added gifs preview

internal/admin/service.go

@@ -2904,6 +2904,32 @@ func (s *Service) StickerDocumentAnimation(ctx context.Context, documentID int64
 	return data, detected, true, nil
 }
 
+// GifCatalogDocumentPreview returns a gif_catalog entry's document bytes for
+// the admin panel's list-page preview, plus the content type to serve it as.
+// Unlike StickerDocumentAnimation there is no gzip/Lottie branch to consider:
+// every document AdminUploadGifMaterial creates is already a plain H.264 MP4
+// (see gif_admin.go), so this only needs to fetch and sanity-check the blob.
+func (s *Service) GifCatalogDocumentPreview(ctx context.Context, documentID int64) ([]byte, string, bool, error) {
+	if s == nil || s.photos == nil || documentID <= 0 {
+		return nil, "", false, nil
+	}
+	chunk, found, err := s.photos.GetFile(ctx, domain.FileDownloadRequest{
+		LocationKey: fmt.Sprintf("doc:%d", documentID),
+		Limit:       domain.MaxGifCatalogUploadSize + 1,
+	})
+	if err != nil {
+		return nil, "", false, err
+	}
+	if !found || chunk.Total <= 0 || chunk.Total > domain.MaxGifCatalogUploadSize || int64(len(chunk.Bytes)) != chunk.Total {
+		return nil, "", false, nil
+	}
+	detected := http.DetectContentType(chunk.Bytes)
+	if detected != "video/mp4" && !strings.HasPrefix(detected, "video/") {
+		return nil, "", false, nil
+	}
+	return chunk.Bytes, detected, true, nil
+}
+
 func isSafeStickerPreviewImageType(value string) bool {
 	switch value {
 	case "image/webp", "image/png", "image/jpeg", "image/gif":

internal/adminapi/server.go

@@ -75,6 +75,7 @@ type Service interface {
 	AddStickerToSet(ctx context.Context, req admin.AddStickerToSetRequest) (admin.CommandResult, error)
 	RemoveStickerFromSet(ctx context.Context, req admin.RemoveStickerFromSetRequest) (admin.CommandResult, error)
 	StickerDocumentAnimation(ctx context.Context, documentID int64) ([]byte, string, bool, error)
+	GifCatalogDocumentPreview(ctx context.Context, documentID int64) ([]byte, string, bool, error)
 	CreateGifCatalogEntry(ctx context.Context, req admin.CreateGifCatalogEntryRequest) (admin.CommandResult, error)
 	SetGifCatalogEnabled(ctx context.Context, req admin.SetGifCatalogEnabledRequest) (admin.CommandResult, error)
 	SetGifCatalogSortOrder(ctx context.Context, req admin.SetGifCatalogSortOrderRequest) (admin.CommandResult, error)
@@ -212,6 +213,7 @@ func (s *Server) routes() http.Handler {
 	mux.HandleFunc("POST /v1/gif-catalog/set-sort-order", s.authenticated(s.handleSetGifCatalogSortOrder))
 	mux.HandleFunc("POST /v1/gif-catalog/delete", s.authenticated(s.handleDeleteGifCatalogEntry))
 	mux.HandleFunc("GET /v1/stickers/documents/{id}/animation", s.authenticated(s.handleStickerDocumentAnimation))
+	mux.HandleFunc("GET /v1/gif-catalog/documents/{id}/preview", s.authenticated(s.handleGifCatalogDocumentPreview))
 	mux.HandleFunc("GET /v1/emoji/{id}/animation", s.authenticated(s.handleEmojiAnimation))
 	mux.HandleFunc("GET /v1/moderation/cases", s.authenticated(s.handleModerationCases))
 	mux.HandleFunc("GET /v1/moderation/cases/{id}", s.authenticated(s.handleModerationCase))
@@ -783,6 +785,27 @@ func (s *Server) handleStickerDocumentAnimation(w http.ResponseWriter, r *http.R
 	_, _ = w.Write(raw)
 }
 
+func (s *Server) handleGifCatalogDocumentPreview(w http.ResponseWriter, r *http.Request) {
+	documentID, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	if err != nil || documentID <= 0 {
+		writeError(w, http.StatusBadRequest, "invalid document id")
+		return
+	}
+	raw, contentType, found, err := s.svc.GifCatalogDocumentPreview(r.Context(), documentID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if !found {
+		writeError(w, http.StatusNotFound, "gif document not found")
+		return
+	}
+	w.Header().Set("Content-Type", contentType)
+	w.Header().Set("Cache-Control", "private, max-age=300")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(raw)
+}
+
 func (s *Server) handleEmojiAnimation(w http.ResponseWriter, r *http.Request) {
 	documentID, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
 	if err != nil || documentID <= 0 {

internal/adminapi/server_test.go

@@ -444,6 +444,10 @@ func (fakeService) StickerDocumentAnimation(context.Context, int64) ([]byte, str
 	return nil, "", false, nil
 }
 
+func (fakeService) GifCatalogDocumentPreview(context.Context, int64) ([]byte, string, bool, error) {
+	return nil, "", false, nil
+}
+
 func (fakeService) CreateGifCatalogEntry(_ context.Context, req admin.CreateGifCatalogEntryRequest) (admin.CommandResult, error) {
 	return admin.CommandResult{CommandID: req.CommandID, Status: "completed", DryRun: req.DryRun}, nil
 }