fix pagination not working in legacy modes with kubernetes apis enabled (#112478)

* dashboards: fix pagination not working in legacy modes with kubernetes apis enabled

pkg/registry/apis/dashboard/search.go

@@ -279,8 +279,12 @@ func (s *SearchHandler) DoSearch(w http.ResponseWriter, r *http.Request) {
 	}
 	if queryParams.Has("offset") {
 		offset, _ = strconv.Atoi(queryParams.Get("offset"))
+		if offset > 0 {
+			page = (offset / limit) + 1
+		}
 	} else if queryParams.Has("page") {
 		page, _ = strconv.Atoi(queryParams.Get("page"))
+		offset = (page - 1) * limit
 	}
 
 	searchRequest := &resourcepb.ResourceSearchRequest{

pkg/registry/apis/dashboard/search_test.go

@@ -189,6 +189,98 @@ func TestSearchFallback(t *testing.T) {
 	})
 }
 
+func TestSearchHandlerPagination(t *testing.T) {
+	t.Run("should calculate offset and page parameters", func(t *testing.T) {
+		limit := 50
+		for i, tt := range []struct {
+			offset         int
+			page           int
+			expectedOffset int
+			expectedPage   int
+		}{
+			{
+				offset:         0,
+				page:           0,
+				expectedOffset: 0,
+				expectedPage:   1,
+			},
+			{
+				offset:         0,
+				page:           1,
+				expectedOffset: 0,
+				expectedPage:   1,
+			},
+			{
+				offset:         0,
+				page:           2,
+				expectedOffset: 50,
+				expectedPage:   2,
+			},
+			{
+				offset:         0,
+				page:           3,
+				expectedOffset: 100,
+				expectedPage:   3,
+			},
+			{
+				offset:         50,
+				page:           0,
+				expectedOffset: 50,
+				expectedPage:   2,
+			},
+			{
+				offset:         100,
+				page:           0,
+				expectedOffset: 100,
+				expectedPage:   3,
+			},
+			{
+				offset:         149,
+				page:           0,
+				expectedOffset: 149,
+				expectedPage:   3,
+			},
+			{
+				offset:         150,
+				page:           0,
+				expectedOffset: 150,
+				expectedPage:   4,
+			},
+		} {
+			mockClient := &MockClient{}
+
+			cfg := &setting.Cfg{
+				UnifiedStorage: map[string]setting.UnifiedStorageConfig{
+					"dashboards.dashboard.grafana.app": {DualWriterMode: rest.Mode0},
+				},
+			}
+			dual := dualwrite.ProvideStaticServiceForTests(cfg)
+			searchHandler := NewSearchHandler(tracing.NewNoopTracerService(), dual, mockClient, mockClient, nil)
+
+			rr := httptest.NewRecorder()
+			endpoint := fmt.Sprintf("/search?limit=%d", limit)
+			if tt.offset > 0 {
+				endpoint = fmt.Sprintf("%s&offset=%d", endpoint, tt.offset)
+			}
+			if tt.page > 0 {
+				endpoint = fmt.Sprintf("%s&page=%d", endpoint, tt.page)
+			}
+			req := httptest.NewRequest("GET", endpoint, nil)
+			req.Header.Add("content-type", "application/json")
+			req = req.WithContext(identity.WithRequester(req.Context(), &user.SignedInUser{Namespace: "test"}))
+
+			searchHandler.DoSearch(rr, req)
+
+			if mockClient.LastSearchRequest == nil {
+				t.Fatalf("expected Search to be called, but it was not")
+			}
+
+			require.Equal(t, int(mockClient.LastSearchRequest.Offset), tt.expectedOffset, fmt.Sprintf("mismatch offset in test %d", i))
+			require.Equal(t, int(mockClient.LastSearchRequest.Page), tt.expectedPage, fmt.Sprintf("mismatch page in test %d", i))
+		}
+	})
+}
+
 func TestSearchHandler(t *testing.T) {
 	t.Run("Multiple comma separated fields will be appended to default dashboard search fields", func(t *testing.T) {
 		// Create a mock client