From 13c50c71bd2464a6c54bfaa975740197798c2fc3 Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Mon, 22 Jan 2024 12:42:39 -0600
Subject: [PATCH] Cache the LNURL response

---
 src/deps.ts        |  1 +
 src/pipeline.ts    |  7 ++++---
 src/utils/lnurl.ts | 24 ++++++++++++++++++++++--
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/deps.ts b/src/deps.ts
index e76c84a5..bf23f9e1 100644
--- a/src/deps.ts
+++ b/src/deps.ts
@@ -88,6 +88,7 @@ export { default as stringifyStable } from 'npm:fast-stable-stringify@^1.0.0';
 export { default as Debug } from 'npm:debug@^4.3.4';
 export {
   LNURL,
+  type LNURLDetails,
   type MapCache,
   NIP05,
 } from 'https://gitlab.com/soapbox-pub/nlib/-/raw/137af48cbc2639a8969d233fc24d2b959f34782a/mod.ts';
diff --git a/src/pipeline.ts b/src/pipeline.ts
index ad12b09e..7ec7c18e 100644
--- a/src/pipeline.ts
+++ b/src/pipeline.ts
@@ -1,8 +1,9 @@
 import { Conf } from '@/config.ts';
+import { encryptAdmin } from '@/crypto.ts';
 import { addRelays } from '@/db/relays.ts';
 import { deleteAttachedMedia } from '@/db/unattached-media.ts';
 import { findUser } from '@/db/users.ts';
-import { Debug, type Event, LNURL } from '@/deps.ts';
+import { Debug, type Event } from '@/deps.ts';
 import { isEphemeralKind } from '@/kinds.ts';
 import { isLocallyFollowed } from '@/queries.ts';
 import { lnurlCallbackResponseSchema } from '@/schemas/lnurl.ts';
@@ -16,7 +17,7 @@ import { fetchWorker } from '@/workers/fetch.ts';
 import { TrendsWorker } from '@/workers/trends.ts';
 import { verifySignatureWorker } from '@/workers/verify.ts';
 import { signAdminEvent } from '@/sign.ts';
-import { encryptAdmin } from '@/crypto.ts';
+import { lnurlCache } from '@/utils/lnurl.ts';
 
 const debug = Debug('ditto:pipeline');
 
@@ -169,7 +170,7 @@ async function submitZaps(event: Event, data: EventData, signal = AbortSignal.ti
     const amount = event.tags.find(([name]) => name === 'amount')?.[1];
     if (lnurl && amount) {
       try {
-        const details = await LNURL.lookup(lnurl, { fetch: fetchWorker, signal });
+        const details = await lnurlCache.fetch(lnurl, { signal });
         if (details.tag === 'payRequest' && details.allowsNostr && details.nostrPubkey) {
           const callback = new URL(details.callback);
           const params = new URLSearchParams();
diff --git a/src/utils/lnurl.ts b/src/utils/lnurl.ts
index d2b4e964..07aae1d2 100644
--- a/src/utils/lnurl.ts
+++ b/src/utils/lnurl.ts
@@ -1,4 +1,24 @@
-import { LNURL } from '@/deps.ts';
+import { Debug, LNURL, type LNURLDetails } from '@/deps.ts';
+import { SimpleLRU } from '@/utils/SimpleLRU.ts';
+import { Time } from '@/utils/time.ts';
+import { fetchWorker } from '@/workers/fetch.ts';
+
+const debug = Debug('ditto:lnurl');
+
+const lnurlCache = new SimpleLRU<string, LNURLDetails>(
+  async (lnurl, { signal }) => {
+    debug(`Lookup ${lnurl}`);
+    try {
+      const result = await LNURL.lookup(lnurl, { fetch: fetchWorker, signal });
+      debug(`Found: ${lnurl}`);
+      return result;
+    } catch (e) {
+      debug(`Not found: ${lnurl}`);
+      throw e;
+    }
+  },
+  { max: 1000, ttl: Time.minutes(30) },
+);
 
 /** Get an LNURL from a lud06 or lud16. */
 function getLnurl({ lud06, lud16 }: { lud06?: string; lud16?: string }, limit?: number): string | undefined {
@@ -12,4 +32,4 @@ function getLnurl({ lud06, lud16 }: { lud06?: string; lud16?: string }, limit?:
   }
 }
 
-export { getLnurl };
+export { getLnurl, lnurlCache };