/// Close callback type for [PrinterPortHandle].
typedef ClosePortCallback = Future<bool> Function(int handle);

/// Represents an open printer port handle.
///
/// Wraps an integer handle and provides a [close] method to release
/// the underlying native port resource. Once closed, the handle
/// becomes invalid.
class PrinterPortHandle {
  /// The integer handle returned by the native layer.
  final int handle;

  /// Callback to close the port. If null, close() is a no-op.
  final ClosePortCallback? _closeCallback;

  /// Whether the port is still valid (not closed).
  bool _isValid;

  /// Creates a [PrinterPortHandle] with the given [handle] and optional [closeCallback].
  PrinterPortHandle({
    required this.handle,
    ClosePortCallback? closeCallback,
  })  : _closeCallback = closeCallback,
        _isValid = true;

  /// Returns true if the port is still open and not closed.
  bool get isValid => _isValid;

  /// Closes the port and marks the handle as invalid.
  ///
  /// Subsequent calls to [close] are no-ops if the port is already closed.
  Future<void> close() async {
    if (!_isValid) {
      return;
    }
    _isValid = false;
    if (_closeCallback != null) {
      await _closeCallback(handle);
    }
  }

  @override
  String toString() => 'PrinterPortHandle(handle: $handle, valid: $_isValid)';
}