safetwitch-backend/routes/proxyRoute.ts

import { Router, Response, Request, NextFunction } from 'express'
import { TwitchAPI } from '../util/scraping/extractor';
import ws, { WebSocket } from 'ws';
import { logger } from '../util/logger';
import { TwitchChatServer } from './chatIrcProxy'

const proxyRouter = Router();
const twitch = new TwitchAPI()
     
proxyRouter.get('/img/:base64Url', async (req: Request, res: Response, next: NextFunction) => {
    const imageUrl = Buffer.from(req.params.base64Url, 'base64url').toString('utf-8')
    if(!imageUrl) return;

    const imageRes = await fetch(imageUrl)
      .catch(next)

    if(!imageRes) return;

    if(imageRes.status !== 200) {
      res.status(imageRes.status).send()
      const error = new Error('Image proxy fetch was not status 200')
      logger.warn(error)
    }

    const arrayBuffer = await imageRes.arrayBuffer()
    const buf = Buffer.from(arrayBuffer)

    res.send(buf)
})


proxyRouter.get('/stream/:username/hls.m3u8', async (req: Request, res: Response, next: NextFunction) => {
  let m3u8Data = await twitch.getStream(req.params.username)
  const urlRegex =/(\b(https?|ftp|file):\/\/[-A-Z0-9+&@#\/%?=~_|!:,.;]*[-A-Z0-9+&@#\/%=~_|])/ig;
  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, `${process.env.URL}/proxy/stream/sub/${base64data}`)
  }

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

proxyRouter.get('/stream/sub/:encodedUrl' , async (req: Request, res: Response, next: NextFunction) => {
  const unencodedUrl = Buffer.from(req.params.encodedUrl, 'base64url').toString()
  const m3u8Fetch = await fetch(unencodedUrl)
  let m3u8Data = await m3u8Fetch.text()
  const urlRegex =/(\b(https?|ftp|file):\/\/[-A-Z0-9+&@#\/%?=~_|!:,.;]*[-A-Z0-9+&@#\/%=~_|])/ig;
  const matches = m3u8Data.match(urlRegex)
  if(!matches) return;

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

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

proxyRouter.get('/stream/segment/:encodedUrl', async (req: Request, res: Response) => {
  const unencodedUrl = Buffer.from(req.params.encodedUrl, 'base64url').toString()
  const data = await fetch(unencodedUrl)
  const arrayBuffer = await data.arrayBuffer()
  const buf = Buffer.from(arrayBuffer)
  res.send(buf)
})



const twitchChatServer = new TwitchChatServer();
export const wsServer = new ws.Server({ noServer: true });
twitchChatServer.startWebSocketServer(wsServer);

export default proxyRouter