Add downloader (video -> mp3) plugin (in music menu)

plugins/downloader/front.js

@@ -0,0 +1,54 @@
+const { ElementFromFile, templatePath, triggerAction } = require("../utils");
+const { ACTIONS, CHANNEL } = require("./actions.js");
+const { downloadVideoToMP3 } = require("./youtube-dl");
+
+let menu = null;
+let progress = null;
+const downloadButton = ElementFromFile(
+	templatePath(__dirname, "download.html")
+);
+
+const observer = new MutationObserver((mutations, observer) => {
+	if (!menu) {
+		menu = document.querySelector("ytmusic-menu-popup-renderer paper-listbox");
+	}
+
+	if (menu && !menu.contains(downloadButton)) {
+		menu.prepend(downloadButton);
+		progress = document.querySelector("#ytmcustom-download");
+	}
+});
+
+global.download = () => {
+	const videoUrl = window.location.href;
+
+	downloadVideoToMP3(
+		videoUrl,
+		(feedback) => {
+			if (!progress) {
+				console.warn("Cannot update progress");
+			} else {
+				progress.innerHTML = feedback;
+			}
+		},
+		(error) => {
+			triggerAction(CHANNEL, ACTIONS.ERROR, error);
+		},
+		() => {
+			if (!progress) {
+				console.warn("Cannot update progress");
+			} else {
+				progress.innerHTML = "Download";
+			}
+		}
+	);
+};
+
+function observeMenu() {
+	observer.observe(document, {
+		childList: true,
+		subtree: true,
+	});
+}
+
+module.exports = observeMenu;