var blankText = ".";

function supportsJava()
{
   // If getElementById isn't supported, there's no java
   // and then validation is server-side only
   if (!document.getElementById)
      return false;
   
   return true;
}

function valBasic(field, errorTextId, required)
{
   // Don't try to do any more on non-java enabled systems
   if (!supportsJava())
      return true;

   /* Get text, if it's blank and not required, stop. */
   var fieldText = field.value;
   if (fieldText == "" && !required)
   {
      var textElement = document.getElementById(errorTextId);
      textElement.firstChild.nodeValue = blankText;
      return true;
   }

   if (fieldText == "")
   {
      var textElement = document.getElementById(errorTextId);
      textElement.firstChild.nodeValue = "Field cannot be blank.";
      return false;
   }

   // Look for invalid characters
   var i = 0;
   for (i = 0; i < fieldText.length; i++)
   {
      if (fieldText.charAt(i) == '\\' ||
         fieldText.charAt(i) == '/' ||
         fieldText.charAt(i) == '\"' ||
         fieldText.charAt(i) == '\'' ||
         fieldText.charAt(i) == ':' ||
         fieldText.charAt(i) == '<' ||
         fieldText.charAt(i) == '>')
      {
         var textElement = document.getElementById(errorTextId);
         textElement.firstChild.nodeValue = "Invalid characters used.";
         return false;
      }
   }

   var textElement = document.getElementById(errorTextId);
   textElement.firstChild.nodeValue = blankText;
   
   return true;
}

function valAlpha(field, errorTextId, required)
{
   // Don't try to do any more on non-java enabled systems
   if (!supportsJava())
      return true;
   
   /* Get text, if it's blank and not required, stop. */
   var fieldText = field.value;
   if (fieldText == "" && !required)
   {
      var textElement = document.getElementById(errorTextId);
      textElement.firstChild.nodeValue = blankText;
      return true;
   }

   // Run basic checks
   if (!valBasic(field, errorTextId, required))
      return false;

   // Run alpha checks
   var i = 0, lowerText = fieldText.toLowerCase();
   for (i = 0; i < lowerText.length; i++)
   {
      if (lowerText.charAt(i) < 'a' || lowerText.charAt(i) > 'z')
      {
         var textElement = document.getElementById(errorTextId);
         textElement.firstChild.nodeValue = "Field must only be 'a' to 'z'.";
         return false;
      }
   }

   var textElement = document.getElementById(errorTextId);
   textElement.firstChild.nodeValue = blankText;
   
   return true;
}

function valPassword(field, compare, errorTextId, required)
{
   // Don't try to do any more on non-java enabled systems
   if (!supportsJava())
      return true;

   /* Get text, if it's blank and not required, stop. */
   var fieldText = field.value;
   if (fieldText == "" && !required)
      return true;

   var compareText = compare.value;

   // Run basic checks
   if (!valBasic(field, errorTextId))
      return false;

   if (fieldText != compareText)
   {
      var textElement = document.getElementById(errorTextId);
      textElement.firstChild.nodeValue = "Password fields do not match.";
      return false;
   }
   
   var textElement = document.getElementById(errorTextId);
   textElement.firstChild.nodeValue = blankText;

   return true;
}

function valEmail(field, errorTextId, required)
{
   // Don't try to do any more on non-java enabled systems
   if (!supportsJava())
      return true;

   /* Get text, if it's blank and not required, stop. */
   var fieldText = field.value;
   if (fieldText == "" && !required)
   {
      var textElement = document.getElementById(errorTextId);
      textElement.firstChild.nodeValue = blankText;
      return true;
   }

   // Run basic checks
   if (!valBasic(field, errorTextId))
      return false;

   var foundAt = false, foundDot = false, valid = true, i = 0;
   for (i = 0; i < fieldText.length; i++)
   {
      if (fieldText.charAt(i) == '@')
      {
         if (foundAt)
         {
            valid = false;
            break;
         }
         foundAt = true;
      }
      if (fieldText.charAt(i) == '.')
         foundDot = true;
   }
   
   if (!valid || !foundAt || !foundDot)
   {
      var textElement = document.getElementById(errorTextId);
      textElement.firstChild.nodeValue = "Must be of the form '[user]@[domain].[type]'";
      return false;
   }

   var textElement = document.getElementById(errorTextId);
   textElement.firstChild.nodeValue = blankText;
      
   return true;
}