youtube-music/plugins/downloader/front.js

const { ipcRenderer } = require('electron');

const { defaultConfig } = require('../../config');
const { getSongMenu } = require('../../providers/dom-elements');
const { ElementFromFile, templatePath } = require('../utils');

let menu = null;
let progress = null;
const downloadButton = ElementFromFile(
  templatePath(__dirname, 'download.html'),
);

let doneFirstLoad = false;

const menuObserver = new MutationObserver(() => {
  if (!menu) {
    menu = getSongMenu();
    if (!menu) {
      return;
    }
  }

  if (menu.contains(downloadButton)) {
    return;
  }

  const menuUrl = document.querySelector('tp-yt-paper-listbox [tabindex="0"] #navigation-endpoint')?.href;
  if (!menuUrl?.includes('watch?') && doneFirstLoad) {
    return;
  }

  menu.prepend(downloadButton);
  progress = document.querySelector('#ytmcustom-download');

  if (doneFirstLoad) {
    return;
  }

  setTimeout(() => doneFirstLoad ||= true, 500);
});

// TODO: re-enable once contextIsolation is set to true
// contextBridge.exposeInMainWorld("downloader", {
// 	download: () => {
global.download = () => {
  let videoUrl = getSongMenu()
    // Selector of first button which is always "Start Radio"
    ?.querySelector('ytmusic-menu-navigation-item-renderer[tabindex="0"] #navigation-endpoint')
    ?.getAttribute('href');
  if (videoUrl) {
    if (videoUrl.startsWith('watch?')) {
      videoUrl = defaultConfig.url + '/' + videoUrl;
    }

    if (videoUrl.includes('?playlist=')) {
      ipcRenderer.send('download-playlist-request', videoUrl);
      return;
    }
  } else {
    videoUrl = global.songInfo.url || window.location.href;
  }

  ipcRenderer.send('download-song', videoUrl);
};

module.exports = () => {
  document.addEventListener('apiLoaded', () => {
    menuObserver.observe(document.querySelector('ytmusic-popup-container'), {
      childList: true,
      subtree: true,
    });
  }, { once: true, passive: true });

  ipcRenderer.on('downloader-feedback', (_, feedback) => {
    if (progress) {
      progress.innerHTML = feedback || 'Download';
    } else {
      console.warn('Cannot update progress');
    }
  });
};