Simplify favorites

lib/db/files_db.dart

@@ -341,6 +341,18 @@ class FilesDB {
     }
   }
 
+  Future<bool> doesFileExistInCollection(
+      int uploadedFileID, int collectionID) async {
+    final db = await instance.database;
+    final rows = await db.query(
+      table,
+      where: '$columnUploadedFileID = ? AND $columnCollectionID = ?',
+      whereArgs: [uploadedFileID, collectionID],
+      limit: 1,
+    );
+    return rows.isNotEmpty;
+  }
+
   List<File> _convertToFiles(List<Map<String, dynamic>> results) {
     final files = List<File>();
     for (final result in results) {

lib/main.dart

@@ -6,7 +6,6 @@ import 'package:path_provider/path_provider.dart';
 import 'package:photos/core/constants.dart';
 import 'package:photos/core/configuration.dart';
 import 'package:photos/services/collections_service.dart';
-import 'package:photos/services/favorites_service.dart';
 import 'package:photos/services/memories_service.dart';
 import 'package:photos/services/sync_service.dart';
 import 'package:photos/ui/home_widget.dart';
@@ -34,7 +33,6 @@ void _main() async {
   await CollectionsService.instance.init();
   await SyncService.instance.init();
   await MemoriesService.instance.init();
-  await FavoritesService.instance.init();
   _sync();
 
   final SentryClient sentry = new SentryClient(dsn: SENTRY_DSN);

lib/services/favorites_service.dart

@@ -6,16 +6,13 @@ import 'package:photos/models/file.dart';
 import 'package:photos/services/collections_service.dart';
 import 'package:photos/utils/crypto_util.dart';
 import 'package:photos/utils/file_uploader.dart';
-import 'package:shared_preferences/shared_preferences.dart';
 
 class FavoritesService {
-  static final _favoritesCollectionIDKey = "favorites_collection_id";
-
-  final _cachedFavoriteFiles = Set<File>();
   Configuration _config;
   CollectionsService _collectionsService;
   FileUploader _fileUploader;
   FilesDB _filesDB;
+  int _cachedFavoritesCollectionID;
 
   FavoritesService._privateConstructor() {
     _config = Configuration.instance;
@@ -25,23 +22,13 @@ class FavoritesService {
   }
   static FavoritesService instance = FavoritesService._privateConstructor();
 
-  SharedPreferences _preferences;
-
-  Future<void> init() async {
-    _preferences = await SharedPreferences.getInstance();
-    if (_preferences.containsKey(_favoritesCollectionIDKey)) {
-      final collectionID = _preferences.getInt(_favoritesCollectionIDKey);
-      _cachedFavoriteFiles
-          .addAll((await _filesDB.getAllInCollection(collectionID)).toSet());
+  Future<bool> isFavorite(File file) async {
+    final collection = await _getFavoritesCollection();
+    if (collection == null) {
+      return false;
     }
-  }
-
-  Set<File> getFavoriteFiles() {
-    return _cachedFavoriteFiles;
-  }
-
-  bool isLiked(File file) {
-    return _cachedFavoriteFiles.contains(file);
+    return _filesDB.doesFileExistInCollection(
+        file.uploadedFileID, collection.id);
   }
 
   Future<void> addToFavorites(File file) async {
@@ -52,7 +39,6 @@ class FavoritesService {
       await _filesDB.update(uploadedFile);
     } else {
       await _collectionsService.addToCollection(collectionID, [file]);
-      _cachedFavoriteFiles.add(file);
     }
   }
 
@@ -63,28 +49,26 @@ class FavoritesService {
       // Do nothing, ignore
     } else {
       await _collectionsService.removeFromCollection(collectionID, [file]);
-      _cachedFavoriteFiles.remove(file);
     }
   }
 
-  Future<Collection> getFavoritesCollection() async {
-    if (!_preferences.containsKey(_favoritesCollectionIDKey)) {
+  Future<Collection> _getFavoritesCollection() async {
+    if (_cachedFavoritesCollectionID == null) {
       final collections = _collectionsService.getCollections();
       for (final collection in collections) {
         if (collection.type == CollectionType.favorites) {
-          await _preferences.setInt(_favoritesCollectionIDKey, collection.id);
+          _cachedFavoritesCollectionID = collection.id;
           return collection;
         }
       }
       return null;
     }
-    return _collectionsService
-        .getCollectionByID(_preferences.getInt(_favoritesCollectionIDKey));
+    return _collectionsService.getCollectionByID(_cachedFavoritesCollectionID);
   }
 
   Future<int> _getOrCreateFavoriteCollectionID() async {
-    if (_preferences.containsKey(_favoritesCollectionIDKey)) {
-      return _preferences.getInt(_favoritesCollectionIDKey);
+    if (_cachedFavoritesCollectionID != null) {
+      return _cachedFavoritesCollectionID;
     }
     final key = CryptoUtil.generateKey();
     final encryptedKeyData = CryptoUtil.encryptSync(key, _config.getKey());
@@ -100,7 +84,7 @@ class FavoritesService {
       CollectionAttributes(),
       null,
     ));
-    await _preferences.setInt(_favoritesCollectionIDKey, collection.id);
+    _cachedFavoritesCollectionID = collection.id;
     return collection.id;
   }
 }

lib/ui/collections_gallery_widget.dart

@@ -128,18 +128,6 @@ class _CollectionsGalleryWidgetState extends State<CollectionsGalleryWidget> {
     });
 
     final collectionsWithThumbnail = List<CollectionWithThumbnail>();
-    final favorites = FavoritesService.instance.getFavoriteFiles().toList();
-    favorites.sort((first, second) {
-      return second.creationTime.compareTo(first.creationTime);
-    });
-    if (favorites.length > 0) {
-      final favoritesCollection =
-          await FavoritesService.instance.getFavoritesCollection();
-      final lastUpdatedFile = await FilesDB.instance
-          .getLastModifiedFileInCollection(favoritesCollection.id);
-      collectionsWithThumbnail.add(CollectionWithThumbnail(
-          favoritesCollection, favorites[0], lastUpdatedFile));
-    }
     final collections = CollectionsService.instance.getCollections();
 
     for (final c in collections) {

lib/ui/detail_page.dart

@@ -178,8 +178,22 @@ class _DetailPageState extends State<DetailPage> {
 
   Widget _getFavoriteButton() {
     final file = _files[_selectedIndex];
+
+    return FutureBuilder(
+      future: FavoritesService.instance.isFavorite(file),
+      builder: (context, snapshot) {
+        if (snapshot.hasData) {
+          return _getLikeButton(file, snapshot.data);
+        } else {
+          return _getLikeButton(file, false);
+        }
+      },
+    );
+  }
+
+  Widget _getLikeButton(File file, bool isLiked) {
     return LikeButton(
-      isLiked: FavoritesService.instance.isLiked(file.uploadedFileID),
+      isLiked: isLiked,
       onTap: (oldValue) async {
         final isLiked = !oldValue;
         bool hasError = false;