service backend

api/pkg/messaging/internal/natsb/NATS.go

@@ -0,0 +1,86 @@
+package natsb
+
+import (
+	me "github.com/tech/sendico/pkg/messaging/envelope"
+	"github.com/tech/sendico/pkg/model"
+	"github.com/tech/sendico/pkg/mutil/mzap"
+	"go.uber.org/zap"
+)
+
+func (b *NatsBroker) Publish(envelope me.Envelope) error {
+	subject := envelope.GetSignature().ToString()
+	b.logger.Debug("Publishing message", mzap.Envelope(envelope))
+
+	// Serialize the message
+	data, err := envelope.Serialize()
+	if err != nil {
+		b.logger.Error("Failed to serialize message", zap.Error(err), mzap.Envelope(envelope))
+		return err
+	}
+
+	if err := b.nc.Publish(subject, data); err != nil {
+		b.logger.Error("Error publishing message", zap.Error(err), mzap.Envelope(envelope))
+		return err
+	}
+
+	b.logger.Debug("Message published", zap.String("subject", subject))
+	return nil
+}
+
+// Subscribe subscribes to a NATS subject and returns a channel for messages
+func (b *NatsBroker) Subscribe(event model.NotificationEvent) (<-chan me.Envelope, error) {
+	subject := event.ToString()
+	b.logger.Info("Subscribing to subject", zap.String("subject", subject))
+
+	// Create a bidirectional channel to send messages to
+	messageChan := make(chan me.Envelope)
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	topicSub, exists := b.topicSubs[subject]
+	if !exists {
+		var err error
+		topicSub, err = NewTopicSubscription(b.logger, b.nc, subject)
+		if err != nil {
+			return nil, err
+		}
+		b.topicSubs[subject] = topicSub
+	}
+
+	// Add the consumer's channel to the topic subscription
+	topicSub.AddConsumer(messageChan)
+
+	// Return the channel as a receive-only channel
+	return messageChan, nil
+}
+
+// Unsubscribe unsubscribes a consumer from a NATS subject
+func (b *NatsBroker) Unsubscribe(event model.NotificationEvent, messageChan <-chan me.Envelope) error {
+	subject := event.ToString()
+	b.logger.Info("Unsubscribing from subject", zap.String("subject", subject))
+
+	b.mu.Lock()
+	topicSub, exists := b.topicSubs[subject]
+	b.mu.Unlock()
+	if !exists {
+		b.logger.Warn("No subscription found for subject", zap.String("subject", subject))
+		return nil
+	}
+
+	// Remove the consumer's channel from the topic subscription
+	topicSub.RemoveConsumer(messageChan)
+	if !topicSub.HasConsumers() {
+		if err := topicSub.Unsubscribe(); err != nil {
+			b.logger.Error("Error unsubscribing from subject", zap.String("subject", subject), zap.Error(err))
+			return err
+		}
+
+		b.mu.Lock()
+		delete(b.topicSubs, subject)
+		b.mu.Unlock()
+	}
+
+	b.logger.Info("Unsubscribed from subject", zap.String("subject", subject))
+	return nil
+}