NIP-19: Add nrelay encoding and decoding

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[] = []