import 'package:flutter/services.dart';

class RupiahInputFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    if (newValue.text.isEmpty) {
      return newValue;
    }

    final digits = newValue.text.replaceAll(RegExp(r'[^0-9]'), '');
    if (digits.isEmpty) {
      return const TextEditingValue(text: '');
    }

    final formatted = _formatRupiah(digits);

    int newOffset = formatted.length;
    if (oldValue.text.isNotEmpty) {
      final oldLength = oldValue.text.replaceAll(RegExp(r'[^0-9]'), '').length;
      final newLength = digits.length;
      final oldCursor = oldValue.selection.baseOffset;

      if (newLength < oldLength) {
        final digitsBeforeCursor = oldValue.text.substring(0, oldCursor).replaceAll(RegExp(r'[^0-9]'), '').length;
        newOffset = (digitsBeforeCursor).clamp(0, formatted.length);
      } else if (oldCursor < oldValue.text.length) {
        final digitsBeforeCursor = oldValue.text.substring(0, oldCursor).replaceAll(RegExp(r'[^0-9]'), '').length;
        newOffset = (digitsBeforeCursor).clamp(0, formatted.length);
      }
    }

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

  String _formatRupiah(String digits) {
    final buffer = StringBuffer();
    final len = digits.length;
    for (int i = 0; i < len; i++) {
      if (i > 0 && (len - i) % 3 == 0) {
        buffer.write('.');
      }
      buffer.write(digits[i]);
    }
    return buffer.toString();
  }

  static String formatNumber(int number) {
    return RupiahInputFormatter()._formatRupiah(number.toString());
  }

  static int? getRawValue(String formattedText) {
    final digits = formattedText.replaceAll(RegExp(r'[^0-9]'), '');
    if (digits.isEmpty) return null;
    return int.tryParse(digits);
  }
}