safetwitch/server/routes/proxy/proxyRoute.ts

import { Streamlink } from '@dragongoose/streamlink';
import { Router, Response, Request, NextFunction } from 'express'

const proxyRouter = Router();

proxyRouter.get('/img', async (req: Request, res: Response, next: NextFunction) => {
    const imageUrl = req.query.imageUrl?.toString()
    if(!imageUrl) return;

    fetch(imageUrl).then((response) => {
        response.body!.pipeTo(
          new WritableStream({
            start() {
              response.headers.forEach((v, n) => res.setHeader(n, v));
            },
            write(chunk) {
              res.write(chunk);
            },
            close() {
              res.end();
            },
          })
        );
      })
      .catch((err) => next(err))
})

proxyRouter.get('/stream/:username/hls.m3u8', (req: Request, res: Response, next: NextFunction) => {
  console.log(req.params.username)
  const streamlink = new Streamlink(`https://twitch.tv/${req.params.username}`, {
    otherArgs: ['--stream-url']
  })

  streamlink.begin()


  streamlink.on('log', async (data) => {
    // m3u8 url
    let twitchM3u8url = data.toString()

    const urlRegex =/(\b(https?|ftp|file):\/\/[-A-Z0-9+&@#\/%?=~_|!:,.;]*[-A-Z0-9+&@#\/%=~_|])/ig;
    const twitchRes = await fetch(twitchM3u8url)
    let m3u8Data = await twitchRes.text()
    const matches = m3u8Data.match(urlRegex)
    if (!matches) return next(new Error('Error proxying HLS'));

    for (let url of matches) {
      const base64data = Buffer.from(url).toString('base64url')
      //m3u8Data = m3u8Data.replace(url, `${process.env.URL}/proxy/hls/${base64data}`)
    }

    res.setHeader('Content-type','application/vnd.apple.mpegurl')
    res.send(m3u8Data)
  })
})

proxyRouter.get('/hls/:encodedUrl' , (req: Request, res: Response, next: NextFunction) => {
  const unencodedUrl = Buffer.from(req.params.encodedUrl, 'base64url').toString()
  fetch(unencodedUrl).then((response) => {
    response.body!.pipeTo(
      new WritableStream({
        start() {
          response.headers.forEach((v, n) => res.setHeader(n, v));
        },
        write(chunk) {
          res.write(chunk);
        },
        close() {
          res.end();
        },
      })
    );
  })
  .catch((err) => next(err))
})

export default proxyRouter