BotZ_app/lib/ui/main_page.dart

import 'package:flutter/material.dart';
import 'package:logger/logger.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'dart:async';

var log = Logger();

class _DataState {
  _DataState(
      {this.userPresent = false,
      this.passPresent = false,
      this.zServerPresent = false,
      this.botZServerPresent = false});
  bool userPresent;
  bool passPresent;
  bool zServerPresent;
  bool botZServerPresent;

  bool all() {
    assert(userPresent != null);
    assert(passPresent != null);
    assert(zServerPresent != null);
    assert(botZServerPresent != null);
    var result =
        userPresent && passPresent && zServerPresent && botZServerPresent;
    return result;
  }

  String toString() {
    return "\tuser: $userPresent\n\tpass: $passPresent\n\tzServer: $zServerPresent\n\tbotZServer: $botZServerPresent";
  }
}

class HomePage extends StatefulWidget {
  HomePage(
      {@required this.nextRoute,
      this.timeout = const Duration(seconds: 1),
      Key key})
      : assert(nextRoute != null),
        super(key: key);
  final String nextRoute;
  final Duration timeout;

  HomePageState createState() => HomePageState();
}

class HomePageState extends State<HomePage> {
  _DataState status = _DataState();
  bool _retrieved = false;
  bool _waitingForWelcome = false;
  String title = "BotZ";

  Future<void> _retriveStateData() async {
    var persistence = await SharedPreferences.getInstance();
    var stateFromPersistence = {
      "user": (persistence.getString("username") != null) ? true : false,
      "pass": (persistence.getString("password") != null) ? true : false,
      "zAddr": (persistence.getString("zAddress") != null) ? true : false,
      "botZAddr": (persistence.getString("botZAddress") != null) ? true : false,
    };
    log.d("State from persistence: ${stateFromPersistence.toString()}");
    setState(() {
      status.userPresent = stateFromPersistence["user"];
      status.passPresent = stateFromPersistence["pass"];
      status.zServerPresent = stateFromPersistence["zAddr"];
      status.botZServerPresent = stateFromPersistence["botZAddr"];
      _retrieved = true;
    });
  }

  @override
  void initState() {
    super.initState();
    _retriveStateData();
  }

  bool _checkData() {
    log.d("State: ${status.toString()}");
    if (status.all()) {
      log.d("Necessary data is present");
      return true;
    }
    log.d("Necessary data is MISSING");
    return false;
  }

  void _goToNextPage() {
    Navigator.pushReplacementNamed(context, widget.nextRoute);
  }

  Future<void> _cleanState() async {
    var persistence = await SharedPreferences.getInstance();
    persistence.setString("username", null);
    persistence.setString("password", null);
    persistence.setString("zAddress", null);
    persistence.setString("botZAddress", null);
    setState(() {
      status.userPresent = false;
      status.passPresent = false;
      status.zServerPresent = false;
      status.botZServerPresent = false;
    });
  }

  Widget mainView() {
    return Center(
        child: Column(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: <Widget>[
        RaisedButton(onPressed: _cleanState, child: Text("Clean state")),
        Column(children: <Widget>[
          Text("Username: ${status.userPresent}"),
          Text("Password: ${status.passPresent}"),
          Text("Z Address: ${status.zServerPresent}"),
          Text("BotZ Address: ${status.botZServerPresent}"),
        ])
      ],
    ));
  }

  Widget _body() {
    log.d("Retrieved: $_retrieved");
    if (_retrieved) {
      if (_checkData()) {
        log.d("Main body");
        return mainView();
      } else {
        if (!_waitingForWelcome) {
          log.d("Go to ask the user for the data...");
          Future.delayed(widget.timeout, _goToNextPage);
          setState(() {
            _waitingForWelcome = true;
          });
        }
      }
    }
    return CircularProgressIndicator();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(title)),
      body: _body(),
    );
  }
}