ComipoDownloader

Manga downloader for comipo.app
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// ==UserScript==
// @name         ComipoDownloader
// @namespace    https://github.com/Timesient/manga-download-scripts
// @version      0.2
// @license      GPL-3.0
// @author       Timesient
// @description  Manga downloader for comipo.app
// @icon         https://www.comipo.app/static/images/common/favicon.ico
// @homepageURL  https://greasyfork.org/scripts/547218-comipodownloader
// @supportURL   https://github.com/Timesient/manga-download-scripts/issues
// @match        https://play.comipo.app/*
// @require      https://unpkg.com/[email protected]/dist/axios.min.js
// @require      https://unpkg.com/[email protected]/dist/jszip.min.js
// @require      https://unpkg.com/[email protected]/dist/FileSaver.min.js
// @require      https://update.greasyfork.org/scripts/451810/1398192/ImageDownloaderLib.js
// @grant        GM_info
// @grant        GM_xmlhttpRequest
// ==/UserScript==

(async function(axios, JSZip, saveAs, ImageDownloader) {
  'use strict';

  // reload page when enter or leave chapter
  const re = /https:\/\/play\.comipo\.app\/.*viewer.*/;
  const oldHref = window.location.href;
  const timer = setInterval(() => {
    const newHref = window.location.href;
    if (newHref === oldHref) return;
    if (re.test(newHref) || re.test(oldHref)) {
      clearInterval(timer);
      window.location.reload();
    }
  }, 200);

  // return if not reading chapter now
  if (!re.test(oldHref)) return;

  const getFileURLPromise = new Promise(resolve => {
    const originXHROpen = XMLHttpRequest.prototype.open;
    XMLHttpRequest.prototype.open = function() {
      const url = arguments[1];
      if (url.includes('viewer-meta.json')) {
        const getFileURL = (fileName) => url.replace('viewer-meta.json', fileName);
        resolve(getFileURL);
      }
      return originXHROpen.apply(this, arguments);
    }
  });

  const getDecryptedKeyPromise = new Promise(resolve => {
    const originFromCharCode = String.fromCharCode;
    String.fromCharCode = function () {
      const result = originFromCharCode.apply(this, arguments);
      if (arguments.length === 64 && Array.from(arguments).every(charCode => /^[0-9a-f]{1}$/.test(originFromCharCode(charCode)))) {
        resolve(result);
      }
      return result;
    }
  });

  // get URL builder and key of decryption
  const getFileURL = await getFileURLPromise;
  const key = await fetch(getFileURL('decryption.key')).then(res => res.ok ? res.text() : getDecryptedKeyPromise);

  // get tilte and url of images
  const metadata = await fetch(getFileURL('viewer-meta.json')).then(res => res.json());
  const title = metadata.meta_data.title || document.querySelector('h1[class*=titleText]')?.textContent || `package_${Date.now()}`;
  const urls = metadata.pages.map(page => getFileURL(page.src));

  // add style patch
  const styleElement = document.createElement('style');
  styleElement.textContent = `#ImageDownloader-DownloadButton { text-align: center !important; }`;
  document.head.appendChild(styleElement);

  // setup ImageDownloader
  ImageDownloader.init({
    maxImageAmount: urls.length,
    getImagePromises,
    title
  });

  // collect promises of decrypted image
  function getImagePromises(startNum, endNum) {
    return urls
      .slice(startNum - 1, endNum)
      .map(url => getDecryptedImage(url)
        .then(ImageDownloader.fulfillHandler)
        .catch(ImageDownloader.rejectHandler)
      );
  }

  // get promise of decrypted image
  async function getDecryptedImage(url) {
    const encryptedArrayBuffer = await fetch(url).then(res => res.arrayBuffer());
    const n = new Uint8Array(key.match(/.{1,2}/g).map(s => parseInt(s, 16)));
    const r = new Uint8Array(encryptedArrayBuffer);
    const i = n.length;
    for (let s = 0; s < r.length; s++) {
      r[s] ^= n[s % i];
    }

    return new Promise(resolve => {
      const image = document.createElement('img');
      image.src = 'data:image/jpg;base64,' + window.btoa(r.reduce((data, byte) => data + String.fromCharCode(byte), ''));
      image.onload = function () {
        const canvas = document.createElement('canvas');
        const context = canvas.getContext('2d');
        canvas.width = this.width;
        canvas.height = this.height;
        context.drawImage(this, 0, 0);
        canvas.toBlob(resolve, 'image/jpeg', 1);
      }
    });
  }

})(axios, JSZip, saveAs, ImageDownloader);