[SecuritySolution] Remove remaining usage of redux-observable (#175678

)

## Summary

In this PR, we're removing all usages of `redux-observable` in favor of
simple middlewares. This work is part of [this tech debt
ticket](#175427) which outlines
the motivation of this move.

A couple shortcuts had to be taken and I added comments further down to
explain the motivation.

### Oddities
Weirdly, the CI reports an increase in async chunks, instead of an
expected decrease due to removing a library.

| id |
[before](9629e66)
|
[after](477348a)
| diff |
| --- | --- | --- | --- |
| `securitySolution` | 11.2MB | 11.4MB | +157.1KB |

I'm not sure, why this is, so if anyone has any insights on how to
examine the async chunks, that would be helpful.

_edit:_ After hours of analyzing Kibana build stats at various stages of
this PR, I found that the changes that are responsible for this increase
in async chunk sum size is this commit:
janmonschke@cde023d
. It only consists of deleted files and deleted imports. Therefore it's
up to webpack to figure out the best way to chunk up the app. In other
words: I can't change it :(

### Tests

You might notice, that I didn't add tests to the middlewares. That is
because the epics didn't have tests either and their functionality is
tested in acceptance tests. As a follow-up of this PR, I will add tests
to all newly-introduced middlewares. My goal here is to keep the changes
as small as possible.

### Checklist

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

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

package.json

@@ -1080,7 +1080,6 @@
     "redux-actions": "^2.6.5",
     "redux-devtools-extension": "^2.13.8",
     "redux-logger": "^3.0.6",
-    "redux-observable": "2.0.0",
     "redux-saga": "^1.1.3",
     "redux-thunk": "^2.4.2",
     "redux-thunks": "^1.0.0",

x-pack/plugins/security_solution/public/common/components/event_details/overview/index.tsx

@@ -30,7 +30,6 @@ import { OverviewCardWithActions, OverviewCard } from './overview_card';
 import { StatusPopoverButton } from './status_popover_button';
 import { SeverityBadge } from '../../severity_badge';
 import { useThrottledResizeObserver } from '../../utils';
-import { isNotNull } from '../../../../timelines/store/helpers';
 
 export const NotGrowingFlexGroup = euiStyled(EuiFlexGroup)`
   flex-grow: 0;
@@ -219,4 +218,8 @@ function hasData(fieldInfo?: EnrichedFieldInfo): fieldInfo is EnrichedFieldInfoW
   return !!fieldInfo && Array.isArray(fieldInfo.values);
 }
 
+function isNotNull<T>(value: T | null): value is T {
+  return value !== null;
+}
+
 Overview.displayName = 'Overview';

x-pack/plugins/security_solution/public/common/store/middlewares.ts

@@ -4,16 +4,18 @@
  * 2.0; you may not use this file except in compliance with the Elastic License
  * 2.0.
  */
+
+import type { CoreStart } from '@kbn/core/public';
 import type { Storage } from '@kbn/kibana-utils-plugin/public';
 
 import { createTimelineMiddlewares } from '../../timelines/store/middlewares/create_timeline_middlewares';
 import { dataTableLocalStorageMiddleware } from './data_table/middleware_local_storage';
 import { userAssetTableLocalStorageMiddleware } from '../../explore/users/store/middleware_storage';
 
-export function createMiddlewares(storage: Storage) {
+export function createMiddlewares(kibana: CoreStart, storage: Storage) {
   return [
     dataTableLocalStorageMiddleware(storage),
     userAssetTableLocalStorageMiddleware(storage),
-    ...createTimelineMiddlewares(),
+    ...createTimelineMiddlewares(kibana),
   ];
 }

x-pack/plugins/security_solution/public/common/store/store.ts

@@ -11,14 +11,12 @@ import type {
   Middleware,
   Dispatch,
   PreloadedState,
-  CombinedState,
   AnyAction,
   Reducer,
 } from 'redux';
 import { applyMiddleware, createStore as createReduxStore } from 'redux';
 import { composeWithDevTools } from 'redux-devtools-extension/developmentOnly';
 import type { EnhancerOptions } from 'redux-devtools-extension';
-import { createEpicMiddleware } from 'redux-observable';
 import type { Observable } from 'rxjs';
 import { BehaviorSubject, pluck } from 'rxjs';
 import type { Storage } from '@kbn/kibana-utils-plugin/public';
@@ -33,18 +31,14 @@ import {
   SERVER_APP_ID,
 } from '../../../common/constants';
 import { telemetryMiddleware } from '../lib/telemetry';
-import { appSelectors } from './app';
-import { timelineSelectors } from '../../timelines/store';
 import * as timelineActions from '../../timelines/store/actions';
 import type { TimelineModel } from '../../timelines/store/model';
-import { inputsSelectors } from './inputs';
 import type { SubPluginsInitReducer } from './reducer';
 import { createInitialState, createReducer } from './reducer';
-import { createRootEpic } from './epic';
 import type { AppAction } from './actions';
 import type { Immutable } from '../../../common/endpoint/types';
 import type { State } from './types';
-import type { TimelineEpicDependencies, TimelineState } from '../../timelines/store/types';
+import type { TimelineState } from '../../timelines/store/types';
 import type { KibanaDataView, SourcererModel, SourcererDataView } from './sourcerer/model';
 import { initDataView } from './sourcerer/model';
 import type { AppObservableLibs, StartedSubPlugins, StartPlugins } from '../../types';
@@ -255,7 +249,7 @@ const stateSanitizer = (state: State) => {
 export const createStore = (
   state: State,
   pluginsReducer: SubPluginsInitReducer,
-  kibana: Observable<CoreStart>,
+  kibana$: Observable<CoreStart>,
   storage: Storage,
   additionalMiddleware?: Array<Middleware<{}, State, Dispatch<AppAction | Immutable<AppAction>>>>
 ): Store<State, Action> => {
@@ -272,23 +266,18 @@ export const createStore = (
 
   const composeEnhancers = composeWithDevTools(enhancerOptions);
 
-  const middlewareDependencies: TimelineEpicDependencies<State> = {
-    kibana$: kibana,
-    selectAllTimelineQuery: inputsSelectors.globalQueryByIdSelector,
-    selectNotesByIdSelector: appSelectors.selectNotesByIdSelector,
-    timelineByIdSelector: timelineSelectors.timelineByIdSelector,
-    timelineTimeRangeSelector: inputsSelectors.timelineTimeRangeSelector,
-  };
-
-  const epicMiddleware = createEpicMiddleware<Action, Action, State, typeof middlewareDependencies>(
-    {
-      dependencies: middlewareDependencies,
-    }
-  );
+  // TODO: Once `createStore` does not use redux-observable, we will not need to pass a
+  // kibana observable anymore. Then we can remove this `any` cast and replace kibana$
+  // with a regular kibana instance.
+  // I'm not doing it in this PR, as this will have an impact on literally hundreds of test files.
+  // A separate PR will be created to clean this up.
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const kibanaObsv = kibana$ as any;
+  const kibana =
+    'source' in kibanaObsv ? kibanaObsv.source._value.kibana : kibanaObsv._value.kibana;
 
   const middlewareEnhancer = applyMiddleware(
-    ...createMiddlewares(storage),
-    epicMiddleware,
+    ...createMiddlewares(kibana, storage),
     telemetryMiddleware,
     ...(additionalMiddleware ?? [])
   );
@@ -299,8 +288,6 @@ export const createStore = (
     composeEnhancers(middlewareEnhancer)
   );
 
-  epicMiddleware.run(createRootEpic<CombinedState<State>>());
-
   return store;
 };