rpcserver: AddInvoice uses groupkey

In this commit we take the user defined group key and allow the asset
specifier to be created over it. All the calls that accept it as an
argument are already groupkey aware.

Author: GeorgeTsagk

rpcserver.go

@@ -7687,13 +7687,29 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 	}
 	iReq := req.InvoiceRequest
 
-	// Do some preliminary checks on the asset ID and make sure we have any
-	// balance for that asset.
-	if len(req.AssetId) != sha256.Size {
-		return nil, fmt.Errorf("asset ID must be 32 bytes")
+	var specifier asset.Specifier
+
+	switch {
+	case len(req.AssetId) > 0 && len(req.GroupKey) > 0:
+		return nil, fmt.Errorf("cannot set both asset id and group key")
+
+	case len(req.AssetId) > 0:
+		if len(req.AssetId) != sha256.Size {
+			return nil, fmt.Errorf("asset ID must be 32 bytes")
+		}
+		var assetID asset.ID
+		copy(assetID[:], req.AssetId)
+		specifier = asset.NewSpecifierFromId(assetID)
+
+	case len(req.GroupKey) > 0:
+		groupKey, err := btcec.ParsePubKey(req.GroupKey)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse group key: %w",
+				err)
+		}
+		specifier = asset.NewSpecifierFromGroupKey(*groupKey)
+
 	}
-	var assetID asset.ID
-	copy(assetID[:], req.AssetId)
 
 	// The peer public key is optional if there is only a single asset
 	// channel.
@@ -7708,8 +7724,6 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		peerPubKey = &parsedKey
 	}
 
-	specifier := asset.NewSpecifierFromId(assetID)
-
 	// We can now query the asset channels we have.
 	assetChan, err := r.rfqChannel(
 		ctx, specifier, peerPubKey, ReceiveIntention,
@@ -7731,15 +7745,32 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		time.Duration(expirySeconds) * time.Second,
 	)
 
-	resp, err := r.AddAssetBuyOrder(ctx, &rfqrpc.AddAssetBuyOrderRequest{
-		AssetSpecifier: &rfqrpc.AssetSpecifier{
+	var rpcSpecifier rfqrpc.AssetSpecifier
+
+	switch {
+	case specifier.HasId():
+		assetID := specifier.UnwrapIdToPtr()
+		rpcSpecifier = rfqrpc.AssetSpecifier{
 			Id: &rfqrpc.AssetSpecifier_AssetId{
 				AssetId: assetID[:],
 			},
-		},
-		AssetMaxAmt: req.AssetAmount,
-		Expiry:      uint64(expiryTimestamp.Unix()),
-		PeerPubKey:  peerPubKey[:],
+		}
+
+	case specifier.HasGroupPubKey():
+		groupKey := specifier.UnwrapGroupKeyToPtr()
+		groupKeyBytes := groupKey.SerializeCompressed()
+		rpcSpecifier = rfqrpc.AssetSpecifier{
+			Id: &rfqrpc.AssetSpecifier_GroupKey{
+				GroupKey: groupKeyBytes,
+			},
+		}
+	}
+
+	resp, err := r.AddAssetBuyOrder(ctx, &rfqrpc.AddAssetBuyOrderRequest{
+		AssetSpecifier: &rpcSpecifier,
+		AssetMaxAmt:    req.AssetAmount,
+		Expiry:         uint64(expiryTimestamp.Unix()),
+		PeerPubKey:     peerPubKey[:],
 		TimeoutSeconds: uint32(
 			rfq.DefaultTimeout.Seconds(),
 		),