NIP-19: Add nrelay encoding and decoding

nip19.test.js

@@ -100,3 +100,12 @@ test('decode naddr from go-nostr with different TLV ordering', () => {
   expect(data.kind).toEqual(30023)
   expect(data.identifier).toEqual('banana')
 })
+
+test('encode and decode nrelay', () => {
+  let url = "wss://relay.nostr.example"
+  let nrelay = nip19.nrelayEncode(url)
+  expect(nrelay).toMatch(/nrelay1\w+/)
+  let {type, data} = nip19.decode(nrelay)
+  expect(type).toEqual('nrelay')
+  expect(data).toEqual(url)
+})

nip19.ts

@@ -82,6 +82,16 @@ export function decode(nip19: string): {
       }
     }
 
+    case 'nrelay': {
+      let tlv = parseTLV(data)
+      if (!tlv[0]?.[0]) throw new Error('missing TLV 0 for nrelay')
+
+      return {
+        type: 'nrelay',
+        data: utf8Decoder.decode(tlv[0][0])
+      }
+    }
+
     case 'nsec':
     case 'npub':
     case 'note':
@@ -160,6 +170,14 @@ export function naddrEncode(addr: AddressPointer): string {
   return bech32.encode('naddr', words, Bech32MaxSize)
 }
 
+export function nrelayEncode(url: string): string {
+  let data = encodeTLV({
+    0: [utf8Encoder.encode(url)]
+  })
+  let words = bech32.toWords(data)
+  return bech32.encode('nrelay', words, Bech32MaxSize)
+}
+
 function encodeTLV(tlv: TLV): Uint8Array {
   let entries: Uint8Array[] = []