package invoices

import (
	"io/ioutil"
	"os"
	"testing"
	"time"

	"github.com/lightningnetwork/lnd/channeldb"
	"github.com/lightningnetwork/lnd/lntypes"
	"github.com/lightningnetwork/lnd/lnwire"
)

var (
	testTimeout = 5 * time.Second

	preimage = lntypes.Preimage{
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	}

	hash = preimage.Hash()

	testInvoiceExpiry = uint32(3)

	testCurrentHeight = int32(0)

	testFinalCltvRejectDelta = int32(3)
)

func decodeExpiry(payReq string) (uint32, error) {
	return uint32(testInvoiceExpiry), nil
}

var (
	testInvoice = &channeldb.Invoice{
		Terms: channeldb.ContractTerm{
			PaymentPreimage: preimage,
			Value:           lnwire.MilliSatoshi(100000),
		},
	}
)

func newTestContext(t *testing.T) (*InvoiceRegistry, func()) {
	cdb, cleanup, err := newDB()
	if err != nil {
		t.Fatal(err)
	}

	// Instantiate and start the invoice registry.
	registry := NewRegistry(cdb, decodeExpiry, testFinalCltvRejectDelta)

	err = registry.Start()
	if err != nil {
		cleanup()
		t.Fatal(err)
	}

	return registry, func() {
		registry.Stop()
		cleanup()
	}
}

// TestSettleInvoice tests settling of an invoice and related notifications.
func TestSettleInvoice(t *testing.T) {
	registry, cleanup := newTestContext(t)
	defer cleanup()

	allSubscriptions := registry.SubscribeNotifications(0, 0)
	defer allSubscriptions.Cancel()

	// Subscribe to the not yet existing invoice.
	subscription, err := registry.SubscribeSingleInvoice(hash)
	if err != nil {
		t.Fatal(err)
	}
	defer subscription.Cancel()

	if subscription.hash != hash {
		t.Fatalf("expected subscription for provided hash")
	}

	// Add the invoice.
	addIdx, err := registry.AddInvoice(testInvoice, hash)
	if err != nil {
		t.Fatal(err)
	}

	if addIdx != 1 {
		t.Fatalf("expected addIndex to start with 1, but got %v",
			addIdx)
	}

	// We expect the open state to be sent to the single invoice subscriber.
	select {
	case update := <-subscription.Updates:
		if update.Terms.State != channeldb.ContractOpen {
			t.Fatalf("expected state ContractOpen, but got %v",
				update.Terms.State)
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	// We expect a new invoice notification to be sent out.
	select {
	case newInvoice := <-allSubscriptions.NewInvoices:
		if newInvoice.Terms.State != channeldb.ContractOpen {
			t.Fatalf("expected state ContractOpen, but got %v",
				newInvoice.Terms.State)
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	hodlChan := make(chan interface{}, 1)

	// Settle invoice with a slightly higher amount.
	amtPaid := lnwire.MilliSatoshi(100500)
	_, err = registry.NotifyExitHopHtlc(
		hash, amtPaid, testInvoiceExpiry, 0, hodlChan,
	)
	if err != nil {
		t.Fatal(err)
	}

	// We expect the settled state to be sent to the single invoice
	// subscriber.
	select {
	case update := <-subscription.Updates:
		if update.Terms.State != channeldb.ContractSettled {
			t.Fatalf("expected state ContractOpen, but got %v",
				update.Terms.State)
		}
		if update.AmtPaid != amtPaid {
			t.Fatal("invoice AmtPaid incorrect")
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	// We expect a settled notification to be sent out.
	select {
	case settledInvoice := <-allSubscriptions.SettledInvoices:
		if settledInvoice.Terms.State != channeldb.ContractSettled {
			t.Fatalf("expected state ContractOpen, but got %v",
				settledInvoice.Terms.State)
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	// Try to settle again. We need this idempotent behaviour after a
	// restart.
	event, err := registry.NotifyExitHopHtlc(
		hash, amtPaid, testInvoiceExpiry, testCurrentHeight, hodlChan,
	)
	if err != nil {
		t.Fatalf("unexpected NotifyExitHopHtlc error: %v", err)
	}
	if event.Preimage == nil {
		t.Fatal("expected settle event")
	}

	// Try to settle again with a higher amount. This should result in a
	// cancel event because after a restart the amount should still be the
	// same. New HTLCs with a different amount should be rejected.
	event, err = registry.NotifyExitHopHtlc(
		hash, amtPaid+600, testInvoiceExpiry, testCurrentHeight,
		hodlChan,
	)
	if err != nil {
		t.Fatalf("unexpected NotifyExitHopHtlc error: %v", err)
	}
	if event.Preimage != nil {
		t.Fatal("expected cancel event")
	}

