detectCardType function

CardType detectCardType(String ccNumStr)

Implementation

CardType detectCardType(String ccNumStr) {
  CardType cardType = CardType.unknown;

  if (ccNumStr.isEmpty) {
    return cardType;
  }

  //TODO error checking for strings with non-numerical chars

  cardNumbersPatterns.forEach(
    (CardType type, Set<List<String>> patterns) {
      for (List<String> patternRange in patterns) {
        // Remove any spaces
        String ccPatternStr = ccNumStr.replaceAll(RegExp(r'\s+\b|\b\s'), '');
        int rangeLen = patternRange[0].length;
        // Trim the CC number str to match the pattern prefix length
        if (rangeLen < ccNumStr.length) {
          ccPatternStr = ccPatternStr.substring(0, rangeLen);
        }

        if (patternRange.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(patternRange[0]);
          int endPatternPrefixAsInt = int.parse(patternRange[1]);
          if (ccPrefixAsInt >= startPatternPrefixAsInt &&
              ccPrefixAsInt <= endPatternPrefixAsInt) {
            // Found a match
            cardType = type;
            break;
          }
        } else {
          // Just compare the single pattern prefix with the CC prefix
          if (ccPatternStr == patternRange[0]) {
            // Found a match
            cardType = type;
            break;
          }
        }
      }
    },
  );

  return cardType;
}