var currentPage = 0;
var page = new Array();
var startPage = document.location.hash?document.location.hash.substring(1):'';

function isNumber(s) {
  return s>'9' ? false : (s<'0' ? false : true);
}

function stripNumbers(s) {
  while (isNumber(s.charAt(s.length-1)))
    s = s.substring(0,s.length-1);
  return s;
}

function hideShow(i,j) {
  hideObject(page[i]);
  showObject(page[j]);
  hideObject('navIndicator'+stripNumbers(page[i]));
  showObject('navIndicator'+stripNumbers(page[j]));
  if (j<=0)
    hideObject('prevID')
  else showObject('prevID');
  if (j>=page.length-1)
    hideObject('nextID')
  else showObject('nextID');
}

function showNext() {
  if (currentPage<page.length-1) {
    hideShow(currentPage,++currentPage);
    return true;
  }
  else return false;
}

function showPrevious() {
  if (currentPage>0) {
    hideShow(currentPage,--currentPage);
    return true;
  }
  else return false;
}

function getPageIndex(pageName) {
  for (n=0; n<page.length; n++)
    if (page[n]==pageName)
      return n;
  return -1;
}

function addPage(pageName) {
  page[page.length] = pageName;
  if (pageName==startPage)
    currentPage = page.length-1;
}

function showCurrentPage() {
  hideShow(currentPage, currentPage);
}

function goTo(pageName) {
  n=getPageIndex(pageName)
  if (n>=0)
    hideShow(currentPage, currentPage=n)
}