import 'package:dio/dio.dart';

String describeLoadError(Object error) {
  if (error is DioException) {
    final statusCode = error.response?.statusCode;

    if (statusCode == 401 || statusCode == 403) {
      return 'Нет доступа: API key отклонён ($statusCode).';
    }

    if (_isNetworkFailure(error)) {
      return 'Backend недоступен: ${error.message ?? error.type.name}.';
    }

    final responseMessage = _responseMessage(error);
    if (responseMessage != null) {
      return 'Backend вернул ошибку $statusCode: $responseMessage';
    }

    if (statusCode != null) {
      return 'Backend вернул ошибку $statusCode.';
    }

    return 'Ошибка запроса: ${error.message ?? error.type.name}.';
  }

  if (error is FormatException) {
    return 'Неожиданный ответ backend: ${error.message}';
  }

  return error.toString();
}

bool _isNetworkFailure(DioException error) {
  return switch (error.type) {
    DioExceptionType.connectionTimeout ||
    DioExceptionType.sendTimeout ||
    DioExceptionType.receiveTimeout ||
    DioExceptionType.connectionError ||
    DioExceptionType.unknown => true,
    _ => false,
  };
}

String? _responseMessage(DioException error) {
  final data = error.response?.data;
  if (data is Map) {
    final value = data['detail'] ?? data['message'] ?? data['error'];
    return value?.toString();
  }
  if (data is String && data.trim().isNotEmpty) {
    return data.trim();
  }
  return null;
}