import 'dart:async';

import 'package:after_layout/after_layout.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      color: Colors.blue,
      home: new Splash(),
    );
  }
}

class Splash extends StatefulWidget {
  @override
  SplashState createState() => new SplashState();
}

class SplashState extends State with AfterLayoutMixin {
  Future checkFirstSeen() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    bool _seen = (prefs.getBool('seen') ?? false);

    if (_seen) {
      Navigator.of(context).pushReplacement(
          new MaterialPageRoute(builder: (context) => new Home()));
    } else {
      await prefs.setBool('seen', true);
      Navigator.of(context).pushReplacement(
          new MaterialPageRoute(builder: (context) => new IntroScreen()));
    }
  }

  @override
  void afterFirstLayout(BuildContext context) => checkFirstSeen();

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Center(
        child: new Text('Loading...'),
      ),
    );
  }
}

class Home extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Hello'),
      ),
      body: new Center(
        child: new Text('This is the second page'),
      ),
    );
  }
}

class IntroScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('IntroScreen'),
      ),
      body: new Center(
        child: new Text('This is the IntroScreen'),
      ),
    );
  }
}