/*
 * This is the function that actually highlights a text string by
 * adding HTML tags before and after all occurrences of the search
 * term. You can pass your own tags if you'd like, or if the
 * highlightStartTag or highlightEndTag parameters are omitted or
 * are empty strings then the default <font> tags will be used.
 */
function doHighlight(bodyText, searchTerm) 
{
	var highlightStartTag = "<span class='highlight'>";
	var highlightEndTag = "</span>";
  
  // find all occurences of the search term in the given text,
  // and add some "highlight" tags to them (we're not using a
  // regular expression search, because we want to filter out
  // matches that occur within HTML tags and script blocks, so
  // we have to do a little extra validation)
  var newText = "";
  var i = -1;
  var lcSearchTerm = searchTerm.toLowerCase();
  var lcBodyText = bodyText.toLowerCase();
    
  while (bodyText.length > 0) 
  {
    i = lcBodyText.indexOf(lcSearchTerm, i+1);
    if (i < 0) 
    {
      newText += bodyText;
      bodyText = "";
    } 
    else 
    {
      // skip anything inside an HTML tag
      if (bodyText.lastIndexOf(">", i) >= bodyText.lastIndexOf("<", i))
      {
        // skip anything inside a <script> block
        if (lcBodyText.lastIndexOf("/script>", i) >= lcBodyText.lastIndexOf("<script", i)) 
        {
          newText += bodyText.substring(0, i) + highlightStartTag + bodyText.substr(i, searchTerm.length) + highlightEndTag;
          bodyText = bodyText.substr(i + searchTerm.length);
          lcBodyText = bodyText.toLowerCase();
          i = -1;
        }
      }
    }
  }
  
  return newText;
}


/*
 * This is sort of a wrapper function to the doHighlight function.
 * It takes the searchText that you pass, optionally splits it into
 * separate words, and transforms the text on the current web page.
 * Only the "searchText" parameter is required; all other parameters
 * are optional and can be omitted.
 */
function highlightSearchTerms(searchText, treatAsPhrase, elementToHighlight)
{
  // if the treatAsPhrase parameter is true, then we should search for 
  // the entire phrase that was entered; otherwise, we will split the
  // search string so that each word is searched for and highlighted
  // individually
  if (treatAsPhrase)
  {
    searchArray = [searchText];
  }
  else
  {
    searchArray = searchText.split(" ");
  }
  
	if (!elementToHighlight || typeof(elementToHighlight.innerHTML) == "undefined") 
		return false;
  
	var bodyText = elementToHighlight.innerHTML;
	var highlighted = false;
	for (var i = 0; i < searchArray.length; i++) 
	{
		if(searchArray[i].length > 0)
		{
			bodyText = doHighlight(bodyText, searchArray[i]);
			highlighted = true;
		}
	}
  
  if(highlighted)
		elementToHighlight.innerHTML = bodyText;
	return true;
}