✨ Refactor application initialization to load configuration and enhance message processing. Introduce effective subscription topic handling and improve error management in NATS consumer. Update tests for publisher error handling and add new dependency injection method for app initialization.

internal/infra/nats/consumer.go

@@ -30,10 +30,7 @@ func ProvideConsumer(
 	cfg *config.Config,
 	logger *zap.Logger,
 ) (*Consumer, error) {
-	subject := cfg.Subscription.Topic
-	if subject == "" {
-		subject = "telegram.>"
-	}
+	subject := cfg.EffectiveSubscriptionTopic()
 
 	consumerName := cfg.NATS.Consumer
 	if consumerName == "" {
@@ -170,8 +167,8 @@ func (c *Consumer) Start(ctx context.Context) error {
 				)
 
 				if isPermanent {
-					if termErr := msg.Term(); termErr != nil {
-						c.logger.Error("Failed to TERM message", zap.Error(termErr))
+					if ackErr := msg.Ack(); ackErr != nil {
+						c.logger.Error("Failed to ACK permanent-error message", zap.Error(ackErr))
 					}
 					continue
 				}
@@ -255,14 +252,16 @@ func (c *Consumer) Shutdown(ctx context.Context) error {
 
 // processMessage processes a single message
 func (c *Consumer) processMessage(ctx context.Context, msg *nats.Msg) error {
-	msgID := msg.Header.Get("Nats-Msg-Id")
-	if msgID == "" {
-		// Use reply subject or generate a simple ID
-		if msg.Reply != "" {
-			msgID = msg.Reply
-		} else {
-			msgID = fmt.Sprintf("msg-%d", time.Now().UnixNano())
-		}
+	msgID, source, err := c.resolveMsgID(msg)
+	if err != nil {
+		return fmt.Errorf("unable to resolve message id: %w", err)
+	}
+	if source != "header" {
+		c.logger.Warn("Message missing NATS id header; using fallback",
+			zap.String("subject", msg.Subject),
+			zap.String("msg_id_source", source),
+			zap.String("msg_id", msgID),
+		)
 	}
 
 	c.logger.Debug("Processing message",
@@ -278,3 +277,16 @@ func (c *Consumer) processMessage(ctx context.Context, msg *nats.Msg) error {
 
 	return nil
 }
+
+func (c *Consumer) resolveMsgID(msg *nats.Msg) (string, string, error) {
+	if id := msg.Header.Get("Nats-Msg-Id"); id != "" {
+		return id, "header", nil
+	}
+
+	meta, err := msg.Metadata()
+	if err != nil {
+		return "", "", fmt.Errorf("fetch metadata: %w", err)
+	}
+
+	return fmt.Sprintf("js-%d", meta.Sequence.Stream), "metadata", nil
+}