Add actorController

src/app.ts

@@ -2,6 +2,7 @@ import { type Context, cors, type Handler, Hono, type HonoEnv, logger, type Midd
 import { type Event } from '@/event.ts';
 import '@/loopback.ts';
 
+import { actorController } from './controllers/activitypub/actor.ts';
 import {
   accountController,
   accountLookupController,
@@ -67,6 +68,8 @@ app.get('/.well-known/host-meta', hostMetaController);
 app.get('/.well-known/nodeinfo', nodeInfoController);
 app.get('/.well-known/nostr.json', nostrController);
 
+app.get('/users/:username', actorController);
+
 app.get('/nodeinfo/:version', nodeInfoSchemaController);
 
 app.get('/api/v1/instance', instanceController);

src/controllers/activitypub/actor.ts

@@ -0,0 +1,23 @@
+import { getAuthor } from '@/client.ts';
+import { db } from '@/db.ts';
+import { toActor } from '@/transformers/nostr-to-activitypub.ts';
+import { activityJson } from '@/utils.ts';
+
+import type { AppController } from '@/app.ts';
+
+const actorController: AppController = async (c) => {
+  const notFound = c.json({ error: 'Not found' }, 404);
+
+  const username = c.req.param('username');
+  const user = await db.users.findFirst({ where: { username } });
+
+  const event = await getAuthor(user.pubkey);
+  if (!event) return notFound;
+
+  const actor = await toActor(event);
+  if (!actor) return notFound;
+
+  return activityJson(c, actor);
+};
+
+export { actorController };

src/transformers/nostr-to-activitypub.ts

@@ -6,9 +6,13 @@ import type { Event } from '@/event.ts';
 import type { Actor } from '@/schemas/activitypub.ts';
 
 /** Nostr metadata event to ActivityPub actor. */
-async function toActor(event: Event<0>, username: string): Promise<Actor> {
+async function toActor(event: Event<0>): Promise<Actor | undefined> {
   const content = parseMetaContent(event);
 
+  if (!content.nip05) return;
+  const [username, hostname] = content.nip05.split('@');
+  if (hostname !== Conf.url.hostname) return;
+
   return {
     type: 'Person',
     id: Conf.local(`/users/${username}`),

src/utils.ts

@@ -1,6 +1,6 @@
 import { getAuthor } from '@/client.ts';
 import { Conf } from '@/config.ts';
-import { nip19, parseFormData, z } from '@/deps.ts';
+import { type Context, nip19, parseFormData, z } from '@/deps.ts';
 import { type Event } from '@/event.ts';
 import { lookupNip05Cached } from '@/nip05.ts';
 
@@ -124,7 +124,26 @@ async function sha256(message: string): Promise<string> {
   return hashHex;
 }
 
+/** JSON-LD context. */
+type LDContext = (string | Record<string, string | Record<string, string>>)[];
+
+/** Add a basic JSON-LD context to ActivityStreams object, if it doesn't already exist. */
+function maybeAddContext<T>(object: T): T & { '@context': LDContext } {
+  return {
+    '@context': ['https://www.w3.org/ns/activitystreams'],
+    ...object,
+  };
+}
+
+/** Like hono's `c.json()` except returns JSON-LD. */
+function activityJson<T, P extends string>(c: Context<any, P>, object: T) {
+  const response = c.json(maybeAddContext(object));
+  response.headers.set('content-type', 'application/activity+json; charset=UTF-8');
+  return response;
+}
+
 export {
+  activityJson,
   bech32ToPubkey,
   buildLinkHeader,
   eventAge,