var collapseDivs, collapseLinks;

function createDocumentStructure (tagName) {
  if (document.getElementsByTagName) {
    var elements = document.getElementsByTagName(tagName);
    collapseDivs = new Array(elements.length);
    collapseLinks = new Array(elements.length);
    for (var i = 0; i < elements.length; i++) {
      var element = elements[i];
      var siblingContainer;
      if (document.createElement && 
          (siblingContainer = document.createElement('div')) &&
          siblingContainer.style) 
      {
        var nextSibling = element.nextSibling;
        element.parentNode.insertBefore(siblingContainer, nextSibling);
        var nextElement = elements[i + 1];
        while (nextSibling != nextElement && nextSibling != null) {
          var toMove = nextSibling;
          nextSibling = nextSibling.nextSibling;
          siblingContainer.appendChild(toMove);
        }
        siblingContainer.style.display = 'none';
        
        collapseDivs[i] = siblingContainer;
        
        createCollapseLink(element, siblingContainer, i);
      }
      else {
        // no dynamic creation of elements possible
        return;
      }
    }
    createCollapseExpandAll(elements[0]);
  }
}

function createCollapseLink (element, siblingContainer, index) {
  var span;
  if (document.createElement && (span = document.createElement('span'))) {
    span.appendChild(document.createTextNode(String.fromCharCode(160)));
    var link = document.createElement('a');
    link.collapseDiv = siblingContainer;
    link.href = '#';
    link.appendChild(document.createTextNode('show'));
    link.onclick = collapseExpandLink;
    collapseLinks[index] = link;
    span.appendChild(link);
    element.appendChild(span);
  }
}

function collapseExpandLink (evt) {
  if (this.collapseDiv.style.display == '') {
    this.parentNode.parentNode.nextSibling.style.display = 'none';
    this.firstChild.nodeValue = 'show';
  }
  else {
    this.parentNode.parentNode.nextSibling.style.display = '';
    this.firstChild.nodeValue = 'hide';
  }

  if (evt && evt.preventDefault) {
    evt.preventDefault();
  }
  return false;
}