/*==================================================================================================

Application:   Utility Function
Author:        John Gardner
Website:       http://www.braemoor.co.uk/software/vat.shtml

Version:       V1.0
Date:          30th July 2005
Description:   Used to check the validity of an EU country VAT number

Version:       V1.1
Date:          3rd August 2005
Description:   Lithuanian legal entities & Maltese check digit checks added.

Version:       V1.2
Date:          20th October 2005
Description:   Italian checks refined (thanks Matteo Mike Peluso).

Version:       V1.3
Date:          16th November 2005
Description:   Error in GB numbers ending in 00 fixed (thanks Guy Dawson).

Version:       V1.4
Date:          28th September 2006
Description:   EU-type numbers added.

Version:       V1.5
Date:          1st January 2007
Description:   Romanian and Bulgarian numbers added.

Version:       V1.6
Date:          7th January 2007
Description:   Error with Slovenian numbers (thanks to Ales Hotko).

Version:       V1.7
Date:          10th February 2007
Description:   Romanian check digits added. 
               Thanks to Dragu Costel for the test suite.

Version:       V1.8
Date:          3rd August 2007
Description:   IE code modified to allow + and * in old format numbers. 
               Thanks to Antonin Moy of Sphere Solutions for pointing out the error.

Version:       V1.9
Date:          6th August 2007
Description:   BE code modified to make a specific check that the leading character of 10 digit 
               numbers is 0 (belts and braces).

Version:       V1.10
Date:          10th August 2007
Description:   Cypriot check digit support added.
               Check digit validation support for non-standard UK numbers

Version:       V1.11
Date:          25th September 2007
Description:   Spain check digit support for personal numbers.
               Author: David Perez Carmona

Version:       V1.12
Date:          23rd November 2009
Description:   GB code modified to take into account new style check digits.
               Thanks to Guy Dawson of Crossflight Ltd for pointing out the necessity.

Version:       V1.13
Date:          7th July 2012
Description:   EL, GB, SE and BE formats updated - thanks to Joost Van Biervliet of VAT Applications

Version:       V.14
Date:          8th April 2013
Description:   BE Pattern match refined
               BG Add check digit checks for all four types of VAT number
               CY Pattern match improved
               CZ Personal pattern match checking improved
               CZ Personal check digits incorporated
               EE improved pattern match
               ES Physical person number checking refined
               GB Check digit support provided for 12 digit VAT codes and range checks included
               IT Bug removed to allow 999 and 888 issuing office codes
               LT temporarily registered taxpayers check digit support added
               LV Natural persons checks added
               RO improved pattern match
               SK improved pattern match and added check digit support
               
               Thanks to Theo Vroom for his help in this latest release.
               
Version:      V1.15
Date:         15th April 2013
              Swedish algorithm re-implemented.
               
Version:      V1.16
Date:         25th July 2013
              Support for Croatian numbers added
              
Version       V1.17
              10th September 2013
              Support for Norwegian MVA numbers added (yes, I know that Norway is not in the EU!)
              
Version       V1.18
              29th October 2013
              Partial support for new style Irish numbers.
              See http://www.revenue.ie/en/practitioner/ebrief/2013/no-032013.html
              Thanks to Simon Leigh for drawing the author's attention to this.
              
Version       V1.19
              31st October 2013
              Support for Serbian PBI numbers added (yes, I know that Serbia is not in the EU!)
              
Version       V1.20
              1st November 2013
              Support for Swiss MWST numbers added (yes, I know that Switzerland is not in the EU!)
              
Version       V1.21
              16th December 2014
              Non-critical code tidies to French and Danish regular expressions. 
              Thanks to Bill Seddon of Lyquidity Solutions
              
Version       V1.22
              14th January 2014
              Non-critical code tidy to regular expression for new format Irish numbers. 
              Thanks to Olivier Reubens of UNIT4 C-Logic N.V.
              
Version       V1.23
              10th April 2014
              Support for Russian INN numbers added (yes, I know that Russia is not in the EU!).
              Thanks to Marco Cesaratto of Arki Tech, Italy
              
Version       V1.24
              4th June 2014
              Check digit validation supported for Irish Type 3 numbers
              Thanks to Olivier Reubens of UNIT4 C-Logic N.V.
              
Version       V1.25
              29th July 2014
              Code improvements
              Thanks to Sébastien Boelpaep and Nate Kerkhofs
              
Version       V1.26
              4th May 2015
              Code improvements to regular expressions
              Thanks to Robert Gust-Bardon of webcraft.ch
              
Version       V1.27
              3rd December 2015
              Extend Swiss optional suffix to allow TVA and ITA
              Thanks to Oskars Petermanis
              
Version       V1.28
              30th August 2016
              Correct Swiss optional suffix to allow TVA and IVA
              Thanks to Jan Verhaegen
              
Parameters:    toCheck - VAT number be checked. 

