// JavaScript Document
$(document).ready(function(){
 
 //how much items per page to show
 var show_per_page = 6; 
 //getting the amount of elements inside content div
 var number_of_items = $('#content').children().size();
 //calculate the number of pages we are going to have
 var number_of_pages = Math.ceil(number_of_items/show_per_page);
 
 //set the value of our hidden input fields
 $('#current_page').val(0);
 $('#show_per_page').val(show_per_page);
 
 //now when we got all we need for the navigation let's make it '
 
 /* 
 what are we going to have in the navigation?
  - link to previous page
  - links to specific pages
  - link to next page
 */
 var navigation_html = '<a class="previous_link" href="javascript:previous();">&nbsp;</a>';
 var current_link = 0;
 while(number_of_pages > current_link){
  navigation_html += '<a class="page_link" href="javascript:go_to_page(' + current_link +')" longdesc="' + current_link +'">'+ (current_link + 1) +'</a>';
  current_link++;
 }
 navigation_html += '<a class="next_link" href="javascript:next();">&nbsp;</a>';
 
 $('#page_navigation').html(navigation_html);
 
 
 //add active_page class to the first page link
 $('#page_navigation .page_link:first').addClass('active_page');
  
 //hide all the elements inside content div
 $('#content').children().css('display', 'none');
 
 //and show the first n (show_per_page) elements
 $('#content').children().slice(0, show_per_page).css('display', 'block');
 
});
 
function previous(){
 
 new_page = parseInt($('#current_page').val()) - 1;
 //if there is an item before the current active link run the function
 if($('.active_page').prev('.page_link').length==true){
  go_to_page(new_page);
 }
 
}
 
function next(){
 new_page = parseInt($('#current_page').val()) + 1;
 //if there is an item after the current active link run the function
 if($('.active_page').next('.page_link').length==true){
  go_to_page(new_page);
 }
 
}
function go_to_page(page_num){
 //get the number of items shown per page
 var show_per_page = parseInt($('#show_per_page').val());
 
 //get the element number where to start the slice from
 start_from = page_num * show_per_page;
 
 //get the element number where to end the slice
 end_on = start_from + show_per_page;
 
 //hide all children elements of content div, get specific items and show them
 $('#content').children().css('display', 'none').slice(start_from, end_on).css('display', 'block');
 
 /*get the page link that has longdesc attribute of the current page and add active_page class to it
 and remove that class from previously active page link*/
 $('.page_link[longdesc=' + page_num +']').addClass('active_page').siblings('.active_page').removeClass('active_page');
 
 //update the current page input field
 $('#current_page').val(page_num);
}