[Discover] Create Discover Shared plugin and features registry

.github/CODEOWNERS

@@ -369,6 +369,7 @@ examples/developer_examples @elastic/appex-sharedux
 examples/discover_customization_examples @elastic/kibana-data-discovery
 x-pack/plugins/discover_enhanced @elastic/kibana-data-discovery
 src/plugins/discover @elastic/kibana-data-discovery
+src/plugins/discover_shared @elastic/kibana-data-discovery
 packages/kbn-discover-utils @elastic/kibana-data-discovery
 packages/kbn-doc-links @elastic/docs
 packages/kbn-docs-utils @elastic/kibana-operations

docs/developer/plugin-list.asciidoc

@@ -94,6 +94,10 @@ This API doesn't support angular, for registering angular dev tools, bootstrap a
 |Contains the Discover application and the saved search embeddable.
 
 
+|{kib-repo}blob/{branch}/src/plugins/discover_shared/README.md[discoverShared]
+|A stateful layer to register shared features and provide an access point to discover without a direct dependency.
+
+
 |{kib-repo}blob/{branch}/src/plugins/embeddable/README.md[embeddable]
 |The Embeddables Plugin provides an opportunity to expose reusable interactive widgets that can be embedded outside the original plugin.
 

package.json

@@ -419,6 +419,7 @@
     "@kbn/discover-customization-examples-plugin": "link:examples/discover_customization_examples",
     "@kbn/discover-enhanced-plugin": "link:x-pack/plugins/discover_enhanced",
     "@kbn/discover-plugin": "link:src/plugins/discover",
+    "@kbn/discover-shared-plugin": "link:src/plugins/discover_shared",
     "@kbn/discover-utils": "link:packages/kbn-discover-utils",
     "@kbn/doc-links": "link:packages/kbn-doc-links",
     "@kbn/dom-drag-drop": "link:packages/kbn-dom-drag-drop",

packages/kbn-optimizer/limits.yml

@@ -37,6 +37,7 @@ pageLoadAssetSize:
   devTools: 38637
   discover: 99999
   discoverEnhanced: 42730
+  discoverShared: 17111
   embeddable: 87309
   embeddableEnhanced: 22107
   enterpriseSearch: 50858
@@ -143,7 +144,7 @@ pageLoadAssetSize:
   snapshotRestore: 79032
   spaces: 57868
   stackAlerts: 58316
-  stackConnectors: 52131
+  stackConnectors: 67227
   synthetics: 40958
   telemetry: 51957
   telemetryManagementSection: 38586

