implement broker

internal/pkg/broker/nats/broker.go

@@ -0,0 +1,101 @@
+package nats
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/jetstream"
+	"github.com/neatflowcv/seven-skies/internal/pkg/broker"
+)
+
+var _ broker.Broker = (*Broker)(nil)
+
+type Broker struct {
+	jet              jetstream.JetStream
+	stream           jetstream.Stream
+	consumerContexts []jetstream.ConsumeContext
+}
+
+// NewBroker url example: nats://127.0.0.1:4222
+func NewBroker(ctx context.Context, url string, streamName string, topics []string) (*Broker, error) {
+	conn, err := nats.Connect(url)
+	if err != nil {
+		return nil, fmt.Errorf("error in connect: %w", err)
+	}
+
+	jet, err := jetstream.New(conn)
+	if err != nil {
+		return nil, fmt.Errorf("error in create jetstream: %w", err)
+	}
+
+	// 같은 이름에 설정이 같으면, 이미 존재하는 스트림을 반환한다. error를 반환하지 않음!
+	stream, err := jet.CreateStream(ctx, jetstream.StreamConfig{ //nolint:exhaustruct
+		Name:     streamName,
+		Subjects: topics,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("error in create stream: %w", err)
+	}
+
+	return &Broker{
+		jet:              jet,
+		stream:           stream,
+		consumerContexts: nil,
+	}, nil
+}
+
+func (b *Broker) Close() {
+	for _, consumerContext := range b.consumerContexts {
+		consumerContext.Stop()
+	}
+}
+
+func (b *Broker) Publish(ctx context.Context, topic string, message []byte) error {
+	_, err := b.jet.Publish(ctx, topic, message)
+	if err != nil {
+		return fmt.Errorf("error in publish: %w", err)
+	}
+
+	return nil
+}
+
+func (b *Broker) Subscribe(ctx context.Context, durable string, fn func(topic string, message []byte) error) error {
+	consumer, err := b.stream.CreateConsumer(ctx, jetstream.ConsumerConfig{ //nolint:exhaustruct
+		Durable:   durable,
+		AckPolicy: jetstream.AckExplicitPolicy,
+	})
+	if err != nil {
+		return fmt.Errorf("error in create consumer: %w", err)
+	}
+
+	consumeContext, err := consumer.Consume(func(msg jetstream.Msg) {
+		topic := msg.Subject()
+		content := msg.Data()
+
+		err := fn(topic, content)
+		if err != nil {
+			log.Println("error in callback", err)
+
+			inErr := msg.Nak()
+			if inErr != nil {
+				log.Println("error in nak", inErr)
+			}
+
+			return
+		}
+
+		inErr := msg.Ack()
+		if inErr != nil {
+			log.Println("error in ack", inErr)
+		}
+	})
+	if err != nil {
+		return fmt.Errorf("error in subscribe: %w", err)
+	}
+
+	b.consumerContexts = append(b.consumerContexts, consumeContext)
+
+	return nil
+}