import 'dart:async';

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  @override
  Widget build(BuildContext context) {
    var futureBuilder = new FutureBuilder(
      future: _getData(),
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        switch (snapshot.connectionState) {
          case ConnectionState.none:
          case ConnectionState.waiting:
            return new Text('loading...');
          default:
            if (snapshot.hasError)
              return new Text('Error: ${snapshot.error}');
            else
              return createListView(context, snapshot);
        }
      },
    );

    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Home Page"),
      ),
      body: futureBuilder,
    );
  }

  Future<List<String>> _getData() async {
    var values = new List<String>();
    values.add("Horses");
    values.add("Goats");
    values.add("Chickens");

    //throw new Exception("Danger Will Robinson!!!");

    await new Future.delayed(new Duration(seconds: 5));

    return values;
  }

  Widget createListView(BuildContext context, AsyncSnapshot snapshot) {
    List<String> values = snapshot.data;
    return new ListView.builder(
        itemCount: values.length,
        itemBuilder: (BuildContext context, int index) {
          return new Column(
            children: <Widget>[
              new ListTile(
                title: new Text(values[index]),
              ),
              new Divider(height: 2.0,),
            ],
          );
        },
    );
  }
}