loopout: use asset client for payment

Author: sputn1ck

loopout.go

@@ -20,9 +20,11 @@ import (
 	"github.com/lightninglabs/loop/sweep"
 	"github.com/lightninglabs/loop/sweepbatcher"
 	"github.com/lightninglabs/loop/utils"
+	"github.com/lightninglabs/taproot-assets/taprpc/tapchannelrpc"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
 )
 
@@ -634,11 +636,16 @@ func (s *loopOutSwap) payInvoices(ctx context.Context) {
 		s.log.Infof("Server recommended routing plugin: %v", pluginType)
 	}
 
+	var useAssetForPayment bool
+	if s.AssetId != nil {
+		useAssetForPayment = true
+	}
+
 	// Use the recommended routing plugin.
 	s.swapPaymentChan = s.payInvoice(
 		ctx, s.SwapInvoice, s.MaxSwapRoutingFee,
 		s.LoopOutContract.OutgoingChanSet,
-		s.LoopOutContract.PaymentTimeout, pluginType, true,
+		s.LoopOutContract.PaymentTimeout, pluginType, true, useAssetForPayment,
 	)
 
 	// Pay the prepay invoice. Won't use the routing plugin here as the
@@ -648,7 +655,7 @@ func (s *loopOutSwap) payInvoices(ctx context.Context) {
 	s.prePaymentChan = s.payInvoice(
 		ctx, s.PrepayInvoice, s.MaxPrepayRoutingFee,
 		s.LoopOutContract.OutgoingChanSet,
-		s.LoopOutContract.PaymentTimeout, RoutingPluginNone, false,
+		s.LoopOutContract.PaymentTimeout, RoutingPluginNone, false, false,
 	)
 }
 
@@ -677,7 +684,7 @@ func (p paymentResult) failure() error {
 func (s *loopOutSwap) payInvoice(ctx context.Context, invoice string,
 	maxFee btcutil.Amount, outgoingChanIds loopdb.ChannelSet,
 	paymentTimeout time.Duration, pluginType RoutingPluginType,
-	reportPluginResult bool) chan paymentResult {
+	reportPluginResult bool, useAsset bool) chan paymentResult {
 
 	resultChan := make(chan paymentResult)
 	sendResult := func(result paymentResult) {
@@ -692,7 +699,7 @@ func (s *loopOutSwap) payInvoice(ctx context.Context, invoice string,
 
 		status, err := s.payInvoiceAsync(
 			ctx, invoice, maxFee, outgoingChanIds, paymentTimeout,
-			pluginType, reportPluginResult,
+			pluginType, reportPluginResult, useAsset,
 		)
 		if err != nil {
 			result.err = err
@@ -717,13 +724,64 @@ func (s *loopOutSwap) payInvoice(ctx context.Context, invoice string,
 	return resultChan
 }
 
+func (s *loopOutSwap) payInvoiceWithAssetClient(ctx context.Context,
+	invoice string) (*lndclient.PaymentStatus, error) {
+
+	totalPaymentTimeout := s.executeConfig.totalPaymentTimeout
+
+	sendReq := &routerrpc.SendPaymentRequest{
+		PaymentRequest: invoice,
+		TimeoutSeconds: int32(totalPaymentTimeout.Seconds()),
+		FeeLimitMsat:   1_000_000,
+	}
+
+	paymentStream, err := s.assets.SendPayment(
+		ctx, &tapchannelrpc.SendPaymentRequest{
+			AssetId:        s.AssetId,
+			PeerPubkey:     s.AssetEdgeNode,
+			PaymentRequest: sendReq,
+		})
+	if err != nil {
+		return nil, err
+	}
+
+	// We want to receive the accepted quote message first, so we know how
+	// many assets we're going to pay.
+	for {
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		default:
+			msg, err := paymentStream.Recv()
+			if err != nil {
+				return nil, err
+			}
+
+			payRes := msg.GetPaymentResult()
+			if payRes == nil {
+				continue
+			}
+
+			return &lndclient.PaymentStatus{
+				State: payRes.Status,
+			}, nil
+		}
+	}
+}
+
 // payInvoiceAsync is the asynchronously executed part of paying an invoice.
 func (s *loopOutSwap) payInvoiceAsync(ctx context.Context,
 	invoice string, maxFee btcutil.Amount,
 	outgoingChanIds loopdb.ChannelSet, paymentTimeout time.Duration,
-	pluginType RoutingPluginType, reportPluginResult bool) (
+	pluginType RoutingPluginType, reportPluginResult bool, useAsset bool) (
 	*lndclient.PaymentStatus, error) {
 
+	// If we want to use an asset for the payment, we need to use the asset
+	// client.
+	if useAsset {
+		return s.payInvoiceWithAssetClient(ctx, invoice)
+	}
+
 	// Extract hash from payment request. Unfortunately the request
 	// components aren't available directly.
 	chainParams := s.lnd.ChainParams