[mob][photos] add hash check for people widget (#6341)

## Description

- [x] Add hash functionality to PeopleHomeWidget to track updation
- [x] Clear hash on albums widget clear

## Tests

- [x] Test if updating different people trigger it or not

mobile/lib/app.dart

@@ -75,7 +75,7 @@ class _EnteAppState extends State<EnteApp> with WidgetsBindingObserver {
       (event) async {
         _changeCallbackDebouncer.run(
           () async =>
-              unawaited(PeopleHomeWidgetService.instance.peopleChanged()),
+              unawaited(PeopleHomeWidgetService.instance.checkPeopleChanged()),
         );
       },
     );

mobile/lib/db/entities_db.dart

@@ -99,4 +99,19 @@ extension EntitiesDB on FilesDB {
     }
     return LocalEntityData.fromJson(maps.first);
   }
+
+  Future<String?> getPreHashForEntities(
+    EntityType type,
+    List<String> ids,
+  ) async {
+    final db = await sqliteAsyncDB;
+    final maps = await db.get(
+      'SELECT GROUP_CONCAT(id || \':\' || updatedAt, \',\') FROM entities WHERE type = ? AND id IN (${List.filled(ids.length, '?').join(',')})',
+      [type.name, ...ids],
+    );
+    if (maps.isEmpty) {
+      return null;
+    }
+    return maps.values.first as String?;
+  }
 }

mobile/lib/services/album_home_widget_service.dart

@@ -110,6 +110,7 @@ class AlbumHomeWidgetService {
     await _setTotalAlbums(null);
     await updateAlbumsStatus(WidgetStatus.syncedEmpty);
     _hasSyncedAlbums = false;
+    await setAlbumsLastHash("");
     await _refreshWidget(message: "AlbumsHomeWidget cleared & updated");
   }
 
@@ -183,7 +184,7 @@ class AlbumHomeWidgetService {
     for (final albumId in albumIds) {
       final collection = CollectionsService.instance.getCollectionByID(albumId);
       if (collection != null) {
-        updationTimestamps += "${collection.updationTime.toString()}_";
+        updationTimestamps += "$albumId:${collection.updationTime.toString()}_";
       }
     }
 
@@ -386,6 +387,7 @@ class AlbumHomeWidgetService {
   }
 
   Future<void> _loadAndRenderAlbums() async {
+    final selectedAlbumIds = await _getEffectiveSelectedAlbumIds();
     final albumsWithFiles = await _getAlbumsWithFiles();
 
     if (albumsWithFiles.isEmpty) {
@@ -465,7 +467,6 @@ class AlbumHomeWidgetService {
     }
 
     // Update the hash to track changes
-    final selectedAlbumIds = await _getEffectiveSelectedAlbumIds();
     final hash = _calculateHash(selectedAlbumIds);
     await setAlbumsLastHash(hash);
 

mobile/lib/services/entity_service.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
 
+import "package:crypto/crypto.dart";
 import "package:ente_crypto/ente_crypto.dart";
 import 'package:flutter/foundation.dart';
 import 'package:logging/logging.dart';
@@ -219,4 +220,22 @@ class EntityService {
       rethrow;
     }
   }
+
+  Future<String?> getPreHashForEntities(
+    EntityType type,
+    List<String> ids,
+  ) async {
+    return await _db.getPreHashForEntities(type, ids);
+  }
+
+  Future<String> getHashForIds(List<String> personIds) async {
+    final preHash = await getPreHashForEntities(EntityType.cgroup, personIds);
+
+    if (preHash == null) {
+      return "";
+    }
+
+    final hash = md5.convert(utf8.encode(preHash)).toString().substring(0, 10);
+    return hash;
+  }
 }

mobile/lib/services/machine_learning/face_ml/person/person_service.dart

@@ -75,7 +75,10 @@ class PersonService {
     final entities = await entityService.getEntities(EntityType.cgroup);
     return entities
         .map(
-          (e) => PersonEntity(e.id, PersonData.fromJson(json.decode(e.data))),
+          (e) => PersonEntity(
+            e.id,
+            PersonData.fromJson(json.decode(e.data)),
+          ),
         )
         .toList();
   }
@@ -85,7 +88,10 @@ class PersonService {
       if (e == null) {
         return null;
       }
-      return PersonEntity(e.id, PersonData.fromJson(json.decode(e.data)));
+      return PersonEntity(
+        e.id,
+        PersonData.fromJson(json.decode(e.data)),
+      );
     });
   }
 
