code refactoring and unit testing

lib/Services/Db.dart

@@ -2,14 +2,19 @@ import 'dart:async';
 import 'dart:io';
 
 import 'package:goalkeeper/Models/Goal.dart';
+import 'package:goalkeeper/Services/Interfaces/IDatabase.dart';
 import 'package:path/path.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:sqflite/sqflite.dart';
 
-class Db {
+class Db implements IDatabase {
   static Database _database; //singleton database object
-  static Db _databaseHelper =
-      new Db._createInstance(); //singleton database helper object
+  Future<Database> get database async {
+    if (_database == null) {
+      _database = await initDatabase();
+    }
+    return _database;
+  }
 
   final String goalsTable = "goal_table";
   final String colId = "id";
@@ -18,11 +23,7 @@ class Db {
   final String colDeadLine = "deadLine";
   final String dbName = "goals.db";
 
-  Db._createInstance();
-
-  factory Db() => _databaseHelper;
-
-  void _createDb(Database db, int newVersion) async {
+  void createDb(Database db, int newVersion) async {
     await db.execute('''
         CREATE TABLE $goalsTable (
         $colId INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -35,19 +36,12 @@ class Db {
   Future<Database> initDatabase() async {
     Directory directory = await getApplicationDocumentsDirectory();
     String path = join(directory.path, dbName);
-    return await openDatabase(path, version: 1, onCreate: _createDb);
-  }
-
-  Future<Database> get database async {
-    if (_database == null) {
-      _database = await initDatabase();
-    }
-    return _database;
+    return await openDatabase(path, version: 1, onCreate: createDb);
   }
 
   Future<List<Map<String, dynamic>>> getGoalsMapList() async {
     Database db = await this.database;
-    return await db.query(goalsTable);
+    return await db.query(goalsTable, orderBy: colId);
   }
 
   Future<int> createGoal(Goal goal) async {

lib/Services/Factory.dart

@@ -0,0 +1,43 @@
+import 'package:goalkeeper/Services/Interfaces/IDatabase.dart';
+import 'package:goalkeeper/Services/Interfaces/IRepository.dart';
+import 'package:goalkeeper/Services/NotificationCenter.dart';
+
+class Factory {
+  static IDatabase databaseSingleton;
+  static IRepository repositorySingleton;
+  static NotificationCenter notificationCenterSingleton;
+
+  static Factory _instance = Factory.createInstance();
+  Factory.createInstance();
+  factory Factory() => _instance;
+
+  // each of the services must comply to the corresponding contract (i.e: interface - which is also class in dart..)
+  // thats why we bound the types with generics
+
+  void registerDatabase<T extends IDatabase>(T database) {
+    if (databaseSingleton == null) databaseSingleton = database;
+  }
+
+  void registerRepository<T extends IRepository>(T repository) {
+    if (repositorySingleton == null) repositorySingleton = repository;
+  }
+
+  void registerNotificationCenter<T extends NotificationCenter>(
+      T notificationCenter) {
+    if (notificationCenterSingleton == null)
+      notificationCenterSingleton = notificationCenter;
+  }
+
+  IDatabase get database => databaseSingleton != null
+      ? databaseSingleton
+      : throw StateError('Register your dependencies before requisting them !');
+
+  IRepository get repository => repositorySingleton != null
+      ? repositorySingleton
+      : throw StateError('Register your dependencies before requisting them !');
+
+  NotificationCenter get notificationCenter => notificationCenterSingleton !=
+          null
+      ? notificationCenterSingleton
+      : throw StateError('Register your dependencies before requisting them !');
+}

lib/Services/GoalsRepository.dart

@@ -1,48 +1,55 @@
+import 'package:flutter/cupertino.dart';
 import 'package:goalkeeper/Models/Goal.dart';
-import 'package:goalkeeper/Services/Db.dart';
+import 'package:goalkeeper/Services/Interfaces/ICache.dart';
+import 'package:goalkeeper/Services/Interfaces/IRepository.dart';
 
-class GoalsRepository {
+import 'Interfaces/IDatabase.dart';
+
+class GoalsRepository implements IRepository, ICache<Goal> {
   List<Goal> _cache = new List<Goal>();
-  static final GoalsRepository instance = new GoalsRepository.getInstance();
-  GoalsRepository.getInstance();
+  IDatabase database;
+  GoalsRepository({@required this.database});
 
-  bool shouldUpdateCache = true;
+  bool shouldSyncCache = true;
 
