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

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

class Item {
  Item({this.key, this.value});

  final int key;
  final int value;
}

class Cone extends InheritedWidget {
  Cone({Key key, Widget child, this.items}) : super(key: key, child: child);

  final List<Item> items;
  final StreamController<List<Item>> streamController = StreamController();
  Stream<List<Item>> get itemStream => streamController.stream;


  void addItem({int key, int value}) {
    print('old items length: ${items.length}');
    items.add(Item(key: key, value: value));
    print('new items length: ${items.length}');
    streamController.sink.add(items);
  }

  static Cone of(BuildContext context) {
    return context.dependOnInheritedWidgetOfExactType<Cone>();
  }

  void dispose() {
    streamController.close();
  }

  @override
  bool updateShouldNotify(a) => true;
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Cone(
      items: [
        Item(key: 0, value: 0),
        Item(key: 1, value: 3),
      ],
      child: MaterialApp(
        debugShowCheckedModeBanner: false,
        home: MyHomePage(),
      ),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('focus test'),
        actions: [
          IconButton(
            icon: Icon(Icons.add),
            onPressed: () => Cone.of(context).addItem(key: 2, value: 5),
          ),
        ],
      ),
      body: Padding(
        padding: EdgeInsets.all(8.0),
        child: StreamBuilder<List<Item>>(
          stream: Cone.of(context).itemStream,
          builder: (context, snap) {
            print('builder: ${snap.hasData}');
            if (!snap.hasData) return Container();

            return ListView(
                children: snap.data
                    .map(
                      (item) => TextField(
                        textInputAction: TextInputAction.next,
                        onSubmitted: (_) => FocusScope.of(context).nextFocus(),
                      ),
                    )
                    .toList());
          },
        ),
      ),
    );
  }
}