dl.emersa.it/src/lib/server/ytdlp.ts

import { create } from 'youtube-dl-exec';
import { env } from '$env/dynamic/private';
import { spawn } from 'node:child_process';
import supportedFormats from '$lib/common/supportedFormats.json';
import { mimeTypeMap } from '$lib/server/helpers';

const YTDLP_PATH: string = env.YTDLP_PATH as string;

export const ytdl = create(YTDLP_PATH);

/**
 * Fetch YouTube metadata (title, uploader/artist)
 */
export async function getYouTubeMetadata(link: string) {
	return await ytdl(link, {
		dumpSingleJson: true,
		noCheckCertificates: true,
		noWarnings: true,
		preferFreeFormats: true
	});
}

/**
 * Streams the YouTube video/audio using youtube-dl-exec
 */
export function streamYouTube(link: string, format: string): ReadableStream<Uint8Array> {
	const mimeType: string | undefined = mimeTypeMap.get(format)
	
	if (!mimeType) {
		throw new Error("Unsupported format");
	}

	return new ReadableStream({
		start(controller) {
			const args = [
				'-o',
				'-',
			].filter(Boolean);

			if(mimeType?.includes('audio')) {
				args.push(...['--extract-audio', '--embed-metadata', '--embed-thumbnail', '--audio-format', format])
			} else if (mimeType.includes('video')) {
				args.push(...['--embed-metadata', '--embed-thumbnail', '--format', format])
			}

			console.info(`${YTDLP_PATH} ${args.join(' ')} ${link}`)

			const process = spawn(YTDLP_PATH, [...args, link], { stdio: ['ignore', 'pipe', 'ignore'] });

			process.stdout.on('data', (chunk) => controller.enqueue(chunk));
			process.stdout.on('end', () => controller.close());
			process.stdout.on('error', (err) => {
				console.error('Stream error:', err);
				controller.error(err);
			});
		}
	});
}