From 1cf9245882e12c67f7487b6ba5065888ae3eb4ac Mon Sep 17 00:00:00 2001
From: Gabriel De Los Rios <gabriel.delosrios@tutamail.com>
Date: Sun, 6 Apr 2025 02:56:37 -0300
Subject: [PATCH] feat(search): add validations

---
 cuit/validations.go | 88 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 cuit/validations.go

diff --git a/cuit/validations.go b/cuit/validations.go
new file mode 100644
index 0000000..0f0679d
--- /dev/null
+++ b/cuit/validations.go
@@ -0,0 +1,88 @@
+package cuit
+
+import (
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/gabdlr/api-cuit-go/utils"
+)
+
+const CUIT_REGEX = `^([\d]{2}-[\d]{8}-[\d]{1}|[\d]{11})$`
+
+var CUIT_TYPES = map[uint8]bool{
+	30: true,
+	33: true,
+	34: true,
+}
+
+func IsValid(cuit string) (isValidCuit bool) {
+	if validateFormat(cuit) {
+		cuit = standardizeCuit(cuit)
+		if validateCuitType(cuit) {
+			isValidCuit = validateWithVerifierDigit(cuit)
+		}
+	}
+	return isValidCuit
+}
+
+func standardizeCuit(cuit string) string {
+	if len(cuit) > 11 {
+		cuit = strings.ReplaceAll(cuit, "-", "")
+	}
+	return cuit
+}
+
+func validateWithVerifierDigit(cuit string) bool {
+	verificationResult := false
+	toVerify := utils.ReverseStringWithBuffer(cuit[:10])
+
+	weightUpResult := 0
+	weightUpFactorCounter := -1
+	weightUpCheckFactor := []int{2, 3, 4, 5, 6, 7}
+
+	verifierDigit, err := strconv.Atoi(cuit[len(cuit)-1:])
+	if err != nil {
+		return false
+	}
+
+	for i := range 10 {
+		if i%6 == 0 {
+			weightUpFactorCounter += 1
+		}
+		weightUp, err := strconv.Atoi(string(toVerify[i]))
+		if err != nil {
+			return verificationResult
+		}
+		weightUpResult += weightUp * weightUpCheckFactor[i-6*weightUpFactorCounter]
+	}
+	mod11WeightupResult := weightUpResult % 11
+
+	switch mod11WeightupResult {
+	case 11:
+		verificationResult = verifierDigit == 0
+	case 10:
+		verificationResult = verifierDigit == 9
+	default:
+		verificationResult = verifierDigit == 11-mod11WeightupResult
+	}
+
+	return verificationResult
+}
+
+func validateCuitType(cuit string) bool {
+	validationResult := false
+	cuitType, err := strconv.Atoi(cuit[:2])
+	if err == nil {
+		validationResult = CUIT_TYPES[uint8(cuitType)]
+	}
+	return validationResult
+}
+
+func validateFormat(cuit string) bool {
+	regexExp, err := regexp.Compile(CUIT_REGEX)
+	if err == nil {
+		return regexExp.MatchString(cuit)
+	}
+	return false
+}