@@ -93,8 +99,10 @@ class PersonService {
     final entities = await entityService.getEntities(EntityType.cgroup);
     final Map<String, PersonEntity> map = {};
     for (var e in entities) {
-      final person =
-          PersonEntity(e.id, PersonData.fromJson(json.decode(e.data)));
+      final person = PersonEntity(
+        e.id,
+        PersonData.fromJson(json.decode(e.data)),
+      );
       map[person.remoteID] = person;
     }
     return map;

mobile/lib/services/people_home_widget_service.dart

@@ -23,6 +23,7 @@ import 'package:synchronized/synchronized.dart';
 class PeopleHomeWidgetService {
   // Constants
   static const String SELECTED_PEOPLE_KEY = "selectedPeopleHW";
+  static const String PEOPLE_LAST_HASH_KEY = "peopleLastHash";
   static const String ANDROID_CLASS_NAME = "EntePeopleWidgetProvider";
   static const String IOS_CLASS_NAME = "EntePeopleWidget";
   static const String PEOPLE_STATUS_KEY = "peopleStatusKey.widget";
@@ -39,6 +40,7 @@ class PeopleHomeWidgetService {
   final Logger _logger = Logger((PeopleHomeWidgetService).toString());
   late final SharedPreferences _prefs;
   final _peopleForceRefreshLock = Lock();
+  final _lock2 = Lock();
   bool _hasSyncedPeople = false;
 
   // Initialization
@@ -69,6 +71,14 @@ class PeopleHomeWidgetService {
     await updatePeopleChanged(true);
   }
 
+  String? getPeopleLastHash() {
+    return _prefs.getString(PEOPLE_LAST_HASH_KEY);
+  }
+
+  Future<void> setPeopleLastHash(String hash) async {
+    await _prefs.setString(PEOPLE_LAST_HASH_KEY, hash);
+  }
+
   Future<int> countHomeWidgets() async {
     return await HomeWidgetService.instance.countHomeWidgets(
       ANDROID_CLASS_NAME,
@@ -112,6 +122,7 @@ class PeopleHomeWidgetService {
     await _setTotalPeople(null);
     _hasSyncedPeople = false;
     await updatePeopleStatus(WidgetStatus.syncedEmpty);
+    await setPeopleLastHash("");
     await _refreshWidget(message: "PeopleHomeWidget cleared & updated");
   }
 
@@ -147,20 +158,22 @@ class PeopleHomeWidgetService {
     await HomeWidgetService.instance.initHomeWidget();
   }
 
-  Future<void> peopleChanged() async {
-    await updatePeopleChanged(true);
+  Future<void> checkPeopleChanged() async {
+    final havePeopleChanged = await _lock2.synchronized(() async {
+      final peopleIds = await _getEffectiveSelectedPeopleIds();
+      final currentHash = await _calculateHash(peopleIds);
+      final lastHash = getPeopleLastHash();
+      if (peopleIds.isEmpty || currentHash == lastHash) {
+        return false;
+      }
+      return true;
+    });
 
-    final cachedMemories = await _getPeople();
-    final currentTotal = cachedMemories.length;
-    final existingTotal = await _getTotalPeople() ?? 0;
-
-    if (existingTotal == currentTotal && existingTotal == 0) {
-      await updatePeopleChanged(false);
-      _logger.info("People empty, no update needed");
+    await updatePeopleChanged(havePeopleChanged);
+    if (!havePeopleChanged) {
+      _logger.info("No changes detected in people, skipping update");
       return;
     }
-
-    _logger.info("People changed, updating widget");
     await initHomeWidget(true);
   }
 
@@ -219,6 +232,10 @@ class PeopleHomeWidgetService {
     await updatePeopleChanged(false);
   }
 
+  Future<String> _calculateHash(List<String> peopleIds) async {
+    return await entityService.getHashForIds(peopleIds);
+  }
+
   Future<bool> _hasAnyBlockers() async {
     // Check if first import is completed
     final hasCompletedFirstImport =
@@ -363,6 +380,7 @@ class PeopleHomeWidgetService {
   }
 
   Future<void> _loadAndRenderPeople() async {
+    final peopleIds = await _getEffectiveSelectedPeopleIds();
     final peopleWithFiles = await _getPeople();
 
     if (peopleWithFiles.isEmpty) {
@@ -448,6 +466,9 @@ class PeopleHomeWidgetService {
       await updatePeopleStatus(WidgetStatus.syncedAll);
     }
 
+    final hash = await _calculateHash(peopleIds);
+    await setPeopleLastHash(hash);
+
     await _refreshWidget(
       message: "Switched to next people set, total: $renderedCount",
     );

mobile/lib/ui/settings/widgets/people_widget_settings.dart

@@ -72,7 +72,7 @@ class _PeopleWidgetSettingsState extends State<PeopleWidgetSettings> {
                             );
                             Navigator.pop(context);
                             await PeopleHomeWidgetService.instance
-                                .peopleChanged();
+                                .checkPeopleChanged();
                           },
                   );
                 },