// In production, we register a service worker to serve assets from local cache.

// This lets the app load faster on subsequent visits in production, and gives

// it offline capabilities. However, it also means that developers (and users)

// will only see deployed updates on the "N+1" visit to a page, since previously

// cached resources are updated in the background.

// To learn more about the benefits of this model, read https://goo.gl/KwvDNy.

// This link also includes instructions on opting out of this behavior.

export default function register() {

  if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {

    window.addEventListener('load', () => {

      const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;

      navigator.serviceWorker

        .register(swUrl)

        .then(registration => {

          registration.onupdatefound = () => {

            const installingWorker = registration.installing;

            installingWorker.onstatechange = () => {

              if (installingWorker.state === 'installed') {

                if (navigator.serviceWorker.controller) {

                  // At this point, the old content will have been purged and

                  // the fresh content will have been added to the cache.

                  // It's the perfect time to display a "New content is

                  // available; please refresh." message in your web app.

                  console.log('New content is available; please refresh.');

                } else {

                  // At this point, everything has been precached.

                  // It's the perfect time to display a

                  // "Content is cached for offline use." message.

                  console.log('Content is cached for offline use.');

                }

              }

            };

          };

        })

        .catch(error => {

          console.error('Error during service worker registration:', error);

        });

    });

  }

}

export function unregister() {

  if ('serviceWorker' in navigator) {

    navigator.serviceWorker.ready.then(registration => {

      registration.unregister();

    });

  }

}