Caching for Workers

export default {
  async fetch(request, env, ctx): Promise<Response> {
    const url = new URL(request.url)
    const key = url.pathname.slice(1)

    if (request.method !== "GET") {
      return new Response("Method not allowed", { status: 405 })
    }

    if (!key) {
      return new Response("No key provided", { status: 400 })
    }

    const cache = caches.default
    const cacheKey = new Request(url.toString(), request)
    const cachedResponse = await cache.match(cacheKey)
    if (cachedResponse) {
      return cachedResponse
    }

    if (key.startsWith("uploads")) {
      return new Response("Uploaded files are not available for download", { status: 404 })
    }

    const object = await env.BUCKET.get(key)
    if (!object) {
      return new Response("Not found", { status: 404 })
    }

    const headers = new Headers()
    object.writeHttpMetadata(headers)
    headers.set("etag", object.httpEtag)
    headers.set("Content-Type", object.httpMetadata?.contentType ?? "application/octet-stream")
    headers.set("Content-Length", object.size.toString())
    headers.set("Cache-Control", "public, max-age=3600")
    headers.set("Vary", "Accept-Encoding")

    const response = new Response(object.body, { headers })
    ctx.waitUntil(cache.put(cacheKey, response.clone()))
    return response
  },
} satisfies ExportedHandler<Env>