/**
 * Cloudflare Worker to add security headers and remove S3 headers.
 * https://jarv.is/notes/security-headers-cloudflare-workers/
 */

let addHeaders = {
  "Content-Security-Policy": "default-src 'self'; script-src 'self' 'unsafe-inline' stats.jarv.is comments.jarv.is buttons.github.io platform.twitter.com cdn.syndication.twimg.com; style-src 'self' 'unsafe-inline' comments.jarv.is platform.twitter.com; img-src 'self' data: https:; font-src 'self' comments.jarv.is; object-src 'self'; media-src 'self'; base-uri 'self'; form-action 'self' platform.twitter.com syndication.twitter.com; frame-src 'self' www.youtube.com www.youtube-nocookie.com platform.twitter.com syndication.twitter.com buttons.github.io codepen.io; frame-ancestors 'self'; worker-src 'none'; connect-src 'self' csp.jarv.is jarvis.report-uri.com stats.jarv.is comments.jarv.is api.github.com syndication.twitter.com; upgrade-insecure-requests; report-uri https://csp.jarv.is/r/d/csp/enforce; report-to default",
  "Report-To": "{\"group\":\"default\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://csp.jarv.is/a/d/g\"}]}",
  "NEL": "{\"report_to\":\"default\",\"max_age\":604800}",
//  "Strict-Transport-Security" : "max-age=1000",
  "X-XSS-Protection": "1; mode=block; report=https://csp.jarv.is/r/d/xss/enforce",
  "X-Frame-Options": "SAMEORIGIN",
  "X-Content-Type-Options": "nosniff",
  "Referrer-Policy": "same-origin",
  "X-DNS-Prefetch-Control": "off",
  "X-UA-Compatible": "IE=edge",
  "X-Permitted-Cross-Domain-Policies": "none",
  "Feature-Policy": "accelerometer 'none'; camera 'none'; geolocation 'none'; gyroscope 'none'; magnetometer 'none'; microphone 'none'; sync-xhr 'none'; payment 'none'; usb 'none'; vr 'none'"
}

let removeHeaders = [
  "Last-Modified",
  "Expires",
  "Public-Key-Pins",
  "X-Powered-By",
  "x-amz-request-id",
  "x-amz-id-2",
  "x-amz-bucket",
  "x-amz-bucket-region",
  "x-amz-error-code",
  "x-amz-error-message",
  "x-amz-error-detail-key",
  "x-amz-version-id"
]

addEventListener("fetch", event => {
  event.respondWith(fetchAndApply(event.request))
})

async function fetchAndApply(request) {
  // Ignore POST and PUT HTTP requests.
  // https://github.com/cloudflare/worker-examples/blob/master/examples/security/ingore-post-and-put.js
  if (request.method === 'POST' || request.method === 'PUT') {
    return new Response('Sorry, that method isn\'t allowed here.',
        { status: 403, statusText: 'Forbidden' })
  }

  // Fetch the original page from the origin
  let response = await fetch(request)

  // Make response headers mutable
  response = new Response(response.body, response)

  // Content-Type and Cache-Control headers based on file extension...
  // ...because S3 sucks at guessing.
  if(response.status === 200) {
    let url = new URL(request.url)

    // Content-Type
    if (new RegExp(`\\.ico$`).test(url.pathname))
      response.headers.set("Content-Type", "image/x-icon")
    else if (new RegExp(`\\.svg$`).test(url.pathname))
      response.headers.set("Content-Type", "image/svg+xml")
    else if (new RegExp(`\\.ttf$`).test(url.pathname))
      response.headers.set("Content-Type", "font/ttf")
    else if (new RegExp(`\\.otf$`).test(url.pathname))
      response.headers.set("Content-Type", "font/otf")
    else if (new RegExp(`\\.eot$`).test(url.pathname))
      response.headers.set("Content-Type", "application/vnd.ms-fontobject")
    else if (new RegExp(`\\.woff$`).test(url.pathname))
      response.headers.set("Content-Type", "font/woff")
    else if (new RegExp(`\\.woff2$`).test(url.pathname))
      response.headers.set("Content-Type", "font/woff2")
    else if (new RegExp(`\\.xml$`).test(url.pathname))
      response.headers.set("Content-Type", "text/xml")
    else if (new RegExp(`\\.mp4$`).test(url.pathname))
      response.headers.set("Content-Type", "video/mp4")
    else if (new RegExp(`\\.webm$`).test(url.pathname))
      response.headers.set("Content-Type", "video/webm")
    else if (new RegExp(`\\.vtt$`).test(url.pathname))
      response.headers.set("Content-Type", "text/vtt")
    else if (new RegExp(`\\.docx$`).test(url.pathname))
      response.headers.set("Content-Type", "application/vnd.openxmlformats-officedocument.wordprocessingml.document")
    else if (new RegExp(`\\.pdf$`).test(url.pathname))
      response.headers.set("Content-Type", "application/pdf")

    // Cache-Control
    if (new RegExp(`\\.(css|js|jpg|png|gif|svg|ico|mp4|webm|vtt|pdf)$`).test(url.pathname))
      response.headers.set("Cache-Control", "max-age=604800, public")
    else if (new RegExp(`\\.(ttf|otf|eot|woff|woff2)$`).test(url.pathname))
      response.headers.set("Cache-Control", "max-age=2628000, public")
    else
      response.headers.set("Cache-Control", "max-age=3600, public")

    // .asc exception
    if (new RegExp(`\\.asc$`).test(url.pathname)) {
      response.headers.set("Content-Type", "text/plain; charset=utf-8")
      response.headers.set("Cache-Control", "max-age=0, no-store, no-cache, must-revalidate")
      response.headers.set("Content-Disposition", "inline; filename=\"jarvis.asc\"")
    }
  }

  // Set each header in addHeaders
  Object.keys(addHeaders).map(function(name, index) {
    response.headers.set(name, addHeaders[name])
  })

  // Delete each header in removeHeaders
  removeHeaders.forEach(function(name){
    response.headers.delete(name)
  })

  // Return the new mutated page
  return response
}