import 'package:flutter/cupertino.dart';

import 'package:flutter/material.dart';

import 'dart:async';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Flutter Demo',
        onGenerateRoute: Router.generateRoute,
        initialRoute: RouteName.first,
        theme: ThemeData(primarySwatch: Colors.blue),
        home: Popview(title: 'title'));
    //  MyHomePage(title: 'App title'));
  }
}

class Popview extends StatefulWidget {
  const Popview({Key? key, required this.title}) : super(key: key);

  final String title;
  @override
  _PopviewState createState() => _PopviewState();
}

class _PopviewState extends State<Popview> {
  String stringFromActivity = 'Send Data on Pop';
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              stringFromActivity,
              style: const TextStyle(fontSize: 20.0),
              textAlign: TextAlign.center,
            ),
            Container(
              height: 20.0,
            ),
            ElevatedButton(
              child: const Text('tap me'),
              onPressed: () => _push(),
            )
          ],
        ),
      ),
    );
  }

  Future _push() async {
    Object? results = await Navigator.of(context).pushNamed(RouteName.second);

    if (results != null) {
      setState(() {
        print('Data received on pop $results');
      });
    }
  }
}

class SecondScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Selecte Smily'),
      ),
      body: ListView.builder(
        itemBuilder: (context, i) {
          return ListTile(
            title: Text('item $i'),
            onTap: () {
              Navigator.of(context).pop('SEND THIS');
            },
          );
        },
        itemCount: 20,
      ),
    );
  }
}

class RouteName {
  static const String first = 'first';
  static const String second = 'second';
}

class Router {
  static Route<dynamic> generateRoute(RouteSettings settings) {
    switch (settings.name) {
      case RouteName.first:
        return CupertinoPageRoute<bool>(
            settings: RouteSettings(name: 'first'),
            builder: (_) => Popview(
                  title: 'first',
                ));
      case RouteName.second:
        return CupertinoPageRoute<bool>(
            settings: RouteSettings(name: settings.name),
            builder: (_) => SecondScreen());
      default:
        return CupertinoPageRoute<bool>(
            settings: RouteSettings(name: settings.name),
            builder: (_) => Scaffold(
                  body: Center(
                    child: Text('No route defined for ${settings.name}'),
                  ),
                ));
    }
  }
}

/// Pop路由
class PopRoute extends PopupRoute {
  PopRoute({required this.child});

  Widget child;

  final Duration _duration = Duration(milliseconds: 300);

  @override
  Color? get barrierColor => null;

  @override
  bool get barrierDismissible => true;

  @override
  String? get barrierLabel => null;

  @override
  Duration get transitionDuration => _duration;

  @override
  Widget buildPage(BuildContext context, Animation<double> animation,
      Animation<double> secondaryAnimation) {
    return child;
  }
}