Automatically refresh conversations

lib/ui/screens/conversation_screen.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:comunic/helpers/conversations_helper.dart';
 import 'package:comunic/helpers/users_helper.dart';
 import 'package:comunic/lists/conversation_messages_list.dart';
@@ -39,6 +41,7 @@ class _ConversationScreenState extends State<ConversationScreen> {
   bool _isMessageValid = false;
   bool _isSendingMessage = false;
   TextEditingController _textEditingController = TextEditingController();
+  Timer _refreshTime;
 
   @override
   void didChangeDependencies() {
@@ -46,6 +49,12 @@ class _ConversationScreenState extends State<ConversationScreen> {
     _initializeLoading();
   }
 
+  @override
+  void deactivate() {
+    super.deactivate();
+    _refreshTime.cancel();
+  }
+
   void _setError(ErrorLevel err) => setState(() => _error = err);
 
   void _setSending(bool sending) => setState(() => _isSendingMessage = sending);
@@ -59,6 +68,11 @@ class _ConversationScreenState extends State<ConversationScreen> {
   Future<void> _initializeLoading() async {
     await _loadMessages(false);
     await _loadMessages(true);
+
+    // Set a timer to regularly update conversation messages
+    if (_refreshTime == null || !_refreshTime.isActive)
+      _refreshTime = Timer.periodic(
+          Duration(milliseconds: 1500), (t) => _loadMessages(true));
   }
 
   /// Load a list of messages
@@ -73,8 +87,7 @@ class _ConversationScreenState extends State<ConversationScreen> {
 
     // In case we are offline and we did not get any message we do not do
     // anything (we wait for the online request)
-    if(messages.length == 0 && !online)
-      return;
+    if (messages.length == 0 && !online) return;
 
     //Then get information about users
     final usersToGet =
@@ -92,12 +105,17 @@ class _ConversationScreenState extends State<ConversationScreen> {
       else
         _messages.addAll(messages);
 
-      //Reverse the order of the messages
-      _messages.sort();
-      final reverse = _messages.reversed;
-      _messages = ConversationMessagesList();
-      _messages.addAll(reverse);
+      //Reverse the order of the messages (if required)
+      if (messages.length > 0) {
+        _messages.sort();
+        final reverse = _messages.reversed;
+        _messages = ConversationMessagesList();
+        _messages.addAll(reverse);
+      }
     });
+
+    // Remove previous errors
+    _setError(ErrorLevel.NONE);
   }
 
   /// Pick and send an image