gistfile1.txt

module.exports.routeGetScreenshot = async function routeGetScreenshot (req, res) {
  /**
  * [GET] [/util/og/:roomId] This will return an image of a screen of 
  * the /util/og/:roomId endpoint
  */

  // set the cache header to a more generous time, since this is used for share links and 
  // we don't want to be calling this 100k's time in a short period. Whatever this value is
  // set to, it will returned a cached screenshot for that time period (in seconds). The trade
  // off here is screenshot freshness with scale. NOTE: Most services cache OG images on their
  // side, we can't rely on people always seeing the latest version regardless of how long
  // we're caching for
  helpers.setCacheHeaders(res, 60 * 8);

  let roomId = ('' + req.param('roomId'));
  // enable .png / .jpg to be passed in, just ignore it if it is
  roomId = roomId.replace('.png', '').replace('.jpg', '');

  const browser = await puppeteer.launch({
    // NOTE: This must be true for localhost since it's a self signed cert.
    // In other environments, it doesn't matter since we're just rendering the
    // OG image from our own server
    ignoreHTTPSErrors: true,
  });
  const page = await browser.newPage();
  await page.setViewport({
    // match width / height to OG image template
    width: 1600,
    height: 914,
    deviceScaleFactor: 2, // higher values generate higher quality screenshots
  });

  // hit the og-card endpoint
  // NOTE: change url based on your envs
  let url = `https://hotline.co/util/og-card/${roomId}`;
  if (NODE_ENV === 'local') {
    url = `http://localhost:7000/util/og-card/${roomId}`;
  }
  

  // load the url
  await page.goto(url);
  
  // screenshot the page
  const screenshot = await page.screenshot({
    type: 'png',
    encoding: 'binary'
  });
  await browser.close(); // make sure you close it!
  
  // set headers so clients know it's an image
  res.set('Content-Type', 'image/png');
  res.set('Content-Length', screenshot.length);
  // SEND IT
  return res.send(screenshot);
};