refactor melt flow

cashu/cashu.go

@@ -422,11 +422,13 @@ var (
 	MintingDisabled              = Error{Detail: "minting is disabled", Code: MintingDisabledErrCode}
 	MintAmountExceededErr        = Error{Detail: "max amount for minting exceeded", Code: AmountLimitExceeded}
 	OutputsOverQuoteAmountErr    = Error{Detail: "sum of the output amounts is greater than quote amount", Code: StandardErrCode}
-	ProofAlreadyUsedErr          = Error{Detail: "proofs already used", Code: ProofAlreadyUsedErrCode}
+	ProofAlreadyUsedErr          = Error{Detail: "proof already used", Code: ProofAlreadyUsedErrCode}
+	ProofPendingErr              = Error{Detail: "proof is pending", Code: ProofAlreadyUsedErrCode}
 	InvalidProofErr              = Error{Detail: "invalid proof", Code: InvalidProofErrCode}
 	NoProofsProvided             = Error{Detail: "no proofs provided", Code: InvalidProofErrCode}
 	DuplicateProofs              = Error{Detail: "duplicate proofs", Code: InvalidProofErrCode}
 	QuoteNotExistErr             = Error{Detail: "quote does not exist", Code: QuoteErrCode}
+	MeltQuotePending             = Error{Detail: "quote is pending", Code: MeltQuotePendingErrCode}
 	MeltQuoteAlreadyPaid         = Error{Detail: "quote already paid", Code: MeltQuoteAlreadyPaidErrCode}
 	MeltAmountExceededErr        = Error{Detail: "max amount for melting exceeded", Code: AmountLimitExceeded}
 	InsufficientProofsAmount     = Error{

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/btcsuite/btcd/btcec/v2 v2.3.3
 	github.com/btcsuite/btcd/btcutil v1.1.5
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0
-	github.com/elnosh/btc-docker-test v0.0.0-20240730150514-6d94d76b8881
+	github.com/elnosh/btc-docker-test v0.0.0-20240927160251-93a4da3d1754
 	github.com/fxamacker/cbor/v2 v2.7.0
 	github.com/golang-migrate/migrate/v4 v4.17.1
 	github.com/gorilla/mux v1.8.0

go.sum

@@ -185,6 +185,8 @@ github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkp
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/elnosh/btc-docker-test v0.0.0-20240730150514-6d94d76b8881 h1:iHr0CRNKU9ilxf+LGUon9XB39lRvLlbbm9C9dx2Y/u0=
 github.com/elnosh/btc-docker-test v0.0.0-20240730150514-6d94d76b8881/go.mod h1:W2G5BhKocXfbC61N4Jy8Z+0rSPGAbDcZsKIr+4B5v9Y=
+github.com/elnosh/btc-docker-test v0.0.0-20240927160251-93a4da3d1754 h1:LYVrpWL+RI13UBb36U0TkFu09X7+haLR/ix2zJVQ+Ac=
+github.com/elnosh/btc-docker-test v0.0.0-20240927160251-93a4da3d1754/go.mod h1:OZ/LMGKylMDHiAh47vr2MjzJGzE2iRafZyqseh7RppA=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=

mint/lightning/lightning.go

@@ -1,10 +1,13 @@
 package lightning
 
+import "context"
+
 // Client interface to interact with a Lightning backend
 type Client interface {
 	CreateInvoice(amount uint64) (Invoice, error)
 	InvoiceStatus(hash string) (Invoice, error)
-	SendPayment(request string, amount uint64) (string, error)
+	SendPayment(ctx context.Context, request string, amount uint64) (PaymentStatus, error)
+	OutgoingPaymentStatus(ctx context.Context, hash string) (PaymentStatus, error)
 	FeeReserve(amount uint64) uint64
 }
 
@@ -16,3 +19,16 @@ type Invoice struct {
 	Amount         uint64
 	Expiry         uint64
 }
+
+type State int
+
+const (
+	Succeeded State = iota
+	Failed
+	Pending
+)
+
+type PaymentStatus struct {
+	Preimage      string
+	PaymentStatus State
+}

mint/lightning/lnd.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
 	"github.com/lightningnetwork/lnd/macaroons"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
@@ -26,7 +27,8 @@ type LndConfig struct {
 }
 
 type LndClient struct {
-	grpcClient lnrpc.LightningClient
+	grpcClient   lnrpc.LightningClient
+	routerClient routerrpc.RouterClient
 }
 
 func SetupLndClient(config LndConfig) (*LndClient, error) {
@@ -41,7 +43,8 @@ func SetupLndClient(config LndConfig) (*LndClient, error) {
 	}
 
 	grpcClient := lnrpc.NewLightningClient(conn)
-	return &LndClient{grpcClient: grpcClient}, nil
+	routerClient := routerrpc.NewRouterClient(conn)
+	return &LndClient{grpcClient: grpcClient, routerClient: routerClient}, nil
 }
 
 func (lnd *LndClient) CreateInvoice(amount uint64) (Invoice, error) {
@@ -89,31 +92,66 @@ func (lnd *LndClient) InvoiceStatus(hash string) (Invoice, error) {
 	return invoice, nil
 }
 
