refactor(go): make raw topics the realtime source

go/vehicle-gateway/cmd/nats-kafka-bridge/main.go

@@ -105,7 +105,9 @@ func loadConfig() config {
 		env("NATS_SUBJECT_GB32960_RAW", env("KAFKA_TOPIC_GB32960_RAW", topics.RawGB32960)):            env("KAFKA_TOPIC_GB32960_RAW", topics.RawGB32960),
 		env("NATS_SUBJECT_JT808_RAW", env("KAFKA_TOPIC_JT808_RAW", topics.RawJT808)):                  env("KAFKA_TOPIC_JT808_RAW", topics.RawJT808),
 		env("NATS_SUBJECT_YUTONG_MQTT_RAW", env("KAFKA_TOPIC_YUTONG_MQTT_RAW", topics.RawYutongMQTT)): env("KAFKA_TOPIC_YUTONG_MQTT_RAW", topics.RawYutongMQTT),
-		env("NATS_SUBJECT_UNIFIED", env("KAFKA_TOPIC_UNIFIED", topics.Unified)):                       env("KAFKA_TOPIC_UNIFIED", topics.Unified),
+	}
+	if unifiedSubject, unifiedTopic, ok := unifiedRouteFromEnv(); ok {
+		route[unifiedSubject] = unifiedTopic
 	}
 	return config{
 		NATSURL:        env("NATS_URL", "nats://127.0.0.1:4222"),
@@ -124,6 +126,24 @@ func loadConfig() config {
 	}
 }
 
+func unifiedRouteFromEnv() (string, string, bool) {
+	subject, hasSubject := envOptional("NATS_SUBJECT_UNIFIED")
+	topic, hasTopic := envOptional("KAFKA_TOPIC_UNIFIED")
+	if !hasSubject && !hasTopic {
+		return "", "", false
+	}
+	if subject == "" {
+		subject = topic
+	}
+	if topic == "" {
+		topic = subject
+	}
+	if subject == "" || topic == "" {
+		return "", "", false
+	}
+	return subject, topic, true
+}
+
 type natsPullSubscription interface {
 	Fetch(int, ...nats.PullOpt) ([]*nats.Msg, error)
 }
@@ -290,6 +310,14 @@ func env(key string, fallback string) string {
 	return value
 }
 
+func envOptional(key string) (string, bool) {
+	value, ok := os.LookupEnv(key)
+	if !ok {
+		return "", false
+	}
+	return strings.TrimSpace(value), true
+}
+
 func envInt(key string, fallback int) int {
 	value := strings.TrimSpace(os.Getenv(key))
 	if value == "" {