and
// retrieved on route hops.
func TestRegisterAttemptWithAMP(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Init payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Create a basic attempt, then modify the route to include AMP data.
	// This bypasses the route validation in NewHtlcAttempt.
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	// Add AMP data to the final hop.
	rootShare := [32]byte{1, 2, 3, 4}
	setID := [32]byte{5, 6, 7, 8}
	childIndex := uint32(42)

	finalHopIdx := len(attempt.Route.Hops) - 1
	attempt.Route.Hops[finalHopIdx].AMP = record.NewAMP(
		rootShare, setID, childIndex,
	)

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err)

	// Fetch the payment and verify AMP data was stored.
	payment, err := paymentDB.FetchPayment(ctx, info.PaymentIdentifier)
	require.NoError(t, err)

	require.Len(t, payment.HTLCs, 1)
	htlc := payment.HTLCs[0]

	// Verify the AMP data on the final hop matches what we set.
	finalHop := htlc.Route.Hops[finalHopIdx]
	require.NotNil(t, finalHop.AMP)
	require.Equal(t, rootShare, finalHop.AMP.RootShare())
	require.Equal(t, setID, finalHop.AMP.SetID())
	require.Equal(t, childIndex, finalHop.AMP.ChildIndex())
}

// TestRegisterAttemptWithBlindedRoute tests that blinded route data
// (EncryptedData, BlindingPoint, TotalAmtMsat) is correctly stored and
// retrieved.
func TestRegisterAttemptWithBlindedRoute(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])

	// Create payment info with amount matching
	// testBlindedRoute.TotalAmount.
	info := &PaymentCreationInfo{
		PaymentIdentifier: rhash,
		Value:             testBlindedRoute.TotalAmount,
		CreationTime:      time.Unix(time.Now().Unix(), 0),
		PaymentRequest:    []byte("blinded"),
	}

	// Init payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Create a basic attempt, then replace the route with testBlindedRoute.
	// This bypasses the route validation in NewHtlcAttempt.
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	// Replace with testBlindedRoute which has the correct blinded route
	// structure.
	attempt.Route = testBlindedRoute

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err)

	// Fetch the payment and verify blinded route data was stored.
	payment, err := paymentDB.FetchPayment(ctx, info.PaymentIdentifier)
	require.NoError(t, err)

	require.Len(t, payment.HTLCs, 1)
	htlc := payment.HTLCs[0]

	// Verify the blinded route data.
	require.Len(t, htlc.Route.Hops, 3)

	// First hop (introduction point) should have BlindingPoint and
	// EncryptedData.
	hop0 := htlc.Route.Hops[0]
	require.Equal(t, []byte{1, 3, 3}, hop0.EncryptedData)
	require.NotNil(t, hop0.BlindingPoint)
	require.True(t, hop0.BlindingPoint.IsEqual(pub))

	// Second hop (intermediate) should have only EncryptedData.
	hop1 := htlc.Route.Hops[1]
	require.Equal(t, []byte{3, 2, 1}, hop1.EncryptedData)
	require.Nil(t, hop1.BlindingPoint)

	// Third hop (final) should have EncryptedData, AmtToForward,
	// OutgoingTimeLock, and TotalAmtMsat.
	hop2 := htlc.Route.Hops[2]
	require.Equal(t, []byte{2, 2, 2}, hop2.EncryptedData)
	require.Equal(t, lnwire.MilliSatoshi(1000), hop2.AmtToForward)
	require.Equal(t, uint32(100), hop2.OutgoingTimeLock)
	require.Equal(t, lnwire.MilliSatoshi(1000), hop2.TotalAmtMsat)
}

// TestFailAttemptWithoutMessage tests that FailAttempt works correctly when
// no failure message is provided.
func TestFailAttemptWithoutMessage(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Init payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Register an attempt.
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err)

