feat: create and implement nodeInfoCache function

src/utils/domains.ts

@@ -0,0 +1,41 @@
+import { fetchWorker } from '@/workers/fetch.ts';
+import { SimpleLRU } from '@/utils/SimpleLRU.ts';
+import { Time } from '@/utils/time.ts';
+
+type NodeInfoV1 = {
+  usage: {
+    users: {
+      total: number;
+      activeMonth: number;
+      activeHalfyear: number;
+    };
+  };
+};
+
+type Domain = string;
+
+export const nodeInfoCache = new SimpleLRU<Domain, NodeInfoV1>(
+  async (key, { signal }) => {
+    try {
+      const url = new URL('/.well-known/nodeinfo', `https://${key}/`);
+      const res = await fetchWorker(url, { signal });
+
+      const { links } = await res.json();
+      if (links.length < 1) throw new Error(`${key} does not have NodeInfo schemas`);
+
+      // NodeInfo is backwards compatible, and we only care about the 'usage' field,
+      // which is present across all versions, so we can make a request to any version
+      const urlNodeInfo = links[0].href;
+
+      const resNodeIndo = await fetchWorker(urlNodeInfo, { signal });
+      const { usage } = await resNodeIndo.json();
+
+      return {
+        usage,
+      };
+    } catch (e) {
+      throw e;
+    }
+  },
+  { max: 500, ttl: Time.hours(1) },
+);