// A dev-only middleware that resets service workers for the current host:port
// This is for dealing with cases where a developer loads the dev and prod
// versions of an app on the same host:port combination, causing the prod
// service worker to hijack subsequent visists in dev mode.

// Note this doesn't always immediately fix the problem - if the server used
// to serve the production app has a long cache header for /service-worker.js,
// this noop service worker will not be able to take effect. In such cases,
// the developer will have to manually unregister the service worker in
// Chrome Devtools -> Application -> Service Workers

const fs = require('fs')
const path = require('path')
const resetScript = fs.readFileSync(path.resolve(__dirname, 'noopServiceWorker.js'), 'utf-8')

module.exports = function createNoopServiceWorkerMiddleware () {
  return function noopServiceWorkerMiddleware (req, res, next) {
    if (req.url === '/service-worker.js') {
      res.setHeader('Content-Type', 'text/javascript')
      res.send(resetScript)
    } else {
      next()
    }
  }
}