This function checks the value of the parameter for a valid European VAT number. 

If the number is found to be invalid format, the function returns a value of false. Otherwise it 
returns the VAT number re-formatted.
  
Example call:
  
  if (checkVATNumber (myVATNumber)) 
      alert ("VAT number has a valid format")
  else 
      alert ("VAT number has invalid format");
                    
---------------------------------------------------------------------------------------------------*/

function checkVATNumber (toCheck) {
 
  // Array holds the regular expressions for the valid VAT number
  var vatexp = new Array ();
  
  // To change the default country (e.g. from the UK to Germany - DE):
  //    1.  Change the country code in the defCCode variable below to "DE".
  //    2.  Remove the question mark from the regular expressions associated with the UK VAT number: 
  //        i.e. "(GB)?" -> "(GB)"
  //    3.  Add a question mark into the regular expression associated with Germany's number 
  //        following the country code: i.e. "(DE)" -> "(DE)?"
  
  var defCCode = "GB";
  
  // Note - VAT codes without the "**" in the comment do not have check digit checking.

  vatexp.push (/^(AT)U(\d{8})$/);                           //** Austria
  vatexp.push (/^(BE)(0?\d{9})$/);                          //** Belgium 
  vatexp.push (/^(BG)(\d{9,10})$/);                         //** Bulgaria 
  vatexp.push (/^(CHE)(\d{9})(MWST|TVA|IVA)?$/);            //** Switzerland
  vatexp.push (/^(CY)([0-59]\d{7}[A-Z])$/);                 //** Cyprus
  vatexp.push (/^(CZ)(\d{8,10})(\d{3})?$/);                 //** Czech Republic
  vatexp.push (/^(DE)([1-9]\d{8})$/);                       //** Germany 
  vatexp.push (/^(DK)(\d{8})$/);                            //** Denmark 
  vatexp.push (/^(EE)(10\d{7})$/);                          //** Estonia 
  vatexp.push (/^(EL)(\d{9})$/);                            //** Greece 
  vatexp.push (/^(ES)([A-Z]\d{8})$/);                       //** Spain (National juridical entities)
  vatexp.push (/^(ES)([A-HN-SW]\d{7}[A-J])$/);              //** Spain (Other juridical entities)
  vatexp.push (/^(ES)([0-9YZ]\d{7}[A-Z])$/);                //** Spain (Personal entities type 1)
  vatexp.push (/^(ES)([KLMX]\d{7}[A-Z])$/);                 //** Spain (Personal entities type 2)
  vatexp.push (/^(EU)(\d{9})$/);                            //** EU-type 
  vatexp.push (/^(FI)(\d{8})$/);                            //** Finland 
  vatexp.push (/^(FR)(\d{11})$/);                           //** France (1)
  vatexp.push (/^(FR)([A-HJ-NP-Z]\d{10})$/);                // France (2)
  vatexp.push (/^(FR)(\d[A-HJ-NP-Z]\d{9})$/);               // France (3)
  vatexp.push (/^(FR)([A-HJ-NP-Z]{2}\d{9})$/);              // France (4)
  vatexp.push (/^(GB)?(\d{9})$/);                           //** UK (Standard)
  vatexp.push (/^(GB)?(\d{12})$/);                          //** UK (Branches)
  vatexp.push (/^(GB)?(GD\d{3})$/);                         //** UK (Government)
  vatexp.push (/^(GB)?(HA\d{3})$/);                         //** UK (Health authority)
  vatexp.push (/^(HR)(\d{11})$/);                           //** Croatia 
  vatexp.push (/^(HU)(\d{8})$/);                            //** Hungary 
  vatexp.push (/^(IE)(\d{7}[A-W])$/);                       //** Ireland (1)
  vatexp.push (/^(IE)([7-9][A-Z\*\+)]\d{5}[A-W])$/);        //** Ireland (2)
  vatexp.push (/^(IE)(\d{7}[A-W][AH])$/);                   //** Ireland (3)
  vatexp.push (/^(IT)(\d{11})$/);                           //** Italy 
  vatexp.push (/^(LV)(\d{11})$/);                           //** Latvia 
  vatexp.push (/^(LT)(\d{9}|\d{12})$/);                     //** Lithunia
  vatexp.push (/^(LU)(\d{8})$/);                            //** Luxembourg 
  vatexp.push (/^(MT)([1-9]\d{7})$/);                       //** Malta
  vatexp.push (/^(NL)(\d{9})B\d{2}$/);                      //** Netherlands
  vatexp.push (/^(NO)(\d{9})$/);                            //** Norway (not EU)
  vatexp.push (/^(PL)(\d{10})$/);                           //** Poland
  vatexp.push (/^(PT)(\d{9})$/);                            //** Portugal
  vatexp.push (/^(RO)([1-9]\d{1,9})$/);                     //** Romania
  vatexp.push (/^(RU)(\d{10}|\d{12})$/);                    //** Russia
  vatexp.push (/^(RS)(\d{9})$/);                            //** Serbia
  vatexp.push (/^(SI)([1-9]\d{7})$/);                       //** Slovenia
  vatexp.push (/^(SK)([1-9]\d[2346-9]\d{7})$/);             //** Slovakia Republic
  vatexp.push (/^(SE)(\d{10}01)$/);                         //** Sweden

