import 'dart:convert';
import 'dart:math';

import 'package:bip340/bip340.dart' as bip340;
import 'package:crypto/crypto.dart';

String signNostrEvent({
  required String privateKey,
  required String publicKey,
  required int kind,
  required List<List<String>> tags,
  required String content,
  int? createdAt,
}) {
  final ts = createdAt ?? DateTime.now().millisecondsSinceEpoch ~/ 1000;
  final ser = jsonEncode([0, publicKey, ts, kind, tags, content]);
  final idBytes = sha256.convert(utf8.encode(ser)).bytes;
  final id = idBytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();

  final rng = Random.secure();
  final aux = List.generate(32, (_) => rng.nextInt(256))
      .map((b) => b.toRadixString(16).padLeft(2, '0'))
      .join();

  final sig = bip340.sign(privateKey, id, aux);

  return jsonEncode({
    'id': id,
    'pubkey': publicKey,
    'created_at': ts,
    'kind': kind,
    'tags': tags,
    'content': content,
    'sig': sig,
  });
}