	// Try to settle again with a lower amount. This should show the same
	// behaviour as settling with a higher amount.
	event, err = registry.NotifyExitHopHtlc(
		hash, amtPaid-600, testInvoiceExpiry, testCurrentHeight,
		hodlChan,
	)
	if err != nil {
		t.Fatalf("unexpected NotifyExitHopHtlc error: %v", err)
	}
	if event.Preimage != nil {
		t.Fatal("expected cancel event")
	}

	// Check that settled amount remains unchanged.
	inv, _, err := registry.LookupInvoice(hash)
	if err != nil {
		t.Fatal(err)
	}
	if inv.AmtPaid != amtPaid {
		t.Fatal("expected amount to be unchanged")
	}

	// Try to cancel.
	err = registry.CancelInvoice(hash)
	if err != channeldb.ErrInvoiceAlreadySettled {
		t.Fatal("expected cancelation of a settled invoice to fail")
	}

	// As this is a direct sette, we expect nothing on the hodl chan.
	select {
	case <-hodlChan:
		t.Fatal("unexpected event")
	default:
	}
}

// TestCancelInvoice tests cancelation of an invoice and related notifications.
func TestCancelInvoice(t *testing.T) {
	registry, cleanup := newTestContext(t)
	defer cleanup()

	allSubscriptions := registry.SubscribeNotifications(0, 0)
	defer allSubscriptions.Cancel()

	// Try to cancel the not yet existing invoice. This should fail.
	err := registry.CancelInvoice(hash)
	if err != channeldb.ErrInvoiceNotFound {
		t.Fatalf("expected ErrInvoiceNotFound, but got %v", err)
	}

	// Subscribe to the not yet existing invoice.
	subscription, err := registry.SubscribeSingleInvoice(hash)
	if err != nil {
		t.Fatal(err)
	}
	defer subscription.Cancel()

	if subscription.hash != hash {
		t.Fatalf("expected subscription for provided hash")
	}

	// Add the invoice.
	amt := lnwire.MilliSatoshi(100000)
	_, err = registry.AddInvoice(testInvoice, hash)
	if err != nil {
		t.Fatal(err)
	}

	// We expect the open state to be sent to the single invoice subscriber.
	select {
	case update := <-subscription.Updates:
		if update.Terms.State != channeldb.ContractOpen {
			t.Fatalf(
				"expected state ContractOpen, but got %v",
				update.Terms.State,
			)
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	// We expect a new invoice notification to be sent out.
	select {
	case newInvoice := <-allSubscriptions.NewInvoices:
		if newInvoice.Terms.State != channeldb.ContractOpen {
			t.Fatalf(
				"expected state ContractOpen, but got %v",
				newInvoice.Terms.State,
			)
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	// Cancel invoice.
	err = registry.CancelInvoice(hash)
	if err != nil {
		t.Fatal(err)
	}

	// We expect the canceled state to be sent to the single invoice
	// subscriber.
	select {
	case update := <-subscription.Updates:
		if update.Terms.State != channeldb.ContractCanceled {
			t.Fatalf(
				"expected state ContractCanceled, but got %v",
				update.Terms.State,
			)
		}
	case <-time.After(testTimeout):
		t.Fatal("no update received")
	}

	// We expect no cancel notification to be sent to all invoice
	// subscribers (backwards compatibility).

	// Try to cancel again.
	err = registry.CancelInvoice(hash)
	if err != nil {
		t.Fatal("expected cancelation of a canceled invoice to succeed")
	}

	// Notify arrival of a new htlc paying to this invoice. This should
	// succeed.
	hodlChan := make(chan interface{})
	event, err := registry.NotifyExitHopHtlc(
		hash, amt, testInvoiceExpiry, testCurrentHeight, hodlChan,
	)
	if err != nil {
		t.Fatal("expected settlement of a canceled invoice to succeed")
	}

	if event.Preimage != nil {
		t.Fatal("expected cancel hodl event")
	}
}

// TestHoldInvoice tests settling of a hold invoice and related notifications.
func TestHoldInvoice(t *testing.T) {
	defer timeout(t)()

	cdb, cleanup, err := newDB()
	defer cleanup()

	// Instantiate and start the invoice registry.
	registry := NewRegistry(cdb, decodeExpiry, testFinalCltvRejectDelta)

	err = registry.Start()
	if err != nil {
		t.Fatal(err)
	}
	defer registry.Stop()

	allSubscriptions := registry.SubscribeNotifications(0, 0)
	defer allSubscriptions.Cancel()

	// Subscribe to the not yet existing invoice.
	subscription, err := registry.SubscribeSingleInvoice(hash)
	if err != nil {
		t.Fatal(err)
	}
	defer subscription.Cancel()

	if subscription.hash != hash {
		t.Fatalf("expected subscription for provided hash")
	}

	// Add the invoice.
	invoice := &channeldb.Invoice{
		Terms: channeldb.ContractTerm{
			PaymentPreimage: channeldb.UnknownPreimage,
			Value:           lnwire.MilliSatoshi(100000),
		},
	}