  // Load up the string to check
  var VATNumber = toCheck.toUpperCase();
  
  // Remove spaces etc. from the VAT number to help validation
  VATNumber = VATNumber.replace (/(\s|-|\.)+/g, '');

  // Assume we're not going to find a valid VAT number
  var valid = false;                         
  
  // Check the string against the regular expressions for all types of VAT numbers
  for (i=0; i<vatexp.length; i++) {
  
    // Have we recognised the VAT number?
    if (vatexp[i].test(VATNumber)) {
      
      // Yes - we have
      var cCode = RegExp.$1;                             // Isolate country code
      var cNumber = RegExp.$2;                           // Isolate the number
      if (cCode.length == 0) cCode = defCCode;           // Set up default country code
      
      // Call the appropriate country VAT validation routine depending on the country code
      if (eval(cCode+"VATCheckDigit ('"+cNumber+"')")) valid = VATNumber;
      
      // Having processed the number, we break from the loop
      break;
    }
  }
  
  // Return with either an error or the reformatted VAT number
  return valid;
}

function ATVATCheckDigit (vatnumber) {

  // Checks the check digits of an Austrian VAT number.
  
  var total = 0;
  var multipliers = [1,2,1,2,1,2,1];
  var temp = 0;
  
  // Extract the next digit and multiply by the appropriate multiplier.  
  for (var i = 0; i < 7; i++) {
    temp = Number(vatnumber.charAt(i)) * multipliers[i];
    if (temp > 9)
      total += Math.floor(temp/10) + temp%10
    else
      total += temp;
  }  
  
  // Establish check digit.
  total = 10 - (total+4) % 10; 
  if (total == 10) total = 0;
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (7,8)) 
    return true
  else 
    return false;
}

function BEVATCheckDigit (vatnumber) {

  // Checks the check digits of a Belgium VAT number.
  
  // Nine digit numbers have a 0 inserted at the front.
  if (vatnumber.length == 9) vatnumber = "0" + vatnumber;
  
  if (vatnumber.slice(1,2) == 0) return false;
  
  // Modulus 97 check on last nine digits
  if (97 - vatnumber.slice (0,8) % 97 == vatnumber.slice (8,10)) 
    return true
  else 
    return false;
}

function BGVATCheckDigit (vatnumber) {

  // Checks the check digits of a Bulgarian VAT number.

  if (vatnumber.length == 9) {
  
    // Check the check digit of 9 digit Bulgarian VAT numbers.
    var total = 0;
    
    // First try to calculate the check digit using the first multipliers  
    var temp = 0;
    for (var i = 0; i < 8; i++) temp += Number(vatnumber.charAt(i)) * (i+1);
    
    // See if we have a check digit yet
    total = temp % 11; 
    if (total != 10) {
      if (total == vatnumber.slice (8)) 
        return true
      else 
        return false;
    }
  
    // We got a modulus of 10 before so we have to keep going. Calculate the new check digit using  
    // the different multipliers  
    var temp = 0;
    for (var i = 0; i < 8; i++) temp += Number(vatnumber.charAt(i)) * (i+3);
    
    // See if we have a check digit yet. If we still have a modulus of 10, set it to 0.
    total = temp % 11; 
    if (total == 10) total = 0;
    if (total == vatnumber.slice (8)) 
      return true
    else 
      return false;
  }
  
  // 10 digit VAT code - see if it relates to a standard physical person
  if ((/^\d\d[0-5]\d[0-3]\d\d{4}$/).test(vatnumber)) {
  
    // Check month
    var month = Number(vatnumber.slice(2,4));
    if ((month > 0 && month < 13) || (month > 20 && month < 33) || (month > 40 && month < 53)) {
    
      // Extract the next digit and multiply by the counter.
      var multipliers = [2,4,8,5,10,9,7,3,6];    
      var total = 0;
      for (var i = 0; i < 9; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
      
      // Establish check digit.
      total = total % 11;
      if (total == 10) total = 0;  
      
      // Check to see if the check digit given is correct, If not, try next type of person
      if (total == vatnumber.substr (9,1)) return true;
    }
  }
  
  // It doesn't relate to a standard physical person - see if it relates to a foreigner.
  
