Show the tasks linked to an event on its screen

lib/src/blocs/event_bloc.dart

@@ -1,19 +1,54 @@
 import 'dart:async';
-import 'package:meta/meta.dart';
 
+import 'package:meta/meta.dart';
+import 'package:rxdart/rxdart.dart';
+
+import '../models/task_model.dart';
 import '../resources/firestore_provider.dart';
 import '../resources/firebase_storage_provider.dart';
+import '../services/auth_service.dart';
+import '../utils.dart' show kTaskListPriorityTransforemer;
 
 /// A business logic component that manages the state for an event screen.
 class EventBloc {
   /// The name of the event being shown.
   final String eventName;
+
+  /// An instance of a firestore provider.
+  final FirestoreProvider _firestore = firestoreProvider;
+
+  /// An instace of the auth service.
+  final AuthService _auth = authService;
+
+  /// A subject of list of task model.
+  final _tasks = BehaviorSubject<List<TaskModel>>();
+
+  // Stream getters.
+  /// An observable of the tasks linked to the event.
+  Observable<List<TaskModel>> get eventTasks =>
+      _tasks.stream.transform(kTaskListPriorityTransforemer);
+
   EventBloc({
     @required this.eventName,
   });
 
   /// Fetches the tasks for the current user that a part of the currently
   /// selected event.
-  void fetchTasks() {}
-  void dispose() {}
+  Future<void> fetchTasks() async {
+    final user = await _auth.currentUser;
+    _firestore.getUserTasks(user.email, event: eventName).pipe(_tasks);
+  }
+
+  /// Marks a task as done in the database.
+  void markTaskAsDone(TaskModel task) async {
+    _firestore.updateTask(
+      task.id,
+      done: true,
+    );
+  }
+
+  void dispose() async {
+    await _tasks.drain();
+    _tasks.close();
+  }
 }