var preview_tabs_order = false;

$(document).ready(function(){
  add_preview_click();

  select_preview_tab('#preview_cost_link');

  preview_tabs_order = ['cost', 'online', 'lesson', 'posters', 'videos', 'ecode', 'cost'];
  setTimeout(select_next_preview_tab, 5000);
});

function add_preview_click() {
  $('#preview_tabs a').click(function () {
          preview_tabs_order = false;
          select_preview_tab(this);
          return false;
      });
}

function select_preview_tab(tab) {
    $('.preview_content').hide();
    $('#preview_tabs li').removeClass();
    $(tab).parent().attr('class', 'selected');
    $('#' + $(tab).attr('id').slice(0, -5)).show();
}

function select_next_preview_tab() {
    if (preview_tabs_order) {
        var tab_name = $('#preview_tabs li.selected a').attr('id').slice(8, -5);

        for(var i = 0; i < preview_tabs_order.length; i++)
            if (tab_name == preview_tabs_order[i]) {
                select_preview_tab('#preview_' + preview_tabs_order[i+1] + '_link');
                break;
            }

        setTimeout(select_next_preview_tab, 5000);
    }
}