  // Extract the next digit and multiply by the counter.
  var multipliers = [21,19,17,13,11,9,7,3,1];    
  var total = 0;
  for (var i = 0; i < 9; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Check to see if the check digit given is correct, If not, try next type of person
  if (total % 10 == vatnumber.substr (9,1)) return true;
  
  // Finally, if not yet identified, see if it conforms to a miscellaneous VAT number
  
  // Extract the next digit and multiply by the counter.
  var multipliers = [4,3,2,7,6,5,4,3,2];    
  var total = 0;
  for (var i = 0; i < 9; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digit.
  total = 11 - total % 11;
  if (total == 10) return false;  
  if (total == 11) total = 0;  
  
  // Check to see if the check digit given is correct, If not, we have an error with the VAT number
  if (total == vatnumber.substr (9,1)) 
    return true;
  else
    return false;
}

function CHEVATCheckDigit (vatnumber) {

  // Checks the check digits of a Swiss VAT number.
  
  // Extract the next digit and multiply by the counter.
  var multipliers = [5,4,3,2,7,6,5,4];    
  var total = 0;
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digit.
  total = 11 - total % 11;
  if (total == 10) return false;  
  if (total == 11) total = 0;  
  
  // Check to see if the check digit given is correct, If not, we have an error with the VAT number
  if (total == vatnumber.substr (8,1)) 
    return true;
  else
    return false;
}

function CYVATCheckDigit (vatnumber) {

  // Checks the check digits of a Cypriot VAT number.
  
  // Not allowed to start with '12'
  if (Number(vatnumber.slice(0,2) == 12)) return false;
  
  // Extract the next digit and multiply by the counter.
  var total = 0;
  for (var i = 0; i < 8; i++) {
    var temp = Number(vatnumber.charAt(i));
    if (i % 2 == 0) {
      switch (temp) {
        case 0: temp = 1; break;
        case 1: temp = 0; break;
        case 2: temp = 5; break;
        case 3: temp = 7; break;
        case 4: temp = 9; break;
        default: temp = temp*2 + 3;
      }
    }
    total += temp;
  }
  
  // Establish check digit using modulus 26, and translate to char. equivalent.
  total = total % 26;
  total = String.fromCharCode(total+65);
  
  // Check to see if the check digit given is correct
  if (total == vatnumber.substr (8,1)) 
    return true 
  else 
    return false;
}

function CZVATCheckDigit (vatnumber) {

  // Checks the check digits of a Czech Republic VAT number.
  
  var total = 0;
  var multipliers = [8,7,6,5,4,3,2];
  
  var czexp = new Array ();
  czexp[0] = (/^\d{8}$/);
  czexp[1] = (/^[0-5][0-9][0|1|5|6]\d[0-3]\d\d{3}$/);
  czexp[2] = (/^6\d{8}$/);
  czexp[3] = (/^\d{2}[0-3|5-8]\d[0-3]\d\d{4}$/);
  var i = 0;
  
  // Legal entities
  if (czexp[0].test(vatnumber)) {    
    
    // Extract the next digit and multiply by the counter.
    for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
    
    // Establish check digit.
    total = 11 - total % 11;
    if (total == 10) total = 0; 
    if (total == 11) total = 1; 
    
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (7,8)) 
      return true
    else 
      return false;
  }  
  
  // Individuals type 1
  else if (czexp[1].test(vatnumber)) {
    if (temp = Number(vatnumber.slice(0,2)) > 53) return false;
    return true;
  }
  
  // Individuals type 2
  else if (czexp[2].test(vatnumber)) {  
    
    // Extract the next digit and multiply by the counter.
    for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i+1)) * multipliers[i];
    
    // Establish check digit.
    total = 11 - total % 11;
    if (total == 10) total = 0; 
    if (total == 11) total = 1; 
    
    // Convert calculated check digit according to a lookup table;
    var lookup  = [8,7,6,5,4,3,2,1,0,9,10];
    if (lookup[total-1] == vatnumber.slice (8,9)) 
      return true
    else 
      return false;
  }
  
  // Individuals type 3
  else if (czexp[3].test(vatnumber)) {
    var temp = Number(vatnumber.slice(0,2)) + Number(vatnumber.slice(2,4)) + Number(vatnumber.slice(4,6)) + Number(vatnumber.slice(6,8)) + Number(vatnumber.slice(8));
    if (temp % 11 == 0 && Number(vatnumber) % 11 == 0)
      return true
    else
      return false;
  }
  
  // else error
  return false;
}

function DEVATCheckDigit (vatnumber) {

  // Checks the check digits of a German VAT number.
  
  var product = 10;
  var sum = 0;     
  var checkdigit = 0;                      
  for (var i = 0; i < 8; i++) {
    
    // Extract the next digit and implement peculiar algorithm!.
    sum = (Number(vatnumber.charAt(i)) + product) % 10;
    if (sum == 0) {sum = 10};
    product = (2 * sum) % 11;
  }
  
  // Establish check digit.  
  if (11 - product == 10) {checkdigit = 0} else {checkdigit = 11 - product};
  