-type SendPaymentResponse struct {
-	PaymentError    string `json:"payment_error"`
-	PaymentPreimage string `json:"payment_preimage"`
-}
-
-func (lnd *LndClient) SendPayment(request string, amount uint64) (string, error) {
+func (lnd *LndClient) SendPayment(ctx context.Context, request string, amount uint64) (PaymentStatus, error) {
 	feeLimit := lnd.FeeReserve(amount)
 	sendPaymentRequest := lnrpc.SendRequest{
 		PaymentRequest: request,
 		FeeLimit:       &lnrpc.FeeLimit{Limit: &lnrpc.FeeLimit_Fixed{Fixed: int64(feeLimit)}},
 	}
 
-	sendPaymentResponse, err := lnd.grpcClient.SendPaymentSync(context.Background(), &sendPaymentRequest)
+	sendPaymentResponse, err := lnd.grpcClient.SendPaymentSync(ctx, &sendPaymentRequest)
 	if err != nil {
-		return "", fmt.Errorf("error making payment: %v", err)
+		// if context deadline is exceeded (1 min), mark payment as pending
+		// if any other error, mark as failed
+		if errors.Is(ctx.Err(), context.DeadlineExceeded) {
+			return PaymentStatus{PaymentStatus: Pending}, nil
+		} else {
+			return PaymentStatus{PaymentStatus: Failed}, err
+		}
 	}
 	if len(sendPaymentResponse.PaymentError) > 0 {
-		return "", fmt.Errorf("error making payment: %v", sendPaymentResponse.PaymentError)
-	}
-	if len(sendPaymentResponse.PaymentPreimage) == 0 {
-		return "", fmt.Errorf("could not make payment")
+		return PaymentStatus{PaymentStatus: Failed}, fmt.Errorf("payment error: %v", sendPaymentResponse.PaymentError)
 	}
 
 	preimage := hex.EncodeToString(sendPaymentResponse.PaymentPreimage)
-	return preimage, nil
+	paymentResponse := PaymentStatus{Preimage: preimage, PaymentStatus: Succeeded}
+	return paymentResponse, nil
+}
+
+func (lnd *LndClient) OutgoingPaymentStatus(ctx context.Context, hash string) (PaymentStatus, error) {
+	hashBytes, err := hex.DecodeString(hash)
+	if err != nil {
+		return PaymentStatus{}, errors.New("invalid hash provided")
+	}
+
+	trackPaymentRequest := routerrpc.TrackPaymentRequest{
+		PaymentHash: hashBytes,
+		// setting this to only get the final payment update
+		NoInflightUpdates: true,
+	}
+
+	trackPaymentStream, err := lnd.routerClient.TrackPaymentV2(ctx, &trackPaymentRequest)
+	if err != nil {
+		return PaymentStatus{PaymentStatus: Failed}, err
+	}
+
+	// this should block until final payment update
+	payment, err := trackPaymentStream.Recv()
+	if err != nil {
+		return PaymentStatus{PaymentStatus: Failed}, fmt.Errorf("payment failed: %w", err)
+	}
+	if payment.Status == lnrpc.Payment_UNKNOWN || payment.Status == lnrpc.Payment_FAILED {
+		return PaymentStatus{PaymentStatus: Failed},
+			fmt.Errorf("payment failed: %s", payment.FailureReason.String())
+	}
+	if payment.Status == lnrpc.Payment_IN_FLIGHT {
+		return PaymentStatus{PaymentStatus: Pending}, nil
+	}
+	if payment.Status == lnrpc.Payment_SUCCEEDED {
+		return PaymentStatus{PaymentStatus: Succeeded, Preimage: payment.PaymentPreimage}, nil
+	}
+
+	return PaymentStatus{PaymentStatus: Failed}, errors.New("unknown")
 }
 
 func (lnd *LndClient) FeeReserve(amount uint64) uint64 {