var reFloat = /^((\d+(\.\d*)?)|((\d*\.)?\d+))$/
var reSignedInteger = /^(|-)?\d+$/
var reInteger = /^\d+$/
var reAlpha = /^[a-zA-Z!@]+$/
var reAlphanumeric = /^[ a-zA-Z0-9!@]+$/
var reEmail = /^.+\@.+\..+$/

var reWhitespace = /^\s+$/;

function isEmpty(s) {
   return ((s == null) || (s.length == 0));
}

function isWhitespace (s) {
// Is s empty?
   return (isEmpty(s) || reWhitespace.test(s));
}

function warnInvalid (theField, s) {
   theField.focus();
   theField.select();
   alert(s);
   return false;
}

function Validate(theField, emptyOK, errorMsg, reEditRules) {
// Expect the following parameters
// 1st parameter : a form field
// 2nd parameter : true or false --> emptyOK or emptyNotOK
// 3rd parameter : error message
// 4th parameter : type of edit rule --> regexp, no enclosed strings

   var rc = true;
   
   if (theField != null) {
      if (isWhitespace(theField.value)) {
         if (emptyOK == false) { 
	    //validation rule -- data expected
            alert(errorMsg + ": no value entered");
            theField.focus();
            return false;
         }
         else
            return true;
      }
   
      if (reEditRules != null) {
         rc = eval( reEditRules + ".test('" + theField.value + "')" );
   
         if (rc == false) {
            warnInvalid (theField, errorMsg);
            return false;
         }
      }
   }

   return true;
}

function checkForm(f) {
   ret=true;

   if (!Validate(f.surname, false, 'You must enter a valid surname', reAlphanumeric)) 
      return false;
   if (!Validate(f.firstname, false, 'You must enter a valid firstname', reAlphanumeric)) 
      return false;
//   if (!Validate(f.country, false, 'You must choose a country', reAlphanumeric)) 
//      return false;
   
   if (!Validate(f.email, false, 'You must enter a valid email address', reEmail))
      return false;

   return ret;
}