/**
* 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({
        paginationClass: "pagination",
        useShortPageNumbering: false,
        items_per_page: 10,
        num_display_entries: 10,
        current_page: 0,
        num_edge_entries: 0,
        link_to: "#",
        prev_text: "<< Previous",
        next_text: "Next >>",
        ellipse_text: "...",
        prev_show_always: true,
        next_show_always: true,
        callback: function () { return false; }
    }, opts || {});

    jQuery("." + opts.paginationClass).each(function () {
        //alert(this);
        return jQuery(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" });
                }
                if (!opts.useShortPageNumbering) {
                    // 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);
                        }
                    }
                }
                if (!opts.useShortPageNumbering) {
                    // Generate interval links
                    for (var i = interval[0]; i < interval[1]; i++) {
                        appendItem(i);
                    }
                }
                if (opts.useShortPageNumbering) {
                    //Generate mid point
                    if (opts.ellipse_text) {
                        jQuery("<span>" + (current_page + 1) + opts.ellipse_text + numPages() + "</span>").appendTo(panel);
                    }
                }
                if (!opts.useShortPageNumbering) {
                    // 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" });
                }
                jQuery("." + opts.paginationClass).each(function () {
                    if (jQuery(this).attr("id") != jQuery(panel).attr("id")) {
                        jQuery(this).html(jQuery(panel).clone(true));
                        //     alert(jQuery(this).attr("id"));
                    }
                });
            }

            // 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
            opts.callback(current_page, this);
        });
    });
}