From 9e73a8e43c361ecd29d0ecbeee380b57aae5a37f Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Sat, 29 Apr 2023 16:23:23 -0500
Subject: [PATCH] Add account lookup endpoint

---
 src/api/accounts.ts | 42 +++++++++++++++++++++++++++++++++++++++++-
 src/app.ts          |  4 +++-
 src/utils.ts        | 30 ++++++++++++++++++++++++++++--
 3 files changed, 72 insertions(+), 4 deletions(-)

diff --git a/src/api/accounts.ts b/src/api/accounts.ts
index 520d524..3b422f4 100644
--- a/src/api/accounts.ts
+++ b/src/api/accounts.ts
@@ -1,7 +1,9 @@
 import { type AppController } from '@/app.ts';
+import { nip19 } from '@/deps.ts';
 
 import { getAuthor } from '../client.ts';
 import { toAccount } from '../transmute.ts';
+import { bech32ToPubkey, isNostrId } from '../utils.ts';
 
 const credentialsController: AppController = async (c) => {
   const pubkey = c.get('pubkey')!;
@@ -14,4 +16,42 @@ const credentialsController: AppController = async (c) => {
   return c.json({ error: 'Could not find user.' }, 404);
 };
 
-export { credentialsController };
+const accountController: AppController = async (c) => {
+  const pubkey = c.req.param('id');
+
+  if (!isNostrId(pubkey)) {
+    return c.json({ error: 'Invalid account ID.' }, 422);
+  }
+
+  const event = await getAuthor(pubkey);
+  if (event) {
+    return c.json(toAccount(event));
+  }
+
+  return c.json({ error: 'Could not find user.' }, 404);
+};
+
+const accountLookupController: AppController = async (c) => {
+  const acct = c.req.query('acct');
+
+  if (!acct) {
+    return c.json({ error: 'Missing `acct` query parameter.' }, 422);
+  }
+
+  if (acct.includes('@')) {
+    // TODO: NIP-05 handling
+    return c.json({ error: 'NIP-05 lookups not yet implemented.' }, 422);
+  }
+
+  const pubkey = bech32ToPubkey(acct);
+  if (pubkey) {
+    const event = await getAuthor(pubkey);
+    if (event) {
+      return c.json(toAccount(event));
+    }
+  }
+
+  return c.json({ error: 'Could not find user.' }, 404);
+};
+
+export { accountController, accountLookupController, credentialsController };
diff --git a/src/app.ts b/src/app.ts
index 0491b3d..cdb1c85 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -1,6 +1,6 @@
 import { type Context, cors, type Handler, Hono, type HonoEnv, type MiddlewareHandler } from '@/deps.ts';
 
-import { credentialsController } from './api/accounts.ts';
+import { accountController, accountLookupController, credentialsController } from './api/accounts.ts';
 import { appCredentialsController, createAppController } from './api/apps.ts';
 import { emptyArrayController, emptyObjectController } from './api/fallback.ts';
 import homeController from './api/home.ts';
@@ -33,6 +33,8 @@ app.post('/oauth/token', createTokenController);
 app.post('/oauth/revoke', emptyObjectController);
 
 app.get('/api/v1/accounts/verify_credentials', requireAuth, credentialsController);
+app.get('/api/v1/accounts/lookup', accountLookupController);
+app.get('/api/v1/accounts/:id', accountController);
 
 app.post('/api/v1/statuses', requireAuth, createStatusController);
 
diff --git a/src/utils.ts b/src/utils.ts
index 00a7ab2..2b15583 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,4 +1,4 @@
-import { Context, getPublicKey } from '@/deps.ts';
+import { Context, getPublicKey, nip19, nip21 } from '@/deps.ts';
 import { type Event } from '@/event.ts';
 
 /** Get the current time in Nostr format. */
@@ -21,4 +21,30 @@ function getKeys(c: Context) {
   }
 }
 
-export { eventDateComparator, getKeys, nostrNow };
+/** Return true if the value is a bech32 string, eg for use with NIP-19. */
+function isBech32(value: unknown): value is string {
+  return typeof value === 'string' && nip21.BECH32_REGEX.test(value);
+}
+
+/** Return true if the value is a Nostr pubkey, private key, or event ID. */
+function isNostrId(value: unknown): value is string {
+  return typeof value === 'string' && /^[0-9a-f]{64}$/.test(value);
+}
+
+/** Get pubkey from bech32 string, if applicable. */
+function bech32ToPubkey(bech32: string): string | undefined {
+  try {
+    const decoded = nip19.decode(bech32);
+
+    switch (decoded.type) {
+      case 'nprofile':
+        return decoded.data.pubkey;
+      case 'npub':
+        return decoded.data;
+    }
+  } catch (_) {
+    //
+  }
+}
+
+export { bech32ToPubkey, eventDateComparator, getKeys, isBech32, isNostrId, nostrNow };