import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

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

    var buffer = new StringBuffer();

    for (int i = 0; i < masaController.length; i++) {
      buffer.write(masaController[i]);
      var nonZeroIndex = i + 1;

      if (nonZeroIndex % 2 == 0 && nonZeroIndex != masaController.length) {
        buffer.write('/');
      }
    }

    var string = buffer.toString();
    return newValue.copyWith(
        text: string,
        selection: new TextSelection.collapsed(offset: string.length));
  }
}