	_, err = registry.AddInvoice(invoice, hash)
	if err != nil {
		t.Fatal(err)
	}

	// We expect the open state to be sent to the single invoice subscriber.
	update := <-subscription.Updates
	if update.Terms.State != channeldb.ContractOpen {
		t.Fatalf("expected state ContractOpen, but got %v",
			update.Terms.State)
	}

	// We expect a new invoice notification to be sent out.
	newInvoice := <-allSubscriptions.NewInvoices
	if newInvoice.Terms.State != channeldb.ContractOpen {
		t.Fatalf("expected state ContractOpen, but got %v",
			newInvoice.Terms.State)
	}

	// Use slightly higher amount for accept/settle.
	amtPaid := lnwire.MilliSatoshi(100500)

	hodlChan := make(chan interface{}, 1)

	// NotifyExitHopHtlc without a preimage present in the invoice registry
	// should be possible.
	event, err := registry.NotifyExitHopHtlc(
		hash, amtPaid, testInvoiceExpiry, testCurrentHeight, hodlChan,
	)
	if err != nil {
		t.Fatalf("expected settle to succeed but got %v", err)
	}
	if event != nil {
		t.Fatalf("unexpect direct settle")
	}

	// Test idempotency.
	event, err = registry.NotifyExitHopHtlc(
		hash, amtPaid, testInvoiceExpiry, testCurrentHeight, hodlChan,
	)
	if err != nil {
		t.Fatalf("expected settle to succeed but got %v", err)
	}
	if event != nil {
		t.Fatalf("unexpect direct settle")
	}

	// We expect the accepted state to be sent to the single invoice
	// subscriber. For all invoice subscribers, we don't expect an update.
	// Those only get notified on settle.
	update = <-subscription.Updates
	if update.Terms.State != channeldb.ContractAccepted {
		t.Fatalf("expected state ContractAccepted, but got %v",
			update.Terms.State)
	}
	if update.AmtPaid != amtPaid {
		t.Fatal("invoice AmtPaid incorrect")
	}

	// Settling with preimage should succeed.
	err = registry.SettleHodlInvoice(preimage)
	if err != nil {
		t.Fatal("expected set preimage to succeed")
	}

	hodlEvent := (<-hodlChan).(HodlEvent)
	if *hodlEvent.Preimage != preimage {
		t.Fatal("unexpected preimage in hodl event")
	}

	// We expect a settled notification to be sent out for both all and
	// single invoice subscribers.
	settledInvoice := <-allSubscriptions.SettledInvoices
	if settledInvoice.Terms.State != channeldb.ContractSettled {
		t.Fatalf("expected state ContractSettled, but got %v",
			settledInvoice.Terms.State)
	}

	update = <-subscription.Updates
	if update.Terms.State != channeldb.ContractSettled {
		t.Fatalf("expected state ContractSettled, but got %v",
			update.Terms.State)
	}

	// Idempotency.
	err = registry.SettleHodlInvoice(preimage)
	if err != channeldb.ErrInvoiceAlreadySettled {
		t.Fatalf("expected ErrInvoiceAlreadySettled but got %v", err)
	}

	// Try to cancel.
	err = registry.CancelInvoice(hash)
	if err == nil {
		t.Fatal("expected cancelation of a settled invoice to fail")
	}
}

func newDB() (*channeldb.DB, func(), error) {
	// First, create a temporary directory to be used for the duration of
	// this test.
	tempDirName, err := ioutil.TempDir("", "channeldb")
	if err != nil {
		return nil, nil, err
	}

	// Next, create channeldb for the first time.
	cdb, err := channeldb.Open(tempDirName)
	if err != nil {
		os.RemoveAll(tempDirName)
		return nil, nil, err
	}

	cleanUp := func() {
		cdb.Close()
		os.RemoveAll(tempDirName)
	}

	return cdb, cleanUp, nil
}

// TestUnknownInvoice tests that invoice registry returns an error when the
// invoice is unknown. This is to guard against returning a cancel hodl event
// for forwarded htlcs. In the link, NotifyExitHopHtlc is only called if we are
// the exit hop, but in htlcIncomingContestResolver it is called with forwarded
// htlc hashes as well.
func TestUnknownInvoice(t *testing.T) {
	registry, cleanup := newTestContext(t)
	defer cleanup()

	// Notify arrival of a new htlc paying to this invoice. This should
	// succeed.
	hodlChan := make(chan interface{})
	amt := lnwire.MilliSatoshi(100000)
	_, err := registry.NotifyExitHopHtlc(
		hash, amt, testInvoiceExpiry, testCurrentHeight, hodlChan,
	)
	if err != channeldb.ErrInvoiceNotFound {
		t.Fatal("expected invoice not found error")
	}
}