-  Future<void> updateCache() async {
+  Future<void> syncCache() async {
     if (_cache.isNotEmpty) _cache.clear();
+    var goalsList = await database.getGoalsList();
     _cache.addAll(goalsList);
-  }
-
-  void purgeCache() {
-    _cache.clear();
-    updateCache();
+    shouldSyncCache = false;
   }
 
   int getGoalsCount() => _cache.length;
 
   Future<List<Goal>> getGoalsList() async {
-    if (shouldUpdateCache) {
-      await updateCache();
-      shouldUpdateCache = false;
+    if (shouldSyncCache) {
+      await syncCache();
     }
     return _cache;
   }
 
   void insert(Goal goal) {
     if (goal.id == null) goal.id = this.getNextId();
-    Db().createGoal(goal);
+    database.createGoal(goal);
     _cache.add(goal);
   }
 
   void delete(Goal goal) {
-    Db().deleteGoal(goal);
+    database.deleteGoal(goal);
     _cache.removeWhere((Goal _goal) => _goal.id == goal.id);
   }
 
   void update(Goal goal) {
-    Db().updateGoal(goal);
-    var itemIndex = _cache.indexOf(goal);
-    _cache.replaceRange(itemIndex, itemIndex + 1, [goal]);
+    database.updateGoal(goal);
+    var itemIndex = _cache.indexWhere((Goal _g) => _g.id == goal.id);
+    if (itemIndex == -1) return;
+
+    if (_cache.length == 1) {
+      _cache.clear();
+      _cache.add(goal);
+    } else {
+      _cache.replaceRange(itemIndex, itemIndex + 1, [goal]);
+    }
   }
 
   int getNextId() {

lib/Services/Interfaces/ICache.dart

@@ -0,0 +1,4 @@
+abstract class ICache<T> {
+  bool shouldSyncCache = true;
+  Future<void> syncCache();
+}

lib/Services/Interfaces/IDatabase.dart

@@ -0,0 +1,9 @@
+import 'package:goalkeeper/Models/Goal.dart';
+
+abstract class IDatabase {
+  Future<int> createGoal(Goal goal);
+  Future<int> updateGoal(Goal goal);
+  Future<int> deleteGoal(Goal goal);
+  Future<int> getCount(Goal goal);
+  Future<List<Goal>> getGoalsList();
+}

lib/Services/Interfaces/IRepository.dart

@@ -0,0 +1,11 @@
+import 'package:goalkeeper/Models/Goal.dart';
+
+abstract class IRepository {
+  int getGoalsCount();
+  void insert(Goal goal);
+  void delete(Goal goal);
+  void update(Goal goal);
+  Goal find(int goalId);
+  int getNextId();
+  Future<List<Goal>> getGoalsList();
+}

lib/Services/Navigation.dart

@@ -2,13 +2,17 @@ import 'package:flutter/cupertino.dart';
 import 'package:goalkeeper/Models/Goal.dart';
 import 'package:goalkeeper/Pages/CreateGoal.dart';
 import 'package:goalkeeper/Pages/EditGoal.dart';
+import 'package:goalkeeper/Services/Factory.dart';
 
 void goToCreateGoal(context) async {
   await Navigator.push(
     context,
     CupertinoPageRoute(
       builder: (context) {
-        return CreateGoal();
+        return CreateGoal(
+          repository: Factory().repository,
+          notificationCenter: Factory().notificationCenter,
+        );
       },
     ),
   );
@@ -19,7 +23,9 @@ void goToEditGoal(context, Goal goal) async {
     context,
     CupertinoPageRoute(
       builder: (context) {
-        return EditGoal(goal);
+        return EditGoal(goal,
+            notificationCenter: Factory().notificationCenter,
+            repository: Factory().repository);
       },
     ),
   );

lib/Services/NotificationCenter.dart

@@ -1,26 +1,23 @@
+import 'package:flutter/foundation.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:goalkeeper/Models/Goal.dart';
-import 'package:goalkeeper/Services/GoalsRepository.dart';
+import 'package:goalkeeper/Services/Interfaces/IRepository.dart';
 
 class NotificationCenter {
   FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
       new FlutterLocalNotificationsPlugin();
 
-  List<PendingNotificationRequest> _pendingNotificationsCache;
-  GoalsRepository repo = GoalsRepository();
+  final IRepository repository;
 
-  static final NotificationCenter instance = NotificationCenter.getInstance();
-  factory NotificationCenter() => instance;
-
-  NotificationCenter.getInstance() {
+  NotificationCenter({@required this.repository}) {
     var initNotificationSettings = getInitSettings();
     flutterLocalNotificationsPlugin.initialize(initNotificationSettings,
         onSelectNotification: defaultCallBack);
   }
 
