From 786d9914aff1375827ea5f23f063bc14f9909ef8 Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Mon, 15 Jan 2024 16:20:10 -0600
Subject: [PATCH] Add LNURL utils

---
 src/utils/lnurl.test.ts | 14 ++++++++++++++
 src/utils/lnurl.ts      | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 src/utils/lnurl.test.ts
 create mode 100644 src/utils/lnurl.ts

diff --git a/src/utils/lnurl.test.ts b/src/utils/lnurl.test.ts
new file mode 100644
index 00000000..a99f2eec
--- /dev/null
+++ b/src/utils/lnurl.test.ts
@@ -0,0 +1,14 @@
+import { assertEquals } from '@/deps-test.ts';
+
+import { lnurlDecode, lnurlEncode } from './lnurl.ts';
+
+const lnurl = 'lnurl1dp68gurn8ghj7um5v93kketj9ehx2amn9uh8wetvdskkkmn0wahz7mrww4excup0dajx2mrv92x9xp';
+const url = 'https://stacker.news/.well-known/lnurlp/odell';
+
+Deno.test('lnurlEncode', () => {
+  assertEquals(lnurlEncode(url), lnurl);
+});
+
+Deno.test('lnurlDecode', () => {
+  assertEquals(lnurlDecode(lnurl), url);
+});
diff --git a/src/utils/lnurl.ts b/src/utils/lnurl.ts
new file mode 100644
index 00000000..6d8e7258
--- /dev/null
+++ b/src/utils/lnurl.ts
@@ -0,0 +1,18 @@
+import { bech32 } from '@/deps.ts';
+
+/** Encode a URL to LNURL format. */
+function lnurlEncode(url: string): `lnurl1${string}` {
+  const data = new TextEncoder().encode(url);
+  const words = bech32.toWords(data);
+  return bech32.encode('lnurl', words);
+}
+
+/** Decode a LNURL into a URL. */
+function lnurlDecode(lnurl: string): string {
+  const { prefix, words } = bech32.decode(lnurl);
+  if (prefix !== 'lnurl') throw new Error('Invalid LNURL');
+  const data = new Uint8Array(bech32.fromWords(words));
+  return new TextDecoder().decode(data);
+}
+
+export { lnurlDecode, lnurlEncode };