/**
 * Project:     CaribMedia javascript library
 * File:        cm.string.js
 *
 * @link http://www.visitaruba.com/plus
 * @copyright 2008 CaribMedia
 * @author Michiel van der Blonk <michiel@caribmedia.com>
 * @package Types
 */

/*
* @Date: Feb 21, 2005
* @Description: This function strips defined chars from a string
* useful in validation routines
* example: str.stripChars("()-") returns the string with any
* brackets and dashes removed
**/
String.prototype.stripChars = function(chars) {
  var i;
  var newstring = "";
  for (i = 0; i < this.length; i++) {
	var mychar = this.charAt(i);
	if (chars.indexOf(mychar) == -1)
	  newstring += mychar;
  }
  return newstring;
};

/**
* @Date: Feb 21, 2005
* @Description: This function extracts defined chars from a string
* useful in validation routines
* it is 'sort of' the reverse of stripChars
* example: str.extractChars("0123456789") returns all digits from the string
**/
String.prototype.extractChars = function(chars) {
  var i;
  var newstring = "";
  for (i = 0; i < this.length; i++) {
	var mychar = this.charAt(i);
	if (chars.indexOf(mychar) != -1)
	  newstring += mychar;
  }
  return newstring;
};

/**
* @Date: Dec 1, 2004
* @Description: This function tests a credit card using the Luhn validation
* The sum of digits must be divisible by 10
* digits in odd positions are doubled, then sum of left+right digit is taken
**/
String.prototype.isValidCreditCard = function()
{
  var nTotal      = 0;
  var nPosition     = 0;
  var bValid      = true; // innocent until proven guilty
  var sCreditCardNumber = this.extractChars("0123456789");
  if (sCreditCardNumber.length < 13)
	bValid = false;
  else
  {
	for ( var i = sCreditCardNumber.length; i > 0 ;  i--)
	{
	  var nDigit      = 0;
	  // advance
	  nPosition++;
	  // get digit
	  nDigit= parseInt(sCreditCardNumber.charAt(i-1));
	  // odd position: add to total
	  if ((nPosition % 2) !== 0)
		 nTotal += parseInt(nDigit);
	  else
	  // even position: add sum of digits to total
	  {
		// calc sum of left and right digit (use parseInt to cut off fractional parts
		var nDoubled = nDigit * 2;
		var nLeftDigit  = parseInt(nDoubled / 10);
		var nRightDigit = nDoubled % 10;
		// get sum of left and right
		nTotal += nLeftDigit + nRightDigit;
	  }
	}
	// if divisible by 10 it is valid
	bValid = (nTotal % 10) === 0;
  }
  return (bValid);
};

/* check if d is a date value
 * formatted means it is in fact a string, formatted as mm/dd/yyyy
 * dates like 44/55/2000 are invalid, even though to JavaScript
 * these _are_ valid
*/
String.prototype.isDate = function(formatted)
{
  var ret = false;
  var val = this.toString();
  var date = new Date(val);

  // it's at least a number
  if (!isNaN(date))
  {
	if (formatted)
	{
	  if (window.console)
			console.assert(typeof Date.prototype.format == 'function');
	  var pattern = new RegExp(date.format(null, '.', true)); // . means you can use e.g. '-' or '/'
	  ret = pattern.test(val);
	}
	else
	  ret = true;
  }
  return ret;
};