Cloudflare image proxy worker to support twitter video cards

worker

addEventListener("fetch", event => {
  event.respondWith(handleRequest(event))
})
CLOUDFLARE_CUSTOMER_ID = '123123' //CHANGE THIS TO YOURS
const CF_THUMBNAIL_URL = `https://customer-${CLOUDFLARE_CUSTOMER_ID}.cloudflarestream.com/`

async function serveAsset(event) {
  
  const url = new URL(event.request.url)
  console.log('serving images', url)

  /* Fix for robots.txt */ 
  if(url.pathname == "/robots.txt"){
    let body = 'User-agent: *\nDisallow:'
    return new Response(body, {
        status: 200}
    )
  }

  const cache = caches.default
  let response = await cache.match(event.request.url)
  console.log('Checking cache')
  if (!response) {
    console.log('No Cache found')
    const cf_thumb_url = `${CF_THUMBNAIL_URL}${url.pathname}${url.search}`
    response = await fetch(cf_thumb_url, { headers: event.request.headers })
    // Cache for however long, here is 4 hours.
    const headers = new Headers(response.headers);
    headers.set("cache-control", `public, max-age=14400`);
    headers.set("vary", "Accept");
    response = new Response(response.body, { ...response, headers })
    event.waitUntil(cache.put(event.request, response.clone()))
  }else{
    console.log('Found image in cache, serving')
  }
  return response
}

async function handleRequest(event) {
  console.log('Requesting the image')
  if (event.request.method === "GET") {
    let response = await serveAsset(event)
    if (response.status > 399) {
      response = new Response(response.statusText, { status: response.status })
    }
    return response
  } else {
    return new Response("Method not allowed", { status: 405 })
  }
}