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Tsinghua E-Reserves Lib Downloader

Download PDF from Tsinghua University Electronic Course Reserves Service Platform

  1. // ==UserScript==
  2. // @name         Tsinghua E-Reserves Lib Downloader
  3. // @namespace    anyi.fan
  4. // @version      0.2.2
  5. // @license      GPL-3.0 License
  6. // @description  Download PDF from Tsinghua University Electronic Course Reserves Service Platform
  7. // @author       A1phaN
  8. // @match        https://ereserves.lib.tsinghua.edu.cn/readkernel/ReadJPG/JPGJsNetPage/*
  9. // @grant        none
  10. // ==/UserScript==
  11.  
  12. const MAX_RETRY = 10;
  13. const QUERY_INTERVAL = 100;
  14.  
  15. const sleep = time => new Promise(res => setTimeout(res, time));
  16. const getImage = async (url, retry = MAX_RETRY) => {
  17.   const img = new Image();
  18.   img.src = url;
  19.   img.style.display = 'none';
  20.   const data = new Promise((res, rej) => {
  21.     img.onload = () => {
  22.       const canvas = document.createElement('canvas');
  23.       canvas.width = img.width;
  24.       canvas.height = img.height;
  25.       canvas.getContext('2d')?.drawImage(img, 0, 0, img.width, img.height);
  26.       res([img, canvas.toDataURL('image/jpeg')]);
  27.     };
  28.     img.onerror = err => {
  29.       retry > 0 ? res(getImage(url, retry - 1)) : rej(err);
  30.     };
  31.   });
  32.   document.body.appendChild(img);
  33.   return data;
  34. };
  35.  
  36. (async () => {
  37.   const scanId = document.querySelector('#scanid')?.value;
  38.   const bookId = location.href.split('/').at(-1);
  39.   const bookNameElement = document.querySelector('#p_bookname');
  40.   const bookName = bookNameElement.innerText;
  41.   const BotuReadKernel = document.cookie.split(';')
  42.     .map(c => c.trim())
  43.     .find(c => c.startsWith('BotuReadKernel='))
  44.     ?.split('=')[1];
  45.   if (!scanId || !BotuReadKernel || !bookName) return;
  46.  
  47.   await new Promise(res => {
  48.     if (window.jspdf) return res();
  49.     const script = document.createElement('script');
  50.     script.src = 'https://cdnjs.cloudflare.com/ajax/libs/jspdf/2.5.1/jspdf.umd.min.js';
  51.     script.onload = res;
  52.     document.body.appendChild(script);
  53.   });
  54.   if (!window.jspdf) return;
  55.  
  56.   const button = document.createElement('span');
  57.   button.className = 'fucBtn icon iconfont';
  58.   button.style = 'margin-left: 8px; position: relative; top: 2px;';
  59.   button.innerHTML =
  60.   `<svg
  61.     t="1703917701009"
  62.     viewBox="0 0 1024 1024"
  63.     version="1.1"
  64.     xmlns="http://www.w3.org/2000/svg"
  65.     p-id="5061"
  66.     height="2rem"
  67.   >
  68.     <path
  69.       d="M896 672c-17.066667 0-32 14.933333-32 32v128c0 6.4-4.266667 10.666667-10.666667 10.666667H170.666667c-6.4 0-10.666667-4.266667-10.666667-10.666667v-128c0-17.066667-14.933333-32-32-32s-32 14.933333-32 32v128c0 40.533333 34.133333 74.666667 74.666667 74.666667h682.666666c40.533333 0 74.666667-34.133333 74.666667-74.666667v-128c0-17.066667-14.933333-32-32-32z"
  70.       fill="#ddd"
  71.       p-id="5062"
  72.     ></path>
  73.     <path
  74.       d="M488.533333 727.466667c6.4 6.4 14.933333 8.533333 23.466667 8.533333s17.066667-2.133333 23.466667-8.533333l213.333333-213.333334c12.8-12.8 12.8-32 0-44.8-12.8-12.8-32-12.8-44.8 0l-157.866667 157.866667V170.666667c0-17.066667-14.933333-32-32-32s-34.133333 14.933333-34.133333 32v456.533333L322.133333 469.333333c-12.8-12.8-32-12.8-44.8 0-12.8 12.8-12.8 32 0 44.8l211.2 213.333334z"
  75.       fill="#ddd"
  76.       p-id="5063"
  77.     ></path>
  78.   </svg>`;
  79.   document.querySelector('.option-list').appendChild(button);
  80.  
