import 'package:flutter/services.dart';

class FrequencyInputFormatter extends TextInputFormatter {
  static const int maxDigits = 5;

  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    String digitsOnly = newValue.text.replaceAll(RegExp(r'[^0-9]'), '');

    if (digitsOnly.length > maxDigits) {
      return oldValue;
    }

    String formatted = digitsOnly;
    if (digitsOnly.length > 3) {
      formatted = '${digitsOnly.substring(0, 3)}.${digitsOnly.substring(3)}';
    }

    if (formatted.endsWith('.') && digitsOnly.length <= 3) {
      formatted = formatted.substring(0, formatted.length - 1);
    }

    return TextEditingValue(
      text: formatted,
      selection: TextSelection.collapsed(offset: formatted.length),
    );
  }
}