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

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

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

class MyHomePage extends StatelessWidget {
  final String title;

  MyHomePage({
    Key? key,
    required this.title,
  }) : super(key: key);

  final FocusNode _focusNode = FocusNode();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter Demo'),
      ),
      body: Center(
        child: Shortcuts(
          shortcuts: const <ShortcutActivator, Intent>{
            SingleActivator(LogicalKeyboardKey.escape): _MyIntent(),
          },
          child: Actions(
            actions: <Type, Action<Intent>>{
              _MyIntent: CallbackAction<_MyIntent>(onInvoke: (_) {
                print('Outer Actions called for _MyIntent');
              }),
            },
            child: Builder(
              builder: (BuildContext context) {
                return Actions(
                  actions: <Type, Action<Intent>>{
                    _MyIntent: CallbackAction<_MyIntent>(onInvoke: (_MyIntent intent) {
                      print('Inner Actions called for _MyIntent');
                      return Actions.invoke(context, intent);
                    }),
                    // The below will not work. I believe it passes the key
                    // through, but not the _MyIntent.
                    /*
                    _MyIntent: _TransparentCallbackAction<_MyIntent>(onInvoke: (_) {
                      print('justin _TransparentCallbackAction invoked?');
                    }),
                    */
                  },
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [            
                      const TextField(
                        decoration: InputDecoration(
                          hintText: 'Tap to focus the field, then press escape.',
                        ),
                      ),
                      TextButton(
                        focusNode: _focusNode,
                        onPressed: () {
                          _focusNode.requestFocus();
                        },
                        child: const Text('Or tap to focus the button before pressing escape.'),
                      ),
                    ],
                  ),
                );
              },
            ),
          ),
        ),
      ),
    );
  }
}

class _MyIntent extends Intent {
  const _MyIntent();
}

// An attempt at creating an Action that passes its Intent through, but it
// doesn't work.  I believe isEnabled and consumesKey are operating on the key
// itself, which is handled by Shortcuts, and no the Intent.
/*
class _TransparentCallbackAction<T extends Intent> extends CallbackAction<T> {
  _TransparentCallbackAction({
    required OnInvokeCallback<T> onInvoke,
  }) : super(onInvoke: onInvoke);

  @override
  bool isEnabled(covariant T intent) => false;

  @override
  bool consumesKey(covariant T intent) => false;
}
*/