173 lines
6.1 KiB
C#
173 lines
6.1 KiB
C#
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using System.Linq;
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namespace FCS.Lib.Utility
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{
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public static class VatFormatValidator
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{
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// https://ec.europa.eu/taxation_customs/vies/faqvies.do#item_11
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// https://ec.europa.eu/taxation_customs/vies/
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public static bool CheckVat(string countryCode, string vatNumber)
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{
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return countryCode.ToUpperInvariant() switch
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{
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"DK" => ValidateFormatDk(vatNumber),
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"NO" => ValidateFormatNo(vatNumber),
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"SE" => ValidateFormatSe(vatNumber),
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_ => false
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};
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}
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private static bool ValidateFormatDk(string vatNumber)
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{
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// https://wiki.scn.sap.com/wiki/display/CRM/Denmark
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// 8 digits 0 to 9
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// C1..C7
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// C8 check-digit MOD11
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// C1 > 0
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// R = (2*C1 + 7*C2 + 6*C3 + 5*C4 + 4*C5 + 3*C6 + 2*C7 + C8)
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return (int)char.GetNumericValue(vatNumber[0]) == 1 && vatNumber.Length == 8 && ValidateMod11(vatNumber);
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}
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private static bool ValidateFormatNo(string vatNumber)
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{
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// https://wiki.scn.sap.com/wiki/display/CRM/Norway
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// 12 digits
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// C1..C8 random 0 to 9
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// C9 check-digit MOD11
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// C10 C11 C12 chars == MVA
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return vatNumber.Length >= 9 && ValidateMod11(vatNumber.Substring(0, 8));
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}
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private static bool ValidateFormatSe(string vatNumber)
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{
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// https://wiki.scn.sap.com/wiki/display/CRM/Sweden
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// 12 digits 0 to 9
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// C10 = (10 – (18 + 5 + 1 + 8 + 4)MOD10 10) MOD10
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// R = S1 + S3 + S5 + S7 + S9
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// Si = int(Ci/5) + (Ci*2)MOD10)
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// https://www.skatteverket.se/skatter/mervardesskattmoms/momsregistreringsnummer.4.18e1b10334ebe8bc80002649.html
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// C11 C12 == 01 (De två sista siffrorna är alltid 01)
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if (vatNumber.Length != 12 || vatNumber.Substring(10) != "01" || long.Parse(vatNumber) == 0)
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return false;
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var r = new[] { 0, 2, 4, 5, 8 }
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.Sum(m => (int)char.GetNumericValue(vatNumber[m]) / 5 +
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(int)char.GetNumericValue(vatNumber[m]) * 2 % 10);
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var c1 = new[] { 1, 3, 5, 7 }.Sum(m => (int)char.GetNumericValue(vatNumber[m]));
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var c10 = (10 - (r + c1) % 10) % 10;
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return $"{vatNumber.Substring(0,9)}{c10}{vatNumber.Substring(9,1)}" == vatNumber;
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}
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private static bool ValidateMod11(string number)
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{
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if (long.Parse(number) == 0)
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return false;
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var sum = 0;
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for (int i = number.Length - 1, multiplier = 1; i >= 0; i--)
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{
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// Console.WriteLine($"char: {number[i]} multiplier: {multiplier}");
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sum += (int)char.GetNumericValue(number[i]) * multiplier;
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if (++multiplier > 7) multiplier = 2;
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}
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return sum % 11 == 0;
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}
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//private static string SanitizeVatNumber(string vatNumber)
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//{
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// var washing = vatNumber.Replace(" ", "").Replace("-", "").ToUpperInvariant();
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// var result = washing.Replace("DK", "").Replace("NO", "").Replace("SE","") ;
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// if (result.Contains("MVA"))
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// result = result.Replace("MVA", "");
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// return result.Length switch
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// {
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// >= 10 => vatNumber[..10],
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// < 10 => result
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// };
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//}
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//private static bool ValidateMod10(string number)
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//{
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// if (long.Parse(number) == 0)
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// return false;
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// var nDigits = number.Length;
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// var nSum = 0;
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// var isSecond = false;
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// for (var i = nDigits - 1; i >= 0; i--)
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// {
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// var d = (int)char.GetNumericValue(number[i]) - '0';
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// if (isSecond)
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// d *= 2;
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// nSum += d / 10;
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// nSum += d % 10;
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// isSecond = !isSecond;
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// }
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// return nSum % 10 == 0;
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//}
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//private static string GetMod10CheckDigit(string number)
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//{
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// var sum = 0;
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// var alt = true;
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// var digits = number.ToCharArray();
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// for (var i = digits.Length - 1; i >= 0; i--)
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// {
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// var curDigit = digits[i] - 48;
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// if (alt)
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// {
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// curDigit *= 2;
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// if (curDigit > 9)
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// curDigit -= 9;
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// }
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// sum += curDigit;
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// alt = !alt;
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// }
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// return sum % 10 == 0 ? "0" : (10 - sum % 10).ToString();
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//}
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//private string AddMod11CheckDigit(string number)
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//{
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// return number + GetMod11CheckDigit(number);
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//}
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//private static string GetMod11CheckDigit(string number)
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//{
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// var sum = 0;
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// for (int i = number.Length - 1, multiplier = 2; i >= 0; i--)
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// {
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// sum += (int)char.GetNumericValue(number[i]) * multiplier;
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// if (++multiplier > 7) multiplier = 2;
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// }
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// var modulo = sum % 11;
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// return modulo is 0 or 1 ? "0" : (11 - modulo).ToString();
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//}
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//private static bool CheckLuhn(string vatNumber)
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//{
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// // https://www.geeksforgeeks.org/luhn-algorithm/
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// var nDigits = vatNumber.Length;
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// var nSum = 0;
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// var isSecond = false;
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// for (var i = nDigits - 1; i >= 0; i--)
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// {
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// var d = (int)char.GetNumericValue(vatNumber[i]) - '0';
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// if (isSecond)
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// d *= 2;
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// // We add two digits to handle
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// // cases that make two digits
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// // after doubling
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// nSum += d / 10;
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// nSum += d % 10;
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// isSecond = !isSecond;
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// }
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// return nSum % 10 == 0;
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//}
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}
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}
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