// Imprved the script from this blog https://www.grahn.io/posts/2020-02-08-s3-vs-b2-static-web-hosting/
// Backblaze Url
const baseURL = "https://f000.backblazeb2.com/file/yourbucket"

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event))
})


async function handleRequest(event) {
  // only allow get requests
  if (event.request.method !== 'GET') {
    return new Response('Method not allowed', { status: 405 })
  }
  // return a cached response if we have one
  const cache = caches.default
  let cachedResponse = await cache.match(event.request)
  if (cachedResponse) {
    return cachedResponse
  }
  
  const parsedUrl = new URL(event.request.url)
  let path = parsedUrl.pathname
  // check if a file or folder and 301 when tailing slash is missing
  let lastSegment = path.substring(path.lastIndexOf('/'))
  if (lastSegment.indexOf('.') === -1) {
    if (!lastSegment.endsWith('/')){
      return Response.redirect('https://' + parsedUrl.hostname + path + '/', 301)
    } else {
      path += 'index.html'
    }
  }

  // fetch content from B2
  const b2Response = await fetch(`${baseURL}${path}`)
  // add some headers
  const headers = {
    'cache-control': 'public, max-age=14400',
    'content-type': b2Response.headers.get('Content-Type')
  }
  const response = new Response(b2Response.body, { ...b2Response, headers })
  // all is well, return the response
  if (response.status < 400){
    event.waitUntil(cache.put(event.request, response.clone()))
    return response
  } else if (response.status == 404){
    // return error page
    return fetch(baseURL + "/404.html")
  }
  // return minimal error page
  if (response.status > 399) {
    return new Response(response.statusText, { status: response.status })
  }
}