  // Compare it with the last two characters of the VAT number. If the same, then it is a valid 
  // check digit.
  if (checkdigit == vatnumber.slice (8,9))
    return true
  else 
    return false;
}

function DKVATCheckDigit (vatnumber) {

  // Checks the check digits of a Danish VAT number.
  
  var total = 0;
  var multipliers = [2,7,6,5,4,3,2,1];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digit.
  total = total % 11;
  
  // The remainder should be 0 for it to be valid..
  if (total == 0) 
    return true
  else 
    return false;
}

function EEVATCheckDigit (vatnumber) {

  // Checks the check digits of an Estonian VAT number.
  
  var total = 0;
  var multipliers = [3,7,1,3,7,1,3,7];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits using modulus 10.
  total = 10 - total % 10;
  if (total == 10) total = 0;
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (8,9))
    return true
  else 
    return false;
}

function ELVATCheckDigit (vatnumber) {

  // Checks the check digits of a Greek VAT number.
  
  var total = 0;
  var multipliers = [256,128,64,32,16,8,4,2];
  
  //eight character numbers should be prefixed with an 0.
  if (vatnumber.length == 8) {vatnumber = "0" + vatnumber};
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digit.
  total = total % 11;
  if (total > 9) {total = 0;};  
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (8,9)) 
    return true
  else 
    return false;
}

function ESVATCheckDigit (vatnumber) {

  // Checks the check digits of a Spanish VAT number.
  
  var total = 0; 
  var temp = 0;
  var multipliers = [2,1,2,1,2,1,2];
  var esexp = new Array ();
  esexp[0] = (/^[A-H|J|U|V]\d{8}$/);
  esexp[1] = (/^[A-H|N-S|W]\d{7}[A-J]$/);
  esexp[2] = (/^[0-9|Y|Z]\d{7}[A-Z]$/);
  esexp[3] = (/^[K|L|M|X]\d{7}[A-Z]$/);
  var i = 0;
  
  // National juridical entities
  if (esexp[0].test(vatnumber)) {
  
    // Extract the next digit and multiply by the counter.
    for (i = 0; i < 7; i++) {
      temp = Number(vatnumber.charAt(i+1)) * multipliers[i];
      if (temp > 9) 
        total += Math.floor(temp/10) + temp%10 
      else 
        total += temp;
    }   
    // Now calculate the check digit itself. 
    total = 10 - total % 10;
    if (total == 10) {total = 0;}
    
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (8,9)) 
      return true
    else 
      return false;
  }
  
  // Juridical entities other than national ones
  else if (esexp[1].test(vatnumber)) {
  
    // Extract the next digit and multiply by the counter.
    for (i = 0; i < 7; i++) {
      temp = Number(vatnumber.charAt(i+1)) * multipliers[i];
      if (temp > 9) 
        total += Math.floor(temp/10) + temp%10 
      else 
        total += temp;
    }    
    
    // Now calculate the check digit itself.
    total = 10 - total % 10;
    total = String.fromCharCode(total+64);
    
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (8,9)) 
      return true
    else 
      return false;
  }
	
  // Personal number (NIF) (starting with numeric of Y or Z)
  else if (esexp[2].test(vatnumber)) {
    var tempnumber = vatnumber;
    if (tempnumber.substring(0,1) == 'Y') tempnumber = tempnumber.replace (/Y/, "1");
    if (tempnumber.substring(0,1) == 'Z') tempnumber = tempnumber.replace (/Z/, "2");
  	return tempnumber.charAt(8) == 'TRWAGMYFPDXBNJZSQVHLCKE'.charAt(Number(tempnumber.substring(0,8)) % 23);
  }
	
  // Personal number (NIF) (starting with K, L, M, or X)
  else if (esexp[3].test(vatnumber)) {
  	return vatnumber.charAt(8) == 'TRWAGMYFPDXBNJZSQVHLCKE'.charAt(Number(vatnumber.substring(1,8)) % 23);
  }
	
  else return false;
}

function EUVATCheckDigit (vatnumber) {

  // We know little about EU numbers apart from the fact that the first 3 digits represent the 
  // country, and that there are nine digits in total.
  return true;
}

function FIVATCheckDigit (vatnumber) {

  // Checks the check digits of a Finnish VAT number.
  
  var total = 0; 
  var multipliers = [7,9,10,5,8,4,2];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digit.
  total = 11 - total % 11;
  if (total > 9) {total = 0;};  
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (7,8)) 
    return true
  else 
    return false;
}

function FRVATCheckDigit (vatnumber) {

  // Checks the check digits of a French VAT number.
  
  if (!(/^\d{11}$/).test(vatnumber)) return true;
  
  // Extract the last nine digits as an integer.
  var total = vatnumber.substring(2); 
  
