import 'package:flutter/material.dart';

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

class TodoApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(title: 'Todo List', home: new TodoList());
  }
}

class TodoList extends StatefulWidget {
  @override
  createState() => new TodoListState();
}

class TodoListState extends State<TodoList> {
  List<String> _todoItems = [];

  void _addTodoItem(String task) {
    if (task.length > 0) {
      setState(() => _todoItems.add(task));
    }
  }

  Widget _buildTodoList() {
    return new ListView.builder(
      itemBuilder: (context, index) {
        if (index < _todoItems.length) {
          return _buildTodoItem(_todoItems[index]);
        }
      },
    );
  }

  Widget _buildTodoItem(String todoText) {
    return new ListTile(title: new Text(todoText));
  }

  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(title: new Text('Todo List')),
      body: _buildTodoList(),
      floatingActionButton: new FloatingActionButton(
          onPressed:
              _pushAddTodoScreen, // pressing this button now opens the new screen
          tooltip: 'Add task',
          child: new Icon(Icons.add)),
    );
  }

  void _pushAddTodoScreen()
  {
    Navigator.of(context).push(new MaterialPageRoute(builder: (context)
    {
      return new Scaffold(
          appBar: new AppBar(title: new Text('Add a new task')),
          body: new TextField(
            autofocus: true,
            onSubmitted: (val)
            {
              _addTodoItem(val);
              Navigator.pop(context); // Close the add todo screen
            },
            decoration: new InputDecoration(
                hintText: 'Enter something to do...',
                contentPadding: const EdgeInsets.all(16.0)),
          ));
    }));
  }
}