// ==UserScript==
// @name        Bing Daily Pictures Download button|必应每日图片下载按钮
// @namespace   https://greasyfork.org/en/users/131965-levinit
// @author      levinit
// @description Add a button for downloading bing-daily-pictures.添加一个必应每日图片下载按钮。
// @include     *://cn.bing.com/
// @include     *://www.bing.com/
// @include     *://www.bing.com/?*
// @include     *://cn.bing.com/?*
// @run-at      document-start
// @version     0.1.1
// @grant       none
// @downloadURL none
// ==/UserScript==
window.onload = function() {
  // 从行内css属性background-image中获取今日必应图片的url()
  let picUrl = document.querySelector("#bgDiv").style.backgroundImage;

  //如果css属性background-image写在外部css或者style标签中
  if (picUrl === "") {
    let style0 = document.styleSheets[0];
    let styles = style0.cssRules.length;
    for (let i = 0; i < styles; i++) {
      if (style0.cssRules[i].selectorText === "#bgDiv") {
        picUrl = style0.cssRules[i].style.backgroundImage;
      }
    }
  }

  //今日必应图片的名称
  let picName = picUrl.substring(
    picUrl.lastIndexOf("/") + 1,
    picUrl.length - 2
  );

  //今日必应图片的url
  picUrl = picUrl.substring(5, picUrl.length - 2);

  //在必应首页添加下载按钮
  let btn = document.createElement("a");
  let text = null;
  if (navigator.language === "zh") {
    text = document.createTextNode("下载今日必应图片");
  } else {
    text = document.createTextNode("Download Today Bing Pictures");
  }
  btn.style.cssText =
    "display:inline-block;padding:0.25em;border-radius:0.25em;position:fixed;z-index:1000;right:20%;top:12%;background-color:#c3d1cf94;font-size: 1.5em;";
  btn.download = picName;
  btn.href = picUrl;
  btn.appendChild(text);
  document.body.appendChild(btn);
};