src/plugins/discover_shared/README.md

@@ -0,0 +1,90 @@
+# Discover Shared
+
+A stateful layer to register shared features and provide an access point to discover without a direct dependency.
+
+## Register new features
+
+The plugin exposes a service to register features that can be opinionatedly used in Discover on both the setup and start lifecycle hooks.
+
+Although this allows for greater flexibility, its purpose is not to customize Discover as a default choice but to be used as a solution to prevent cyclic dependency between plugins that interact with Discover.
+
+To register a new feature, let's take a more practical case.
+
+> _We want to introduce the LogsAIAssistant in the Discover flyout. Porting all the logic of the Observability AI Assistant into Discover is not an option, and we don't want Discover to directly depend on the AI Assistant codebase._
+
+We can solve this case with some steps:
+
+### Define a feature registration contract
+
+First of all, we need to define an interface to which the plugin registering the AI Assistant and Discover can adhere.
+
+The `DiscoverFeaturesService` already defines a union of available features and uses them to strictly type the exposed registry from the discover_shared plugin, so we can update it with the new feature:
+
+```tsx
+// src/plugins/discover_shared/public/services/discover_features/types.ts
+
+export interface SecurityAIAssistantFeature {
+  id: 'security-ai-assistant';
+  render: (/* Update with deps required for this integration */) => React.ReactNode;
+  // Add any prop required for the feature
+}
+
+export interface ObservabilityLogsAIAssistantFeature {
+  id: 'observability-logs-ai-assistant';
+  render: (deps: {doc: DataTableRecord}) => React.ReactNode;
+  // Add any prop required for the feature
+}
+
+// This should be a union of all the available client features.
+export type DiscoverFeature = SecurityAIAssistantFeature | ObservabilityLogsAIAssistantFeature;
+```
+
+### Discover consumes the registered feature
+
+Once we have an interface for the feature, Discover can now retrieve it and use its content if is registered by any app in Kibana.
+
+```tsx
+// Somewhere in the unified doc viewer
+
+function LogsOverviewAIAssistant ({ doc }) {
+  const { discoverShared } = getUnifiedDocViewerServices();
+
+  const logsAIAssistantFeature = discoverShared.features.registry.getById('observability-logs-ai-assistant')
+
+  if (logsAIAssistantFeature) {
+    return logsAIAssistantFeature.render({ doc })
+  }
+}
+```
+
+### Register the feature
+
+Having an interface for the feature and Discover consuming its definition, we are left with the registration part.
+
+For our example, we'll go to the logs app that owns the LogsAIAssistant codebase and register the feature:
+
+```tsx
+// x-pack/plugins/observability_solution/logs_shared/public/plugin.ts
+
+export class LogsSharedPlugin implements LogsSharedClientPluginClass {
+  // The rest of the plugin implementation is hidden for a cleaner example
+
+  public start(core: CoreStart, plugins: LogsSharedClientStartDeps) {
+    const {  observabilityAIAssistant } = plugins;
+
+    const LogAIAssistant = createLogAIAssistant({ observabilityAIAssistant });
+
+    // Strict typing on the registry will let you know which features you can register
+    plugins.discoverShared.features.registry.register({
+      id: 'observability-logs-ai-assistant',
+      render: ({doc}) => <LogAIAssistant doc={doc}/>
+    })
+
+    return {
+      LogAIAssistant,
+    };
+  }
+}
+```
+
+At this point, the feature should work correctly when registered and we have not created any direct dependency between the Discover and LogsShared apps.

src/plugins/discover_shared/common/features_registry/features_registry.test.tsx

@@ -0,0 +1,58 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { FeaturesRegistry } from './features_registry';
+
+type TestFeature =
+  | { id: 'feature-id-1'; adHocProperty1?: string }
+  | { id: 'feature-id-2'; adHocProperty2?: string }
+  | { id: 'feature-id-3'; adHocProperty3?: string };
+
+describe('FeaturesRegistry', () => {
+  describe('#register', () => {
+    test('should add a feature to the registry', () => {
+      const registry = new FeaturesRegistry<TestFeature>();
+
+      registry.register({ id: 'feature-id-1' });
+
+      expect(registry.getById('feature-id-1')).toBeDefined();
+    });
+
+    test('should throw an error when a feature is already registered by the given id', () => {
+      const registry = new FeaturesRegistry<TestFeature>();
+
+      registry.register({ id: 'feature-id-1' });
+
+      expect(() => registry.register({ id: 'feature-id-1' })).toThrow(
+        'FeaturesRegistry#register: feature with id "feature-id-1" already exists in the registry.'
+      );
+    });
+  });
+
+  describe('#getById', () => {
+    test('should retrieve a feature by its id', () => {
+      const registry = new FeaturesRegistry<TestFeature>();
+
+      registry.register({ id: 'feature-id-1', adHocProperty1: 'test' });
+      registry.register({ id: 'feature-id-2', adHocProperty2: 'test' });
+
+      expect(registry.getById('feature-id-1')).toEqual({
+        id: 'feature-id-1',
+        adHocProperty1: 'test',
+      });
+    });
+
+    test('should return undefined if there is no feature registered by the given id', () => {
+      const registry = new FeaturesRegistry<TestFeature>();
+
+      registry.register({ id: 'feature-id-1' });
+
+      expect(registry.getById('feature-id-2')).toBeUndefined();
+    });
+  });
+});

src/plugins/discover_shared/common/features_registry/features_registry.ts

@@ -0,0 +1,26 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+import { BaseFeature } from './types';
+
+export class FeaturesRegistry<Feature extends BaseFeature = BaseFeature> {
+  private readonly features = new Map<Feature['id'], Feature>();
+
+  register(feature: Feature): void {
+    if (this.features.has(feature.id)) {
+      throw new Error(
+        `FeaturesRegistry#register: feature with id "${feature.id}" already exists in the registry.`
+      );
+    }
+
+    this.features.set(feature.id, feature);
+  }
+
+  getById<Id extends Feature['id']>(id: Id) {
+    return this.features.get(id) as Extract<Feature, { id: Id }> | undefined;
+  }
+}

