var currentPage = 0;
var lastID = -1;

function ImageData(name, description, url) {
  this.name=name;
  this.description = description;
  this.url=url;
}

function SelectImg(id) {

  var topPic = currentPage * picsPerPage;

  if (lastID >= 0) {
    document.getElementById("image" + lastID).className = "thumbNormal";
  }
  var theMainImage = "images/" + image[id + topPic].name + ".jpg";
  document.getElementById("mainpic").src = theMainImage;
  document.getElementById("mainpiclink").href = image[id + topPic].url;
  lastID = id;
}

function LoadTrigger() {
  var set = getParameter("set");
  if (set == "") {
    set = 0;
  } else {
    set = parseInt(set);
  }
  LoadPage(set);
}

function LoadPage(page) {
  currentPage = page;
  var topPic = currentPage * picsPerPage;
  for (var x=0; x < picsPerPage; x++) {
    if (x + topPic < totalPics) {
      // This is a comment - uncomment this to display prompts to show picture names
      //alert("images/thumbs/' + image[x + topPic].name + '.jpg");
      document.getElementById("image" + x).innerHTML = '<img class="thumbNormal" onclick="SelectImg(' + x + ')" src="images/thumbs/' + image[x + topPic].name + '.jpg" />';
      document.getElementById("t" + x).innerHTML = image[x + topPic].description;
      if (image[x + topPic].url != "") {
        document.getElementById("more" + x).innerHTML = '<a class="textlink" href="' + image[x + topPic].url + '">more information...</a>';
      }
    } else {
      document.getElementById("image" + x).innerHTML = "";
      document.getElementById("t" + x).innerHTML = "";
      document.getElementById("more" + x).innerHTML = "";
    }
  }
      if (page > 0) {
          var previousPage = currentPage - 1;
          document.getElementById("previous").innerHTML = '<a href="?set=' + previousPage + '"><img src="graphics/previous.jpg"></a>';
      } else {
          document.getElementById("previous").innerHTML = '';
      }
      var nextPage = currentPage + 1;
      if (totalPics > nextPage * picsPerPage) {
          document.getElementById("next").innerHTML = '<a href="?set=' + nextPage + '"><img src="graphics/next.jpg"></a>';
      } else {
          document.getElementById("next").innerHTML = '';
      }
  
  SelectImg(0);
  
}

function getParameter( name )
{
  name = name.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
  var regexS = "[\\?&]"+name+"=([^&#]*)";
  var regex = new RegExp( regexS );
  var results = regex.exec( window.location.href );
  if( results == null )
    return "";
  else
    return results[1];
}

window.onload = LoadTrigger;