import 'dart:convert';
import 'package:crypto/crypto.dart';

/// أداة توليد توقيع HMAC-SHA256 للمصادقة مع الباك إند
class HmacUtility {
  /// Generate HMAC-SHA256 signature
  /// message = timestamp|api_key|payload
  static String generateSignature({
    required String apiKey,
    required String apiSecret,
    required String payload,
    required int timestamp,
  }) {
    final message = '$timestamp|$apiKey|$payload';
    final hmac = Hmac(sha256, utf8.encode(apiSecret));
    final digest = hmac.convert(utf8.encode(message));
    return digest.toString();
  }

  /// Build authenticated headers for API requests
  static Map<String, String> buildHeaders({
    required String apiKey,
    required String apiSecret,
    required String payload,
  }) {
    final timestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000;
    final signature = generateSignature(
      apiKey: apiKey,
      apiSecret: apiSecret,
      payload: payload,
      timestamp: timestamp,
    );

    return {
      'Content-Type': 'application/json',
      'X-API-Key': apiKey,
      'X-Signature': signature,
      'X-Timestamp': timestamp.toString(),
    };
  }
}