feat(go): add nats kafka ingest bridge

go/vehicle-gateway/internal/eventbus/nats_sink.go

@@ -0,0 +1,117 @@
+package eventbus
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/nats-io/nats.go"
+
+	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
+)
+
+type NATSConfig struct {
+	URL            string
+	Name           string
+	RawSubjects    map[envelope.Protocol]string
+	UnifiedSubject string
+}
+
+type NATSSink struct {
+	conn           *nats.Conn
+	publisher      natsPublisher
+	rawSubjects    map[envelope.Protocol]string
+	unifiedSubject string
+}
+
+type NATSPublishOption = nats.PubOpt
+
+type natsPublisher interface {
+	Publish(context.Context, string, []byte, ...NATSPublishOption) error
+}
+
+func NewNATSSink(cfg NATSConfig) (*NATSSink, error) {
+	if cfg.URL == "" {
+		return nil, errors.New("nats url is required")
+	}
+	name := cfg.Name
+	if name == "" {
+		name = "lingniu-vehicle-gateway"
+	}
+	conn, err := nats.Connect(cfg.URL, nats.Name(name), nats.Timeout(5*time.Second))
+	if err != nil {
+		return nil, err
+	}
+	js, err := conn.JetStream()
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+	sink := newNATSSinkWithPublisher(natsJetStreamPublisher{js: js}, cfg)
+	sink.conn = conn
+	return sink, nil
+}
+
+func newNATSSinkWithPublisher(publisher natsPublisher, cfg NATSConfig) *NATSSink {
+	rawSubjects := map[envelope.Protocol]string{
+		envelope.ProtocolGB32960:    "vehicle.raw.gb32960.v1",
+		envelope.ProtocolJT808:      "vehicle.raw.jt808.v1",
+		envelope.ProtocolYutongMQTT: "vehicle.raw.yutong-mqtt.v1",
+	}
+	for protocol, subject := range cfg.RawSubjects {
+		if subject != "" {
+			rawSubjects[protocol] = subject
+		}
+	}
+	unifiedSubject := cfg.UnifiedSubject
+	if unifiedSubject == "" {
+		unifiedSubject = "vehicle.event.unified.v1"
+	}
+	return &NATSSink{
+		publisher:      publisher,
+		rawSubjects:    rawSubjects,
+		unifiedSubject: unifiedSubject,
+	}
+}
+
+func (s *NATSSink) PublishRaw(ctx context.Context, env envelope.FrameEnvelope) error {
+	subject, ok := s.rawSubjects[env.Protocol]
+	if !ok || subject == "" {
+		return fmt.Errorf("raw subject not configured for protocol %s", env.Protocol)
+	}
+	return s.publish(ctx, subject, env)
+}
+
+func (s *NATSSink) PublishUnified(ctx context.Context, env envelope.FrameEnvelope) error {
+	if s.unifiedSubject == "" {
+		return errors.New("unified subject is empty")
+	}
+	return s.publish(ctx, s.unifiedSubject, env)
+}
+
+func (s *NATSSink) Close() error {
+	if s == nil || s.conn == nil {
+		return nil
+	}
+	_ = s.conn.Drain()
+	s.conn.Close()
+	return nil
+}
+
+func (s *NATSSink) publish(ctx context.Context, subject string, env envelope.FrameEnvelope) error {
+	payload, err := env.MarshalJSONBytes()
+	if err != nil {
+		return err
+	}
+	return s.publisher.Publish(ctx, subject, payload, nats.MsgId(env.StableEventID()))
+}
+
+type natsJetStreamPublisher struct {
+	js nats.JetStreamContext
+}
+
+func (p natsJetStreamPublisher) Publish(ctx context.Context, subject string, data []byte, opts ...NATSPublishOption) error {
+	_, err := p.js.Publish(subject, data, append(opts, nats.Context(ctx))...)
+	return err
+}