From 01befbb07dc8cb49f70368c31cf48ed6015beb89 Mon Sep 17 00:00:00 2001
From: Johannes Millan <johannes.millan@gmail.com>
Date: Tue, 19 Apr 2022 20:47:48 +0200
Subject: [PATCH] feat(perf): simplify distinctUntilChanged check

---
 .../work-context/store/work-context.selectors.ts |  4 ++++
 .../work-context/work-context.service.ts         |  7 ++++---
 src/app/util/is-shallow-equal.ts                 | 16 ++++++++++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 src/app/util/is-shallow-equal.ts

diff --git a/src/app/features/work-context/store/work-context.selectors.ts b/src/app/features/work-context/store/work-context.selectors.ts
index 12c213ec84..45f0ae411f 100644
--- a/src/app/features/work-context/store/work-context.selectors.ts
+++ b/src/app/features/work-context/store/work-context.selectors.ts
@@ -72,6 +72,10 @@ export const selectActiveWorkContext = createSelector(
   },
 );
 
+export const selectActiveContextTheme = createSelector(
+  selectActiveWorkContext,
+  (workContext) => workContext.theme,
+);
 export const selectStartableTasksForActiveContext = createSelector(
   selectActiveWorkContext,
   selectTaskEntities,
diff --git a/src/app/features/work-context/work-context.service.ts b/src/app/features/work-context/work-context.service.ts
index c83a1b1a51..3d2846f0e0 100644
--- a/src/app/features/work-context/work-context.service.ts
+++ b/src/app/features/work-context/work-context.service.ts
@@ -28,7 +28,6 @@ import {
 import { TODAY_TAG } from '../tag/tag.const';
 import { TagService } from '../tag/tag.service';
 import { Task, TaskPlanned, TaskWithSubTasks } from '../tasks/task.model';
-import { distinctUntilChangedObject } from '../../util/distinct-until-changed-object';
 import { getWorklogStr } from '../../util/get-work-log-str';
 import { hasTasksToWorkOn, mapEstimateRemainingFromTasks } from './work-context.util';
 import {
@@ -65,6 +64,8 @@ import { selectNotesById } from '../note/store/note.reducer';
 import { TranslateService } from '@ngx-translate/core';
 import { T } from '../../t.const';
 import { distinctUntilChangedSimpleArray } from '../../util/distinct-until-changed-simple-array';
+import { isShallowEqual } from '../../util/is-shallow-equal';
+import { distinctUntilChangedObject } from '../../util/distinct-until-changed-object';
 
 @Injectable({
   providedIn: 'root',
@@ -81,7 +82,7 @@ export class WorkContextService {
 
   // should be treated as private
   _afterDataLoaded$: Observable<unknown> = this._isAllDataLoaded$.pipe(
-    filter((v) => v === true),
+    filter((v) => v),
     shareReplay(1),
   );
 
@@ -170,7 +171,7 @@ export class WorkContextService {
 
   currentTheme$: Observable<WorkContextThemeCfg> = this.activeWorkContext$.pipe(
     map((awc) => awc.theme),
-    distinctUntilChanged(distinctUntilChangedObject),
+    distinctUntilChanged<WorkContextThemeCfg>(isShallowEqual),
   );
 
   advancedCfg$: Observable<WorkContextAdvancedCfg> = this.activeWorkContext$.pipe(
diff --git a/src/app/util/is-shallow-equal.ts b/src/app/util/is-shallow-equal.ts
new file mode 100644
index 0000000000..745314c1c7
--- /dev/null
+++ b/src/app/util/is-shallow-equal.ts
@@ -0,0 +1,16 @@
+export const isShallowEqual = (
+  a: { [key: string]: boolean | number | string | undefined | null },
+  b: { [key: string]: boolean | number | string | undefined | null },
+): boolean => {
+  const keys1 = Object.keys(a);
+  const keys2 = Object.keys(b);
+  if (keys1.length !== keys2.length) {
+    return false;
+  }
+  for (const key of keys1) {
+    if (a[key] !== b[key]) {
+      return false;
+    }
+  }
+  return true;
+};