Show who is writing messages

lib/helpers/events_helper.dart

@@ -50,6 +50,14 @@ class DeletedCommentEvent {
   DeletedCommentEvent(this.commentID);
 }
 
+/// Writing message in conversation event
+class WritingMessageInConversationEvent {
+  final int convID;
+  final int userID;
+
+  WritingMessageInConversationEvent(this.convID, this.userID);
+}
+
 /// New conversation message
 class NewConversationMessageEvent {
   final ConversationMessage msg;

lib/helpers/websocket_helper.dart

@@ -144,6 +144,12 @@ class WebSocketHelper {
         EventsHelper.emit(DeletedCommentEvent(msg.data));
         break;
 
+      // A user is writing a new message
+      case "writing_message_in_conv":
+        EventsHelper.emit(WritingMessageInConversationEvent(
+            msg.data["conv_id"], msg.data["user_id"]));
+        break;
+
       // Created new conversation message
       case "new_conv_message":
         EventsHelper.emit(NewConversationMessageEvent(

lib/ui/screens/conversation_screen.dart

@@ -17,6 +17,7 @@ import 'package:comunic/ui/tiles/server_conversation_message_tile.dart';
 import 'package:comunic/ui/widgets/account_image_widget.dart';
 import 'package:comunic/ui/widgets/safe_state.dart';
 import 'package:comunic/ui/widgets/scroll_watcher.dart';
+import 'package:comunic/ui/widgets/user_writing_in_conv_notifier.dart';
 import 'package:comunic/utils/date_utils.dart';
 import 'package:comunic/utils/files_utils.dart';
 import 'package:comunic/utils/intl_utils.dart';
@@ -649,6 +650,7 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
               : null,
         ),
         _messages.length == 0 ? _buildNoMessagesNotice() : _buildMessagesList(),
+        UserWritingInConvNotifier(convID: _conversation.id),
         _sendCancel != null ? _buildSendingWidget() : _buildSendMessageForm(),
         _showEmojiPicker ? _buildEmojiContainer() : Container(),
       ],

lib/ui/widgets/user_writing_in_conv_notifier.dart

@@ -0,0 +1,84 @@
+import 'package:comunic/helpers/events_helper.dart';
+import 'package:comunic/helpers/server_config_helper.dart';
+import 'package:comunic/helpers/users_helper.dart';
+import 'package:comunic/lists/users_list.dart';
+import 'package:comunic/ui/widgets/safe_state.dart';
+import 'package:comunic/utils/intl_utils.dart';
+import 'package:comunic/utils/log_utils.dart';
+import 'package:flutter/material.dart';
+
+/// User writing a message in a conversation notifier
+///
+/// @author Pierre Hubert
+
+class UserWritingInConvNotifier extends StatefulWidget {
+  final int convID;
+
+  const UserWritingInConvNotifier({Key key, @required this.convID})
+      : assert(convID != null),
+        super(key: key);
+
+  @override
+  _UserWritingInConvNotifierState createState() =>
+      _UserWritingInConvNotifierState();
+}
+
+class _UserWritingInConvNotifierState
+    extends SafeState<UserWritingInConvNotifier> {
+  final _usersInfo = UsersList();
+
+  final _list = List();
+
+  @override
+  void initState() {
+    this.listen<WritingMessageInConversationEvent>((ev) async {
+      try {
+        if (ev.convID != widget.convID) return;
+
+        if (!_usersInfo.hasUser(ev.userID))
+          _usersInfo.add(await UsersHelper().getSingleWithThrow(ev.userID));
+
+        _handleEvent(ev.userID);
+      } catch (e, s) {
+        logError(e, s);
+      }
+    });
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) => Padding(
+        padding: EdgeInsets.only(left: 5, right: 5),
+        child: Align(
+          alignment: Alignment.centerLeft,
+          child: Text(
+            writingText,
+            style: TextStyle(fontSize: 10),
+            textAlign: TextAlign.justify,
+          ),
+        ),
+      );
+
+  String get writingText {
+    if (_list.isEmpty) return "";
+
+    final users = _list.toSet().map((e) => _usersInfo.getUser(e)).toList();
+
+    if (users.length == 1)
+      return tr("%1% is writing...", args: {"1": users.first.fullName});
+
+    return tr("%1% and %2% are writing...", args: {
+      "1": users.first.fullName,
+      "2": users.sublist(1).map((e) => e.fullName).join(", ")
+    });
+  }
+
+  void _handleEvent(int userID) async {
+    setState(() => this._list.add(userID));
+
+    await Future.delayed(
+        Duration(seconds: srvConfig.conversationsPolicy.writingEventLifetime));
+
+    setState(() => this._list.removeAt(0));
+  }
+}