import 'package:dio/dio.dart';
import 'package:patbond_flutter/core/network/api_envelope.dart';
import 'package:patbond_flutter/core/network/api_exception.dart';
import 'package:patbond_flutter/core/network/token_refresher.dart';
import 'package:patbond_flutter/features/auth/session_manager.dart';

/// API 基地址：`--dart-define=PATBOND_API_BASE_URL=...` 注入，默认本机后端。
const String patbondApiBaseUrl = String.fromEnvironment(
  'PATBOND_API_BASE_URL',
  defaultValue: 'http://127.0.0.1:8081',
);

/// 构建全局共用的 Dio 实例。
///
/// `validateStatus` 放行所有状态码：错误信封由 [ApiClient] 统一解析成
/// 类型化异常，不依赖 dio 的 4xx/5xx 抛错路径。
Dio buildPatbondDio({required SessionManager session, String? baseUrl}) {
  final dio = Dio(
    BaseOptions(
      baseUrl: baseUrl ?? patbondApiBaseUrl,
      connectTimeout: const Duration(seconds: 5),
      sendTimeout: const Duration(seconds: 10),
      receiveTimeout: const Duration(seconds: 10),
      contentType: Headers.jsonContentType,
      validateStatus: (_) => true,
    ),
  );
  dio.interceptors.add(AuthInterceptor(session));
  return dio;
}

/// 鉴权拦截器：对标记 [ApiClient.requiresAuthExtra] 的请求附加
/// `Authorization: Bearer`，并统一携带设备标识。
class AuthInterceptor extends Interceptor {
  AuthInterceptor(this._session);

  final SessionManager _session;

  @override
  void onRequest(RequestOptions options, RequestInterceptorHandler handler) {
    final deviceId = _session.deviceId;
    if (deviceId != null) {
      options.headers['X-Device-Id'] = deviceId;
    }
    if (options.extra[ApiClient.requiresAuthExtra] == true) {
      final token = _session.accessToken;
      if (token != null) {
        options.headers['Authorization'] = 'Bearer $token';
      }
    }
    handler.next(options);
  }
}

/// HTTP 客户端封装：错误信封 → 类型化异常，401/40101 → 刷新后重放一次。
class ApiClient {
  ApiClient({
    required this._dio,
    required this._session,
    required this._refresher,
  });

  /// RequestOptions.extra 标记：该请求需要 Bearer 鉴权。
  static const requiresAuthExtra = 'patbond.requiresAuth';

  final Dio _dio;
  final SessionManager _session;
  final TokenRefresher _refresher;

  /// 发起请求并返回信封中的 `data`。
  ///
  /// 鉴权请求遇 HTTP 401 或 code 40101 时：经单飞刷新后原样重放一次；
  /// 重放仍失败则清会话并抛 [SessionExpiredException]。
  Future<Object?> request(
    String path, {
    String method = 'POST',
    Object? body,
    Map<String, Object?>? headers,
    bool requiresAuth = false,
  }) async {
    var response = await _send(
      path,
      method: method,
      body: body,
      headers: headers,
      requiresAuth: requiresAuth,
    );

    if (requiresAuth && _isAuthFailure(response)) {
      await _refresher.refresh();
      response = await _send(
        path,
        method: method,
        body: body,
        headers: headers,
        requiresAuth: requiresAuth,
      );
      if (_isAuthFailure(response)) {
        await _session.clearSession();
        throw const SessionExpiredException('刷新后重放仍未通过鉴权');
      }
    }

    return _unwrap(response);
  }

  Future<Response<Object?>> _send(
    String path, {
    required String method,
    required bool requiresAuth,
    Object? body,
    Map<String, Object?>? headers,
  }) async {
    try {
      return await _dio.request<Object?>(
        path,
        data: body,
        options: Options(
          method: method,
          headers: headers,
          extra: {requiresAuthExtra: requiresAuth},
        ),
      );
    } on DioException catch (error) {
      throw ApiNetworkException('请求失败：${error.type.name}');
    }
  }

  bool _isAuthFailure(Response<Object?> response) {
    if (response.statusCode == 401) return true;
    return ApiEnvelope.tryParse(response.data)?.code ==
        ApiCodes.accessTokenInvalid;
  }

  Object? _unwrap(Response<Object?> response) {
    final status = response.statusCode ?? 0;
    if (status == 429) {
      throw const ApiRateLimitException();
    }
    final envelope = ApiEnvelope.tryParse(response.data);
    if (envelope == null || status >= 500) {
      throw ApiNetworkException('响应异常：HTTP $status');
    }
    if (envelope.code == ApiCodes.ok) {
      return envelope.data;
    }
    throw ApiBusinessException(code: envelope.code, message: envelope.message);
  }
}