/*
 * @Author: your name
 * @Date: 2021-07-02 17:15:50
 * @LastEditTime: 2021-07-04 18:10:34
 * @LastEditors: Please set LastEditors
 * @Description: In User Settings Edit
 * @FilePath: /xiaomai-cloud-class-web/src/core/downLoad.js
 */
window.download = function download(data, strFileName, strMimeType) {
  var self = window, // this script is only for browsers anyway...
    defaultMime = 'application/octet-stream', // this default mime also triggers iframe downloads
    mimeType = strMimeType || defaultMime,
    payload = data,
    url = !strFileName && !strMimeType && payload,
    anchor = document.createElement('a'),
    toString = function (a) {
      return String(a);
    },
    myBlob = self.Blob || self.MozBlob || self.WebKitBlob || toString,
    fileName = strFileName || 'download',
    blob,
    reader;
  myBlob = myBlob.call ? myBlob.bind(self) : Blob;

  if (String(this) === 'true') {
    //reverse arguments, allowing download.bind(true, "text/xml", "export.xml") to act as a callback
    payload = [payload, mimeType];
    mimeType = payload[0];
    payload = payload[1];
  }

  if (url && url.length < 2048) {
    // if no filename and no mime, assume a url was passed as the only argument
    fileName = url.split('/').pop().split('?')[0];
    anchor.href = url; // assign href prop to temp anchor
    if (anchor.href.indexOf(url) !== -1) {
      // if the browser determines that it's a potentially valid url path:
      var ajax = new XMLHttpRequest();
      ajax.open('GET', url, true);
      ajax.responseType = 'blob';
      ajax.onload = function (e) {
        download(e.target.response, fileName, defaultMime);
      };
      setTimeout(function () {
        ajax.send();
      }, 0); // allows setting custom ajax headers using the return:
      return ajax;
    } // end if valid url?
  } // end if url?

  //go ahead and download dataURLs right away
  if (/^data\:[\w+\-]+\/[\w+\-]+[,;]/.test(payload)) {
    if (payload.length > 1024 * 1024 * 1.999 && myBlob !== toString) {
      payload = dataUrlToBlob(payload);
      mimeType = payload.type || defaultMime;
    } else {
      return navigator.msSaveBlob // IE10 can't do a[download], only Blobs:
        ? navigator.msSaveBlob(dataUrlToBlob(payload), fileName)
        : saver(payload); // everyone else can save dataURLs un-processed
    }
  } //end if dataURL passed?

  blob = payload instanceof myBlob ? payload : new myBlob([payload], { type: mimeType });

  function dataUrlToBlob(strUrl) {
    var parts = strUrl.split(/[:;,]/),
      type = parts[1],
      decoder = parts[2] == 'base64' ? atob : decodeURIComponent,
      binData = decoder(parts.pop()),
      mx = binData.length,
      i = 0,
      uiArr = new Uint8Array(mx);

    for (i; i < mx; ++i) uiArr[i] = binData.charCodeAt(i);

    return new myBlob([uiArr], { type: type });
  }

  function saver(url, winMode) {
    if ('download' in anchor) {
      //html5 A[download]
      anchor.href = url;
      anchor.setAttribute('download', fileName);
      anchor.className = 'download-js-link';
      anchor.innerHTML = 'downloading...';
      anchor.style.display = 'none';
      document.body.appendChild(anchor);
      setTimeout(function () {
        anchor.click();
        document.body.removeChild(anchor);
        if (winMode === true) {
          setTimeout(function () {
            self.URL.revokeObjectURL(anchor.href);
          }, 250);
        }
      }, 66);
      return true;
    }

    // handle non-a[download] safari as best we can:
    if (/(Version)\/(\d+)\.(\d+)(?:\.(\d+))?.*Safari\//.test(navigator.userAgent)) {
      url = url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
      if (!window.open(url)) {
        // popup blocked, offer direct download:
        if (window.confirm('Displaying New Document\n\nUse Save As... to download, then click back to return to this page.')) {
          window.location.href = url;
        }
      }
      return true;
    }

    //do iframe dataURL download (old ch+FF):
    var f = document.createElement('iframe');
    document.body.appendChild(f);

    if (!winMode) {
      // force a mime that will download:
      url = 'data:' + url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
    }
    f.src = url;
    setTimeout(function () {
      document.body.removeChild(f);
    }, 333);
  } //end saver

  if (navigator.msSaveBlob) {
    // IE10+ : (has Blob, but not a[download] or URL)
    return navigator.msSaveBlob(blob, fileName);
  }

  if (self.URL) {
    // simple fast and modern way using Blob and URL:
    saver(self.URL.createObjectURL(blob), true);
  } else {
    // handle non-Blob()+non-URL browsers:
    if (typeof blob === 'string' || blob.constructor === toString) {
      try {
        return saver('data:' + mimeType + ';base64,' + self.btoa(blob));
      } catch (y) {
        return saver('data:' + mimeType + ',' + encodeURIComponent(blob));
      }
    }

    // Blob but not URL support:
    reader = new FileReader();
    reader.onload = function (e) {
      saver(this.result);
    };
    reader.readAsDataURL(blob);
  }
  return true;
}; /* end download() */
 