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

void main() {
  runApp(const MyApp());
}

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

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

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

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> with DeltaTextInputClient {
  TextInputConnection? _imeConnection;

  TextEditingValue _currentTextEditingValue = const TextEditingValue(
    text: 'Press SHIFT + Left arrow to expand the selection upstream',
    selection: TextSelection.collapsed(offset: 57),
  );

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

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

  @override
  void updateEditingValueWithDeltas(List<TextEditingDelta> textEditingDeltas) {
    TextEditingValue newValue = _currentTextEditingValue.copyWith();
    for (final delta in textEditingDeltas) {
      print('Applying delta: $delta');
      newValue = delta.apply(newValue);
    }

    print('New editing value: $newValue');

    setState(() {
      _currentTextEditingValue = newValue;
    });
  }

  void _attachToIme() {
    if (_imeConnection != null && _imeConnection!.attached) {
      return;
    }

    const config = TextInputConfiguration(
      enableDeltaModel: true,
      inputType: TextInputType.multiline,
      inputAction: TextInputAction.newline,
    );
    _imeConnection = TextInput.attach(this, config);
    _imeConnection!.setEditingState(_currentTextEditingValue);
    _imeConnection!.show();
  }

  void _detachFromIme() {
    _imeConnection?.close();
    _imeConnection = null;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Focus(
        autofocus: true,
        child: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text('Text: ${_currentTextEditingValue.text}'),
              const SizedBox(height: 30),
              Text('Selection: ${_currentTextEditingValue.selection}'),
              const SizedBox(height: 30),
              Text('Selected text: ${_currentTextEditingValue.selection.textInside(_currentTextEditingValue.text)}'),
            ],
          ),
        ),
      ),
    );
  }

  @override
  void connectionClosed() {}

  @override
  AutofillScope? get currentAutofillScope => null;

  @override
  TextEditingValue? get currentTextEditingValue => _currentTextEditingValue;

  @override
  void didChangeInputControl(TextInputControl? oldControl, TextInputControl? newControl) {}

  @override
  void insertContent(KeyboardInsertedContent content) {}

  @override
  void insertTextPlaceholder(Size size) {}

  @override
  void performAction(TextInputAction action) {}

  @override
  void performPrivateCommand(String action, Map<String, dynamic> data) {}

  @override
  void performSelector(String selectorName) {}

  @override
  void removeTextPlaceholder() {}

  @override
  void showAutocorrectionPromptRect(int start, int end) {}

  @override
  void showToolbar() {}

  @override
  void updateEditingValue(TextEditingValue value) {}

  @override
  void updateFloatingCursor(RawFloatingCursorPoint point) {}
}