	// Fail the attempt without a failure message (nil Message).
	failInfo := &HTLCFailInfo{
		Reason:             HTLCFailUnreadable,
		FailureSourceIndex: 2,
		Message:            nil, // No message.
	}

	payment, err := paymentDB.FailAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID, failInfo,
	)
	require.NoError(t, err)
	require.NotNil(t, payment)

	// Verify the attempt was failed.
	require.Len(t, payment.HTLCs, 1)
	htlc := payment.HTLCs[0]
	require.NotNil(t, htlc.Failure)
	require.Equal(t, HTLCFailUnreadable, htlc.Failure.Reason)
	require.Equal(t, uint32(2), htlc.Failure.FailureSourceIndex)
	require.Nil(t, htlc.Failure.Message)
}

// TestFailAttemptWithMessage tests that FailAttempt correctly stores and
// retrieves a failure message.
func TestFailAttemptWithMessage(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Init payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Register an attempt.
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err)

	// Create a failure message.
	failureMsg := lnwire.NewTemporaryChannelFailure(nil)

	// Fail the attempt with a failure message.
	failInfo := &HTLCFailInfo{
		Reason:             HTLCFailUnreadable,
		FailureSourceIndex: 1,
		Message:            failureMsg,
	}

	payment, err := paymentDB.FailAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID, failInfo,
	)
	require.NoError(t, err)
	require.NotNil(t, payment)

	// Verify the attempt was failed.
	require.Len(t, payment.HTLCs, 1)
	htlc := payment.HTLCs[0]
	require.NotNil(t, htlc.Failure)
	require.Equal(t, HTLCFailUnreadable, htlc.Failure.Reason)
}

// TestFailAttemptOnSucceededPayment tests that FailAttempt returns an error
// when trying to fail an attempt on an already succeeded payment.
func TestFailAttemptOnSucceededPayment(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Init payment.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Register an attempt.
	attempt := genAttemptWithHash(t, 0, genSessionKey(t), rhash)

	_, err = paymentDB.RegisterAttempt(ctx, info.PaymentIdentifier, attempt)
	require.NoError(t, err)

	// Settle the attempt, which makes the payment succeed.
	_, err = paymentDB.SettleAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID,
		&HTLCSettleInfo{Preimage: preimg},
	)
	require.NoError(t, err)

	// Now try to fail the same attempt - this should fail because the
	// payment is already succeeded.
	failInfo := &HTLCFailInfo{
		Reason: HTLCFailUnreadable,
	}

	_, err = paymentDB.FailAttempt(
		ctx, info.PaymentIdentifier, attempt.AttemptID, failInfo,
	)
	require.Error(t, err)
	require.ErrorIs(t, err, ErrPaymentAlreadySucceeded)
}

// TestFetchPaymentWithNoAttempts tests that FetchPayment correctly returns a
// payment that has been initialized but has no HTLC attempts yet. This tests
// the early return path in batchLoadPaymentDetailsData when there are no
// attempts.
func TestFetchPaymentWithNoAttempts(t *testing.T) {
	t.Parallel()

	ctx := t.Context()

	paymentDB, _ := NewTestDB(t)

	preimg := genPreimage(t)
	rhash := sha256.Sum256(preimg[:])
	info := genPaymentCreationInfo(t, rhash)

	// Init payment but don't register any attempts.
	err := paymentDB.InitPayment(ctx, info.PaymentIdentifier, info)
	require.NoError(t, err)

	// Fetch the payment - it should have no HTLCs.
	payment, err := paymentDB.FetchPayment(ctx, info.PaymentIdentifier)
	require.NoError(t, err)
	require.NotNil(t, payment)

	// Verify the payment has no HTLCs.
	require.Empty(t, payment.HTLCs)

	// Verify the payment info is correct.
	require.Equal(t, info.PaymentIdentifier, payment.Info.PaymentIdentifier)
	require.Equal(t, info.Value, payment.Info.Value)
	require.Equal(t, StatusInitiated, payment.Status)
}