/**
* This jQuery plugin displays pagination links inside the selected elements.
*
* @author Gabriel Birke (birke *at* d-scribe *dot* de)
* @version 1.2
* @param {int} maxentries Number of entries to paginate
* @param {Object} opts Several options (see README for documentation)
* @return {Object} jQuery Object
*/
jQuery.fn.pagination = function(maxentries, opts) {
  opts = jQuery.extend({
    items_per_page: 10,
    num_display_entries: 10,
    current_page: 0,
    num_edge_entries: 0,
    link_to: "#",
    prev_text: "Prev",
    next_text: "Next",
    ellipse_text: "...",
    prev_show_always: true,
    next_show_always: true,
    callback: function() { return false; }
  }, opts || {});

  return this.each(function() {
    /**
    * Calculate the maximum number of pages
    */
    function numPages() {
      return Math.ceil(maxentries / opts.items_per_page);
    }

    /**
    * Calculate start and end point of pagination links depending on 
    * current_page and num_display_entries.
    * @return {Array}
    */
    function getInterval() {
      var ne_half = Math.ceil(opts.num_display_entries / 2);
      var np = numPages();
      var upper_limit = np - opts.num_display_entries;
      var start = current_page > ne_half ? Math.max(Math.min(current_page - ne_half, upper_limit), 0) : 0;
      var end = current_page > ne_half ? Math.min(current_page + ne_half, np) : Math.min(opts.num_display_entries, np);
      return [start, end];
    }

    /**
    * This is the event handling function for the pagination links. 
    * @param {int} page_id The new page number
    */
    function pageSelected(page_id, evt) {
      current_page = page_id;
      drawLinks();
      var continuePropagation = opts.callback(page_id, panel);
      if (!continuePropagation) {
        if (evt.stopPropagation) {
          evt.stopPropagation();
        }
        else {
          evt.cancelBubble = true;
        }
      }
      return continuePropagation;
    }

    /**
    * This function inserts the pagination links into the container element
    */
    function drawLinks() {
      panel.empty();
      var interval = getInterval();
      var np = numPages();
      // This helper function returns a handler function that calls pageSelected with the right page_id
      var getClickHandler = function(page_id) {
        return function(evt) { return pageSelected(page_id, evt); }
      }
      // Helper function for generating a single link (or a span tag if it's the current page)
      var appendItem = function(page_id, appendopts) {
        page_id = page_id < 0 ? 0 : (page_id < np ? page_id : np - 1); // Normalize page id to sane value
        appendopts = jQuery.extend({ text: page_id + 1, classes: "" }, appendopts || {});
        if (page_id == current_page) {
          var lnk = jQuery("<span class='current'>" + (appendopts.text) + "</span>");
        }
        else {
          var lnk = jQuery("<a>" + (appendopts.text) + "</a>")
						.bind("click", getClickHandler(page_id))
						.attr('href', opts.link_to.replace(/__id__/, page_id));


        }
        if (appendopts.classes) { lnk.addClass(appendopts.classes); }
        panel.append(lnk);
      }
      // Generate "Previous"-Link
      if (opts.prev_text && (current_page > 0 || opts.prev_show_always)) {
        appendItem(current_page - 1, { text: opts.prev_text, classes: "prev" });
      }
      // Generate starting points
      if (interval[0] > 0 && opts.num_edge_entries > 0) {
        var end = Math.min(opts.num_edge_entries, interval[0]);
        for (var i = 0; i < end; i++) {
          appendItem(i);
        }
        if (opts.num_edge_entries < interval[0] && opts.ellipse_text) {
          jQuery("<span>" + opts.ellipse_text + "</span>").appendTo(panel);
        }
      }
      // Generate interval links
      for (var i = interval[0]; i < interval[1]; i++) {
        appendItem(i);
      }
      // Generate ending points
      if (interval[1] < np && opts.num_edge_entries > 0) {
        if (np - opts.num_edge_entries > interval[1] && opts.ellipse_text) {
          jQuery("<span>" + opts.ellipse_text + "</span>").appendTo(panel);
        }
        var begin = Math.max(np - opts.num_edge_entries, interval[1]);
        for (var i = begin; i < np; i++) {
          appendItem(i);
        }

      }
      // Generate "Next"-Link
      if (opts.next_text && (current_page < np - 1 || opts.next_show_always)) {
        appendItem(current_page + 1, { text: opts.next_text, classes: "next" });
      }
    }

    // Extract current_page from options
    var current_page = opts.current_page;
    // Create a sane value for maxentries and items_per_page
    maxentries = (!maxentries || maxentries < 0) ? 1 : maxentries;
    opts.items_per_page = (!opts.items_per_page || opts.items_per_page < 0) ? 1 : opts.items_per_page;
    // Store DOM element for easy access from all inner functions
    var panel = jQuery(this);
    // Attach control functions to the DOM element 
    this.selectPage = function(page_id) { pageSelected(page_id); }
    this.prevPage = function() {
      if (current_page > 0) {
        pageSelected(current_page - 1);
        return true;
      }
      else {
        return false;
      }
    }
    this.nextPage = function() {
      if (current_page < numPages() - 1) {
        pageSelected(current_page + 1);
        return true;
      }
      else {
        return false;
      }
    }
    // When all initialisation is done, draw the links
    drawLinks();
    // call callback function


    /** COMMENT TO AVBOID THE SEARCH AFTER INITIALIZATION OF THE PLUGIN **/
    //opts.callback(current_page, this);
  });
}