/**
 * ValidateSpanishID. Returns the type of document and checks its validity.
 * 
 * Usage:
 *     ValidateSpanishID( str );
 * 
 *     > ValidateSpanishID( '12345678Z' );
 *     // { type: 'dni', valid: true }
 *     
 *     > ValidateSpanishID( 'B83375575' );
 *     // { type: 'cif', valid: false }
 * 
 * The algorithm is adapted from other solutions found at:
 * - http://www.compartecodigo.com/javascript/validar-nif-cif-nie-segun-ley-vigente-31.html
 * - http://es.wikipedia.org/wiki/C%C3%B3digo_de_identificaci%C3%B3n_fiscal
 */

ValidateSpanishID = (function() {
  'use strict';
  
  var DNI_REGEX = /^(\d{8})([A-Z])$/;
  var CIF_REGEX = /^([ABCDEFGHJKLMNPQRSUVW])(\d{7})([0-9A-J])$/;
  var NIE_REGEX = /^[XYZ]\d{7,8}[A-Z]$/;

  var ValidateSpanishID = function( str ) {

    // Ensure upcase and remove whitespace
    str = str.toUpperCase().replace(/\s/, '');

    var valid = false;
    var type = spainIdType( str );

    switch (type) {
      case 'dni':
        valid = validDNI( str );
        break;
      case 'nie':
        valid = validNIE( str );
        break;
      case 'cif':
        valid = validCIF( str );
        break;
    }

    return {
      type: type,
      valid: valid
    };

  };

  var spainIdType = function( str ) {
    if ( str.match( DNI_REGEX ) ) {
      return 'dni';
    }
    if ( str.match( CIF_REGEX ) ) {
      return 'cif';
    }
    if ( str.match( NIE_REGEX ) ) {
      return 'nie';
    }
  };

  var validDNI = function( dni ) {
    var dni_letters = "TRWAGMYFPDXBNJZSQVHLCKE";
    var letter = dni_letters.charAt( parseInt( dni, 10 ) % 23 );
    
    return letter == dni.charAt(8);
  };

  var validNIE = function( nie ) {

    // Change the initial letter for the corresponding number and validate as DNI
    var nie_prefix = nie.charAt( 0 );

    switch (nie_prefix) {
      case 'X': nie_prefix = 0; break;
      case 'Y': nie_prefix = 1; break;
      case 'Z': nie_prefix = 2; break;
    }

    return validDNI( nie_prefix + nie.substr(1) );

  };

  var validCIF = function( cif ) {

    var match = cif.match( CIF_REGEX );
    var letter  = match[1],
        number  = match[2],
        control = match[3];

    var even_sum = 0;
    var odd_sum = 0;
    var n;

    for ( var i = 0; i < number.length; i++) {
      n = parseInt( number[i], 10 );

      // Odd positions (Even index equals to odd position. i=0 equals first position)
      if ( i % 2 === 0 ) {
        // Odd positions are multiplied first.
        n *= 2;

        // If the multiplication is bigger than 10 we need to adjust
        odd_sum += n < 10 ? n : n - 9;

      // Even positions
      // Just sum them
      } else {
        even_sum += n;
      }

    }

    var control_digit = (10 - (even_sum + odd_sum).toString().substr(-1) );
    var control_letter = 'JABCDEFGHI'.substr( control_digit, 1 );

    // Control must be a digit
    if ( letter.match( /[ABEH]/ ) ) {
      return control == control_digit;

    // Control must be a letter
    } else if ( letter.match( /[KPQS]/ ) ) {
      return control == control_letter;

    // Can be either
    } else {
      return control == control_digit || control == control_letter;
    }

  };

  return ValidateSpanishID;
})();