From 2e17ad5e30d26b00f7dc1844784224e0b1b0b4f3 Mon Sep 17 00:00:00 2001
From: Alex Rybchenko <arybchenko@box.com>
Date: Wed, 13 Jul 2022 16:17:54 +0200
Subject: [PATCH] replaced internal observable with a mapping from the storage
 API

Signed-off-by: Alex Rybchenko <arybchenko@box.com>
---
 plugins/shortcuts/src/Shortcuts.tsx           |  3 +-
 .../src/api/LocalStoredShortcuts.test.ts      | 19 ++++---
 .../shortcuts/src/api/LocalStoredShortcuts.ts | 49 ++++++-------------
 plugins/shortcuts/src/api/ShortcutApi.ts      |  5 ++
 4 files changed, 33 insertions(+), 43 deletions(-)

diff --git a/plugins/shortcuts/src/Shortcuts.tsx b/plugins/shortcuts/src/Shortcuts.tsx
index b8af1f2e29..3c48e2bae2 100644
--- a/plugins/shortcuts/src/Shortcuts.tsx
+++ b/plugins/shortcuts/src/Shortcuts.tsx
@@ -40,7 +40,8 @@ export interface ShortcutsProps {
 export const Shortcuts = (props: ShortcutsProps) => {
   const shortcutApi = useApi(shortcutsApiRef);
   const shortcuts = useObservable(
-    useMemo(() => shortcutApi.shortcut$(), [shortcutApi]),
+    shortcutApi.shortcut$(),
+    shortcutApi.snapshot(),
   );
   const [anchorEl, setAnchorEl] = React.useState<Element | undefined>();
   const loading = Boolean(!shortcuts);
diff --git a/plugins/shortcuts/src/api/LocalStoredShortcuts.test.ts b/plugins/shortcuts/src/api/LocalStoredShortcuts.test.ts
index c8401e8b1a..dbea91863c 100644
--- a/plugins/shortcuts/src/api/LocalStoredShortcuts.test.ts
+++ b/plugins/shortcuts/src/api/LocalStoredShortcuts.test.ts
@@ -27,17 +27,22 @@ describe('LocalStoredShortcuts', () => {
     );
     const shortcut: Shortcut = { id: 'id', title: 'title', url: '/url' };
 
-    await shortcutApi.add(shortcut);
+    const observerNextHandler = jest.fn();
 
     await new Promise<void>(resolve => {
-      const subscription = shortcutApi.shortcut$().subscribe(data => {
-        expect(data).toEqual(
-          expect.arrayContaining([{ ...shortcut, id: expect.anything() }]),
-        );
-        subscription.unsubscribe();
-        resolve();
+      shortcutApi.shortcut$().subscribe({
+        next: data => {
+          observerNextHandler(data);
+          resolve();
+        },
       });
+      shortcutApi.add(shortcut);
     });
+
+    expect(observerNextHandler).toHaveBeenCalledTimes(1);
+    expect(observerNextHandler).toHaveBeenCalledWith(
+      expect.arrayContaining([{ ...shortcut, id: expect.anything() }]),
+    );
   });
 
   it('should add shortcuts with ids', async () => {
diff --git a/plugins/shortcuts/src/api/LocalStoredShortcuts.ts b/plugins/shortcuts/src/api/LocalStoredShortcuts.ts
index 884f561aaa..ba3722da66 100644
--- a/plugins/shortcuts/src/api/LocalStoredShortcuts.ts
+++ b/plugins/shortcuts/src/api/LocalStoredShortcuts.ts
@@ -15,41 +15,45 @@
  */
 
 import { pageTheme } from '@backstage/theme';
-import ObservableImpl from 'zen-observable';
 import { v4 as uuid } from 'uuid';
 import { ShortcutApi } from './ShortcutApi';
 import { Shortcut } from '../types';
 import { StorageApi } from '@backstage/core-plugin-api';
+import Observable from 'zen-observable';
 
 /**
  * Implementation of the ShortcutApi that uses the StorageApi to store shortcuts.
  */
 export class LocalStoredShortcuts implements ShortcutApi {
-  constructor(private readonly storageApi: StorageApi) {
-    this.storageApi.observe$<Shortcut[]>('items').subscribe({
-      next: () => this.notify(),
-    });
-  }
+  constructor(private readonly storageApi: StorageApi) {}
 
   shortcut$() {
-    return this.observable;
+    return Observable.from(this.storageApi.observe$<Shortcut[]>('items')).map(
+      snapshot => snapshot.value ?? [],
+    );
+  }
+
+  snapshot() {
+    return Array.from(
+      this.storageApi.snapshot<Shortcut[]>('items').value ?? [],
+    ).sort((a, b) => (a.title >= b.title ? 1 : -1));
   }
 
   async add(shortcut: Omit<Shortcut, 'id'>) {
-    const shortcuts = this.get();
+    const shortcuts = this.snapshot();
     shortcuts.push({ ...shortcut, id: uuid() });
 
     await this.storageApi.set('items', shortcuts);
   }
 
   async remove(id: string) {
-    const shortcuts = this.get().filter(s => s.id !== id);
+    const shortcuts = this.snapshot().filter(s => s.id !== id);
 
     await this.storageApi.set('items', shortcuts);
   }
 
   async update(shortcut: Shortcut) {
-    const shortcuts = this.get().filter(s => s.id !== shortcut.id);
+    const shortcuts = this.snapshot().filter(s => s.id !== shortcut.id);
     shortcuts.push(shortcut);
 
     await this.storageApi.set('items', shortcuts);
@@ -64,33 +68,8 @@ export class LocalStoredShortcuts implements ShortcutApi {
     return pageTheme[theme].colors[0];
   }
 
-  private subscribers = new Set<
-    ZenObservable.SubscriptionObserver<Shortcut[]>
-  >();
-
-  private readonly observable = new ObservableImpl<Shortcut[]>(subscriber => {
-    subscriber.next(this.get());
-    this.subscribers.add(subscriber);
-
-    return () => {
-      this.subscribers.delete(subscriber);
-    };
-  });
-
   private readonly THEME_MAP: Record<string, keyof typeof pageTheme> = {
     catalog: 'home',
     docs: 'documentation',
   };
-
-  private get() {
-    return Array.from(
-      this.storageApi.snapshot<Shortcut[]>('items').value ?? [],
-    ).sort((a, b) => (a.title >= b.title ? 1 : -1));
-  }
-
-  private notify() {
-    for (const subscription of this.subscribers) {
-      subscription.next(this.get());
-    }
-  }
 }
diff --git a/plugins/shortcuts/src/api/ShortcutApi.ts b/plugins/shortcuts/src/api/ShortcutApi.ts
index 893a2fd74b..542e77bac8 100644
--- a/plugins/shortcuts/src/api/ShortcutApi.ts
+++ b/plugins/shortcuts/src/api/ShortcutApi.ts
@@ -28,6 +28,11 @@ export interface ShortcutApi {
    */
   shortcut$(): Observable<Shortcut[]>;
 
+  /**
+   * Returns an immediate snapshot of shortcuts, sorted by title
+   */
+  snapshot(): Shortcut[];
+
   /**
    * Generates a unique id for the shortcut and then saves it.
    */