loopin: refactor LoopIn to return struct instead of tuple

Author: bhandras

client.go

@@ -464,15 +464,15 @@ func (s *Client) waitForInitialized(ctx context.Context) error {
 
 // LoopIn initiates a loop in swap.
 func (s *Client) LoopIn(globalCtx context.Context,
-	request *LoopInRequest) (*lntypes.Hash, btcutil.Address, error) {
+	request *LoopInRequest) (*LoopInSwapInfo, error) {
 
 	log.Infof("Loop in %v (last hop: %v)",
 		request.Amount,
 		request.LastHop,
 	)
 
 	if err := s.waitForInitialized(globalCtx); err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
 	// Create a new swap object for this swap.
@@ -486,15 +486,19 @@ func (s *Client) LoopIn(globalCtx context.Context,
 		globalCtx, &swapCfg, initiationHeight, request,
 	)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
 	// Post swap to the main loop.
 	s.executor.initiateSwap(globalCtx, swap)
 
 	// Return hash so that the caller can identify this swap in the updates
 	// stream.
-	return &swap.hash, swap.htlc.Address, nil
+	swapInfo := &LoopInSwapInfo{
+		SwapHash:    swap.hash,
+		HtlcAddress: swap.htlc.Address,
+	}
+	return swapInfo, nil
 }
 
 // LoopInQuote takes an amount and returns a break down of estimated

interface.go

@@ -235,6 +235,17 @@ type LoopInQuote struct {
 	CltvDelta int32
 }
 
+// LoopInSwapInfo contains essential information of a loop-in swap after the
+// swap is initiated.
+type LoopInSwapInfo struct { // nolint
+	// SwapHash contains the sha256 hash of the swap preimage.
+	SwapHash lntypes.Hash
+
+	// HtlcAddress contains the swap htlc address, where the loop-in
+	// funds will be paid.
+	HtlcAddress btcutil.Address
+}
+
 // SwapInfoKit contains common swap info fields.
 type SwapInfoKit struct {
 	// Hash is the sha256 hash of the preimage that unlocks the htlcs. It

loopd/swapclient_server.go

@@ -409,16 +409,16 @@ func (s *swapClientServer) LoopIn(ctx context.Context,
 		}
 		req.LastHop = &lastHop
 	}
-	hash, htlc, err := s.impl.LoopIn(ctx, req)
+	swapInfo, err := s.impl.LoopIn(ctx, req)
 	if err != nil {
 		log.Errorf("Loop in: %v", err)
 		return nil, err
 	}
 
 	return &looprpc.SwapResponse{
-		Id:          hash.String(),
-		IdBytes:     hash[:],
-		HtlcAddress: htlc.String(),
+		Id:          swapInfo.SwapHash.String(),
+		IdBytes:     swapInfo.SwapHash[:],
+		HtlcAddress: swapInfo.HtlcAddress.String(),
 	}, nil
 }