/* Derived from http://www.kryogenix.org/code/browser/searchhi/ */

// Loop through referrer search keywords
function googleSearchHighlight() {
  var i, w, ref, qs, qsa, qsip, words;
  var contentBlock = "maincontent";

  if (!document.createElement) return;
  ref = document.referrer;
  if (ref.indexOf('?') == -1) return;
  qs = ref.substr(ref.indexOf('?') + 1);
  qsa = qs.split('&');
  for (i = 0; i < qsa.length; i++) {
    qsip = qsa[i].split('=');
    if (qsip.length == 1) continue;
    if (qsip[0] == 'q' || qsip[0] == 'p') { // q= for Google, p= for Yahoo
      words = unescape(qsip[1].replace(/\+/g,' ')).split(/\s+/);
      for (w = 0; w < words.length; w++) {
        highlightWord(document.getElementById(contentBlock), words[w], w);
      }
    }
  }
}

// Apply highlighting to search keywords
function highlightWord(node,word,word_cn) {
  var hi_cn, tempNodeVal, tempWordVal, re, pn, nv, ni;
  var str, before, after, docWordVal, hiwordtext, hiword;
  var wholeWord = true;

  // Iterate into this nodes childNodes
  if (node.hasChildNodes) {
    for (hi_cn = 0; hi_cn < node.childNodes.length; hi_cn++) {
      highlightWord(node.childNodes[hi_cn], word, word_cn);
    }
  }

  // And do this node itself
  if (node.nodeType == 3) { // text node
    tempNodeVal = node.nodeValue.toLowerCase();
    tempWordVal = word.toLowerCase();
    str = (wholeWord) ? tempWordVal + '[^a-z]' : tempWordVal;
    re = new RegExp(str);
    if (tempNodeVal.search(re) != -1) {
      pn = node.parentNode;
      if (pn.className.indexOf("searchword") == -1) {
        // word has not already been highlighted!
        nv = node.nodeValue;
        ni = tempNodeVal.indexOf(tempWordVal);
        // Create a load of replacement nodes
        before = document.createTextNode(nv.substr(0, ni));
        docWordVal = nv.substr(ni, word.length);
        after = document.createTextNode(nv.substr(ni + word.length));
        hiwordtext = document.createTextNode(docWordVal);
        hiword = document.createElement("span");
        hiword.className = "searchword" + (word_cn + 1);
        hiword.appendChild(hiwordtext);
        pn.insertBefore(before, node);
        pn.insertBefore(hiword, node);
        pn.insertBefore(after, node);
        pn.removeChild(node);
      }
    }
  }
}