veilid/veilid-flutter/example/lib/history_text_editing_controller.dart

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

/// TextField History Controller
class HistoryTextEditingController {
  HistoryTextEditingController(
      {required this.setState, TextEditingController? controller})
      : _controller = controller ?? TextEditingController() {
    _historyFocusNode = FocusNode(onKeyEvent: (_node, event) {
      if (event.runtimeType == KeyDownEvent &&
          event.logicalKey == LogicalKeyboardKey.arrowUp) {
        if (_historyPosition > 0) {
          if (_historyPosition == _history.length) {
            _historyCurrentEdit = _controller.text;
          }
          _historyPosition -= 1;
          setState(() {
            _controller.text = _history[_historyPosition];
          });
        }
        return KeyEventResult.handled;
      } else if (event.runtimeType == KeyDownEvent &&
          event.logicalKey == LogicalKeyboardKey.arrowDown) {
        if (_historyPosition < _history.length) {
          _historyPosition += 1;
          setState(() {
            if (_historyPosition == _history.length) {
              _controller.text = _historyCurrentEdit;
            } else {
              _controller.text = _history[_historyPosition];
            }
          });
        }
        return KeyEventResult.handled;
      } else if (event.runtimeType == KeyDownEvent) {
        _historyPosition = _history.length;
        _historyCurrentEdit = _controller.text;
      }
      return KeyEventResult.ignored;
    });
  }

  void submit(String v) {
    // add to history
    if (_history.isEmpty || _history.last != v) {
      _history.add(v);
      if (_history.length > 100) {
        _history.removeAt(0);
      }
    }
    _historyPosition = _history.length;
    setState(() {
      _controller.text = '';
    });
  }

  FocusNode get focusNode => _historyFocusNode;
  TextEditingController get controller => _controller;

  ////////////////////////////////////////////////////////////////////////////

  late void Function(void Function()) setState;
  final TextEditingController _controller;
  late final FocusNode _historyFocusNode;

  final List<String> _history = [];
  int _historyPosition = 0;
  String _historyCurrentEdit = '';
}