(function ($) {
    /**
     *设置元素的fixed或者static的触发
     *
     * @author ******@tuniu.com
     * @private sticky
     * @param {Object} options
     */
    $.fn.sticky = function (options) {
        var isFixed  = false; //是否是固定位置
        var self     = this;
        var defaults = {
            y: 0 // 元素固定位置时距顶部的距离
        };

        this.settings = $.extend(defaults, options);
        this.offsetY  = $(this).offset().top - this.settings.y; //元素固定距离状态触发时，body的scrollTop()

        $(window).scroll(function () {
            var scrollTop = $(window).scrollTop();
            if (!isFixed && scrollTop > self.offsetY) {
                $(self).css({
                    position: 'fixed',
                    left: 0,
                    top: self.settings.y
                });
                isFixed = true;
            } else if (isFixed && scrollTop <= self.offsetY) {
                $(self).css({
                    position: 'static'
                });
                isFixed = false;
            }
        });
    };

    /**
     *a标签点击后到达另外一个元素的位置的动画
     *
     * @author ******@tuniu.com
     * @private {Method} positionScroll
     * @param {Object} options //到达另外一个位置时距顶部的距离
     */
    $.fn.positionScroll = function (options) {
        var defaults = { flag: 0 };
        var items    = $(this).find('a');
        var opt      = $.extend(defaults, options);

        items.bind('click', function (e) {
            if (!$(this).data('to')) return false;
            $('html,body').animate({
                scrollTop: $($(this).data('to')).offset()
                    .top - opt.flag
            }, 500);
            e.preventDefault();
        });
    };

    /**
    * 弹出对话框
    *
    * @param option {Object} 弹出的对话框的设置
    *
    */
    $.dialog = function(option) {
        var defaults = {
            id: 'dialog' + (+new Date()),
            title: '',
            content: '',
            showClose: true,
            opacity: 60,
            zIndex: 9999
        };
        var closeHtml = '';
        var element = null;
        var bodyHeight = $('body').height();
        var settings = $.extend(defaults, option);


        function setLayer() {
            var scrollTop = $(window).scrollTop();
            var scrollLeft = $(window).scrollLeft();
            var gutterW = $(window).width() - element.outerWidth();
            var gutterH = $(window).height() - element.outerHeight();

            if(gutterH <= 0) {
                gutterH = 30;
            }

            element.css({
                left: gutterW / 2 + scrollLeft,
                top : gutterH / 2 + scrollTop
            });
        };

        settings.showClose && (closeHtml += '<a href="javascript:void(0);" class="closeDialog">脳</a>');

        $('body').append(
            '<div class="dialog-window" id="'+ settings.id +'" style="z-index: '+ (settings.zIndex + 1) +';">'
                +'<div class="dialog-header"><h3>'+ settings.title +'</h3>'+ closeHtml +'</div>'
                +'<div class="dialog-content">'+ settings.content +'</div>'
                +'</div>'
            +'<div class="mask" style="height: '+ bodyHeight +'px; z-index: '+ settings.zIndex +'; opacity: '+ (settings.opacity / 100) +'; filter: alpha(opacity='+ settings.opacity +');"></div>'
        );

        element = $('#' + settings.id);
        setLayer();

        $(window).on('resize', setLayer);

        element.find('.closeDialog').on('click', function() {
            element.next('.mask').remove();
            element.remove();
        });
    };
})(jQuery);

.mask {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    background-color: #000
}
.dialog-window {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 648px;
    border: 1px solid #3f0f9a;
    border-radius: 10px;
    background: #fff
}

.dialog-window .dialog-header {
    position: relative;
    height: 40px
}

.dialog-window .dialog-header h3 {
    position: absolute;
    top: 18px;
    left: -9px;
    width: 118px;
    border-radius: 15px;
    background: #ec374f;
    color: #fff;
    text-align: center;
    font-weight: 600;
    font-size: 18px;
    line-height: 30px
}

.dialog-window .dialog-content {
    padding: 20px;
    line-height: 20px
}

.dialog-window .dialog-content p {
    margin: 0 0 5px
}

.closeDialog {
    position: absolute;
    top: -15px;
    right: -15px;
    width: 30px;
    height: 30px;
    border-radius: 100%;
    background: #232323;
    color: #fff;
    text-align: center;
    font-weight: 600;
    font-size: 18px;
    font-family: sisum;
    line-height: 30px;
    transition: background-color .5s
}

.closeDialog:hover {
    background-color: #111;
    color: #fff
}