import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../auth/auth_state.dart';
import '../config/app_config.dart';
import '../config/app_constants.dart';
import '../config/license_copy.dart';
import '../errors/error_reporter.dart';
import '../../providers/connectivity_provider.dart';
import '../../providers/license_provider.dart';
import 'retry_interceptor.dart';

/// Public Dio instance for unauthenticated calls (login / refresh)
final _publicDio = _buildPublicDio();

Dio _buildPublicDio() {
  final dio = Dio(BaseOptions(
    baseUrl: AppConfig.apiBaseUrl,
    connectTimeout: AppConstants.publicConnectTimeout,
    receiveTimeout: AppConstants.publicReceiveTimeout,
  ));
  dio.interceptors.add(RetryInterceptor(dio));
  return dio;
}

final apiClientProvider = Provider<ApiClient>((ref) {
  // 只监听登录/登出，不监听 token 内容变化。
  // token refresh 只改 accessToken，isLoggedIn 不变，provider 不重建，
  // 避免旧 Dio 被 close 后还在执行 fetch 导致 "adapter was closed"。
  ref.watch(authStateProvider.select((s) => s.isLoggedIn));
  final user = ref.read(authStateProvider).user;

  final client = ApiClient(
    token: user?.accessToken,
    refreshToken: user?.refreshToken,
    onTokensRefreshed: (accessToken, refreshToken) {
      ref
          .read(authStateProvider.notifier)
          .updateAccessToken(accessToken, refreshToken);
    },
    onAuthFailed: (reason) {
      if (ref.read(authStateProvider).isLoggedIn) {
        if (reason != null) {
          ref.read(sessionEndedMessageProvider.notifier).state = reason;
        }
        ref.read(authStateProvider.notifier).logout();
      }
    },
    onConnectionError: () {
      ref.read(connectivityProvider.notifier).forceCheck();
    },
    onForbidden: (body) {
      final map = body is Map ? body : const <String, dynamic>{};
      final code = map['code'];
      final phase = map['phase'];
      // 只读角色写被拒：直接提示（无需刷新授权）。
      if (code == 'READONLY_USER') {
        ref.read(apiMessageProvider.notifier).state =
            LicenseCopy.readonlyUserToast;
        return;
      }
      // 授权过期（readonly/locked）写被拒：刷新授权令横幅/按钮即时降级，并提示。
      if (phase == 'readonly' || phase == 'locked') {
        ref.read(licenseProvider.notifier).refresh().then((_) {
          final lic = ref.read(licenseProvider).valueOrNull;
          ref.read(apiMessageProvider.notifier).state = lic != null
              ? LicenseCopy.writeBlockedToast(lic)
              : '授权已过期，无法执行写操作';
        });
      }
      // 其它 403（管理员/超管权限不足等）不在此统一处理，交由调用方。
    },
  );
  ref.onDispose(client.dispose);
  return client;
});

class ApiClient {
  late final Dio _dio;
  bool _disposed = false;

  /// 当前 refresh token。续期会轮换它，故必须可变并随响应更新——
  /// provider 不会因 token 变化重建本实例（只监听 isLoggedIn）。
  String? _refreshToken;

  /// 单飞：并发 401 共享同一次刷新。否则每个 401 各发一次 /auth/refresh，
  /// 各自轮换 jti，后到的请求重放已被取代的 jti → 触发盗用检测吊销整条会话。
  Future<String?>? _refreshing;

  void Function(String accessToken, String refreshToken)? _onTokensRefreshed;
  void Function(String? reason)? _onAuthFailed;

  ApiClient({
    String? token,
    String? refreshToken,
    void Function(String accessToken, String refreshToken)? onTokensRefreshed,
    void Function(String? reason)? onAuthFailed,
    void Function()? onConnectionError,
    void Function(dynamic body)? onForbidden,
  }) {
    _refreshToken = refreshToken;
    _onTokensRefreshed = onTokensRefreshed;
    _onAuthFailed = onAuthFailed;
    _dio = Dio(BaseOptions(
      baseUrl: AppConfig.apiBaseUrl,
      connectTimeout: AppConstants.publicConnectTimeout,
      receiveTimeout: AppConstants.publicReceiveTimeout,
      headers: {
        if (token != null) 'Authorization': 'Bearer $token',
      },
    ));

    // 网络层错误自动重试（须在错误处理拦截器之前，先重试再走 401/上报逻辑）
    _dio.interceptors.add(RetryInterceptor(_dio));

    // 网络错误 + 401 拦截器
    _dio.interceptors.add(
      InterceptorsWrapper(
        onError: (DioException e, ErrorInterceptorHandler handler) async {
          if (_disposed) return handler.next(e);

          // 网络层错误（连接拒绝、超时等）→ 立即触发连通性检测
          final isNetworkError = e.type == DioExceptionType.connectionError ||
              e.type == DioExceptionType.connectionTimeout ||
              e.type == DioExceptionType.receiveTimeout ||
              e.type == DioExceptionType.sendTimeout;
          if (isNetworkError) {
            onConnectionError?.call();
            return handler.next(e);
          }

