feat: notification service

pkg/notificationintent/publisher.go

@@ -0,0 +1,73 @@
+package notificationintent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/redis/go-redis/v9"
+)
+
+// RedisClient stores the minimal Redis command surface required by Publisher.
+type RedisClient interface {
+	// XAdd appends one entry to a Redis Stream.
+	XAdd(context.Context, *redis.XAddArgs) *redis.StringCmd
+}
+
+// PublisherConfig stores the dependencies and stream name used by Publisher.
+type PublisherConfig struct {
+	// Client appends normalized intents to Redis Streams.
+	Client RedisClient
+
+	// Stream stores the Redis Stream name. When empty, DefaultIntentsStream is
+	// used.
+	Stream string
+}
+
+// Publisher publishes normalized notification intents into the Notification
+// Service ingress stream.
+type Publisher struct {
+	client RedisClient
+	stream string
+}
+
+// NewPublisher constructs a Publisher from cfg.
+func NewPublisher(cfg PublisherConfig) (*Publisher, error) {
+	if cfg.Client == nil {
+		return nil, errors.New("new notification intent publisher: nil redis client")
+	}
+	if cfg.Stream == "" {
+		cfg.Stream = DefaultIntentsStream
+	}
+
+	return &Publisher{
+		client: cfg.Client,
+		stream: cfg.Stream,
+	}, nil
+}
+
+// Publish validates intent and appends it with plain XADD. It does not trim
+// the stream and does not perform hidden retries.
+func (publisher *Publisher) Publish(ctx context.Context, intent Intent) (string, error) {
+	if ctx == nil {
+		return "", errors.New("publish notification intent: nil context")
+	}
+	if publisher == nil || publisher.client == nil {
+		return "", errors.New("publish notification intent: nil publisher")
+	}
+
+	values, err := intent.Values()
+	if err != nil {
+		return "", fmt.Errorf("publish notification intent: %w", err)
+	}
+
+	entryID, err := publisher.client.XAdd(ctx, &redis.XAddArgs{
+		Stream: publisher.stream,
+		Values: values,
+	}).Result()
+	if err != nil {
+		return "", fmt.Errorf("publish notification intent: xadd: %w", err)
+	}
+
+	return entryID, nil
+}