taprpc+rpcserver: unify marshaling, add asset amount to sell quote

Fixes #1234.

Simplifies and unifies the marshaling of sell quotes and adds the asset
amount by converting the request's max amount using the quote.

rpcserver.go

@@ -6819,13 +6819,9 @@ func marshallRfqEvent(eventInterface fn.Event) (*rfqrpc.RfqEvent, error) {
 		}, nil
 
 	case *rfq.PeerAcceptedSellQuoteEvent:
-		rpcAcceptedQuote, err := taprpc.MarshalAcceptedSellQuoteEvent(
+		rpcAcceptedQuote := taprpc.MarshalAcceptedSellQuoteEvent(
 			event,
 		)
-		if err != nil {
-			return nil, fmt.Errorf("error marshalling accepted "+
-				"sell quote event: %w", err)
-		}
 
 		eventRpc := &rfqrpc.RfqEvent_PeerAcceptedSellQuote{
 			PeerAcceptedSellQuote: &rfqrpc.PeerAcceptedSellQuoteEvent{
@@ -7061,36 +7057,12 @@ func (r *rpcServer) SendPayment(req *tchrpc.SendPaymentRequest,
 				"accepted quote")
 		}
 
-		invoice, err := zpay32.Decode(
-			pReq.PaymentRequest, r.cfg.Lnd.ChainParams,
-		)
-		if err != nil {
-			return fmt.Errorf("error decoding payment request: %w",
-				err)
-		}
-
-		rate := quote.AssetRate.Rate
-
 		// Calculate the equivalent asset units for the given invoice
 		// amount based on the asset-to-BTC conversion rate.
-		numAssetUnits := rfqmath.MilliSatoshiToUnits(
-			*invoice.MilliSat, rate,
-		)
-
-		sellOrder := &rfqrpc.PeerAcceptedSellQuote{
-			Peer: quote.Peer.String(),
-			Id:   quote.ID[:],
-			Scid: uint64(quote.ID.Scid()),
-			BidAssetRate: &rfqrpc.FixedPoint{
-				Coefficient: rate.Coefficient.String(),
-				Scale:       uint32(rate.Scale),
-			},
-			AssetAmount: numAssetUnits.ToUint64(),
-			Expiry:      uint64(quote.AssetRate.Expiry.Unix()),
-		}
+		sellOrder := taprpc.MarshalAcceptedSellQuote(*quote)
 
 		// Send out the information about the quote on the stream.
-		err = stream.Send(&tchrpc.SendPaymentResponse{
+		err := stream.Send(&tchrpc.SendPaymentResponse{
 			Result: &tchrpc.SendPaymentResponse_AcceptedSellOrder{
 				AcceptedSellOrder: sellOrder,
 			},
@@ -7101,8 +7073,8 @@ func (r *rpcServer) SendPayment(req *tchrpc.SendPaymentRequest,
 		}
 
 		rpcsLog.Infof("Using quote for %v asset units at %v asset/BTC "+
-			"from peer %x with SCID %d", numAssetUnits,
-			rate.String(), quote.Peer, quote.ID.Scid())
+			"from peer %x with SCID %d", sellOrder.AssetAmount,
+			quote.AssetRate.String(), quote.Peer, quote.ID.Scid())
 
 		htlc := rfqmsg.NewHtlc(nil, fn.Some(quote.ID))
 
@@ -7243,15 +7215,9 @@ func (r *rpcServer) SendPayment(req *tchrpc.SendPaymentRequest,
 				err)
 		}
 
