var userAgent = window.navigator.userAgent;
var browserVers = parseInt(userAgent.charAt(userAgent.indexOf("/")+1),10);

var selected = '';
var preloadFlag = false;

function newImage(arg) {
  if (document.images) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
  }
}

function findElement(n,ly) {
  if (browserVers < 4)
    return document[n];
  var curDoc = ly ? ly.document : document;
  var elem = curDoc[n];
  if (!elem) {
    for (var i=0;i<curDoc.layers.length;i++) {
      elem = findElement(n,curDoc.layers[i]);
      if (elem) return elem;
    }
  }
  return elem;
}

function show(item, parent) {
  var item = document.getElementById(item);
  var parent = document.getElementById(parent);
  item.style.visibility = 'visible';
  item.style.left = "200px";
  item.style.top = "200px";
}

function hide(item, parent) {
  var item = document.getElementById(item);
  var parent = document.getElementById(parent);
  item.style.visibility = 'hidden';
}

function findImage(x) {
  img = null;
  if (document.layers) {
    img = findElement(x,0);
  } else {
    img = document.images[x];
  }
  return img;
}

function changeImagesArray(array) {
  if (document.images && (preloadFlag == true)) {
    for (var i=0; i<array.length; i+=2) {
      img = findImage(array[i]);
      if (img) {
        img.src = array[i+1];
      }
    }
  }
}

function changeImage(x,y) {
  foo = newImage(y);
  img = findImage(x);
  if (img) {
    img.src = y;
  }
}

function changeImages() {
  changeImagesArray(changeImages.arguments);
}

function toggleImages() {
  for (var i=0; i<toggleImages.arguments.length; i+=2) {
    if (selected == toggleImages.arguments[i]) {
      changeImagesArray(toggleImages.arguments[i+1]);
    }
  }
}

function preloadImages(array) {
  if (document.images) {
    for (var i = 0; i < array.length; i += 1) {
      newImage(array[i]);
    }
    preloadFlag = true;
  }
}

var buttons = new Array(
  'Home',
      'images/Home.jpg',
      'images/Home-over.jpg',
      'images/Home-sel.jpg',
  'Studs',
      'images/Studs.jpg',
      'images/Studs-over.jpg',
      'images/Studs-sel.jpg',
  'Available',
      'images/Available.jpg',
      'images/Available-over.jpg',
      'images/Available-sel.jpg',
  'Kittens',
      'images/Kittens.jpg',
      'images/Kittens-over.jpg',
      'images/Kittens-sel.jpg',
  'Queens',
      'images/Queens.jpg',
      'images/Queens-over.jpg',
      'images/Queens-sel.jpg',
  'Mail',
      'images/Mail.jpg',
      'images/Mail-over.jpg',
      'images/Mail-sel.jpg'
);

var btn_current_selection = '';

function over(button) {
  var j;
  for (var i = 0; i < buttons.length; i += 4) {
    j = 1;
    if (button                == buttons[i]) { j = 2; }
    if (btn_current_selection == buttons[i]) { j = 3; }
    changeImage(buttons[i], buttons[i + j]);
  }
}

function select(button) {
  btn_current_selection = button;
  over('');
}

function preloadButtons() {
  for (var i = 0; i < buttons.length; i += 4) {
    newImage(buttons[i + 1]);
    newImage(buttons[i + 2]);
    newImage(buttons[i + 2]);
  }
}