sw.js

import { UniversalResolver, DidDht, DidWeb } from '@web5/dids';

if (self instanceof ServiceWorkerGlobalScope) {

  const DidResolver = new UniversalResolver({ didResolvers: [DidDht, DidWeb] });
  const didUrlRegex = /^https?:\/\/dweb\/(([^\/]+)\/.*)?$/;
  const httpToHttpsRegex = /^http:/;
  const trailingSlashRegex = /\/$/;

  self.addEventListener('fetch', event => {
    const match = event.request.url.match(didUrlRegex);
    if (match) {
      event.respondWith((async () => {
        const normalizedUrl = event.request.url.replace(httpToHttpsRegex, 'https:').replace(trailingSlashRegex, '');
        const cachedResponse = await caches.open('drl').then(cache => cache.match(normalizedUrl));
        return cachedResponse || handleEvent(event, match[2], match[1]);
      })());
    }
  });

  async function handleEvent(event, did, route){
    try {
      const result = await DidResolver.resolve(did);
      return await fetchResource(event, result.didDocument, route);
    }
    catch(error){
      if (error instanceof Response) {
        return error;
      }
      console.log(`Error in DID URL fetch: ${error}`);
      return new Response('DID URL fetch error', { status: 500 });
    }
  }

  async function fetchResource(event, ddo, route) {
    let endpoints = ddo?.service?.find(service => service.type === 'DecentralizedWebNode')?.serviceEndpoint;
        endpoints = (Array.isArray(endpoints) ? endpoints : [endpoints]).filter(url => url.startsWith('http'));
    if (!endpoints?.length) {
      throw new Response('DWeb Node resolution failed: no valid endpoints found.', { status: 530 })
    }

    for (const endpoint of endpoints) {
      try {
        const response = await fetch(`${endpoint.replace(trailingSlashRegex, '')}/${route}`, { headers: event.request.headers });
        if (response.ok) {
          return response;
        }
        console.log(`DWN endpoint error: ${response.status}`);
        return new Response('DWeb Node request failed', { status: response.status }) 
      }
      catch (error) {
        console.log(`DWN endpoint error: ${error}`);
        return new Response('DWeb Node request failed: ' + error, { status: 500 }) 
      }
    }
  }

}
else {
  navigator.serviceWorker.register(new URL(import.meta.url), { type: 'module' })
    .then(registration => {
        console.log('Service Worker registered with scope:', registration.scope);
    })
    .catch(error => {
        console.error('Service Worker registration failed:', error);
    });
}