-		// Calculate the equivalent asset units for the given invoice
-		// amount based on the asset-to-BTC conversion rate.
-		numAssetUnits := rfqmath.MilliSatoshiToUnits(
-			*invoice.MilliSat, *assetRate,
-		)
-
 		rpcsLog.Infof("Got quote for %v asset units at %v asset/BTC "+
-			"from peer %x with SCID %d", numAssetUnits, assetRate,
-			peerPubKey, acceptedQuote.Scid)
+			"from peer %x with SCID %d", acceptedQuote.AssetAmount,
+			assetRate, peerPubKey, acceptedQuote.Scid)
 
 		var rfqID rfqmsg.ID
 		copy(rfqID[:], acceptedQuote.Id)

taprpc/marshal.go

@@ -15,6 +15,8 @@ import (
 	"github.com/lightninglabs/taproot-assets/commitment"
 	"github.com/lightninglabs/taproot-assets/fn"
 	"github.com/lightninglabs/taproot-assets/rfq"
+	"github.com/lightninglabs/taproot-assets/rfqmath"
+	"github.com/lightninglabs/taproot-assets/rfqmsg"
 	"github.com/lightninglabs/taproot-assets/taprpc/rfqrpc"
 	"github.com/lightningnetwork/lnd/keychain"
 )
@@ -522,25 +524,37 @@ func MarshalAsset(ctx context.Context, a *asset.Asset,
 }
 
 // MarshalAcceptedSellQuoteEvent marshals a peer accepted sell quote event to
-// its rpc representation.
+// its RPC representation.
 func MarshalAcceptedSellQuoteEvent(
-	event *rfq.PeerAcceptedSellQuoteEvent) (*rfqrpc.PeerAcceptedSellQuote,
-	error) {
+	event *rfq.PeerAcceptedSellQuoteEvent) *rfqrpc.PeerAcceptedSellQuote {
+
+	return MarshalAcceptedSellQuote(event.SellAccept)
+}
+
+// MarshalAcceptedSellQuote marshals a peer accepted sell quote to its RPC
+// representation.
+func MarshalAcceptedSellQuote(
+	accept rfqmsg.SellAccept) *rfqrpc.PeerAcceptedSellQuote {
 
 	rpcAssetRate := &rfqrpc.FixedPoint{
-		Coefficient: event.AssetRate.Rate.Coefficient.String(),
-		Scale:       uint32(event.AssetRate.Rate.Scale),
+		Coefficient: accept.AssetRate.Rate.Coefficient.String(),
+		Scale:       uint32(accept.AssetRate.Rate.Scale),
 	}
 
-	// TODO(ffranr): Add SellRequest payment max amount to
-	//  PeerAcceptedSellQuote.
+	// Calculate the equivalent asset units for the given total BTC amount
+	// based on the asset-to-BTC conversion rate.
+	numAssetUnits := rfqmath.MilliSatoshiToUnits(
+		accept.Request.PaymentMaxAmt, accept.AssetRate.Rate,
+	)
+
 	return &rfqrpc.PeerAcceptedSellQuote{
-		Peer:         event.Peer.String(),
-		Id:           event.ID[:],
-		Scid:         uint64(event.ShortChannelId()),
+		Peer:         accept.Peer.String(),
+		Id:           accept.ID[:],
+		Scid:         uint64(accept.ShortChannelId()),
 		BidAssetRate: rpcAssetRate,
-		Expiry:       uint64(event.AssetRate.Expiry.Unix()),
-	}, nil
+		Expiry:       uint64(accept.AssetRate.Expiry.Unix()),
+		AssetAmount:  numAssetUnits.ScaleTo(0).ToUint64(),
+	}
 }
 
 // MarshalAcceptedBuyQuoteEvent marshals a peer accepted buy quote event to
@@ -636,14 +650,8 @@ func NewAddAssetSellOrderResponse(
 
 	switch e := event.(type) {
 	case *rfq.PeerAcceptedSellQuoteEvent:
-		rpcAcceptedQuote, err := MarshalAcceptedSellQuoteEvent(e)
-		if err != nil {
-			return nil, fmt.Errorf("unable to marshal accepted "+
-				"sell quote event to RPC: %w", err)
-		}
-
 		resp.Response = &rfqrpc.AddAssetSellOrderResponse_AcceptedQuote{
-			AcceptedQuote: rpcAcceptedQuote,
+			AcceptedQuote: MarshalAcceptedSellQuoteEvent(e),
 		}
 		return resp, nil