From 799c428396cef39a4fdb3581f350a1d158930685 Mon Sep 17 00:00:00 2001
From: Chris Gianelloni <wolf31o2@blinklabs.io>
Date: Wed, 8 May 2024 08:58:19 -0400
Subject: [PATCH] feat: endpoints for gRPC watch module for LocalTxMonitor

Signed-off-by: Chris Gianelloni <wolf31o2@blinklabs.io>
---
 internal/utxorpc/api.go   |   3 +
 internal/utxorpc/watch.go | 138 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 internal/utxorpc/watch.go

diff --git a/internal/utxorpc/api.go b/internal/utxorpc/api.go
index e39debc..c877811 100644
--- a/internal/utxorpc/api.go
+++ b/internal/utxorpc/api.go
@@ -19,6 +19,7 @@ import (
 	"net/http"
 
 	"github.com/utxorpc/go-codegen/utxorpc/v1alpha/submit/submitconnect"
+	"github.com/utxorpc/go-codegen/utxorpc/v1alpha/watch/watchconnect"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/h2c"
 
@@ -28,7 +29,9 @@ import (
 func Start(cfg *config.Config) error {
 	mux := http.NewServeMux()
 	submitPath, submitHandler := submitconnect.NewSubmitServiceHandler(&submitServiceServer{})
+	watchPath, watchHandler := watchconnect.NewWatchServiceHandler(&watchServiceServer{})
 	mux.Handle(submitPath, submitHandler)
+	mux.Handle(watchPath, watchHandler)
 	err := http.ListenAndServe(
 		fmt.Sprintf("%s:%d", cfg.Utxorpc.ListenAddress, cfg.Utxorpc.ListenPort),
 		// Use h2c so we can serve HTTP/2 without TLS
diff --git a/internal/utxorpc/watch.go b/internal/utxorpc/watch.go
new file mode 100644
index 0000000..948cfe7
--- /dev/null
+++ b/internal/utxorpc/watch.go
@@ -0,0 +1,138 @@
+// Copyright 2024 Blink Labs Software
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utxorpc
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	connect "connectrpc.com/connect"
+	"github.com/blinklabs-io/adder/event"
+	input_chainsync "github.com/blinklabs-io/adder/input/chainsync"
+	ocommon "github.com/blinklabs-io/gouroboros/protocol/common"
+	watch "github.com/utxorpc/go-codegen/utxorpc/v1alpha/watch"
+	"github.com/utxorpc/go-codegen/utxorpc/v1alpha/watch/watchconnect"
+
+	"github.com/blinklabs-io/cardano-node-api/internal/node"
+)
+
+// watchServiceServer implements the WatchService API
+type watchServiceServer struct {
+	watchconnect.UnimplementedWatchServiceHandler
+}
+
+// WatchTx
+func (s *watchServiceServer) WatchTx(
+	ctx context.Context,
+	req *connect.Request[watch.WatchTxRequest],
+	stream *connect.ServerStream[watch.WatchTxResponse],
+) error {
+	predicate := req.Msg.GetPredicate() // Predicate
+	fieldMask := req.Msg.GetFieldMask()
+	log.Printf("Got a WatchTx request with predicate %v and fieldMask %v", predicate, fieldMask)
+
+	// Setup event channel
+	eventChan := make(chan event.Event, 10)
+	connCfg := node.ConnectionConfig{
+		ChainSyncEventChan: eventChan,
+	}
+	// Connect to node
+	oConn, err := node.GetConnection(&connCfg)
+	if err != nil {
+		log.Printf("ERROR: %s", err)
+		return err
+	}
+	defer func() {
+		// Close Ouroboros connection
+		oConn.Close()
+	}()
+
+	// Get current tip
+	tip, err := oConn.ChainSync().Client.GetCurrentTip()
+	if err != nil {
+		log.Printf("ERROR: %s", err)
+		return err
+	}
+	// Start the sync with the node
+	err = oConn.ChainSync().Client.Sync([]ocommon.Point{tip.Point})
+	if err != nil {
+		log.Printf("ERROR: %s", err)
+		return err
+	}
+
+	// Wait for events
+	for {
+		evt, ok := <-eventChan
+		if !ok {
+			log.Printf("ERROR: channel closed")
+			return fmt.Errorf("ERROR: channel closed")
+		}
+
+		switch evt.Type {
+		case "chainsync.block":
+			// Get event context to get the block chain information
+			context := evt.Context
+			if context == nil {
+				log.Printf("ERROR: empty block context")
+				return fmt.Errorf("ERROR: empty block context")
+			}
+			bc := context.(input_chainsync.BlockContext)
+			// Get event payload to get the block data
+			payload := evt.Payload
+			if payload == nil {
+				log.Printf(
+					"ERROR: empty payload: block: %d, slot: %d",
+					bc.BlockNumber,
+					bc.SlotNumber,
+				)
+				return fmt.Errorf(
+					"ERROR: empty payload: block: %d, slot: %d",
+					bc.BlockNumber,
+					bc.SlotNumber,
+				)
+			}
+			be := payload.(input_chainsync.BlockEvent)
+			block := be.Block // gOuorboros Block
+
+			// Loop through transactions
+			for _, tx := range block.Transactions() {
+				resp := &watch.WatchTxResponse{}
+				var act watch.AnyChainTx
+				var actc watch.AnyChainTx_Cardano
+				cTx := tx.Utxorpc() // *cardano.Tx
+				actc.Cardano = cTx
+				act.Chain = &actc
+				var wtra watch.WatchTxResponse_Apply
+				wtra.Apply = &act
+				resp.Action = &wtra
+				if predicate == nil {
+					err := stream.Send(resp)
+					if err != nil {
+						return err
+					}
+				} else {
+					// TODO: filter from all Predicate types
+					err := stream.Send(resp)
+					if err != nil {
+						return err
+					}
+				}
+			}
+		}
+		// Log event
+		log.Printf("event: %v", evt)
+	}
+}