loopout/asset: add asset rate

Author: sputn1ck

client.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightninglabs/loop/sweep"
 	"github.com/lightninglabs/loop/sweepbatcher"
 	"github.com/lightninglabs/loop/utils"
+	"github.com/lightninglabs/taproot-assets/taprpc/rfqrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/routing/route"
 	"google.golang.org/grpc"
@@ -661,54 +662,12 @@ func (s *Client) LoopOutQuote(ctx context.Context,
 	// If we use an Asset we'll rfq to get the asset amounts to use for
 	// the swap.
 	if request.AssetRFQRequest != nil {
-		rfqReq := request.AssetRFQRequest
-		if rfqReq.Expiry == 0 {
-			rfqReq.Expiry = time.Now().Add(defaultRFQExpiry).Unix()
-		}
-
-		if rfqReq.MaxLimitMultiplier == 0 {
-			rfqReq.MaxLimitMultiplier = defaultRFQMaxLimitMultiplier
-		}
-
-		// First we'll get the prepay rfq.
-		prepayRfq, err := s.assetClient.GetRfqForAsset(
-			ctx, quote.PrepayAmount, rfqReq.AssetId,
-			rfqReq.AssetEdgeNode, rfqReq.Expiry,
-			rfqReq.MaxLimitMultiplier,
-		)
-		if err != nil {
-			return nil, err
-		}
-
-		// The actual invoice swap amount is the requested amount plus
-		// the swap fee minus the prepay amount.
-		invoiceAmt := request.Amount + quote.SwapFee -
-			quote.PrepayAmount
-
-		swapRfq, err := s.assetClient.GetRfqForAsset(
-			ctx, invoiceAmt, rfqReq.AssetId,
-			rfqReq.AssetEdgeNode, rfqReq.Expiry,
-			rfqReq.MaxLimitMultiplier,
-		)
+		rfq, err := s.getAssetRfq(ctx, loopOutQuote, request)
 		if err != nil {
 			return nil, err
 		}
 
-		// We'll also want the asset name to verify for the client.
-		assetName, err := s.assetClient.GetAssetName(
-			ctx, rfqReq.AssetId,
-		)
-		if err != nil {
-			return nil, err
-		}
-
-		loopOutQuote.LoopOutRfq = &LoopOutRfq{
-			PrepayRfqId:       prepayRfq.Id,
-			MaxPrepayAssetAmt: prepayRfq.AssetAmount,
-			SwapRfqId:         swapRfq.Id,
-			MaxSwapAssetAmt:   swapRfq.AssetAmount,
-			AssetName:         assetName,
-		}
+		loopOutQuote.LoopOutRfq = rfq
 	}
 
 	return loopOutQuote, nil
@@ -1000,3 +959,77 @@ func (s *Client) AbandonSwap(ctx context.Context,
 
 	return nil
 }
+
+// getAssetRfq returns a prepay and swap rfq for the asset swap.
+func (s *Client) getAssetRfq(ctx context.Context, quote *LoopOutQuote,
+	request *LoopOutQuoteRequest) (*LoopOutRfq, error) {
+
+	if s.assetClient == nil {
+		return nil, errors.New("asset client must be set " +
+			"when trying to loop out with an asset")
+	}
+	rfqReq := request.AssetRFQRequest
+	if rfqReq.Expiry == 0 {
+		rfqReq.Expiry = time.Now().Add(defaultRFQExpiry).Unix()
+	}
+
+	if rfqReq.MaxLimitMultiplier == 0 {
+		rfqReq.MaxLimitMultiplier = defaultRFQMaxLimitMultiplier
+	}
+
+	// First we'll get the prepay rfq.
+	prepayRfq, err := s.assetClient.GetRfqForAsset(
+		ctx, quote.PrepayAmount, rfqReq.AssetId,
+		rfqReq.AssetEdgeNode, rfqReq.Expiry,
+		rfqReq.MaxLimitMultiplier,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	prepayAssetRate, err := rfqrpc.UnmarshalFixedPoint(
+		prepayRfq.BidAssetRate,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// The actual invoice swap amount is the requested amount plus
+	// the swap fee minus the prepay amount.
+	invoiceAmt := request.Amount + quote.SwapFee -
+		quote.PrepayAmount
+
+	swapRfq, err := s.assetClient.GetRfqForAsset(
+		ctx, invoiceAmt, rfqReq.AssetId,
+		rfqReq.AssetEdgeNode, rfqReq.Expiry,
+		rfqReq.MaxLimitMultiplier,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	swapAssetRate, err := rfqrpc.UnmarshalFixedPoint(
+		swapRfq.BidAssetRate,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// We'll also want the asset name to verify for the client.
+	assetName, err := s.assetClient.GetAssetName(
+		ctx, rfqReq.AssetId,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &LoopOutRfq{
+		PrepayRfqId:       prepayRfq.Id,
+		MaxPrepayAssetAmt: prepayRfq.AssetAmount,
+		PrepayAssetRate:   prepayAssetRate,
+		SwapRfqId:         swapRfq.Id,
+		MaxSwapAssetAmt:   swapRfq.AssetAmount,
+		SwapAssetRate:     swapAssetRate,
+		AssetName:         assetName,
+	}, nil
+}