  81.   const downloadPDF = async () => {
  82.     try {
  83.       button.onclick = null;
  84.       let doc = null;
  85.       let page = 1;
  86.       const chapters = await (
  87.         await fetch(
  88.           '/readkernel/KernelAPI/BookInfo/selectJgpBookChapters',
  89.           {
  90.             body: `SCANID=${scanId}`,
  91.             headers: {
  92.               Botureadkernel: BotuReadKernel,
  93.               'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8',
  94.             },
  95.             method: 'POST',
  96.           },
  97.         )
  98.       ).json();
  99.       if (chapters.code !== 1 || !Array.isArray(chapters.data)) {
  100.         alert('Get chapters data failed!');
  101.         return;
  102.       }
  103.  
  104.       for (let chap = 0; chap < chapters.data.length; ++chap) {
  105.         bookNameElement.innerText = `${bookName}（正在获取第 ${chap + 1} 章...）`;
  106.         const chapter = chapters.data[chap];
  107.         const chapterData = await (
  108.           await fetch(
  109.             '/readkernel/KernelAPI/BookInfo/selectJgpBookChapter',
  110.             {
  111.               body: `EMID=${chapter.EMID}&BOOKID=${bookId}`,
  112.               headers: {
  113.                 Botureadkernel: BotuReadKernel,
  114.                 'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8',
  115.               },
  116.               method: 'POST',
  117.             },
  118.           )
  119.         ).json();
  120.         if (chapterData.code !== 1 || !Array.isArray(chapterData.data.JGPS)) {
  121.           alert(`Get chapter ${chap + 1} ${chapter.EFRAGMENTNAME} data failed!`);
  122.           return;
  123.         }
  124.  
  125.         for (let i = 0; i < chapterData.data.JGPS.length; ++i) {
  126.           const jpg = chapterData.data.JGPS[i];
  127.           try {
  128.             const [img, dataURL] = await getImage(`/readkernel/JPGFile/DownJPGJsNetPage?filePath=${jpg.hfsKey}`);
  129.             if (!doc) {
  130.               doc = new jspdf.jsPDF({ format: [img.width, img.height], unit: 'px' });
  131.             } else {
  132.               doc.addPage([img.width, img.height]);
  133.             }
  134.             doc.addImage(dataURL, 'JPEG', 0, 0, img.width, img.height);
  135.             bookNameElement.innerText = `${bookName}（正在获取第 ${chap + 1} 章，已完成: ${i + 1} / ${chapterData.data.JGPS.length}）`;
  136.             await sleep(QUERY_INTERVAL);
  137.           } catch(e) {
  138.             alert(`Get page ${i + 1} of chapter ${chap + 1} ${chapter.EFRAGMENTNAME} failed!`);
  139.             return;
  140.           }
  141.         }
  142.         doc.outline.add(null, chapter.EFRAGMENTNAME, { pageNumber: page });
  143.         page += chapterData.data.JGPS.length;
  144.       }
  145.       if (doc) {
  146.         const filename = `${bookName}.pdf`;
  147.         try {
  148.           doc.save(filename);
  149.         } catch(e) {
  150.           if (e instanceof RangeError && e.message === 'Invalid string length') {
  151.             // jsPDF exceeds the maximum string length
  152.             doc.__private__.resetCustomOutputDestination();
  153.             const content = doc.__private__.out('');
  154.             content.pop();
  155.             const blob = new Blob(
  156.               content.map((line, idx) => {
  157.                 const str = idx === content.length - 1 ? line : line + '\n';
  158.                 const arrayBuffer = new ArrayBuffer(str.length);
  159.                 const uint8Array = new Uint8Array(arrayBuffer);
  160.                 for (let i = 0; i < str.length; ++i) {
  161.                   uint8Array[i] = str.charCodeAt(i);
  162.                 }
  163.                 return arrayBuffer;
  164.               }),
  165.               { type: 'application/pdf' },
  166.             );
  167.             const a = document.createElement('a');
  168.             a.download = filename;
  169.             a.rel = 'noopener';
  170.             a.href = URL.createObjectURL(blob);
  171.             a.click();
  172.           } else {
  173.             alert(`Unexpected Error when saving pdf: ${e?.message ?? e}`);
  174.           }
  175.         }
  176.       }
  177.       bookNameElement.innerText = `${bookName}（下载完成）`;
  178.     } finally {
  179.       button.onclick = downloadPDF;
  180.     }
  181.   };
  182.   button.onclick = downloadPDF;
  183. })();