Add Credit Card validation checker and tests to v2. (#141)

# Describe Request

Add Credit Card validation checker and tests to v2.

# Change Type

New code.

v2/credit_card.go

@@ -0,0 +1,156 @@
+// Copyright (c) 2023-2024 Onur Cinar.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+// https://github.com/cinar/checker
+
+package v2
+
+import (
+	"reflect"
+	"regexp"
+	"strings"
+)
+
+const (
+	// nameCreditCard is the name of the credit card check.
+	nameCreditCard = "credit-card"
+)
+
+var (
+	// ErrNotCreditCard indicates that the given value is not a valid credit card number.
+	ErrNotCreditCard = NewCheckError("CreditCard")
+
+	// amexExpression is the regexp for the AMEX cards. They start with 34 or 37, and has 15 digits.
+	amexExpression = "(?:^(?:3[47])[0-9]{13}$)"
+	amexPattern    = regexp.MustCompile(amexExpression)
+
+	// dinersExpression is the regexp for the Diners cards. They start with 305, 36, 38, and has 14 digits.
+	dinersExpression = "(?:^3(?:(?:05[0-9]{11})|(?:[68][0-9]{12}))$)"
+	dinersPattern    = regexp.MustCompile(dinersExpression)
+
+	// discoverExpression is the regexp for the Discover cards. They start with 6011 and has 16 digits.
+	discoverExpression = "(?:^6011[0-9]{12}$)"
+	discoverPattern    = regexp.MustCompile(discoverExpression)
+
+	// jcbExpression is the regexp for the JCB 15 cards. They start with 2131, 1800, and has 15 digits, or start with 35 and has 16 digits.
+	jcbExpression = "(?:^(?:(?:2131)|(?:1800)|(?:35[0-9]{3}))[0-9]{11}$)"
+	jcbPattern    = regexp.MustCompile(jcbExpression)
+
+	// masterCardExpression is the regexp for the MasterCard cards. They start with 51, 52, 53, 54, or 55, and has 15 digits.
+	masterCardExpression = "(?:^5[12345][0-9]{14}$)"
+	masterCardPattern    = regexp.MustCompile(masterCardExpression)
+
+	// unionPayExpression is the regexp for the UnionPay cards. They start either with 62 or 67, and has 16 digits, or they start with 81 and has 16 to 19 digits.
+	unionPayExpression = "(?:(?:6[27][0-9]{14})|(?:81[0-9]{14,17})^$)"
+	unionPayPattern    = regexp.MustCompile(unionPayExpression)
+
+	// visaExpression is the regexp for the Visa cards. They start with 4 and has 13 or 16 digits.
+	visaExpression = "(?:^4[0-9]{12}(?:[0-9]{3})?$)"
+	visaPattern    = regexp.MustCompile(visaExpression)
+
+	// anyCreditCardPattern is the regexp for any credit card.
+	anyCreditCardPattern = regexp.MustCompile(strings.Join([]string{
+		amexExpression,
+		dinersExpression,
+		discoverExpression,
+		jcbExpression,
+		masterCardExpression,
+		unionPayExpression,
+		visaExpression,
+	}, "|"))
+
+	// creditCardPatterns is the mapping for credit card names to patterns.
+	creditCardPatterns = map[string]*regexp.Regexp{
+		"amex":       amexPattern,
+		"diners":     dinersPattern,
+		"discover":   discoverPattern,
+		"jcb":        jcbPattern,
+		"mastercard": masterCardPattern,
+		"unionpay":   unionPayPattern,
+		"visa":       visaPattern,
+	}
+)
+
+// IsAnyCreditCard checks if the given value is a valid credit card number.
+func IsAnyCreditCard(number string) (string, error) {
+	return isCreditCard(number, anyCreditCardPattern)
+}
+
+// IsAmexCreditCard checks if the given valie is a valid AMEX credit card.
+func IsAmexCreditCard(number string) (string, error) {
+	return isCreditCard(number, amexPattern)
+}
+
+// IsDinersCreditCard checks if the given valie is a valid Diners credit card.
+func IsDinersCreditCard(number string) (string, error) {
+	return isCreditCard(number, dinersPattern)
+}
+
+// IsDiscoverCreditCard checks if the given valie is a valid Discover credit card.
+func IsDiscoverCreditCard(number string) (string, error) {
+	return isCreditCard(number, discoverPattern)
+}
+
+// IsJcbCreditCard checks if the given valie is a valid JCB 15 credit card.
+func IsJcbCreditCard(number string) (string, error) {
+	return isCreditCard(number, jcbPattern)
+}
+
+// IsMasterCardCreditCard checks if the given valie is a valid MasterCard credit card.
+func IsMasterCardCreditCard(number string) (string, error) {
+	return isCreditCard(number, masterCardPattern)
+}
+
+// IsUnionPayCreditCard checks if the given valie is a valid UnionPay credit card.
+func IsUnionPayCreditCard(number string) (string, error) {
+	return isCreditCard(number, unionPayPattern)
+}
+
+// IsVisaCreditCard checks if the given valie is a valid Visa credit card.
+func IsVisaCreditCard(number string) (string, error) {
+	return isCreditCard(number, visaPattern)
+}
+
+// makeCreditCard makes a checker function for the credit card checker.
+func makeCreditCard(config string) CheckFunc[reflect.Value] {
+	patterns := []*regexp.Regexp{}
+
+	if config != "" {
+		for _, card := range strings.Split(config, ",") {
+			pattern, ok := creditCardPatterns[card]
+			if !ok {
+				panic("unknown credit card name")
+			}
+
+			patterns = append(patterns, pattern)
+		}
+	} else {
+		patterns = append(patterns, anyCreditCardPattern)
+	}
+
+	return func(value reflect.Value) (reflect.Value, error) {
+		if value.Kind() != reflect.String {
+			panic("string expected")
+		}
+
+		number := value.String()
+
+		for _, pattern := range patterns {
+			_, err := isCreditCard(number, pattern)
+			if err == nil {
+				return value, nil
+			}
+		}
+
+		return value, ErrNotCreditCard
+	}
+}
+
+// isCreditCard checks if the given number based on the given credit card pattern and the Luhn algorithm check digit.
+func isCreditCard(number string, pattern *regexp.Regexp) (string, error) {
+	if !pattern.MatchString(number) {
+		return number, ErrNotCreditCard
+	}
+
+	return IsLUHN(number)
+}