refactor: isolate playback and upload use cases

services/api/internal/playback/personalizer.go

@@ -0,0 +1,58 @@
+package playback
+
+import (
+	"context"
+	"time"
+
+	"github.com/google/uuid"
+
+	"pipu/api/internal/api/gen"
+	"pipu/api/internal/auth"
+	"pipu/api/internal/library"
+	"pipu/api/internal/platform/sign"
+)
+
+type ReactionReader interface {
+	Reactions(context.Context, uuid.UUID, []uuid.UUID) (map[uuid.UUID]string, error)
+}
+
+// Personalizer decorates catalog DTOs independently of HTTP handlers.
+type Personalizer struct {
+	store  ReactionReader
+	signer *sign.Signer
+	now    func() time.Time
+}
+
+var _ library.Personalizer = (*Personalizer)(nil)
+
+func NewPersonalizer(store ReactionReader, signer *sign.Signer) *Personalizer {
+	return &Personalizer{store: store, signer: signer, now: func() time.Time { return time.Now().UTC() }}
+}
+
+// Personalize реализует library.Personalizer.
+func (h *Personalizer) Personalize(ctx context.Context, rows []library.TrackRow, out []gen.Track) error {
+	p, ok := auth.PrincipalFrom(ctx)
+	if !ok {
+		return nil
+	}
+	ids := make([]uuid.UUID, len(rows))
+	for i, r := range rows {
+		ids[i] = r.ID
+	}
+	reactions, err := h.store.Reactions(ctx, p.UserID, ids)
+	if err != nil {
+		return err
+	}
+	now := h.now()
+	for i := range out {
+		if out[i].Available {
+			u := StreamURL(h.signer, p.UserID, rows[i].ID, now)
+			out[i].StreamUrl = &u
+		}
+		if r, ok := reactions[rows[i].ID]; ok {
+			rr := gen.Reaction(r)
+			out[i].Reaction = &rr
+		}
+	}
+	return nil
+}