Add LNURL utils

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);
+});

src/utils/lnurl.ts

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+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 };