Added properties and functions to the event bloc for showing the upload status snackbar

lib/src/blocs/event_bloc.dart

@@ -28,6 +28,9 @@ class EventBloc {
   /// An instace of the auth service.
   final AuthService _auth = authService;
 
+  /// An instance of the upload status service.
+  final UploadStatusService _uploadStatus = uploadStatusService;
+
   /// A subject of list of task model.
   final _tasks = BehaviorSubject<List<TaskModel>>();
 
@@ -46,6 +49,9 @@ class EventBloc {
   /// A subject of a cache that contains the image files.
   final _images = BehaviorSubject<Map<String, Future<File>>>();
 
+  /// A subject of a flag that indicates if there is a snack bar showing.
+  final _snackBarStatus = BehaviorSubject<bool>(seedValue: false);
+
   /// The event being managed by this bloc.
   EventModel _event;
 
@@ -68,6 +74,13 @@ class EventBloc {
   /// An observable of a cache of the images files.
   Observable<Map<String, Future<File>>> get images => _images.stream;
 
+  /// An observable of a flag that indicates whether or not a snackBar is
+  /// currently showing.
+  ValueObservable<bool> get snackBarStatus => _snackBarStatus.stream;
+
+  /// An observable of the status of files being uploaded.
+  Observable<UploadStatus> get uploadStatus => _uploadStatus.status;
+
   // Sinks getters.
   /// Starts the fetching process for an image given its path.
   Function(String) get fetchImage => _imagesFetcher.sink.add;
@@ -75,6 +88,9 @@ class EventBloc {
   /// Starts the fetching process for an image thumbail given its path.
   Function(String) get fetchThumbnail => _imagesThumbnailsFetcher.sink.add;
 
+  /// Updates the snack bar status.
+  Function(bool) get updateSnackBarStatus => _snackBarStatus.sink.add;
+
   EventBloc({
     @required this.eventName,
   }) {
@@ -143,6 +159,8 @@ class EventBloc {
   }
 
   void dispose() async {
+    await _snackBarStatus.drain();
+    _snackBarStatus.close();
     await _imagesThumbnailsFetcher.drain();
     _imagesThumbnailsFetcher.close();
     await _imagesFetcher.drain();

lib/src/blocs/home_bloc.dart

@@ -9,8 +9,6 @@ import '../services/auth_service.dart';
 
 export '../services/auth_service.dart' show FirebaseUser;
 
-// TODO: Add the text search functionality.
-
 /// A business logic component that manages the state of the home screen.
 class HomeBloc {
   /// An instance of the auth service.

lib/src/resources/firebase_storage_provider.dart

@@ -6,11 +6,16 @@ import 'package:firebase_storage/firebase_storage.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:uuid/uuid.dart';
 
+import '../services/upload_status_service.dart';
+
 export 'package:firebase_storage/firebase_storage.dart'
     show StorageUploadTask, StorageTaskSnapshot;
 
 /// A connection to the firebase sotrage bucket.
 class FirebaseStorageProvider {
+  /// An instance of the upload status service.
+  final UploadStatusService _uploadStatus = uploadStatusService;
+
   /// The reference to the root path of the storage bucket.
   final StorageReference _storage;
 
@@ -35,10 +40,12 @@ class FirebaseStorageProvider {
     final String fileId = _uuid.v1();
     final StorageReference fileReference =
         _storage.child('$folder$fileId.$type');
-    return fileReference.putFile(
+    final uploadTask = fileReference.putFile(
       file,
       StorageMetadata(contentType: 'image/png'),
     );
+    _uploadStatus.addNewUpload(uploadTask);
+    return uploadTask;
   }
 
   /// Deletes a file from the firebase storage bucket given its path.

lib/src/screens/event_screen.dart

@@ -41,9 +41,6 @@ class _EventScreenState extends State<EventScreen>
   /// Needed for showing snackbars.
   BuildContext _scaffoldContext;
 
-  /// Flag that indicates if there is a snackbar currently being shown.
-  bool _hasSnackBar = false;
-
   initState() {
     super.initState();
     bloc = EventBloc(eventName: widget.eventName);

lib/src/services/upload_status_service.dart

@@ -5,24 +5,32 @@ import 'package:rxdart/rxdart.dart';
 
 /// A service that maintains a record of the upload operations made to
 /// the firebase storage bucket.
-class _UploadStatusService {
+class UploadStatusService {
   /// A subject of the current status of uploads.
   final _status = BehaviorSubject<UploadStatus>();
 
   /// A map that contains the information about all the current upload tasks.
-  Map<StorageUploadTask, List<int>> tasksData =
+  Map<StorageUploadTask, List<int>> _tasksData =
       <StorageUploadTask, List<int>>{};
 
   /// An observable of the status for all current upload tasks.
   Observable<UploadStatus> get status => _status.stream;
 
+  /// Creates a new service that maintains a record of the upload operations
+  /// made to the firebase storage bucket.
+  ///
+  /// Avoid multiple instantiaion of this service. Either use the
+  /// [uploadStatusService] singleton or instantiate once, the state will be
+  /// lost otherwise.
+  UploadStatusService();
+
   /// Adds a new upload task to be tracked.
   ///
   /// The task gets automatically removed when done.
   void addNewUpload(StorageUploadTask task) async {
     final initialSnap = task.lastSnapshot;
     // Initialize the map entry with the initial values.
-    tasksData[task] = [
+    _tasksData[task] = [
       initialSnap.bytesTransferred,
       initialSnap.totalByteCount,
     ];
@@ -30,7 +38,7 @@ class _UploadStatusService {
       (StorageTaskEvent event) {
         // Update the map with the current values.
         final snap = event.snapshot;
-        tasksData[task] = [
+        _tasksData[task] = [
           snap.bytesTransferred,
           snap.totalByteCount,
         ];
@@ -38,14 +46,14 @@ class _UploadStatusService {
       },
     );
     await task.onComplete;
-    tasksData.remove(task);
+    _tasksData.remove(task);
   }
 
   /// Updates the _status subject with the most current data.
   void _sendUpdate() {
     int totalBytes = 0, bytestTransferred = 0;
     double percentage = 0.0;
-    tasksData.forEach(
+    _tasksData.forEach(
       (_, data) {
         bytestTransferred += data[0];
         totalBytes += data[1];
@@ -56,7 +64,7 @@ class _UploadStatusService {
     }
     _status.sink.add(UploadStatus(
       percentage: percentage,
-      numberOfFiles: tasksData.length,
+      numberOfFiles: _tasksData.length,
     ));
   }
 
@@ -83,4 +91,4 @@ class UploadStatus {
   });
 }
 
-final uploadStatusService = _UploadStatusService();
+final uploadStatusService = UploadStatusService();

lib/src/utils.dart

@@ -1,7 +1,10 @@
 import 'dart:async';
 
 import 'package:flutter/material.dart';
+import 'package:rxdart/rxdart.dart';
+
 import './models/task_model.dart';
+import './services/upload_status_service.dart';
 
 const kLowPriorityColor = Color(0xFF06AD12);
 const kMediumPriorityColor = Color(0xFFF6A93B);
@@ -67,3 +70,10 @@ String getImageThumbnailPath(String path) {
   tokens.last = 'thumb@' + tokens.last;
   return tokens.join('/');
 }
+
+///
+void showUploadStatusSnackBar(
+  BuildContext context,
+  Observable<UploadStatus> uploadStatus,
+  ValueObservable<bool> snackBarStatus,
+) {}