src/plugins/discover_shared/common/features_registry/index.ts

@@ -0,0 +1,9 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+export { FeaturesRegistry } from './features_registry';

src/plugins/discover_shared/common/features_registry/types.ts

@@ -0,0 +1,11 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+export interface BaseFeature {
+  id: string;
+}

src/plugins/discover_shared/common/index.ts

@@ -0,0 +1,9 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+export { FeaturesRegistry } from './features_registry';

src/plugins/discover_shared/jest.config.js

@@ -0,0 +1,18 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+module.exports = {
+  preset: '@kbn/test',
+  rootDir: '../../..',
+  roots: ['<rootDir>/src/plugins/discover_shared'],
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/discover_shared',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: [
+    '<rootDir>/src/plugins/discover_shared/{common,public,server}/**/*.{js,ts,tsx}',
+  ],
+};

src/plugins/discover_shared/kibana.jsonc

@@ -0,0 +1,13 @@
+{
+  "type": "plugin",
+  "id": "@kbn/discover-shared-plugin",
+  "owner": "@elastic/kibana-data-discovery",
+  "description": "A stateful layer to register shared features and provide an access point to discover without a direct dependency",
+  "plugin": {
+    "id": "discoverShared",
+    "server": false,
+    "browser": true,
+    "requiredPlugins": [],
+    "optionalPlugins": [],
+  },
+}

src/plugins/discover_shared/public/index.ts

@@ -0,0 +1,20 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { DiscoverSharedPlugin } from './plugin';
+
+export function plugin() {
+  return new DiscoverSharedPlugin();
+}
+
+export type { DiscoverSharedPublicSetup, DiscoverSharedPublicStart } from './types';
+export type {
+  ObservabilityLogsAIAssistantFeatureRenderDeps,
+  ObservabilityLogsAIAssistantFeature,
+  DiscoverFeature,
+} from './services/discover_features';

src/plugins/discover_shared/public/mocks.ts

@@ -0,0 +1,33 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import {
+  createDiscoverFeaturesServiceSetupMock,
+  createDiscoverFeaturesServiceStartMock,
+} from './services/discover_features/discover_features_service.mock';
+import { DiscoverSharedPublicSetup, DiscoverSharedPublicStart } from './types';
+
+export type Setup = jest.Mocked<DiscoverSharedPublicSetup>;
+export type Start = jest.Mocked<DiscoverSharedPublicStart>;
+
+const createSetupContract = (): Setup => {
+  return {
+    features: createDiscoverFeaturesServiceSetupMock(),
+  };
+};
+
+const createStartContract = (): Start => {
+  return {
+    features: createDiscoverFeaturesServiceStartMock(),
+  };
+};
+
+export const discoverSharedPluginMock = {
+  createSetupContract,
+  createStartContract,
+};

src/plugins/discover_shared/public/plugin.ts

@@ -0,0 +1,26 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { DiscoverFeaturesService } from './services/discover_features';
+import { DiscoverSharedPublicPlugin } from './types';
+
+export class DiscoverSharedPlugin implements DiscoverSharedPublicPlugin {
+  private discoverFeaturesService: DiscoverFeaturesService = new DiscoverFeaturesService();
+
+  public setup() {
+    return {
+      features: this.discoverFeaturesService.setup(),
+    };
+  }
+
+  public start() {
+    return {
+      features: this.discoverFeaturesService.start(),
+    };
+  }
+}

src/plugins/discover_shared/public/services/discover_features/discover_features_service.mock.ts

@@ -0,0 +1,15 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { FeaturesRegistry } from '../../../common';
+import { DiscoverFeature } from './types';
+
+const registry = new FeaturesRegistry<DiscoverFeature>();
+
+export const createDiscoverFeaturesServiceSetupMock = () => ({ registry });
+export const createDiscoverFeaturesServiceStartMock = () => ({ registry });