refactor: service worker (#21250)

web/src/service-worker/request.ts

@@ -0,0 +1,63 @@
+import { get, put } from './cache';
+
+const isURL = (request: URL | RequestInfo): request is URL => (request as URL).href !== undefined;
+const isRequest = (request: RequestInfo): request is Request => (request as Request).url !== undefined;
+
+const assertResponse = (response: Response) => {
+  if (!(response instanceof Response)) {
+    throw new TypeError('Fetch did not return a valid Response object');
+  }
+};
+
+const getCacheKey = (request: URL | Request) => {
+  if (isURL(request)) {
+    return request.toString();
+  }
+
+  if (isRequest(request)) {
+    return request.url;
+  }
+
+  throw new Error(`Invalid request: ${request}`);
+};
+
+const pendingRequests = new Map<string, AbortController>();
+
+export const handleRequest = async (request: URL | Request) => {
+  const cacheKey = getCacheKey(request);
+
+  const cachedResponse = await get(cacheKey);
+  if (cachedResponse) {
+    return cachedResponse;
+  }
+
+  try {
+    const cancelToken = new AbortController();
+    pendingRequests.set(cacheKey, cancelToken);
+    const response = await fetch(request, { signal: cancelToken.signal });
+
+    assertResponse(response);
+    put(cacheKey, response);
+
+    return response;
+  } catch (error) {
+    console.log(error);
+    return new Response(undefined, {
+      status: 499,
+      statusText: `Request canceled: Instructions unclear, accidentally interrupted myself (${error})`,
+    });
+  } finally {
+    pendingRequests.delete(cacheKey);
+  }
+};
+
+export const cancelRequest = (url: URL) => {
+  const cacheKey = getCacheKey(url);
+  const pending = pendingRequests.get(cacheKey);
+  if (!pending) {
+    return;
+  }
+
+  pending.abort();
+  pendingRequests.delete(cacheKey);
+};