import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: DropdownFocusDemo(),
    );
  }
}

class DropdownFocusDemo extends StatefulWidget {
  const DropdownFocusDemo({super.key});

  @override
  State<DropdownFocusDemo> createState() => _DropdownFocusDemoState();
}

class _DropdownFocusDemoState extends State<DropdownFocusDemo> {
  FocusNode _focusNode = FocusNode();
  String _selectedValue = 'One';

  void _replaceFocusNode() {
    setState(() {
      _focusNode.dispose();
      _focusNode = FocusNode();
      print('FocusNode replaced');
    });
  }

  @override
  void dispose() {
    _focusNode.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Dropdown Focus Demo')),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            DropdownButtonFormField<String>(
              focusNode: _focusNode,
              focusColor: Colors.yellow,
              decoration: InputDecoration(
                filled: true,
                contentPadding: EdgeInsets.symmetric(vertical: 100),
              ),
              value: _selectedValue,
              items: const [
                DropdownMenuItem(value: 'One', child: Text('One')),
                DropdownMenuItem(value: 'Two', child: Text('Two')),
              ],
              onChanged: (value) {
                setState(() {
                  _selectedValue = value!;
                });
              },
            ),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: () {
                _focusNode.requestFocus();
              },
              child: const Text('Request Focus'),
            ),
            ElevatedButton(
              onPressed: _replaceFocusNode,
              child: const Text('Replace FocusNode'),
            ),
            ElevatedButton(
              onPressed: () {
                FocusManager.instance.primaryFocus?.unfocus();
              },
              child: const Text('Remove FocusNode'),
            ),
          ],
        ),
      ),
    );
  }
}