mobile: fix widgets do not refresh after app data is cleared, require a restart.

apps/mobile/android/app/src/main/java/com/streetwriters/notesnook/RCTNNativeModule.java

@@ -193,6 +193,16 @@ public class RCTNNativeModule extends ReactContextBaseJavaModule {
         }
     }
 
+    /**
+     * Redraws every widget from scratch. Needed because the app can be stopped while its widgets
+     * stay on the home screen: clearing app data empties the store without the widgets ever being
+     * told, so they keep showing content that is gone until something forces a redraw.
+     */
+    @ReactMethod
+    public void refreshWidgets() {
+        WidgetUtils.refreshAll(mContext);
+    }
+
     @ReactMethod
     public void updateReminderWidget() {
         AppWidgetManager wm = AppWidgetManager.getInstance(mContext);

apps/mobile/android/app/src/main/java/com/streetwriters/notesnook/WidgetUtils.java

@@ -1,6 +1,8 @@
 package com.streetwriters.notesnook;
 
 import android.app.ActivityOptions;
+import android.appwidget.AppWidgetManager;
+import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
@@ -18,9 +20,11 @@ import com.streetwriters.notesnook.datatypes.Reminder;
 
 import java.util.ArrayList;
 import java.util.Calendar;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Shared helpers for the home screen widgets.
@@ -36,6 +40,56 @@ public class WidgetUtils {
      */
     private static final int MAX_REMINDERS = 50;
 
+    /**
+     * Redraws every widget that currently exists, and drops stored notes for widgets that no
+     * longer do.
+     *
+     * Everything else keys off what we have stored, which is fine while the app is running but
+     * leaves widgets showing content that no longer exists once the store is emptied underneath
+     * them (clearing app data) or a widget is removed while the app is stopped (onDeleted never
+     * arrives). Starting from the widgets the system knows about, rather than from our own data,
+     * is what makes this self-correcting.
+     *
+     * NoteWidget is left alone deliberately: it is a static button with no stored state, and its
+     * layout depends on the size it was last given.
+     */
+    static void refreshAll(Context context) {
+        AppWidgetManager manager = AppWidgetManager.getInstance(context);
+
+        int[] noteWidgetIds = manager.getAppWidgetIds(
+                new ComponentName(context, NotePreviewWidget.class));
+        removeOrphanedNotes(context, noteWidgetIds);
+        for (int appWidgetId : noteWidgetIds) {
+            NotePreviewWidget.updateAppWidget(context, manager, appWidgetId);
+        }
+
+        for (int appWidgetId : manager.getAppWidgetIds(
+                new ComponentName(context, ReminderWidgetProvider.class))) {
+            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget_reminders);
+            ReminderWidgetProvider.updateAppWidget(context, manager, appWidgetId, views);
+        }
+    }
+
+    /**
+     * Drops stored notes whose widget is gone, so the preferences file cannot grow forever.
+     */
+    private static void removeOrphanedNotes(Context context, int[] liveWidgetIds) {
+        Set<String> live = new HashSet<>();
+        for (int appWidgetId : liveWidgetIds) live.add(String.valueOf(appWidgetId));
+
+        SharedPreferences preferences = context.getSharedPreferences(PREFERENCES, Context.MODE_PRIVATE);
+        SharedPreferences.Editor edit = preferences.edit();
+        boolean changed = false;
+
+        for (String key : preferences.getAll().keySet()) {
+            // Leave anything that is not a widget id alone, the reminders list included.
+            if (parseWidgetId(key) == null || live.contains(key)) continue;
+            edit.remove(key);
+            changed = true;
+        }
+        if (changed) edit.apply();
+    }
+
     /**
      * The note each note widget is showing, keyed by widget id.
      *

apps/mobile/app/hooks/use-app-events.tsx

@@ -81,6 +81,7 @@ import {
   setUpdateAvailableMessage
 } from "../services/message";
 import Navigation from "../services/navigation";
+import { NotePreviewWidget } from "../services/note-preview-widget";
 import Notifications from "../services/notifications";
 import PremiumService from "../services/premium";
 import SettingsService from "../services/settings";
@@ -574,6 +575,11 @@ export const useAppEvents = () => {
   useEffect(() => {
     if (isAppLoading) return;
 
+    // Widgets outlive the app process, so they can be left showing content the app no longer has
+    // (most obviously after the user clears app data). Nothing can run at that moment, so the
+    // first launch afterwards is the earliest chance to put them right.
+    NotePreviewWidget.updateNotes();
+
     let subscriptions: EventManagerSubscription[] = [];
     const eventManager = db.eventManager;
     subscriptions = [

apps/mobile/app/services/note-preview-widget.ts

@@ -34,6 +34,10 @@ export const NotePreviewWidget = {
 
         NotesnookModule.updateWidgetNote(id, JSON.stringify(newNote));
       }
+      // Redraw from the widgets that actually exist rather than only the ones we
+      // have notes for. After app data is cleared there are none, and the widgets
+      // would otherwise keep showing content that no longer exists.
+      NotesnookModule.refreshWidgets();
     }, 500);
   },
   updateNote: async (id: string, note: Note) => {

apps/mobile/app/utils/notesnook-module.ts

@@ -45,6 +45,7 @@ interface NotesnookModuleInterface {
   hasWidgetNote: (noteId: string) => Promise<boolean>;
   updateWidgetNote: (noteId: string, data: string) => void;
   updateReminderWidget: () => void;
+  refreshWidgets: () => void;
   isGestureNavigationEnabled: () => boolean;
   addShortcut: (
     id: string,
@@ -81,6 +82,7 @@ export const NotesnookModule: NotesnookModuleInterface = Platform.select({
     hasWidgetNote: () => {},
     updateWidgetNote: () => {},
     updateReminderWidget: () => {},
+    refreshWidgets: () => {},
     isGestureNavigationEnabled: () => true,
     addShortcut: () => Promise.resolve(false),
     removeShortcut: () => Promise.resolve(false),