import { createGateway, type GatewayCache } from '@nibling/npm-gateway';
import type { ResponseCache } from './cache.ts';
import type { Gateway } from './context.ts';

/** The Workers Cache API as a GatewayCache. Keys become URLs under this worker's origin. */
function responseCache(cache: ResponseCache, origin: string, waitUntil: Gateway['waitUntil']): GatewayCache {
  const url = (key: string) => new URL(`/npm/cache/${encodeURIComponent(key)}`, origin).toString();
  return {
    async get(key) {
      return (await cache.match(url(key)))?.text();
    },
    async put(key, value, ttl) {
      waitUntil(cache.put(url(key), new Response(value, { headers: { 'cache-control': `public, max-age=${ttl}` } })));
    },
  };
}

/** dev.nibling.npm.getClosure and this worker's did:web document, answered by
 * @nibling/npm-gateway: this worker is one gateway among any that implement the query, and the
 * kernel works with none. */
export function handleNpm(g: Gateway, request: Request): Promise<Response> {
  return createGateway({ fetch: g.fetch, cache: responseCache(g.cache, g.origin, g.waitUntil), didWeb: true }).fetch(request);
}