  // Establish check digit.
  total = (total*100+12) % 97;
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (0,2)) 
    return true
  else 
    return false;
}

function GBVATCheckDigit (vatnumber) {

  // Checks the check digits of a UK VAT number.
  
  var multipliers = [8,7,6,5,4,3,2];
  
  // Government departments
  if (vatnumber.substr(0,2) == 'GD') {
    if (vatnumber.substr(2,3) < 500) 
      return true 
    else 
      return false;
  }
  
  // Health authorities
  if (vatnumber.substr(0,2) == 'HA') {
    if (vatnumber.substr(2,3) > 499) 
      return true 
    else 
      return false;
  }
  
  // Standard and commercial numbers
  var total = 0;
  
  // 0 VAT numbers disallowed!
  if (Number(vatnumber.slice(0)) == 0) return false;
  
  // Check range is OK for modulus 97 calculation
  var no = Number(vatnumber.slice(0,7));
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];

  // Old numbers use a simple 97 modulus, but new numbers use an adaptation of that (less 55). Our 
  // VAT number could use either system, so we check it against both.

  // Establish check digits by subtracting 97 from total until negative.
  var cd = total;
  while (cd > 0) {cd = cd - 97;}    

  // Get the absolute value and compare it with the last two characters of the VAT number. If the 
  // same, then it is a valid traditional check digit. However, even then the number must fit within
  // certain specified ranges.
  cd = Math.abs(cd);
  if (cd == vatnumber.slice (7,9) && no < 9990001 && (no < 100000 || no > 999999) && (no < 9490001 || no > 9700000)) return true;
  
  // Now try the new method by subtracting 55 from the check digit if we can - else add 42
  if (cd >= 55) 
    cd = cd - 55
  else
    cd = cd + 42;
  if (cd == vatnumber.slice (7,9) && no > 1000000) 
    return true;
  else
    return false; 
}

function HRVATCheckDigit (vatnumber) {

  // Checks the check digits of a Croatian VAT number using ISO 7064, MOD 11-10 for check digit.
  
  var product = 10;
  var sum = 0;     
  var checkdigit = 0; 
  
  for (var i = 0; i < 10; i++) {
    
    // Extract the next digit and implement the algorithm
    sum = (Number(vatnumber.charAt(i)) + product) % 10;
    if (sum == 0) {sum = 10};
    product = (2 * sum) % 11;
  }
  
  // Now check that we have the right check digit
  if ((product + vatnumber.slice (10,11)*1) % 10== 1)
    return true
  else 
    return false;
}

function HUVATCheckDigit (vatnumber) {

  // Checks the check digits of a Hungarian VAT number.
  
  var total = 0;
  var multipliers = [9,7,3,1,9,7,3];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digit.
  total = 10 - total % 10; 
  if (total == 10) total = 0;
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (7,8)) 
    return true
  else 
    return false;
}

function IEVATCheckDigit (vatnumber) {

  // Checks the check digits of an Irish VAT number.
  
  var total = 0; 
  var multipliers = [8,7,6,5,4,3,2];  
 
  // If the code is type 1 format, we need to convert it to the new before performing the validation.
  if (/^\d[A-Z\*\+]/.test(vatnumber)) vatnumber = "0" + vatnumber.substring(2,7) + vatnumber.substring(0,1) + vatnumber.substring(7,8);
    
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // If the number is type 3 then we need to include the trailing A or H in the calculation
  if (/^\d{7}[A-Z][AH]$/.test(vatnumber)) {
  
    // Add in a multiplier for the character A (1*9=9) or H (8*9=72)
    if (vatnumber.charAt(8) == 'H')
      total += 72
    else
      total += 9;    
  }
  
  // Establish check digit using modulus 23, and translate to char. equivalent.
  total = total % 23;
  if (total == 0)
    total = "W"
  else
    total = String.fromCharCode(total+64);
    
  // Compare it with the eighth character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (7,8)) 
    return true
  else 
    return false;
}

function ITVATCheckDigit (vatnumber) {

  // Checks the check digits of an Italian VAT number.
  
  var total = 0;
  var multipliers = [1,2,1,2,1,2,1,2,1,2];
  var temp;
    
  // The last three digits are the issuing office, and cannot exceed more 201, unless 999 or 888
  if (Number(vatnumber.slice(0,7))==0) return false;
  temp=Number(vatnumber.slice(7,10));
  if ((temp<1) || (temp>201) && temp != 999 && temp != 888) return false;
  
  // Extract the next digit and multiply by the appropriate  
  for (var i = 0; i < 10; i++) {
    temp = Number(vatnumber.charAt(i)) * multipliers[i];
    if (temp > 9) 
      total += Math.floor(temp/10) + temp%10 
    else 
      total += temp;
  }
  
  // Establish check digit.
  total = 10 - total % 10;
  if (total > 9) {total = 0;};  
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (10,11)) 
    return true
  else 
    return false;
}

function LTVATCheckDigit (vatnumber) {

  // Checks the check digits of a Lithuanian VAT number.
  
