[hw-6] add notifier service, kafka

loms/internal/infra/messaging/kafka/order_event.go

@@ -0,0 +1,7 @@
+package kafka
+
+type OrderEvent struct {
+	OrderID int64  `json:"order_id"`
+	Status  string `json:"status"`
+	Moment  string `json:"moment"`
+}

loms/internal/infra/messaging/kafka/producer.go

@@ -0,0 +1,110 @@
+package kafka
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"time"
+
+	"route256/loms/internal/domain/entity"
+
+	"github.com/IBM/sarama"
+	"github.com/rs/zerolog/log"
+
+	pb "route256/pkg/api/loms/v1"
+)
+
+type statusProducer struct {
+	topic    string
+	producer sarama.AsyncProducer
+}
+
+func NewStatusProducer(topic string, producer sarama.AsyncProducer) (*statusProducer, error) {
+	p := &statusProducer{topic: topic, producer: producer}
+	go p.runCallbacks()
+
+	return p, nil
+}
+
+func mapOrderStatus(pbStatus string) (string, error) {
+	switch pbStatus {
+	case pb.OrderStatus_ORDER_STATUS_AWAITING_PAYMENT.String():
+		return "awaiting payment", nil
+	case pb.OrderStatus_ORDER_STATUS_CANCELLED.String():
+		return "cancelled", nil
+	case pb.OrderStatus_ORDER_STATUS_FAILED.String():
+		return "failed", nil
+	case pb.OrderStatus_ORDER_STATUS_NEW.String():
+		return "new", nil
+	case pb.OrderStatus_ORDER_STATUS_PAYED.String():
+		return "payed", nil
+	default:
+		return "", fmt.Errorf("unexpected OrderStatus: %v", pbStatus)
+	}
+}
+
+func (p *statusProducer) runCallbacks() {
+	for {
+		select {
+		case err, ok := <-p.producer.Errors():
+			if !ok {
+				return
+			}
+
+			log.Error().Err(err).Msgf("kafka publish error")
+		case _, ok := <-p.producer.Successes():
+			if !ok {
+				return
+			}
+
+			// TODO: add msg metrics (latency/partition/offset)
+		}
+	}
+}
+
+func (p *statusProducer) Send(ctx context.Context, id entity.ID, status string) error {
+	log.Debug().Msgf("sending event for id: %d; status: %s", id, status)
+
+	newStatus, err := mapOrderStatus(status)
+	if err != nil {
+		return err
+	}
+
+	evt := OrderEvent{
+		OrderID: int64(id),
+		Status:  newStatus,
+		Moment:  time.Now().UTC().Format(time.RFC3339Nano),
+	}
+
+	value, err := json.Marshal(evt)
+	if err != nil {
+		return fmt.Errorf("marshal event: %w", err)
+	}
+
+	return p.SendRaw(ctx, id, value)
+}
+
+func (p *statusProducer) SendRaw(ctx context.Context, id entity.ID, value []byte) error {
+	if len(value) == 0 {
+		return fmt.Errorf("empty message value")
+	}
+
+	msg := &sarama.ProducerMessage{
+		Topic:     p.topic,
+		Key:       sarama.StringEncoder(strconv.FormatInt(int64(id), 10)),
+		Value:     sarama.ByteEncoder(value),
+		Timestamp: time.Now(),
+	}
+
+	select {
+	case p.producer.Input() <- msg:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func (p *statusProducer) Close() error {
+	return p.producer.Close()
+}