function getImages(target) {

    var photoSwipeBox = '<div class="pswp" tabindex="-1" role="dialog" aria-hidden="true">' +
        '      <div class="pswp__bg"></div>' +
        '      <div class="pswp__scroll-wrap">' +
        '        <div class="pswp__container">' +
        '          <div class="pswp__item"></div>' +
        '          <div class="pswp__item"></div>' +
        '          <div class="pswp__item"></div>' +
        '        </div>' +
        '        <div class="pswp__ui pswp__ui--hidden">' +
        '          <div class="pswp__top-bar">' +
        '            <div class="pswp__counter"></div>' +
        '            <button class="pswp__button pswp__button--close" title="关闭"></button>' +
        '            <button class="pswp__button pswp__button--download" title="下载原图" ></button>' +
        '           <button class="pswp__button pswp__button--zoom" title="缩放"></button>' +
        '            <div class="pswp__preloader">' +
        '              <div class="pswp__preloader__icn">' +
        '                <div class="pswp__preloader__cut">' +
        '                  <div class="pswp__preloader__donut"></div>' +
        '                </div>' +
        '              </div>' +
        '            </div>' +
        '          </div>' +
        '          <button' +
        '            class="pswp__button pswp__button--arrow--left"' +
        '            title="上一张"' +
        '          ></button>' +
        '          <button' +
        '            class="pswp__button pswp__button--arrow--right"' +
        '            title="下一张"' +
        '          ></button>' +
        '          <div class="pswp__caption">' +
        '            <div class="pswp__caption__center"></div>' +
        '          </div>' +
        '        </div>' +
        '      </div>' +
        '    </div>'
    var photoSwipeBoxDiv = document.createElement('div');
    photoSwipeBoxDiv.innerHTML = photoSwipeBox;
    document.body.appendChild(photoSwipeBoxDiv);
    
    var imgs = [];
    var currentIndex = 0

    var targetEle = document.querySelector(target);
    if(!targetEle) {
        var iframeList = document.querySelectorAll('iframe')
        for(var i =0; i < iframeList.length; i++) {
             if(iframeList[i].contentWindow.document.querySelector(target)) {
                 targetEle = iframeList[i].contentWindow.document.querySelector(target);
                 break;
             }
        }
    }
    var images = targetEle.querySelectorAll('img');
    var imgIndex = 0;
    for(var index =0; index < images.length; index++) {
        var img = images[index];
        var orisrc = img.getAttribute('orisrc')
        if(orisrc && (orisrc.indexOf("virtual_attach_file.vsb") > -1 || orisrc.indexOf("virtual_resource_file.jsp") > -1)) {
            imgs.push({
                src: orisrc,
                w: img.naturalWidth,
                h: img.naturalHeight
            });
            img.setAttribute('index',imgIndex);
            img.addEventListener('click', function (e) {
                currentIndex =  this.getAttribute('index') * 1;
                previewImage();
            });
            imgIndex++;
        }
    }

    var gallery = null;
    function previewImage() {
        if(isIE()) {
            var imgURL = imgs[currentIndex].src
            window.open(imgURL,'_blank');
        }else {
            var pswpElement = document.querySelectorAll('.pswp')[0];
            // index 当前图片的下标 timeToIdle 鼠标悬浮多久后，隐藏界面上的按钮，设置为0，则不隐藏
            gallery = new PhotoSwipe( pswpElement, PhotoSwipeUI_Default, imgs, {index:currentIndex, timeToIdle: 0});
            gallery.init()
        }
    }

    var downloadBtn = document.querySelector('.pswp__button--download')
    downloadBtn.addEventListener('click', function () {
        if(isWeChatWorkBrowser()) {
            window.alert("可在浏览器打开此网页来下载文件")
        }else {
            var imgsrc = gallery.currItem.src
            var fileSuffix = getQueryParam(imgsrc, 'e') || ""
            let filename = new Date().getTime() + fileSuffix
            if (navigator.msSaveBlob) {
                var xhr = new XMLHttpRequest();
                xhr.open('GET', imgsrc, true);
                xhr.responseType = 'blob';
                xhr.onload = function () {
                    if (xhr.status === 200) {
                        navigator.msSaveBlob(xhr.response, filename);
                    }
                };
                xhr.send();
            } else {
                var a = document.createElement('a')
                a.href = imgsrc
                a.download = filename
                a.click()
            }
        }
    })

    function getQueryParam(url, paramName) {
        var paramRegex = new RegExp('[?&]' + paramName + '=([^&#]*)');
        var match = paramRegex.exec(url);
        return match ? decodeURIComponent(match[1]) : null;
    }

    function isIE() {
        var userAgent = navigator.userAgent;
        var isIE = userAgent.indexOf('MSIE') > -1 || userAgent.indexOf('Trident/') > -1;
        var is360 = userAgent.indexOf('360EE') > -1 || userAgent.indexOf('360SE') > -1;
        return isIE || is360;
    }

    // 企业微信提示：可在浏览器打开此网页来下载文件
    function isWeChatWorkBrowser() {
        const userAgent = navigator.userAgent;
        return userAgent.indexOf("wxwork") > -1;
    }

}