/**
 * 功能：页码切换
 * 作者：wjb
 * 时间：2019-11-25
 */
  function pagination($content, $wrap, options) {
        this.$wrap = $wrap;
        this.$content = $content;
        this.options = $.extend({}, pagination.defaultoptions, options);
        this.init();
    }
    pagination.defaultoptions = {
        size: 4
    };
    pagination.prototype.init = function () {
		console.log(this.$content);
        var totalitemnum = this.$content.children().length;
        var totalpagenum = this.totalpagenum = math.ceil(totalitemnum / this.options.size);
		
        this.currentpage = 1;
        this.$wrap.empty();
        this.$content.children(':gt(' + (this.options.size - 1) + ')').hide();
        this.$wrap.append([
            '<span class="page_box">',
            '<a class="prev">上一页</a>',
            '<span class="num">',
            '</span>',
            '<a class="next">下一页</a>',
            '</span>'
        ].join(''));
        for (var i = 0; i < totalpagenum; i++) {
            var $btn = $('<span class="page-item">' + (i + 1) + '</span>');
            $btn.data('page', i + 1);
            this.$wrap.find('.num').append($btn);
        }
        this.$wrap.find('.num').children().eq(0).addclass('current');
        this.initevents();
    };
    pagination.prototype.initevents = function () {
        var _this = this;
        var $prev = this.$wrap.find('.prev');
        var $next = this.$wrap.find('.next');
        var $num = this.$wrap.find('.num');

        $prev.on('click', function () {
            _this.prev();
        });
        $next.on('click', function () {
            _this.next();
        });
        $num.on('click', '.page-item', function () {
            var page = $(this).data('page');
            _this.goto(page);
        });
    };
    pagination.prototype.prev = function () {
        this.goto(this.currentpage - 1);
    };
    pagination.prototype.next = function () {
        this.goto(this.currentpage + 1);
    };
    pagination.prototype.goto = function (num) {
        if (typeof num !== 'number') {
            throw new error('e');
        }
        if(num > this.totalpagenum || num <= 0) {
            return false;
        }

        this.currentpage = num;

        this.$wrap.find('.num')
            .children().eq(this.currentpage - 1)
            .addclass('current').siblings('.current')
            .removeclass('current');

        var left = (this.currentpage - 1) * this.options.size;
        var right = left + this.options.size;

        var $shouldshow = this.$content.children().filter(function (index) {
            return left <= index && index < right;
        });
        this.$content.children().hide();
        $shouldshow.show();
    };