// $Id$

/**
 * JavaScript function to check an email address conforms to RFC822 (http://www.ietf.org/rfc/rfc0822.txt)
 *
 * Version: 0.2
 * Author: Ross Kendall
 * Created: 2006-12-16
 * Updated: 2007-03-22
 *
 * Based on the PHP code by Cal Henderson
 * http://iamcal.com/publish/articles/php/parsing_email/
 */

/*

Portions copyright (C) 2006  Ross Kendall - http://rosskendall.com
Portions copyright (C) 1993-2005 Cal Henderson - http://iamcal.com

Licenced under Creative Commons _or_ GPL according to the terms below...

--

 Licensed under a Creative Commons Attribution-ShareAlike 2.5 License

 You are free:

    * to Share -- to copy, distribute, display, and perform the work
    * to Remix -- to make derivative works

 Under the following conditions:

    * Attribution. You must attribute the work in the manner specified by the author or licensor.
    * Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one.

    * For any reuse or distribution, you must make clear to others the license terms of this work.
    * Any of these conditions can be waived if you get permission from the copyright holder.

 http://creativecommons.org/licenses/by-sa/2.5/

--

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 http://www.gnu.org/copyleft/gpl.html

*/


function isRFC822ValidEmail(sEmail) {

  var sQtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
  var sDtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
  var sAtom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
  var sQuotedPair = '\\x5c[\\x00-\\x7f]';
  var sDomainLiteral = '\\x5b(' + sDtext + '|' + sQuotedPair + ')*\\x5d';
  var sQuotedString = '\\x22(' + sQtext + '|' + sQuotedPair + ')*\\x22';
  var sDomain_ref = sAtom;
  var sSubDomain = '(' + sDomain_ref + '|' + sDomainLiteral + ')';
  var sWord = '(' + sAtom + '|' + sQuotedString + ')';
  var sDomain = sSubDomain + '(\\x2e' + sSubDomain + ')*';
  var sLocalPart = sWord + '(\\x2e' + sWord + ')*';
  var sAddrSpec = sLocalPart + '\\x40' + sDomain; // complete RFC822 email address spec
  var sValidEmail = '^' + sAddrSpec + '$'; // as whole string
  
  var reValidEmail = new RegExp(sValidEmail);
  
  if (reValidEmail.test(sEmail)) {
    return true;
  }
  
  return false;
}


/* example usage...
Using the function below, with html like this:
 <form method=post name="myform" action="/myscript.php">
 Email:<input type=text name="email" value="" size="30" />
 <input type="submit" name="submit" value="Submit" onClick="return checkEmailField(document.myform.elements['email']);" />
 </form>
*/
function checkEmailField(emailField) {
  var email = emailField.value;
  if (!isRFC822ValidEmail(email)) {
    alert("Please enter a valid email address.");
    emailField.focus();
    return false;
  }

  return true;
}