feat: game lobby service

lobby/internal/adapters/redisstate/streamoffsetstore.go

@@ -0,0 +1,78 @@
+package redisstate
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"galaxy/lobby/internal/ports"
+
+	"github.com/redis/go-redis/v9"
+)
+
+// StreamOffsetStore provides the Redis-backed storage used for
+// persisted Redis Stream consumer progress. The key per stream label is
+// produced by Keyspace.StreamOffset.
+type StreamOffsetStore struct {
+	client *redis.Client
+	keys   Keyspace
+}
+
+// NewStreamOffsetStore constructs one Redis-backed stream-offset store.
+func NewStreamOffsetStore(client *redis.Client) (*StreamOffsetStore, error) {
+	if client == nil {
+		return nil, errors.New("new lobby stream offset store: nil redis client")
+	}
+	return &StreamOffsetStore{
+		client: client,
+		keys:   Keyspace{},
+	}, nil
+}
+
+// Load returns the last processed entry id for streamLabel when one is
+// stored.
+func (store *StreamOffsetStore) Load(ctx context.Context, streamLabel string) (string, bool, error) {
+	if store == nil || store.client == nil {
+		return "", false, errors.New("load lobby stream offset: nil store")
+	}
+	if ctx == nil {
+		return "", false, errors.New("load lobby stream offset: nil context")
+	}
+	if strings.TrimSpace(streamLabel) == "" {
+		return "", false, errors.New("load lobby stream offset: stream label must not be empty")
+	}
+
+	value, err := store.client.Get(ctx, store.keys.StreamOffset(streamLabel)).Result()
+	switch {
+	case errors.Is(err, redis.Nil):
+		return "", false, nil
+	case err != nil:
+		return "", false, fmt.Errorf("load lobby stream offset: %w", err)
+	}
+	return value, true, nil
+}
+
+// Save stores entryID as the new offset for streamLabel.
+func (store *StreamOffsetStore) Save(ctx context.Context, streamLabel, entryID string) error {
+	if store == nil || store.client == nil {
+		return errors.New("save lobby stream offset: nil store")
+	}
+	if ctx == nil {
+		return errors.New("save lobby stream offset: nil context")
+	}
+	if strings.TrimSpace(streamLabel) == "" {
+		return errors.New("save lobby stream offset: stream label must not be empty")
+	}
+	if strings.TrimSpace(entryID) == "" {
+		return errors.New("save lobby stream offset: entry id must not be empty")
+	}
+
+	if err := store.client.Set(ctx, store.keys.StreamOffset(streamLabel), entryID, 0).Err(); err != nil {
+		return fmt.Errorf("save lobby stream offset: %w", err)
+	}
+	return nil
+}
+
+// Compile-time interface assertion.
+var _ ports.StreamOffsetStore = (*StreamOffsetStore)(nil)