Add notification settings, which allows muting decky/plugin toast notifications (#479)

* Add notification settings, which allows muting decky/plugin toast notifications

* Fix typos

frontend/src/notification-service.tsx

@@ -0,0 +1,51 @@
+import { DeckyState } from './components/DeckyState';
+import { getSetting, setSetting } from './utils/settings';
+
+export interface NotificationSettings {
+  deckyUpdates: boolean;
+  pluginUpdates: boolean;
+}
+
+export const DEFAULT_NOTIFICATION_SETTINGS: NotificationSettings = {
+  deckyUpdates: true,
+  pluginUpdates: true,
+};
+
+/**
+ * A Service class for managing the notification settings
+ *
+ * It's mostly responsible for sending setting updates to the server and keeping the local state in sync.
+ */
+export class NotificationService {
+  constructor(private deckyState: DeckyState) {}
+
+  async init() {
+    const notificationSettings = await getSetting<Partial<NotificationSettings>>('notificationSettings', {});
+
+    // Adding a fallback to the default settings to be backwards compatible if we ever add new notification settings
+    this.deckyState.setNotificationSettings({
+      ...DEFAULT_NOTIFICATION_SETTINGS,
+      ...notificationSettings,
+    });
+  }
+
+  /**
+   * Sends the new notification settings to the server and persists it locally in the decky state
+   *
+   * @param notificationSettings The new notification settings
+   */
+  async update(notificationSettings: NotificationSettings) {
+    await setSetting('notificationSettings', notificationSettings);
+    this.deckyState.setNotificationSettings(notificationSettings);
+  }
+
+  /**
+   * For a specific event, returns true if a notification should be shown
+   *
+   * @param event The notification event that should be checked
+   * @returns true if the notification should be shown
+   */
+  shouldNotify(event: keyof NotificationSettings) {
+    return this.deckyState.publicState().notificationSettings[event];
+  }
+}