Connect Firebase

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:/Component/fade_transition.dart';
import 'package:/cek_login.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter_account_kit/flutter_account_kit.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:package_info/package_info.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:url_launcher/url_launcher.dart';

class SplashScreen extends StatefulWidget {
  @override
  _SplashScreenState createState() => _SplashScreenState();
}

final versi = FirebaseDatabase.instance.reference().child('versi');
final maintenance = FirebaseDatabase.instance.reference().child('maintenance');

class _SplashScreenState extends State<SplashScreen> {
  StreamSubscription<Event> _onVersi;
  StreamSubscription<Event> _onMaintenance;
  bool _isMaintenance = false, _isUpdate = false;
  String currVersi = "";

  @override
  void initState() {
    super.initState();
    cekLogout();
    // getSimInfo();

    _onVersi = versi.onValue.listen(_onValueVersi);
    _onMaintenance = maintenance.onValue.listen(_onValueMaintenance);

    PackageInfo.fromPlatform().then((PackageInfo packageInfo) {
      setState(() {
        currVersi = packageInfo.version;
      });
    });
  }

  void _onValueVersi(Event event) {
    if (currVersi != event.snapshot.value) {
      if (mounted) {
        setState(() {
          _isUpdate = true;
        });
      }
    } else {
      setState(() {
        _isUpdate = false;
      });
      navigationPage();
    }
  }

  void _onValueMaintenance(Event event) {
    if (mounted) {
      setState(() {
        _isMaintenance = event.snapshot.value;
      });
      navigationPage();
    }
  }

  void navigationPage() {
    // print(_isMaintenance.toString()+" - "+_isUpdate.toString());
    Future.delayed(Duration(seconds: 3)).then((_) {
      if (_isMaintenance == false && _isUpdate == false) {
        Navigator.pushAndRemoveUntil(context, FadeRoute(widget: CekLogin()),
            (Route<dynamic> route) => false);
      }
    });
  }

  @override
  void dispose() {
    _onVersi.cancel();
    _onMaintenance.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: _isMaintenance
          ? BuildMaintenance()
          : _isUpdate ? BuildUpdate(launch: _launch) : BuildSplash(),
    );
  }


}

class BuildSplash extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
        height: double.infinity,
        width: double.infinity,
        alignment: Alignment(0.0, 0.0),
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: FractionalOffset.topLeft,
            end: FractionalOffset.bottomRight,
            colors: <Color>[
              Colors.cyan[600],
              Colors.cyan[800],
            ],
          ),
        ),
        padding: EdgeInsets.all(48.0),
        child: Image.asset(
          "assets/logo_putih.png",
          fit: BoxFit.cover,
        ));
  }
}

class BuildMaintenance extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      height: double.infinity,
      width: double.infinity,
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: FractionalOffset.topLeft,
          end: FractionalOffset.bottomRight,
          colors: <Color>[
            Colors.cyan[600],
            Colors.cyan[800],
          ],
        ),
      ),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Padding(
            padding: EdgeInsets.symmetric(horizontal: 58.0),
            child: Image.asset(
              "assets/logo_putih.png",
              fit: BoxFit.cover,
            ),
          ),
          Container(
            padding: EdgeInsets.symmetric(horizontal: 35.0),
            margin: EdgeInsets.only(top: 40.0),
            child: Text(
              "Aplikasi sedang dalam perbaikan.\nMohon kembali beberapa saat lagi.",
              style: TextStyle(fontSize: 17.0, color: Colors.white),
              textAlign: TextAlign.center,
            ),
          )
        ],
      ),
    );
  }
}

class BuildUpdate extends StatelessWidget {
  final launch;

  const BuildUpdate({Key key, this.launch}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      height: double.infinity,
      width: double.infinity,
      alignment: Alignment(0.0, 0.0),
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: FractionalOffset.topLeft,
          end: FractionalOffset.bottomRight,
          colors: <Color>[
            Colors.cyan[600],
            Colors.cyan[800],
          ],
        ),
      ),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Padding(
            padding: EdgeInsets.symmetric(horizontal: 58.0),
            child: Image.asset(
              "assets/logo_putih.png",
              fit: BoxFit.cover,
            ),
          ),
          Container(
            padding: EdgeInsets.symmetric(horizontal: 35.0),
            margin: EdgeInsets.only(top: 40.0),
            child: Text(
              "Versi baru tersedia.\nSilahkan Update ke versi terbaru.",
              style: TextStyle(fontSize: 17.0, color: Colors.white),
              textAlign: TextAlign.center,
            ),
          ),
          Container(
            margin: EdgeInsets.only(top: 30.0),
            padding: EdgeInsets.symmetric(horizontal: 120.0),
            child: FlatButton(
              onPressed: launch,
              padding: EdgeInsets.all(15.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Icon(
                    FontAwesomeIcons.googlePlay,
                    size: 18.0,
                  ),
                  Padding(
                    padding: EdgeInsets.only(left: 15.0),
                    child: Text(
                      "Update",
                      style: TextStyle(fontSize: 20.0),
                    ),
                  ),
                ],
              ),
              textColor: Colors.white,
              color: Colors.teal[300],
            ),
          )
        ],
      ),
    );
  }
}