Implemented the onLoadingStateChanged callback

lib/src/chatbox.dart

@@ -1,4 +1,5 @@
 import 'dart:convert';
+import 'dart:async';
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -15,6 +16,7 @@ import './predicate.dart';
 
 typedef SendMessageHandler = void Function(SendMessageEvent event);
 typedef TranslationToggledHandler = void Function(TranslationToggledEvent event);
+typedef LoadingStateHandler = void Function(LoadingState state);
 
 class SendMessageEvent {
   final ConversationData conversation;
@@ -36,6 +38,8 @@ class TranslationToggledEvent {
     isEnabled = json['isEnabled'];
 }
 
+enum LoadingState { loading, loaded }
+
 /// A messaging UI for just a single conversation.
 ///
 /// Create a Chatbox through [Session.createChatbox] and then call [mount] to show it.
@@ -57,6 +61,7 @@ class ChatBox extends StatefulWidget {
 
   final SendMessageHandler? onSendMessage;
   final TranslationToggledHandler? onTranslationToggled;
+  final LoadingStateHandler? onLoadingStateChanged;
 
   const ChatBox({
     Key? key,
@@ -73,6 +78,7 @@ class ChatBox extends StatefulWidget {
     this.asGuest,
     this.onSendMessage,
     this.onTranslationToggled,
+    this.onLoadingStateChanged,
   }) : super(key: key);
 
   @override
@@ -121,14 +127,18 @@ class ChatBoxState extends State<ChatBox> {
       // If it's the first time that the widget is built, then build everything
       _webViewCreated = true;
 
+      // Here a Timer is needed, as we can't change the widget's state while the widget
+      // is being constructed, and the callback may very possibly change the state
+      Timer.run(() => widget.onLoadingStateChanged?.call(LoadingState.loading));
+
       execute('let chatBox;');
 
       _createSession();
       _createChatBox();
       // messageFilter and highlightedWords are set as options for the chatbox
       _createConversation();
 
-      execute('chatBox.mount(document.getElementById("talkjs-container"));');
+      execute('chatBox.mount(document.getElementById("talkjs-container")).then(() => JSCLoadingState.postMessage("loaded"));');
     } else {
       // If it's not the first time that the widget is built,
       // then check what needs to be rebuilt
@@ -161,6 +171,7 @@ class ChatBoxState extends State<ChatBox> {
       javascriptChannels: <JavascriptChannel>{
         JavascriptChannel(name: 'JSCSendMessage', onMessageReceived: _jscSendMessage),
         JavascriptChannel(name: 'JSCTranslationToggled', onMessageReceived: _jscTranslationToggled),
+        JavascriptChannel(name: 'JSCLoadingState', onMessageReceived: _jscLoadingState),
     });
   }
 
@@ -339,6 +350,14 @@ class ChatBoxState extends State<ChatBox> {
     widget.onTranslationToggled?.call(TranslationToggledEvent.fromJson(json.decode(message.message)));
   }
 
+  void _jscLoadingState(JavascriptMessage message) {
+    if (kDebugMode) {
+      print('📗 chatbox._jscLoadingState: ${message.message}');
+    }
+
+    widget.onLoadingStateChanged?.call(LoadingState.loaded);
+  }
+
   /// For internal use only. Implementation detail that may change anytime.
   ///
   /// Return a string with a unique ID

lib/src/conversationlist.dart

@@ -1,4 +1,5 @@
 import 'dart:convert';
+import 'dart:async';
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -10,6 +11,7 @@ import './session.dart';
 import './conversation.dart';
 import './user.dart';
 import './predicate.dart';
+import './chatbox.dart';
 
 typedef SelectConversationHandler = void Function(SelectConversationEvent event);
 
@@ -80,6 +82,7 @@ class ConversationList extends StatefulWidget {
   final ConversationPredicate feedFilter;
 
   final SelectConversationHandler? onSelectConversation;
+  final LoadingStateHandler? onLoadingStateChanged;
 
   const ConversationList({
     Key? key,
@@ -88,6 +91,7 @@ class ConversationList extends StatefulWidget {
     this.theme,
     this.feedFilter = const ConversationPredicate(),
     this.onSelectConversation,
+    this.onLoadingStateChanged,
   }) : super(key: key);
 
   @override
@@ -121,11 +125,15 @@ class ConversationListState extends State<ConversationList> {
     if (!_webViewCreated) {
       _webViewCreated = true;
 
+      // Here a Timer is needed, as we can't change the widget's state while the widget
+      // is being constructed, and the callback may very possibly change the state
+      Timer.run(() => widget.onLoadingStateChanged?.call(LoadingState.loading));
+
       _createSession();
       _createConversationList();
       // feedFilter is set as an option for the inbox
 
-      execute('conversationList.mount(document.getElementById("talkjs-container"));');
+      execute('conversationList.mount(document.getElementById("talkjs-container")).then(() => JSCLoadingState.postMessage("loaded"));');
     } else {
       // If it's not the first time that the widget is built,
       // then check what needs to be rebuilt
@@ -142,6 +150,7 @@ class ConversationListState extends State<ConversationList> {
       onPageFinished: _onPageFinished,
       javascriptChannels: <JavascriptChannel>{
         JavascriptChannel(name: 'JSCSelectConversation', onMessageReceived: _jscSelectConversation),
+        JavascriptChannel(name: 'JSCLoadingState', onMessageReceived: _jscLoadingState),
     });
   }
 
@@ -243,6 +252,14 @@ class ConversationListState extends State<ConversationList> {
     widget.onSelectConversation?.call(SelectConversationEvent.fromJson(json.decode(message.message)));
   }
 
+  void _jscLoadingState(JavascriptMessage message) {
+    if (kDebugMode) {
+      print('📗 conversationlist._jscLoadingState: ${message.message}');
+    }
+
+    widget.onLoadingStateChanged?.call(LoadingState.loaded);
+  }
+
   /// For internal use only. Implementation detail that may change anytime.
   ///
   /// Return a string with a unique ID