be_happy_public/lib/presentation/components/utils/card_formatter.dart

import 'package:flutter/services.dart';

class CardNumberFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue,
      TextEditingValue newValue,
      ) {
    var text = newValue.text.replaceAll(' ', '');
    var buffer = StringBuffer();
    for (int i = 0; i < text.length; i++) {
      buffer.write(text[i]);
      var nonZeroIndex = i + 1;
      if (nonZeroIndex % 4 == 0 && nonZeroIndex != text.length) {
        buffer.write(' '); // Добавляем пробел каждые 4 цифры
      }
    }
    var string = buffer.toString();
    return newValue.copyWith(
      text: string,
      selection: TextSelection.collapsed(offset: string.length),
    );
  }
}

class CardMonthInputFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue,
      TextEditingValue newValue,
      ) {
    var newText = newValue.text;
    if (newValue.selection.baseOffset == 0) return newValue;

    var buffer = StringBuffer();
    for (int i = 0; i < newText.length; i++) {
      buffer.write(newText[i]);
      var nonZeroIndex = i + 1;
      if (nonZeroIndex % 2 == 0 && nonZeroIndex != newText.length) {
        buffer.write('/'); // Добавляем слэш после 2-й цифры
      }
    }
    var string = buffer.toString();
    return newValue.copyWith(
      text: string,
      selection: TextSelection.collapsed(offset: string.length),
    );
  }
}