Add kind to nevent decode and encode (#304)

README.md

@@ -154,6 +154,7 @@ let relaysForEvent = pool.seenOn('44e1827635450ebb3c5a7d12c1f8e7b2b514439ac10a67
 
 pool.close()
 ```
+
 read more details about `batchedList` on this pr: [https://github.com/nbd-wtf/nostr-tools/pull/279](https://github.com/nbd-wtf/nostr-tools/pull/279#issue-1859315757)
 
 ### Parsing references (mentions) from a content using NIP-10 and NIP-27

nip19.test.ts

@@ -6,8 +6,10 @@ import {
   npubEncode,
   nrelayEncode,
   nsecEncode,
+  neventEncode,
   type AddressPointer,
   type ProfilePointer,
+  EventPointer,
 } from './nip19.ts'
 
 test('encode and decode nsec', () => {
@@ -72,6 +74,40 @@ test('encode and decode naddr', () => {
   expect(pointer.identifier).toEqual('banana')
 })
 
+test('encode and decode nevent', () => {
+  let pk = getPublicKey(generatePrivateKey())
+  let relays = ['wss://relay.nostr.example.mydomain.example.com', 'wss://nostr.banana.com']
+  let naddr = neventEncode({
+    id: pk,
+    relays,
+    kind: 30023,
+  })
+  expect(naddr).toMatch(/nevent1\w+/)
+  let { type, data } = decode(naddr)
+  expect(type).toEqual('nevent')
+  const pointer = data as EventPointer
+  expect(pointer.id).toEqual(pk)
+  expect(pointer.relays).toContain(relays[0])
+  expect(pointer.kind).toEqual(30023)
+})
+
+test('encode and decode nevent with kind 0', () => {
+  let pk = getPublicKey(generatePrivateKey())
+  let relays = ['wss://relay.nostr.example.mydomain.example.com', 'wss://nostr.banana.com']
+  let naddr = neventEncode({
+    id: pk,
+    relays,
+    kind: 0,
+  })
+  expect(naddr).toMatch(/nevent1\w+/)
+  let { type, data } = decode(naddr)
+  expect(type).toEqual('nevent')
+  const pointer = data as EventPointer
+  expect(pointer.id).toEqual(pk)
+  expect(pointer.relays).toContain(relays[0])
+  expect(pointer.kind).toEqual(0)
+})
+
 test('decode naddr from habla.news', () => {
   let { type, data } = decode(
     'naddr1qq98yetxv4ex2mnrv4esygrl54h466tz4v0re4pyuavvxqptsejl0vxcmnhfl60z3rth2xkpjspsgqqqw4rsf34vl5',

nip19.ts

@@ -11,6 +11,19 @@ const Bech32MaxSize = 5000
  */
 export const BECH32_REGEX = /[\x21-\x7E]{1,83}1[023456789acdefghjklmnpqrstuvwxyz]{6,}/
 
+function integerToUint8Array(number: number) {
+  // Create a Uint8Array with enough space to hold a 32-bit integer (4 bytes).
+  const uint8Array = new Uint8Array(4)
+
+  // Use bitwise operations to extract the bytes.
+  uint8Array[0] = (number >> 24) & 0xff // Most significant byte (MSB)
+  uint8Array[1] = (number >> 16) & 0xff
+  uint8Array[2] = (number >> 8) & 0xff
+  uint8Array[3] = number & 0xff // Least significant byte (LSB)
+
+  return uint8Array
+}
+
 export type ProfilePointer = {
   pubkey: string // hex
   relays?: string[]
@@ -20,6 +33,7 @@ export type EventPointer = {
   id: string // hex
   relays?: string[]
   author?: string
+  kind?: number
 }
 
 export type AddressPointer = {
@@ -73,13 +87,15 @@ export function decode(nip19: string): DecodeResult {
       if (!tlv[0]?.[0]) throw new Error('missing TLV 0 for nevent')
       if (tlv[0][0].length !== 32) throw new Error('TLV 0 should be 32 bytes')
       if (tlv[2] && tlv[2][0].length !== 32) throw new Error('TLV 2 should be 32 bytes')
+      if (tlv[3] && tlv[3][0].length !== 4) throw new Error('TLV 3 should be 4 bytes')
 
       return {
         type: 'nevent',
         data: {
           id: bytesToHex(tlv[0][0]),
           relays: tlv[1] ? tlv[1].map(d => utf8Decoder.decode(d)) : [],
           author: tlv[2]?.[0] ? bytesToHex(tlv[2][0]) : undefined,
+          kind: tlv[3]?.[0] ? parseInt(bytesToHex(tlv[3][0]), 16) : undefined,
         },
       }
     }
@@ -172,11 +188,18 @@ export function nprofileEncode(profile: ProfilePointer): `nprofile1${string}` {
 }
 
 export function neventEncode(event: EventPointer): `nevent1${string}` {
+  let kindArray
+  if (event.kind != undefined) {
+    kindArray = integerToUint8Array(event.kind)
+  }
+
   let data = encodeTLV({
     0: [hexToBytes(event.id)],
     1: (event.relays || []).map(url => utf8Encoder.encode(url)),
     2: event.author ? [hexToBytes(event.author)] : [],
+    3: kindArray ? [new Uint8Array(kindArray)] : [],
   })
+
   return encodeBech32('nevent', data)
 }