          // 服务端 5xx 错误上报（4xx 是业务/权限错误，不上报）
          final statusCode = e.response?.statusCode ?? 0;
          if (statusCode >= 500) {
            reportError(
              '[${e.requestOptions.method}] ${e.requestOptions.path} → $statusCode',
              e.stackTrace,
              errorType: ErrorType.apiError,
            );
          }

          // 403：写权限被拒（只读角色 / 授权过期）。交给上层刷新授权 + 提示。
          // 后端契约：body 带 code=READONLY_USER 或 phase=readonly|locked。
          if (e.response?.statusCode == 403) {
            if (!_disposed) onForbidden?.call(e.response?.data);
            return handler.next(e);
          }

          // 账号被停用/删除：中间件返回 401 + code=USER_DISABLED。这是终态，
          // 续期也救不回（refresh 会因 is_active=0 再次失败），直接强制重新登录。
          if (e.response?.statusCode == 401 &&
              e.response?.data is Map &&
              e.response?.data['code'] == 'USER_DISABLED') {
            if (!_disposed) {
              _onAuthFailed?.call('您的账号已被停用或删除，请重新登录或联系管理员');
            }
            return handler.next(e);
          }

          if (e.response?.statusCode == 401 && (_refreshToken ?? '').isNotEmpty) {
            debugPrint('[ApiClient] got 401 on ${e.requestOptions.path}, trying refresh...');
            final newToken = await _refreshAccessToken();
            if (newToken == null) {
              return handler.next(e);
            }
            try {
              final opts = e.requestOptions;
              opts.headers['Authorization'] = 'Bearer $newToken';
              final retryResp = await _dio.fetch(opts);
              return handler.resolve(retryResp);
            } catch (retryErr) {
              return handler.next(retryErr is DioException ? retryErr : e);
            }
          } else if (e.response?.statusCode == 401) {
            debugPrint('[ApiClient] got 401 on ${e.requestOptions.path}, no refresh token');
          }
          return handler.next(e);
        },
      ),
    );
  }

  /// 单飞刷新：并发 401 复用同一次 /auth/refresh，避免多次轮换 jti 触发盗用检测。
  /// 成功返回新的 access token；失败（含会话已撤销）返回 null 并通知 onAuthFailed。
  Future<String?> _refreshAccessToken() {
    return _refreshing ??= _doRefresh().whenComplete(() => _refreshing = null);
  }

  Future<String?> _doRefresh() async {
    try {
      final resp = await _publicDio.post('/auth/refresh', data: {
        'refresh_token': _refreshToken,
      });
      final data = resp.data['data'] as Map;
      final newAccess = data['access_token'] as String;
      // 后端轮换 refresh token，必须采纳新值（无则沿用旧值，兼容老后端）。
      final newRefresh = (data['refresh_token'] as String?) ?? _refreshToken;
      _refreshToken = newRefresh;
      _dio.options.headers['Authorization'] = 'Bearer $newAccess';
      if (!_disposed && newRefresh != null) {
        _onTokensRefreshed?.call(newAccess, newRefresh);
      }
      return newAccess;
    } catch (refreshErr) {
      debugPrint('[ApiClient] refresh failed: $refreshErr');
      // 区分「被踢/会话失效」与普通登录过期，便于登录页给出明确提示
      String? reason;
      if (refreshErr is DioException &&
          refreshErr.response?.data is Map &&
          refreshErr.response?.data['code'] == 'SESSION_REVOKED') {
        reason = '您的账号已在其他设备登录，或登录已失效，请重新登录';
      }
      if (!_disposed) _onAuthFailed?.call(reason);
      return null;
    }
  }

  /// 仅供测试：访问内部 Dio，以便挂载 mock adapter 走真实拦截器（401/403 等）。
  @visibleForTesting
  Dio get dioForTest => _dio;

  /// 取消所有进行中的请求，标记实例为已废弃
  void dispose() {
    _disposed = true;
    _dio.close(force: true);
  }

  Future<Response> get(String path, {Map<String, dynamic>? params}) =>
      _dio.get(path, queryParameters: params);

  Future<List<int>> getBytes(String path) async {
    final resp = await _dio.get<List<int>>(path,
        options: Options(responseType: ResponseType.bytes));
    return resp.data ?? [];
  }

  Future<Response> post(String path, {dynamic data}) =>
      _dio.post(path, data: data);

  Future<Response> put(String path, {dynamic data}) =>
      _dio.put(path, data: data);

  Future<Response> patch(String path, {dynamic data}) =>
      _dio.patch(path, data: data);

  Future<Response> delete(String path) => _dio.delete(path);
}

/// Unauthenticated client for login/refresh
class PublicApiClient {
  static Future<Response> post(String path, {dynamic data}) =>
      _publicDio.post(path, data: data);
}