160 lines
No EOL
5.3 KiB
C#
160 lines
No EOL
5.3 KiB
C#
using System.Linq;
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namespace FCS.Lib.Utility
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{
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public static class VatUtils
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{
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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" => CheckVatNumberDenmark(vatNumber),
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"NO" => CheckVatNumberNorway(vatNumber),
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"SE" => CheckVatNumberSweden(vatNumber),
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_ => false
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};
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}
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public static bool CheckVatNumberDenmark(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 Modulo 11 check digit
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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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public static bool CheckVatNumberNorway(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 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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public static bool CheckVatNumberSweden(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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// C1 = (10 - (R + C2 + C4 + C6 + C8) modulo 10) modulo 10
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// R = S1 + S3 + S5 + S7 + S9
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// Si = int(Ci/5) + (Ci*2) modulo 10)
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// C11 C12 >= 01 <= 94
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//
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// Validate full string using Luhn algoritm
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// 12 chars
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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 $"{vatNumber.Substring(0,9)}{c10}{vatNumber.Substring(9,1)}" == vatNumber;
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}
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public static bool ValidateMod11(string number)
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{
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if (long.Parse(number) == 0)
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return false;
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var sum = 0;
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for (int i = number.Length - 1, multiplier = 1; i >= 0; i--)
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{
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// Console.WriteLine($"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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public 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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public 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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public static string AddMod11CheckDigit(string number)
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{
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return number + GetMod11CheckDigit(number);
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}
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public 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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} |