interface.go

@@ -6,6 +6,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/swap"
+	"github.com/lightninglabs/taproot-assets/rfqmath"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/lightningnetwork/lnd/zpay32"
@@ -228,13 +229,20 @@ type LoopOutRfq struct {
 	// used to pay for the prepay invoice.
 	MaxPrepayAssetAmt uint64
 
+	// PrepayAssetRate is the rate at which the asset is exchanged for
+	// bitcoin.
+	PrepayAssetRate *rfqmath.BigIntFixedPoint
+
 	// SwapRfqId is the ID of the swap RFQ.
 	SwapRfqId []byte
 
 	// MaxSwapAssetAmt is the maximum amount of the asset that will be used
 	// to pay for the swap invoice.
 	MaxSwapAssetAmt uint64
 
+	// SwapAssetRate is the rate at which the asset is exchanged for bitcoin.
+	SwapAssetRate *rfqmath.BigIntFixedPoint
+
 	// AssetName is the human readable name of the asset.
 	AssetName string
 }

loopd/swapclient_server.go

@@ -33,6 +33,7 @@ import (
 	"github.com/lightninglabs/loop/staticaddr/withdraw"
 	"github.com/lightninglabs/loop/swap"
 	"github.com/lightninglabs/loop/swapserverrpc"
+	"github.com/lightninglabs/taproot-assets/rfqmath"
 	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/queue"
@@ -804,8 +805,14 @@ func (s *swapClientServer) LoopOutQuote(ctx context.Context,
 		response.AssetRfqInfo = &looprpc.AssetRfqInfo{
 			PrepayRfqId:       quote.LoopOutRfq.PrepayRfqId,
 			MaxPrepayAssetAmt: quote.LoopOutRfq.MaxPrepayAssetAmt,
+			PrepayAssetRate: marshalFixedPoint(
+				quote.LoopOutRfq.PrepayAssetRate,
+			),
 			SwapRfqId:       quote.LoopOutRfq.SwapRfqId,
 			MaxSwapAssetAmt: quote.LoopOutRfq.MaxSwapAssetAmt,
+			SwapAssetRate: marshalFixedPoint(
+				quote.LoopOutRfq.SwapAssetRate,
+			),
 			AssetName: quote.LoopOutRfq.AssetName,
 		}
 	}
@@ -2319,3 +2326,14 @@ func toClientReservation(
 		Expiry:        res.Expiry,
 	}
 }
+
+// marshalFixedpoint marshals a fixed point from the tap rfqmath package to the
+// looprpc package.
+func marshalFixedPoint(bigIntFixedPoint *rfqmath.BigIntFixedPoint,
+) *looprpc.FixedPoint {
+
+	return &looprpc.FixedPoint{
+		Coefficient: bigIntFixedPoint.Coefficient.String(),
+		Scale:       uint32(bigIntFixedPoint.Scale),
+	}
+}