Flutter Navigator 2.0 + Notification test

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final delegate = AppRouteDelegate();
  final parser = AppRouteInformationParser();
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routerDelegate: delegate,
      routeInformationParser: parser,
      title: 'Nav2',
    );
  }
}

class AppRoutePath {
  final String message;
  final bool isUnknown;

  AppRoutePath.home()
      : message = null,
        isUnknown = false;

  AppRoutePath.detail(this.message) : isUnknown = false;

  AppRoutePath.unknown()
      : message = null,
        isUnknown = true;
}

class AppRoutingEvent extends Notification {
  final String message;

  AppRoutingEvent(this.message);
}

class AppRouteDelegate extends RouterDelegate<AppRoutePath>
    with ChangeNotifier, PopNavigatorRouterDelegateMixin<AppRoutePath> {
  final GlobalKey<NavigatorState> navigatorKey;
  AppRouteDelegate() : navigatorKey = GlobalKey<NavigatorState>();
  String message;

  bool _handleNavigationEvent(AppRoutingEvent event) {
    message = event.message;
    notifyListeners();
    return true;
  }

  AppRoutePath get currentConfiguration =>
      message == null ? AppRoutePath.home() : AppRoutePath.detail(message);

  @override
  Widget build(BuildContext context) {
    return NotificationListener<AppRoutingEvent>(
      onNotification: _handleNavigationEvent,
      child: Navigator(
        key: navigatorKey,
        pages: [
          MaterialPage(
            key: ValueKey('HomeScreen'),
            child: HomeScreen(),
          ),
          if (message != null)
            MaterialPage(
              key: ValueKey(message),
              child: DetailScreen(
                message: message,
              ),
            )
        ],
        onPopPage: (route, result) {
          if (!route.didPop(result)) {
            return false;
          }
          message = null;
          notifyListeners();
          return true;
        },
      ),
    );
  }

  @override
  Future<void> setNewRoutePath(AppRoutePath path) async {
    if (path.isUnknown) {
      message = null;
    }

    if (path.message != null) {
      message = path.message;
    }
  }
}

class AppRouteInformationParser extends RouteInformationParser<AppRoutePath> {
  @override
  Future<AppRoutePath> parseRouteInformation(
      RouteInformation routeInformation) async {
    final uri = Uri.parse(routeInformation.location);

    if (uri.pathSegments.isEmpty) {
      return AppRoutePath.home();
    }

    if (uri.pathSegments.length == 2) {
      if (uri.pathSegments[0] != 'details') return AppRoutePath.unknown();

      final message = uri.pathSegments[1];

      return AppRoutePath.detail(message);
    }

    return AppRoutePath.unknown();
  }

  @override
  RouteInformation restoreRouteInformation(AppRoutePath path) {
    if (path.message == null) {
      return RouteInformation(location: '/');
    }
    if (path.message != null) {
      return RouteInformation(location: '/details/${path.message}');
    }
    return null;
  }
}

class DetailScreen extends StatelessWidget {
  final String message;

  const DetailScreen({Key key, this.message}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Detail')),
      body: Center(
        child: Text(message ?? 'No message'),
      ),
    );
  }
}

class HomeScreen extends StatefulWidget {
  final Function(String) onTap;

  const HomeScreen({Key key, this.onTap}) : super(key: key);
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  void onTap(String message) {
    widget.onTap?.call(message) ?? AppRoutingEvent(message).dispatch(context);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Home')),
      body: Column(
        children: [
          TextButton(
            onPressed: () => onTap('Detail 1'),
            child: Text('Detail 1'),
          ),
          TextButton(
            onPressed: () => onTap('Detail 2'),
            child: Text('Detail 2'),
          )
        ],
      ),
    );
  }
}