youtube-music/providers/song-info-front.js

const { ipcRenderer } = require("electron");
const { getImage } = require("./song-info");

global.songInfo = {};

const $ = s => document.querySelector(s);
const $$ = s => Array.from(document.querySelectorAll(s));

ipcRenderer.on("update-song-info", async (_, extractedSongInfo) => {
	global.songInfo = JSON.parse(extractedSongInfo);
	global.songInfo.image = await getImage(global.songInfo.imageSrc);
});

// used because 'loadeddata' or 'loadedmetadata' weren't firing on song start for some users (https://github.com/th-ch/youtube-music/issues/473)
const srcChangedEvent = new CustomEvent('srcChanged');

const singleton = (fn) => {
	let called = false;
	return (...args) => {
		if (called) return;
		called = true;
		return fn(...args);
	}
}

module.exports.setupSeekedListener = singleton(() => {
	document.querySelector('video')?.addEventListener('seeked', v => ipcRenderer.send('seeked', v.target.currentTime));
});

module.exports.setupTimeChangedListener = singleton(() => {
	const progressObserver = new MutationObserver(mutations => {
		ipcRenderer.send('timeChanged', mutations[0].target.value);
		global.songInfo.elapsedSeconds = mutations[0].target.value;
	});
	progressObserver.observe($('#progress-bar'), { attributeFilter: ["value"] });
});

module.exports.setupRepeatChangedListener = singleton(() => {
	const repeatObserver = new MutationObserver(mutations => {
		ipcRenderer.send('repeatChanged', mutations[0].target.title);
	});
	repeatObserver.observe($('#right-controls .repeat'), { attributeFilter: ["title"] });

	// Emit the initial value as well; as it's persistent between launches.
	ipcRenderer.send('repeatChanged', $('#right-controls .repeat').title);
});

module.exports.setupVolumeChangedListener = singleton((api) => {
	$('video').addEventListener('volumechange', (_) => {
		ipcRenderer.send('volumeChanged', api.getVolume());
	});
	// Emit the initial value as well; as it's persistent between launches.
	ipcRenderer.send('volumeChanged', api.getVolume());
});

module.exports = () => {
	document.addEventListener('apiLoaded', apiEvent => {
		ipcRenderer.on("setupTimeChangedListener", async () => {
			this.setupTimeChangedListener();
		});
	
		ipcRenderer.on("setupRepeatChangedListener", async () => {
			this.setupRepeatChangedListener();
		});
	
		ipcRenderer.on("setupVolumeChangedListener", async () => {
			this.setupVolumeChangedListener(apiEvent.detail);
		});

		ipcRenderer.on("setupSeekedListener", async () => {
			this.setupSeekedListener();
		});
		
		const video = $('video');
		// name = "dataloaded" and abit later "dataupdated"
		apiEvent.detail.addEventListener('videodatachange', (name, _dataEvent) => {
			if (name !== 'dataloaded') return;
			video.dispatchEvent(srcChangedEvent);
			sendSongInfo();
		})

		for (const status of ['playing', 'pause']) {
			video.addEventListener(status, e => {
				if (Math.round(e.target.currentTime) > 0) {
					ipcRenderer.send("playPaused", {
						isPaused: status === 'pause',
						elapsedSeconds: Math.floor(e.target.currentTime)
					});
				}
			});
		}

		function sendSongInfo() {
			const data = apiEvent.detail.getPlayerResponse();

			data.videoDetails.album = $$(
				".byline.ytmusic-player-bar > .yt-simple-endpoint"
			).find(e => e.href?.includes("browse"))?.textContent;

			data.videoDetails.elapsedSeconds = Math.floor(video.currentTime);
			data.videoDetails.isPaused = false;
			ipcRenderer.send("video-src-changed", JSON.stringify(data));
		}
	}, { once: true, passive: true });
};