import 'package:fl_lib/fl_lib.dart';

final _seperator = Pfs.seperator;

/// It's used on platform's file system.
/// So use [Platform.pathSeparator] to join path.
class LocalPath {
  final String _prefixPath;
  String _path = _seperator;
  String? _prePath;
  String get path => _prefixPath + _path;

  LocalPath(String prefixPath) : _prefixPath = _trimSuffix(prefixPath);

  void update(String newPath) {
    _prePath = _path;
    if (newPath == '..') {
      _path = _path.substring(0, _path.lastIndexOf(_seperator));
      if (_path == '') {
        _path = _seperator;
      }
      return;
    }
    if (newPath == _seperator) {
      _path = _seperator;
      return;
    }
    _path = _path.joinPath(newPath);
  }

  bool get canBack => path != '$_prefixPath$_seperator';

  bool undo() {
    if (_prePath == null || _path == _prePath) {
      return false;
    }
    _path = _prePath!;
    return true;
  }
}

String _trimSuffix(String prefixPath) {
  if (prefixPath.endsWith(_seperator)) {
    return prefixPath.substring(0, prefixPath.length - 1);
  }
  return prefixPath;
}