class InputValidators {
  static double? number(String? value) =>
      double.tryParse((value ?? '').trim().replaceAll(',', '.'));

  static String? requiredText(String? value) =>
      value == null || value.trim().isEmpty ? 'Bitte ausfüllen' : null;

  static String? nonNegative(String? value, {bool optional = false}) {
    if (optional && (value ?? '').trim().isEmpty) return null;
    final parsed = number(value);
    return parsed == null || !parsed.isFinite || parsed < 0
        ? 'Zahl ab 0 eingeben'
        : null;
  }

  static String? positive(String? value) {
    final parsed = number(value);
    return parsed == null || !parsed.isFinite || parsed <= 0
        ? 'Zahl größer 0 eingeben'
        : null;
  }

  static String? hours(String? value) {
    final parsed = int.tryParse((value ?? '').trim());
    return parsed == null || parsed < 0 ? 'Ganze Zahl ab 0 eingeben' : null;
  }

  static String? minutes(String? value) {
    final parsed = int.tryParse((value ?? '').trim());
    return parsed == null || parsed < 0 || parsed > 59
        ? '0 bis 59 eingeben'
        : null;
  }
}