// Form validators. Screens reference these rather than writing closures
// inline, so an error message reads the same wherever the rule applies.

String? requiredField(String? value) =>
    (value == null || value.trim().isEmpty) ? 'Required' : null;

String? validPort(String? value) {
  if (value == null || value.trim().isEmpty) return null; // falls back to 22
  final port = int.tryParse(value.trim());
  if (port == null) return 'Numbers only';
  if (port < 1 || port > 65535) return 'Must be 1–65535';
  return null;
}

String? validHost(String? value) {
  if (value == null || value.trim().isEmpty) return 'Required';
  if (value.trim().contains(' ')) return 'No spaces allowed';
  return null;
}

/// An absolute POSIX path, as every remote target must be.
String? validRemotePath(String? value) {
  if (value == null || value.trim().isEmpty) return 'Required';
  if (!value.trim().startsWith('/')) return 'Must start with /';
  return null;
}