feat: bank card.

bank_card/validator.go

@@ -0,0 +1,54 @@
+package bank_card
+
+// IsValidLuhn 使用Luhn算法校验银行卡号码
+// @see https://en.wikipedia.org/wiki/Luhn_algorithm
+// @see https://www.geeksforgeeks.org/luhn-algorithm/
+// @see https://medium.com/@akshaymohite/luhns-algorithm-to-validate-credit-debit-card-numbers-1952e6c7a9d0
+// @see https://www.woshipm.com/pd/371041.html
+func IsValidLuhn(cardNo string) bool {
+	length := len(cardNo)
+	if length == 0 {
+		return false
+	}
+
+	if !isNumberString(cardNo) {
+		return false
+	}
+
+	sum := 0
+	second := false
+	for i := length - 1; i >= 0; i-- {
+		d := cardNo[i] - '0'
+
+		if second == true {
+			d = d * 2
+		}
+
+		sum += int(d) / 10
+		sum += int(d) % 10
+
+		second = !second
+	}
+
+	return sum%10 == 0
+}
+
+// IsValidBankCardNo 是否合法的银行卡号
+func IsValidBankCardNo(cardNo string) bool {
+	length := len(cardNo)
+	if length < 12 || length > 19 {
+		return false
+	}
+	return IsValidLuhn(cardNo)
+}
+
+// isNumberString 验证字符是数字
+func isNumberString(s string) bool {
+	length := len(s)
+	for i := 0; i < length; i++ {
+		if s[i] < '0' || s[i] > '9' {
+			return false
+		}
+	}
+	return true
+}