[dashboard] Do not reset panel to undefined or empty last saved state (#203158)

Part of https://github.com/elastic/kibana/issues/201627

This is a short term fix for serverless and 8.x branches (long term fix
is an architectural change that will only be merged into 9.0 and 8.18
branches).

Fix prevents users from reseting a panel edited via embeddable transfer
service. This prevents panel from getting into an invalid state.

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

examples/embeddable_examples/public/app/presentation_container_example/page_api.ts

@@ -250,6 +250,7 @@ export function getPageApi() {
           children$.next(children);
         }
         newPanels = {};
+        return true;
       },
       timeRange$,
       unsavedChanges: unsavedChanges$ as PublishingSubject<object | undefined>,

packages/presentation/presentation_containers/interfaces/unsaved_changes/children_unsaved_changes.test.ts

@@ -14,11 +14,11 @@ import { waitFor } from '@testing-library/react';
 describe('childrenUnsavedChanges$', () => {
   const child1Api = {
     unsavedChanges: new BehaviorSubject<object | undefined>(undefined),
-    resetUnsavedChanges: () => undefined,
+    resetUnsavedChanges: () => true,
   };
   const child2Api = {
     unsavedChanges: new BehaviorSubject<object | undefined>(undefined),
-    resetUnsavedChanges: () => undefined,
+    resetUnsavedChanges: () => true,
   };
   const children$ = new BehaviorSubject<{ [key: string]: unknown }>({});
   const onFireMock = jest.fn();
@@ -99,7 +99,7 @@ describe('childrenUnsavedChanges$', () => {
       ...children$.value,
       child3: {
         unsavedChanges: new BehaviorSubject<object | undefined>({ key1: 'modified value' }),
-        resetUnsavedChanges: () => undefined,
+        resetUnsavedChanges: () => true,
       },
     });
 

packages/presentation/presentation_containers/interfaces/unsaved_changes/initialize_unsaved_changes.ts

@@ -95,10 +95,19 @@ export const initializeUnsavedChanges = <RuntimeState extends {} = {}>(
       unsavedChanges,
       resetUnsavedChanges: () => {
         const lastSaved = lastSavedState$.getValue();
+
+        // Do not reset to undefined or empty last saved state
+        // Temporary fix for https://github.com/elastic/kibana/issues/201627
+        // TODO remove when architecture fix resolves issue.
+        if (comparatorKeys.length && (!lastSaved || Object.keys(lastSaved).length === 0)) {
+          return false;
+        }
+
         for (const key of comparatorKeys) {
           const setter = comparators[key][1]; // setter function is the 1st element of the tuple
           setter(lastSaved?.[key] as RuntimeState[typeof key]);
         }
+        return true;
       },
       snapshotRuntimeState,
     } as PublishesUnsavedChanges<RuntimeState> & HasSnapshottableState<RuntimeState>,

packages/presentation/presentation_publishing/interfaces/publishes_unsaved_changes.ts

@@ -11,7 +11,7 @@ import { PublishingSubject } from '../publishing_subject';
 
 export interface PublishesUnsavedChanges<Runtime extends object = object> {
   unsavedChanges: PublishingSubject<Partial<Runtime> | undefined>;
-  resetUnsavedChanges: () => void;
+  resetUnsavedChanges: () => boolean;
 }
 
 export const apiPublishesUnsavedChanges = (api: unknown): api is PublishesUnsavedChanges => {

src/plugins/controls/public/controls/mocks/control_mocks.ts

@@ -43,7 +43,9 @@ export const getMockedBuildApi =
       uuid,
       parentApi: controlGroupApi ?? getMockedControlGroupApi(),
       unsavedChanges: new BehaviorSubject<Partial<StateType> | undefined>(undefined),
-      resetUnsavedChanges: () => {},
+      resetUnsavedChanges: () => {
+        return true;
+      },
       type: factory.type,
     };
   };

src/plugins/controls/public/controls/timeslider_control/get_timeslider_control_factory.test.tsx

@@ -48,7 +48,9 @@ describe('TimesliderControlApi', () => {
       uuid,
       parentApi: controlGroupApi,
       unsavedChanges: new BehaviorSubject<Partial<TimesliderControlState> | undefined>(undefined),
-      resetUnsavedChanges: () => {},
+      resetUnsavedChanges: () => {
+        return true;
+      },
       type: factory.type,
     };
   }

src/plugins/dashboard/public/dashboard_container/embeddable/dashboard_container.tsx

@@ -68,6 +68,7 @@ import { KibanaRenderContextProvider } from '@kbn/react-kibana-context-render';
 import { LocatorPublic } from '@kbn/share-plugin/common';
 import { ExitFullScreenButtonKibanaProvider } from '@kbn/shared-ux-button-exit-full-screen';
 
+import { i18n } from '@kbn/i18n';
 import { DASHBOARD_CONTAINER_TYPE, DashboardApi, DashboardLocatorParams } from '../..';
 import type { DashboardAttributes } from '../../../server/content_management';
 import { DashboardContainerInput, DashboardPanelMap, DashboardPanelState } from '../../../common';
@@ -957,7 +958,16 @@ export class DashboardContainer
     for (const panelId of Object.keys(currentChildren)) {
       if (this.getInput().panels[panelId]) {
         const child = currentChildren[panelId];
-        if (apiPublishesUnsavedChanges(child)) child.resetUnsavedChanges();
+        if (apiPublishesUnsavedChanges(child)) {
+          const success = child.resetUnsavedChanges();
+          if (!success) {
+            coreServices.notifications.toasts.addWarning(
+              i18n.translate('dashboard.reset.panelError', {
+                defaultMessage: 'Unable to reset panel changes',
+              })
+            );
+          }
+        }
       } else {
         // if reset resulted in panel removal, we need to update the list of children
         delete currentChildren[panelId];