detectCCType function

List<CreditCardType> detectCCType(String ccNumStr)

This function determines the potential CC types based on the cardPatterns. Returns a list of CreditCardTypes with the most likely type as the first.

Implementation

List<CreditCardType> detectCCType(String ccNumStr) {
  List<CreditCardType> cardTypes = [];
  ccNumStr = ccNumStr.replaceAll(_whiteSpace, '');

  if (ccNumStr.isEmpty) {
    return _customCards.cards.values.toList();
  }

  // Check that only numerics are in the string
  if (_nonNumeric.hasMatch(ccNumStr)) {
    return cardTypes;
  }

  _customCards.cards.forEach(
    (String cardName, CreditCardType type) {
      for (Pattern pattern in type.patterns) {
        // Remove any spaces
        String ccPatternStr = ccNumStr;
        int patternLen = pattern.prefixes[0].length;
        // Trim the CC number str to match the pattern prefix length
        if (patternLen < ccNumStr.length) {
          ccPatternStr = ccPatternStr.substring(0, patternLen);
        }

        if (pattern.prefixes.length > 1) {
          // Convert the prefix range into numbers then make sure the
          // CC num is in the pattern range.
          // Because Strings don't have '>=' type operators
          int ccPrefixAsInt = int.parse(ccPatternStr);
          int startPatternPrefixAsInt = int.parse(pattern.prefixes[0]);
          int endPatternPrefixAsInt = int.parse(pattern.prefixes[1]);
          if (ccPrefixAsInt >= startPatternPrefixAsInt &&
              ccPrefixAsInt <= endPatternPrefixAsInt) {
            // Found a match
            type.matchStrength = _determineMatchStrength(
              ccNumStr,
              pattern.prefixes[0],
            );
            cardTypes.add(type);
            break;
          }
        } else {
          // Just compare the single pattern prefix with the CC prefix
          if (ccPatternStr == pattern.prefixes[0]) {
            // Found a match
            type.matchStrength = _determineMatchStrength(
              ccNumStr,
              pattern.prefixes[0],
            );
            cardTypes.add(type);
            break;
          }
        }
      }
    },
  );

  cardTypes.sort((a, b) => b.matchStrength.compareTo(a.matchStrength));
  return cardTypes;
}