/**
* 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: "Précédent",
                next_text: "Suivant",
                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
                opts.callback(current_page, this);
        });
}