ibi-scrape-pres.user.js

// ==UserScript==
// @name         IBI Presentations slide scraper
// @namespace    https://gist.github.com/gbowsky
// @version      1.2
// @description  Downloads first 300 slides from BBB video conference.
// @downloadURL  https://gist.github.com/gbowsky/2b5592a133c466285e062e5d4561d40e/raw/ibi-scrape-pres.user.js
// @updateURL    https://gist.github.com/gbowsky/2b5592a133c466285e062e5d4561d40e/raw/ibi-scrape-pres.user.js
// @author       gbowsky
// @match        https://vu.ibi.spb.ru/*/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=https://bigbluebutton.org/
// @grant        GM_xmlhttpRequest
// ==/UserScript==

const maxSlideLength = 300;

if (typeof GM_download !== 'function') {
    if (typeof GM_xmlhttpRequest !== 'function') {
        throw new Error('GM_xmlhttpRequest is undefined. Please set @grant GM_xmlhttpRequest at metadata block.');
    }

    function GM_download (url, name) {
        if (url == null) return;

        var data = {
            method: 'GET',
            responseType: 'arraybuffer',

            onload: function (res) {
                var blob = new Blob([res.response], {type: 'application/octet-stream'});
                var url = URL.createObjectURL(blob); // blob url

                var a = document.createElement('a');
                a.setAttribute('href', url);
                a.setAttribute('download', data.name != null ? data.name : 'filename');
                document.documentElement.appendChild(a);

                // call download
                // a.click() or CLICK the download link can't modify filename in Firefox (why?)
                // Solution from FileSaver.js, https://github.com/eligrey/FileSaver.js/
                var e = new MouseEvent('click');
                a.dispatchEvent(e);

                document.documentElement.removeChild(a);

                setTimeout(function(){
                    // reduce memory usage
                    URL.revokeObjectURL(url);
                    if ('close' in blob) blob.close(); // File Blob.close() API, not supported by all the browser right now
                    blob = undefined;
                }, 1000);

                if (typeof data.onafterload === 'function') data.onafterload(); // call onload function
            }

            // error object of onerror function is not supported right now
        };

        if (typeof url === 'string') {
            data.url = url;
            data.name = name;
        }
        else {
            if (url instanceof Object === false) return;

            // as documentation, you can only use [url, name, headers, saveAs, onload, onerror] function, but we won't check them
            // Notice: saveAs is not supported
            if (url.url == null) return;

            for (var i in url) {
                if (i === 'onload') data.onafterload = url.onload; // onload function support
                else data[i] = url[i];
            }
        }

        // it returns this GM_xhr, thought not mentioned in documentation
        return GM_xmlhttpRequest(data);
    }
}

function addBtn() {
    const parent = document.querySelector('button[aria-label="Транслировать веб-камеру"]').parentElement;
    const button = document.createElement('button');
    button.className = "button--Z2dosza lg--Q7ufB primary--1IbqAO";
    button.textContent = "Скачать 100 слайдов";
    button.addEventListener("click", downloadAll, false);
    parent.appendChild(button);
}

function addBtnRecord() {
    document.querySelector('style').textContent += '.bbb-download:before { content: "📥"; }'
    const parent = document.querySelector('.right');
    const div = document.createElement('div');
    const button = document.createElement('button');
    const inner = document.createElement('span');
    inner.className = 'bbb-download';
    div.className = 'button-wrapper';
    button.className = "button default circle";

    button.addEventListener("click", downloadRecording, false);

    button.appendChild(inner);
    div.appendChild(button);
    parent.appendChild(div);
}

async function downloadRecording() {
    const href = document.querySelector('.presentation image').getAttribute('href');
    let parts = href.split('/');

    for(let index = 1; index < maxSlideLength; index++) {
        parts[parts.length - 1] = `slide-${index}.png`
        if (await checkURL(parts.join('/'))) {
            GM_download(parts.join('/'), `${index}-${parts[parts.length -2]}-bbimg.png`);
        }
    }
}

async function downloadAll() {
    const href = document.querySelector('[data-test=whiteboard] image').getAttribute('xlink:href');
    let parts = href.split('/');
    parts[parts.length - 2] = 'png';

    for(let index = 1; index < maxSlideLength; index++) {
        parts[parts.length - 1] = String(index);
        if (await checkURL(parts.join('/'))) {
            GM_download(parts.join('/'), `${index}-${parts[parts.length -3]}-bbimg.png`);
        }
    }
}

async function checkURL(url) {
  const data = await fetch(url);
  return data.status === 200;
}

function callback() {
    if (!checkIfRecording()) {
        addBtn();
    } else {
        addBtnRecord();
    }
}

function checkIfRecording() {
    return document.querySelector('.presentation image') !== null;
}

function check() {
    return document.querySelector('[data-test=whiteboard] image') !== null || document.querySelector('.presentation image') !== null;
}

(function() {
    'use strict';

    let inval = setInterval(() => {
        if (check()) {
            clearInterval(inval);
            callback();
        }
    }, 500);
})();