/*
* jquery pager plugin
* version 1.0 (12/22/2008)
* @requires jquery v1.2.6 or later
*
* example at: http://jonpauldavies.github.com/jquery/pager/pagerdemo.html
*
* copyright (c) 2008-2009 jon paul davies
* dual licensed under the mit and gpl licenses:
* http://www.opensource.org/licenses/mit-license.php
* http://www.gnu.org/licenses/gpl.html
* 
* read the related blog post and contact the author at http://www.j-dee.com/2008/12/22/jquery-pager-plugin/
*
* this version is far from perfect and doesn't manage it's own state, therefore contributions are more than welcome!
*
* usage: .pager({ pagenumber: 1, pagecount: 15, buttonclickcallback: pagerclicktest });
*
* where pagenumber is the visible page number
*       pagecount is the total number of pages to display
*       buttonclickcallback is the method to fire when a pager button is clicked.
*
* buttonclickcallback signiture is pagerclicktest = function(pageclickednumber) 
* where pageclickednumber is the number of the page clicked in the control.
*
* the included pager.css file is a dependancy but can obviously tweaked to your wishes
* tested in ie6 ie7 firefox & safari. any browser strangeness, please report.
*/
(function ($) {

    $.fn.pager = function (options) {

        var opts = $.extend({}, $.fn.pager.defaults, options);

        return this.each(function () {

            // 空出的目标元素，然后渲染器提供的选项
            $(this).empty().append(renderpager(parseint(options.pagenumber), parseint(options.pagecount), options.buttonclickcallback));

            // specify correct cursor activity
        });
    };

    //渲染和返回器提供的选项
    function renderpager(pagenumber, pagecount, buttonclickcallback) {

        // setup $pager to hold render
        var $pager = $('<ul class="pages"></ul>');

        // add in the previous and next buttons
        $pager.append(renderbutton('首页', pagenumber, pagecount, buttonclickcallback)).append(renderbutton('<', pagenumber, pagecount, buttonclickcallback));

        // pager currently only handles 10 viewable pages ( could be easily parameterized, maybe in next version ) so handle edge cases
        var startpoint = 1;
        var endpoint = 10;


        if (pagenumber > 5 && pagenumber < 95) {
            startpoint = pagenumber - 4;
            endpoint = pagenumber + 5;
            if (endpoint > pagecount) {
                startpoint = pagecount - 9;
                endpoint = pagecount;
            }
        } else if (pagenumber >= 95 && pagenumber < 1000) {
            startpoint = pagenumber - 3;
            endpoint = pagenumber + 4;
            if (endpoint > pagecount) {
                startpoint = pagecount - 4;
                endpoint = pagecount;
            }
        } else if (pagenumber >= 1000 && pagenumber < 10000) {
            startpoint = pagenumber - 3;
            endpoint = pagenumber + 3;
            if (endpoint > pagecount) {
                startpoint = pagecount - 3;
                endpoint = pagecount;
            }
        }
        else if (pagenumber >= 10000) {
            startpoint = pagenumber - 2;
            endpoint = pagenumber + 2;
            if (endpoint > pagecount) {
                startpoint = pagecount - 2;
                endpoint = pagecount;
            }
        }
        else {
            if (endpoint > pagecount) {
                endpoint = pagecount;
            }
        }

        if (startpoint < 1) {
            startpoint = 1;
        }

        // loop thru visible pages and render buttons
        for (var page = startpoint; page <= endpoint; page++) {

            var currentbutton = $('<li class="page-number">' + (page) + '</li>');

            page == pagenumber ? currentbutton.addclass('pgcurrent') : currentbutton.click(function () { buttonclickcallback(this.firstchild.data); });
            currentbutton.appendto($pager);
        }

        // render in the next and last buttons before returning the whole rendered control back.
        $pager.append(renderbutton('>', pagenumber, pagecount, buttonclickcallback)).append(renderbutton('尾页', pagenumber, pagecount, buttonclickcallback));
        $pager.append("<li> 共" + pagecount + "页</li>");
        var jumnumber;
        if (pagenumber < 1) {
            jumnumber = 1;
        } else if (pagenumber >= pagecount) {
            jumnumber = pagecount;
        }
        else {
            jumnumber = pagenumber + 1;
        }
        $pager.append("<li style='width:85px'> 到第<input type='text\'  value='" + jumnumber + "' size='3' id='jumpto' name='jumpto' title='指定页码' style='width: 30px;margin: 0 5px;  text-align: center;'>页</li>");

        var pagego = $('<li> <input name="" type="image" src="/images/buttonpageno.jpg" style="margin-top: 3px; border:0" /></li>');
        pagego.click(function () {

            var pageon = $("#jumpto").val();

            //定义正则表达式部分 
            var reg = /^\d+$/;
            var re = pageon.match(reg);
            if (re == null) {
                alert("跳转页数只能为数字!");
                $("#jumpto").val(1);
            }
            else {
                if (re < 1) {
                    re = 1;
                }
                else if (re > pagecount) {
                    re = pagecount;
                }
                buttonclickcallback(re);
            }

        });
        pagego.appendto($pager);
        return $pager;
    }

    // renders and returns a 'specialized' button, ie 'next', 'previous' etc. rather than a page number button
    function renderbutton(buttonlabel, pagenumber, pagecount, buttonclickcallback) {

        var $button = $('<li class="pgnext">' + buttonlabel + '</li>');

        var destpage = 1;

        // work out destination page for required button type
        switch (buttonlabel) {
            case "首页":
                destpage = 1;
                break;
            case "<":
                destpage = pagenumber - 1;
                break;
            case ">":
                destpage = pagenumber + 1;
                break;
            case "尾页":
                destpage = pagecount;
                break;
        }

        // disable and 'grey' out buttons if not needed.
        if (buttonlabel == "首页" || buttonlabel == "<") {
            pagenumber <= 1 ? $button.addclass('pgempty') : $button.click(function () { buttonclickcallback(destpage); });
        }
        else {
            pagenumber >= pagecount ? $button.addclass('pgempty') : $button.click(function () { buttonclickcallback(destpage); });
        }

        return $button;
    }

    // pager defaults. hardly worth bothering with in this case but used as placeholder for expansion in the next version
    $.fn.pager.defaults = {
        pagenumber: 1,
        pagecount: 1
    };

})(jquery);