  // 9 character VAT numbers are for legal persons
  if (vatnumber.length == 9) {
  
    // 8th character must be one
    if (!(/^\d{7}1/).test(vatnumber)) return false;
    
    // Extract the next digit and multiply by the counter+1.
    var total = 0;
    for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * (i+1);
    
    // Can have a double check digit calculation!
    if (total % 11 == 10) {
      var multipliers = [3,4,5,6,7,8,9,1];
      total = 0;
      for (i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
    }
    
    // Establish check digit.
    total = total % 11;
    if (total == 10) {total = 0;}; 
    
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (8,9)) 
      return true
    else 
      return false;
  }
  
  // 12 character VAT numbers are for temporarily registered taxpayers
  else {
  
    // 11th character must be one
    if (!(/^\d{10}1/).test(vatnumber)) return false;
    
    // Extract the next digit and multiply by the counter+1.
    var total = 0;
    var multipliers = [1,2,3,4,5,6,7,8,9,1,2];
    for (var i = 0; i < 11; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
    
    // Can have a double check digit calculation!
    if (total % 11 == 10) {
      var multipliers = [3,4,5,6,7,8,9,1,2,3,4];
      total = 0;
      for (i = 0; i < 11; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
    }
    
    // Establish check digit.
    total = total % 11;
    if (total == 10) {total = 0;}; 
    
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (11,12)) 
      return true
    else 
      return false;
  }
}

function LUVATCheckDigit (vatnumber) {

  // Checks the check digits of a Luxembourg VAT number.
  
  if (vatnumber.slice (0,6) % 89 == vatnumber.slice (6,8)) 
    return true
  else 
    return false;
}

function LVVATCheckDigit (vatnumber) {

  // Checks the check digits of a Latvian VAT number.
  
  // Differentiate between legal entities and natural bodies. For the latter we simply check that
  // the first six digits correspond to valid DDMMYY dates.
  if ((/^[0-3]/).test(vatnumber)) {
    if ((/^[0-3][0-9][0-1][0-9]/).test(vatnumber) )
      return true
    else
      return false;
  }
  
  else {
  
    var total = 0;
    var multipliers = [9,1,4,8,3,10,2,5,7,6];
    
    // Extract the next digit and multiply by the counter.
    for (var i = 0; i < 10; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
    
    // Establish check digits by getting modulus 11.
    if (total%11 == 4 && vatnumber[0] ==9) total = total - 45;
    if (total%11 == 4) 
      total = 4 - total%11
    else if (total%11 > 4) 
      total = 14 - total%11
    else if (total%11 < 4) 
      total = 3 - total%11;
    
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (10,11)) 
      return true
    else 
      return false;
  }
}

function MTVATCheckDigit (vatnumber) {

  // Checks the check digits of a Maltese VAT number.
  
  var total = 0;
  var multipliers = [3,4,6,7,8,9];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 6; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits by getting modulus 37.
  total = 37 - total % 37;
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (6,8) * 1) 
    return true
  else 
    return false;
}

function NLVATCheckDigit (vatnumber) {

  // Checks the check digits of a Dutch VAT number.
  
  var total = 0;
  var multipliers = [9,8,7,6,5,4,3,2];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits by getting modulus 11.
  total = total % 11;
  if (total > 9) {total = 0;};  
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (8,9)) 
    return true
  else 
    return false;
}

function NOVATCheckDigit (vatnumber) {

  // Checks the check digits of a Norwegian VAT number.
  // See http://www.brreg.no/english/coordination/number.html
  
  var total = 0;
  var multipliers = [3,2,7,6,5,4,3,2];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits by getting modulus 11. Check digits > 9 are invalid
  total = 11 - total % 11;
  if (total == 11) {total = 0;}
  if (total < 10) {  
  
    // Compare it with the last character of the VAT number. If it's the same, then it's valid.
    if (total == vatnumber.slice (8,9)) 
      return true
    else 
      return false;
  }
}

function PLVATCheckDigit (vatnumber) {

  // Checks the check digits of a Polish VAT number.
  
  var total = 0;
  var multipliers = [6,5,7,2,3,4,5,6,7];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 9; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits subtracting modulus 11 from 11.
  total = total % 11;
  if (total > 9) {total = 0;};
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (9,10)) 
    return true
  else 
    return false;
}

function PTVATCheckDigit (vatnumber) {

  // Checks the check digits of a Portugese VAT number.
  
  var total = 0;
  var multipliers = [9,8,7,6,5,4,3,2];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 8; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits subtracting modulus 11 from 11.
  total = 11 - total % 11;
  if (total > 9) {total = 0;};
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (8,9)) 
    return true
  else 
    return false;
}

function ROVATCheckDigit (vatnumber) {

  // Checks the check digits of a Romanian VAT number.
  
