362 lines
No EOL
12 KiB
C#
362 lines
No EOL
12 KiB
C#
// ***********************************************************************
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// Assembly : FCS.Lib.Utility
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// Author : FH
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// Created : 03-30-2022
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//
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// Last Modified By : FH
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// Last Modified On : 04-19-2022
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// ***********************************************************************
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// <copyright file="VatFormatValidator.cs" company="FCS-TECH">
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// Copyright (C) 2022 FCS Frede's Computer Services.
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as
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// published by the Free Software Foundation, either version 3 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see [https://www.gnu.org/licenses]
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// </copyright>
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// <summary></summary>
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// ***********************************************************************
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using System.Collections.Generic;
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using System.Linq;
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using System.Text.RegularExpressions;
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namespace FCS.Lib.Utility
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{
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/// <summary>
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/// Vat format validator
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/// </summary>
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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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//https://www.bolagsverket.se/apierochoppnadata.2531.html
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/// <summary>
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/// Check vat number format
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/// </summary>
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/// <param name="countryCode"></param>
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/// <param name="vatNumber"></param>
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/// <returns>bool indicating if the vat number conform to country specification</returns>
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public static bool CheckVat(string countryCode, string vatNumber)
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{
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if (string.IsNullOrWhiteSpace(vatNumber))
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return false;
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var sanitizedVat = SanitizeVatNumber(vatNumber);
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return countryCode.ToUpperInvariant() switch
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{
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"DK" => ValidateDkVat(sanitizedVat),
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"NO" => ValidateNoOrg(sanitizedVat),
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"SE" => ValidateSeOrg(sanitizedVat),
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_ => false
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};
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}
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/// <summary>
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/// sanitize vat number
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/// </summary>
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/// <param name="vatNumber"></param>
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/// <returns>sanitized string</returns>
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public static string SanitizeVatNumber(string vatNumber)
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{
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if (string.IsNullOrWhiteSpace(vatNumber))
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return "";
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// remove anything but digits
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var regexObj = new Regex(@"[^\d]");
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return regexObj.Replace(vatNumber, "");
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}
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private static bool ValidateDkVat(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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if(vatNumber.Length == 8 && long.TryParse(vatNumber, out _))
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return ValidateMod11(vatNumber);
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return false;
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}
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private static bool ValidateNoOrg(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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try
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{
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if (vatNumber.Length == 9 && long.TryParse(vatNumber, out _))
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return ValidateMod11(vatNumber);
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return false;
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}
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catch
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{
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return false;
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}
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}
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private static bool ValidateSeOrg(string orgNumber)
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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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// EU MOMS => C11 C12 == 01 (De två sista siffrorna är alltid 01)
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// C11 C12 is not used inside Sweden
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// C1 is type of org and C2 to C9 is org number
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// C10 is check digit
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var orgToCheck = orgNumber;
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if (long.Parse(orgToCheck) == 0)
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return false;
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switch (orgToCheck.Length)
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{
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// personal vat se
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case 6:
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return ValidateFormatSeExt(orgToCheck);
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case < 10:
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return false;
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// strip EU extension `01`
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case 12:
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orgNumber = orgNumber.Substring(0, 10);
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break;
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}
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var c10 = C10(orgToCheck);
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// compare calculated org number with incoming org number
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return $"{orgToCheck.Substring(0, 9)}{c10}" == orgNumber;
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}
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private static int C10(string vatToCheck)
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{
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// check digit calculation
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var r = new[] { 0, 2, 4, 6, 8 }
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.Sum(m => (int)char.GetNumericValue(vatToCheck[m]) / 5 +
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(int)char.GetNumericValue(vatToCheck[m]) * 2 % 10);
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var c1 = new[] { 1, 3, 5, 7 }.Sum(m => (int)char.GetNumericValue(vatToCheck[m]));
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var c10 = (10 - (r + c1) % 10) % 10;
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return c10;
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}
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private static bool ValidateFormatSeExt(string ssn)
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{
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// Swedish personally held companies uses SSN number
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// a relaxed validation is required as only first 6 digits is supplied
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// birthday format e.g. 991231
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if (ssn.Length is not 6 or 10 || int.Parse(ssn) == 0)
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return false;
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var y = int.Parse(ssn.Substring(0,2));
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var m = int.Parse(ssn.Substring(2,2));
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var d = int.Parse(ssn.Substring(4,2));
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// this calculation is only valid within 21st century
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var leap = y % 4 == 0; // 2000 was a leap year;
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// day
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if(d is < 1 or > 31)
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return false;
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// month
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switch (m)
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{
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// feb
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case 2:
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{
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if (leap)
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return d <= 29;
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return d <= 28;
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}
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// apr, jun, sep, nov
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case 4 or 6 or 9 or 11:
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return d <= 30;
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// jan, mar, may, july, aug, oct, dec
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case 1 or 3 or 5 or 7 or 8 or 10 or 12:
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return true;
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// does not exist
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default:
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return false;
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}
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}
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private static bool ValidateMod11(string number)
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{
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try
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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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catch
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{
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return false;
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}
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}
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///// <summary>
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/////
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///// </summary>
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///// <param name="ssn"></param>
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///// <returns></returns>
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//public static string FakeVatSsnSe(string ssn)
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//{
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// var fake = ssn.PadRight(9, '8');
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// var c10 = SeGenerateCheckDigit(fake);
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// return $"{fake}{c10}";
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//}
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///// <summary>
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/////
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///// </summary>
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///// <param name="org"></param>
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///// <returns></returns>
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//public static bool OrgIsPrivate(string org)
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//{
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// var orgType = new List<string>() { };
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// return ValidateFormatSeExt(org.Substring(0, 5));
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//}
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///// <summary>
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/////
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///// </summary>
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///// <param name="vatNumber"></param>
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///// <returns></returns>
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//public 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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//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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} |