myhomie_app/lib/Screens/Debug/DebugPage.dart

import 'package:flare_flutter/flare_actor.dart';
import 'package:flutter/material.dart';
import 'package:myhomie_app/Helpers/MQTTHelper.dart';
import 'package:myhomie_app/app_context.dart';
import 'package:provider/provider.dart';

class DebugPage extends StatefulWidget {
  DebugPage({Key key}) : super(key: key);

  @override
  _DebugPageState createState() => _DebugPageState();
}

class _DebugPageState extends State<DebugPage> {
  List<String> lastMessages = [];

  @override
  Widget build(BuildContext context) {
    final AppContext appContext = Provider.of<AppContext>(context);
    String lastMessage = "test";

    //lastMessage = MQTTHelper.instance.getLastMessage() == null ? "rien" : MQTTHelper.instance.getLastMessage();

    return Scaffold(
      appBar: AppBar(
        title: Text("Debug"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            /*new Container(
            width: 150,
              height: 150,
              child: FlareActor(
                'assets/animations/MDLF_animation.flr',
                alignment: Alignment.center,
                fit: BoxFit.scaleDown,
                animation: 'Rotate',
              ),
            ),*/
            new Expanded(
                child: new ListView.separated
                  (
                    reverse: true,
                    separatorBuilder: (context, index) {
                      return Container(
                        width: 50,
                        height: 50,
                        child: FlareActor(
                          'assets/animations/MDLF_animation.flr',
                          alignment: Alignment.center,
                          fit: BoxFit.scaleDown,
                          animation: 'Rotate',
                        ),
                      );
                    },
                    itemCount: appContext.getLastMQTTMessages()?.length,
                    itemBuilder: (BuildContext ctxt, int Index) {
                      if (appContext.getLastMQTTMessages().length > 0) {
                        if (appContext.getLastMQTTMessages()[Index].toString().length > 350) {
                          var textToShow = appContext.getLastMQTTMessages()[Index].toString().substring(0,350);
                          return new Text("$textToShow ...");
                        } else {
                          return new Text(appContext.getLastMQTTMessages()[Index].toString());
                        }
                      }else {
                        return new Text("rien");
                      }
                    }
                )
            ),
          ],
        ),
      ),
      /*floatingActionButton: FloatingActionButton(
        onPressed: () => {},
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),*/
    );
  }

  Widget buildBody(BuildContext context, int index) {
    return new Text(lastMessages[index]);
  }
}