✨ Expand Docker Compose development stack to include observability tools: OpenTelemetry Collector, Jaeger, Prometheus, and Grafana. Update README with new usage instructions for the observability stack and enhance Taskfile for streamlined development commands. Introduce sample telegram generation utility and improve NATS configuration for core and JetStream modes.

internal/infra/nats/consumer.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/nats-io/nats.go"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
@@ -26,6 +27,7 @@ type Consumer struct {
 	logger       *zap.Logger
 	subject      string
 	consumerName string
+	mode         string
 	meter        metric.Meter
 	ackPending   metric.Int64Histogram
 	redelivered  metric.Int64Histogram
@@ -48,6 +50,11 @@ func ProvideConsumer(
 		consumerName = "telegram-consumer"
 	}
 
+	mode := strings.ToLower(cfg.NATS.Mode)
+	if mode == "" {
+		mode = "jetstream"
+	}
+
 	consumer := &Consumer{
 		conn:         conn,
 		js:           js,
@@ -56,12 +63,20 @@ func ProvideConsumer(
 		logger:       logger,
 		subject:      subject,
 		consumerName: consumerName,
+		mode:         mode,
 	}
 	consumer.initMetrics()
 
-	// Create consumer if it doesn't exist
-	if err := consumer.ensureConsumer(); err != nil {
-		return nil, fmt.Errorf("failed to ensure consumer: %w", err)
+	if consumer.mode == "jetstream" {
+		// Create consumer if it doesn't exist
+		if err := consumer.ensureConsumer(); err != nil {
+			return nil, fmt.Errorf("failed to ensure consumer: %w", err)
+		}
+	} else {
+		logger.Info("Running consumer in core NATS mode",
+			zap.String("subject", subject),
+			zap.String("queue_group", cfg.Subscription.QueueGroup),
+		)
 	}
 
 	return consumer, nil
@@ -130,6 +145,14 @@ func (c *Consumer) ensureConsumer() error {
 
 // Start starts consuming messages
 func (c *Consumer) Start(ctx context.Context) error {
+	if c.mode == "core" {
+		return c.startCore(ctx)
+	}
+
+	return c.startJetStream(ctx)
+}
+
+func (c *Consumer) startJetStream(ctx context.Context) error {
 	streamName := c.cfg.NATS.Stream
 	if streamName == "" {
 		streamName = "TELEGRAM"
@@ -224,6 +247,46 @@ func (c *Consumer) Start(ctx context.Context) error {
 	}
 }
 
+func (c *Consumer) startCore(ctx context.Context) error {
+	queueGroup := c.cfg.Subscription.QueueGroup
+	if queueGroup == "" {
+		queueGroup = c.consumerName
+	}
+
+	handler := func(msg *nats.Msg) {
+		if err := c.processMessage(ctx, msg); err != nil {
+			isPermanent := app.IsPermanent(err)
+			c.logger.Error("Failed to process message (core mode)",
+				zap.String("subject", msg.Subject),
+				zap.Error(err),
+				zap.Bool("permanent", isPermanent),
+			)
+		}
+	}
+
+	sub, err := c.conn.QueueSubscribe(c.subject, queueGroup, handler)
+	if err != nil {
+		return fmt.Errorf("failed to subscribe to %s: %w", c.subject, err)
+	}
+	if err := c.conn.Flush(); err != nil {
+		return fmt.Errorf("failed to flush NATS connection: %w", err)
+	}
+
+	c.logger.Info("Started core NATS subscription",
+		zap.String("subject", c.subject),
+		zap.String("queue_group", queueGroup),
+	)
+
+	<-ctx.Done()
+	c.logger.Info("Stopping core NATS consumer", zap.Error(ctx.Err()))
+
+	if err := sub.Drain(); err != nil && !errors.Is(err, nats.ErrConnectionClosed) {
+		return fmt.Errorf("failed to drain core subscription: %w", err)
+	}
+
+	return ctx.Err()
+}
+
 func (c *Consumer) emitConsumerStats(ctx context.Context, streamName string) {
 	interval := c.cfg.App.MonitorInterval
 	if interval <= 0 {
@@ -393,6 +456,10 @@ func (c *Consumer) resolveMsgID(msg *nats.Msg) (string, string, error) {
 		return id, "header", nil
 	}
 
+	if c.mode == "core" {
+		return uuid.NewString(), "generated", nil
+	}
+
 	meta, err := msg.Metadata()
 	if err != nil {
 		return "", "", fmt.Errorf("fetch metadata: %w", err)