   Future<bool> defaultCallBack(String goalId) {
     if (goalId != null) {
-      Goal goal = repo.find(int.parse(goalId));
+      Goal goal = repository.find(int.parse(goalId));
       // still need to figure how to go to EditPage from here !
       print('got this notification: $goal');
     }
@@ -71,10 +68,9 @@ class NotificationCenter {
   }
 
   Future<bool> goalHasNotification(Goal goal) async {
-    if (_pendingNotificationsCache == null)
-      _pendingNotificationsCache =
-          await flutterLocalNotificationsPlugin.pendingNotificationRequests();
-    return _pendingNotificationsCache
+    var pendingNotifications =
+        await flutterLocalNotificationsPlugin.pendingNotificationRequests();
+    return pendingNotifications
         .any((notification) => notification.id == goal.id);
   }
 
@@ -83,7 +79,7 @@ class NotificationCenter {
     if (hasNotification) {
       flutterLocalNotificationsPlugin.cancel(goal.id);
     }
-    // if there is notification then update, and insert
+    // if there is notification then update, and insert it anyway
     scheduleNotification(goal);
   }
 }

lib/main.dart

@@ -1,11 +1,33 @@
 import 'package:dynamic_theme/dynamic_theme.dart';
 import 'package:flutter/material.dart';
 import 'package:goalkeeper/Pages/Home.dart';
+import 'package:goalkeeper/Services/Db.dart';
+import 'package:goalkeeper/Services/Factory.dart';
+import 'package:goalkeeper/Services/GoalsRepository.dart';
+import 'package:goalkeeper/Services/Interfaces/IRepository.dart';
+import 'package:goalkeeper/Services/NotificationCenter.dart';
 import 'package:goalkeeper/Utils/colors.dart';
 
-void main() => runApp(MyApp());
+void main() {
+  prepareDependencies();
+  runApp(MyApp(
+    repository: Factory().repository,
+  ));
+}
+
+// Composition root for our dependencies !
+void prepareDependencies() {
+  var factory = Factory();
+  factory.registerDatabase(Db());
+  factory.registerRepository(GoalsRepository(database: factory.database));
+  factory.registerNotificationCenter(
+      NotificationCenter(repository: factory.repository));
+}
 
 class MyApp extends StatelessWidget {
+  final IRepository repository;
+  MyApp({@required this.repository});
+
   @override
   Widget build(BuildContext context) {
     return DynamicTheme(
@@ -19,7 +41,7 @@ class MyApp extends StatelessWidget {
         return MaterialApp(
           title: "Goalkeeper",
           theme: theme,
-          home: Home(),
+          home: Home(repository: this.repository),
         );
       },
     );

lib/pages/CreateGoal.dart

@@ -2,29 +2,40 @@ import "package:flutter/cupertino.dart";
 import "package:flutter/material.dart";
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:goalkeeper/Models/Goal.dart';
-import 'package:goalkeeper/Services/GoalsRepository.dart';
+import 'package:goalkeeper/Services/Interfaces/IRepository.dart';
 import 'package:goalkeeper/Services/NotificationCenter.dart';
 import 'package:goalkeeper/Utils/HelperUtils.dart';
 import 'package:goalkeeper/Utils/ThemeUtils.dart';
 import "package:goalkeeper/Utils/colors.dart";
 import "package:goalkeeper/Utils/pickers.dart";
 
 class CreateGoal extends StatefulWidget {
+  final IRepository repository;
+  final NotificationCenter notificationCenter;
+
+  CreateGoal({@required this.repository, @required this.notificationCenter});
+
   @override
   State<StatefulWidget> createState() {
-    return CreateGoalState();
+    return CreateGoalState(
+        repository: this.repository,
+        notificationCenter: this.notificationCenter);
   }
 }
 
 class CreateGoalState extends State<CreateGoal> {
-  GoalsRepository repo = GoalsRepository();
+  final IRepository repository;
+  final NotificationCenter notificationCenter;
 
   Goal goal = new Goal("", "");
   Color invertColor;
 
   FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
       new FlutterLocalNotificationsPlugin();
 
+  CreateGoalState(
+      {@required this.repository, @required this.notificationCenter});
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -195,12 +206,11 @@ class CreateGoalState extends State<CreateGoal> {
     Navigator.pop(context);
     if (goal.title.trim().isNotEmpty) {
       if (goal.id == null) {
-        repo.insert(goal);
+        repository.insert(goal);
       } else {
-        repo.update(goal);
+        repository.update(goal);
       }
-      var noty = NotificationCenter();
-      noty.scheduleNotification(goal);
+      notificationCenter.scheduleNotification(goal);
     }
   }