// Import MaterialApp and other widgets which we can use to quickly create a material app

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

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

class TodoApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Todo List',
      home: new TodoList(),
      theme: ThemeData(
        brightness: Brightness.light,
        primaryColor: Colors.red,
      ),
      darkTheme: ThemeData(
        brightness: Brightness.dark,
      ),
    );
  }
}

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

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

  // Instead of autogenerating a todo item, _addTodoItem now accepts a string
  void _addTodoItem(String task) {
    // Only add the task if the user actually entered something
    if (task.length > 0) {
      setState(() => _todoItems.add(task));
    }
  }

  // Build the whole list of todo items
  Widget _buildTodoList() {
    return new ListView.builder(
      itemBuilder: (context, index) {
        // itemBuilder will be automatically be called as many times as it takes for the
        // list to fill up its available space, which is most likely more than the
        // number of todo items we have. So, we need to check the index is OK.
        if (index < _todoItems.length) {
          return _buildTodoItem(_todoItems[index], index);
        }
      },
    );
  }

  // Build a single todo item
  Widget _buildTodoItem(String todoText, int index) {
    return new ListTile(
      title: new Text(todoText),
      onTap: () => _promptRemoveTodoItem(index),
    );
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(title: new Text('Todo List')),
      body: _buildTodoList(),
      floatingActionButton: new FloatingActionButton(
        backgroundColor: Theme.of(context).primaryColor,
        onPressed: _pushAddTodoScreen,
        // pressing this button now opens the new screen
        tooltip: "Add task",
        child: new IconTheme(
          data: new IconThemeData(color: Colors.black87),
          child: new Icon(Icons.add),
        ),
      ),
    );
  }

  void _pushAddTodoScreen() {
    // Push this page onto the stack
    Navigator.of(context).push(
        // MaterialPageRoute will automatically animate the screen entry, as well
        // as adding a back button to close it
        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)),
          ));
    }));
  }

  // Much like _addTodoItem, this modifies the array of todo strings and
  // notifies the app that the state has changed by using setState
  void _removeTodoItem(int index) {
    setState(() => _todoItems.removeAt(index));
  }

  // Show an alert dialog asking the user to confirm that the task is done
  void _promptRemoveTodoItem(int index) {
    showDialog(
        context: context,
        builder: (BuildContext context) {
          return new AlertDialog(
              title: new Text('Mark "${_todoItems[index]}" as done?'),
              actions: <Widget>[
                new FlatButton(
                    child: new Text('CANCEL'),
                    onPressed: () => Navigator.of(context).pop()),
                new FlatButton(
                    child: new Text('MARK AS DONE'),
                    onPressed: () {
                      _removeTodoItem(index);
                      Navigator.of(context).pop();
                    })
              ]);
        });
  }

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

  @override
  void deactivate() {
    setSP();
    super.deactivate();
  }

  void getSP() async {
    var prefs = await SharedPreferences.getInstance();
    _todoItems = prefs.getStringList("key") ?? _todoItems;
  }

  void setSP() async {
    var prefs = await SharedPreferences.getInstance();
    prefs.setStringList("key", _todoItems);
  }
}