  var multipliers = [7,5,3,2,1,7,5,3,2];
  
  // Extract the next digit and multiply by the counter.
  var VATlen = vatnumber.length;
  multipliers = multipliers.slice (10-VATlen);
  var total = 0;
  for (var i = 0; i < vatnumber.length-1; i++) {
    total += Number(vatnumber.charAt(i)) * multipliers[i];
  }  
  
  // Establish check digits by getting modulus 11.
  total = (10 * total) % 11;
  if (total == 10) total = 0; 
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (total == vatnumber.slice (vatnumber.length-1, vatnumber.length))
    return true
  else 
    return false;
}

function RSVATCheckDigit (vatnumber) {

  // Checks the check digits of a Serbian VAT number using ISO 7064, MOD 11-10 for check digit.
  
  var product = 10;
  var sum = 0;     
  var checkdigit = 0; 
  
  for (var i = 0; i < 8; i++) {
    
    // Extract the next digit and implement the algorithm
    sum = (Number(vatnumber.charAt(i)) + product) % 10;
    if (sum == 0) {sum = 10};
    product = (2 * sum) % 11;
  }
  
  // Now check that we have the right check digit
  if ((product + vatnumber.slice (8,9)*1) % 10== 1)
    return true
  else 
    return false;
}
function RUVATCheckDigit (vatnumber) {

  // Checks the check digits of a Russian INN number 
  // See http://russianpartner.biz/test_inn.html for algorithm 
 
  // 10 digit INN numbers
	if (vatnumber.length == 10) {
		var total = 0;
		var multipliers = [2,4,10,3,5,9,4,6,8,0]
		for (var i = 0; i < 10; i++) {
			total += Number(vatnumber.charAt(i)) * multipliers[i];
		}
		total = total % 11
		if (total > 9) {total = total % 10} 
    
		// Compare it with the last character of the VAT number. If it is the same, then it's valid
		if (total == vatnumber.slice (9,10)) 
			return true
		else 
			return false
   
  // 12 digit INN numbers
	} else if(vatnumber.length == 12){
		var total1 = 0
		var multipliers1 = [7,2,4,10,3,5,9,4,6,8,0]
		var total2 = 0
		var multipliers2 = [3,7,2,4,10,3,5,9,4,6,8,0]
		
		for (var i = 0; i < 11; i++) total1 += Number(vatnumber.charAt(i)) * multipliers1[i];
		total1 = total1 % 11
		if (total1 > 9) {total1 = total1 % 10} 
		
		for (var i = 0; i < 11; i++) total2 += Number(vatnumber.charAt(i)) * multipliers2[i];
		total2 = total2 % 11
		if (total2 > 9) {total2 = total2 % 10}  
		
		// Compare the first check with the 11th character and the second check with the 12th and last 
    // character of the VAT number. If they're both the same, then it's valid
		if ((total1 == vatnumber.slice (10,11)) && (total2 == vatnumber.slice (11,12)))
			return true
		else 
			return false
	}
}

function SEVATCheckDigit (vatnumber) {

  // Calculate R where R = R1 + R3 + R5 + R7 + R9, and Ri = INT(Ci/5) + (Ci*2) modulo 10
  var R = 0;
  var digit;
  for (var i = 0; i < 9; i=i+2) {
    digit = Number(vatnumber.charAt(i));
    R += Math.floor(digit / 5)  + ((digit * 2) % 10);
  }
  
  // Calculate S where S = C2 + C4 + C6 + C8
  var S = 0;
  for (var i = 1; i < 9; i=i+2) S += Number(vatnumber.charAt(i));
  
  // Calculate the Check Digit
  var cd = (10 - (R + S) % 10) % 10;  
  
  // Compare it with the last character of the VAT number. If it's the same, then it's valid.
  if (cd == vatnumber.slice (9,10)) 
    return true
  else 
    return false;
}

function SIVATCheckDigit (vatnumber) {

  // Checks the check digits of a Slovenian VAT number.
  
  var total = 0; 
  var multipliers = [8,7,6,5,4,3,2];
  
  // Extract the next digit and multiply by the counter.
  for (var i = 0; i < 7; i++) total += Number(vatnumber.charAt(i)) * multipliers[i];
  
  // Establish check digits using modulus 11
  total = 11 - total % 11;
  if (total == 10) {total = 0;};  
  
  // Compare the number with the last character of the VAT number. If it is the 
  // same, then it's a valid check digit.
  if (total != 11 && total == vatnumber.slice (7,8)) 
    return true
  else 
    return false;
}

function SKVATCheckDigit (vatnumber) {

  // Checks the check digits of a Slovakian VAT number.
  
  // Check that the modulus of the whole VAT number is 0 - else error
  if (Number(vatnumber % 11) == 0) 
    return true
  else 
    return false;
}
