import 'dart:developer';
import 'dart:io';
import 'package:dio/dio.dart';
import 'local_database.dart';

/// API 基础地址。可通过 --dart-define=API_BASE_URL=http://host:5000 覆盖。
const String baseUrl = String.fromEnvironment(
  'API_BASE_URL',
  defaultValue: 'http://localhost:5000',
);

class ApiException implements Exception {
  final int? code;
  final String message;

  const ApiException(this.message, {this.code});

  @override
  String toString() => message;
}

/// Dio HTTP 客户端封装——带 token 注入、401 自动刷新
class ApiClient {
  final Dio _dio;
  final LocalDatabase _db;

  ApiClient({required LocalDatabase db})
    : _db = db,
      _dio = Dio(BaseOptions(
        baseUrl: baseUrl,
        connectTimeout: const Duration(seconds: 15),
        receiveTimeout: const Duration(seconds: 60),
        headers: {'Content-Type': 'application/json'},
      )) {
    _dio.interceptors.add(_AuthInterceptor(this));
    _dio.interceptors.add(LogInterceptor(requestBody: false, responseBody: false));
  }

  Dio get dio => _dio;

  Future<String?> get accessToken => _db.read('access_token');
  Future<String?> get refreshToken => _db.read('refresh_token');

  Future<void> saveTokens(String access, String refresh) async {
    await _db.write('access_token', access);
    await _db.write('refresh_token', refresh);
  }

  Future<void> clearTokens() async {
    await _db.delete('access_token');
    await _db.delete('refresh_token');
  }

  /// 带 token 的 GET 请求
  Future<Response> get(String path, {Map<String, dynamic>? queryParameters}) async {
    return _request(_dio.get(path, queryParameters: queryParameters));
  }

  /// 带 token 的 POST 请求
  Future<Response> post(String path, {dynamic data}) async {
    return _request(_dio.post(path, data: data));
  }

  /// 带 token 的 PUT 请求
  Future<Response> put(String path, {dynamic data}) async {
    return _request(_dio.put(path, data: data));
  }

  /// 带 token 的 DELETE 请求
  Future<Response> delete(String path) async {
    return _request(_dio.delete(path));
  }

  /// 上传文件（multipart），返回文件 URL
  Future<String?> uploadFile(String path, File file, {String fieldName = 'file'}) async {
    final formData = FormData.fromMap({
      fieldName: await MultipartFile.fromFile(file.path, filename: file.path.split('/').last),
    });
    final res = await _request(_dio.post(path, data: formData));
    final data = res.data;
    if (data is Map) {
      final topUrl = data['url']?.toString();
      if (topUrl != null && topUrl.isNotEmpty) return topUrl;

      final payload = data['data'];
      if (payload is Map) {
        final url = payload['url']?.toString();
        return url != null && url.isNotEmpty ? url : null;
      }
      if (payload is List && payload.isNotEmpty && payload.first is Map) {
        final first = payload.first as Map;
        final url = first['url']?.toString();
        return url != null && url.isNotEmpty ? url : null;
      }
    }
    return null;
  }

  Response _ensureBusinessSuccess(Response response) {
    final body = response.data;
    if (body is Map && body.containsKey('code')) {
      final rawCode = body['code'];
      final code = rawCode is int ? rawCode : int.tryParse('$rawCode');
      if (code != null && code != 0) {
        throw ApiException(
          body['message']?.toString().trim().isNotEmpty == true
              ? body['message'].toString()
              : '请求失败',
          code: code,
        );
      }
    }
    return response;
  }

  Future<Response> _request(Future<Response> request) async {
    try {
      return _ensureBusinessSuccess(await request);
    } on DioException catch (error) {
      final body = error.response?.data;
      final message = body is Map && body['message']?.toString().trim().isNotEmpty == true
          ? body['message'].toString()
          : error.type == DioExceptionType.connectionTimeout ||
                  error.type == DioExceptionType.receiveTimeout
              ? '请求超时，请稍后重试'
              : error.type == DioExceptionType.connectionError
                  ? '无法连接服务器，请检查网络或后端地址'
                  : '请求失败，请稍后重试';
      final rawCode = body is Map ? body['code'] : null;
      throw ApiException(
        message,
        code: rawCode is int
            ? rawCode
            : int.tryParse('$rawCode') ?? error.response?.statusCode,
      );
    }
  }
}

/// 认证拦截器：自动注入 token + 401 刷新
class _AuthInterceptor extends Interceptor {
  final ApiClient _client;

  _AuthInterceptor(this._client);

  @override
  void onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
    if (!options.path.contains('/auth/')) {
      final token = await _client.accessToken;
      if (token != null) {
        options.headers['Authorization'] = 'Bearer $token';
      }
    }
    handler.next(options);
  }

  @override
  void onError(DioException err, ErrorInterceptorHandler handler) async {
    if (err.response?.statusCode == 401) {
      final refresh = await _client.refreshToken;
      if (refresh != null) {
        try {
          final response = await Dio(BaseOptions(baseUrl: baseUrl))
              .post('/api/auth/refresh', data: {'refreshToken': refresh});
          final data = response.data['data'];
          if (data != null) {
            await _client.saveTokens(data['accessToken'], data['refreshToken']);
            final opts = err.requestOptions;
            final token = data['accessToken'];
            opts.headers['Authorization'] = 'Bearer $token';
            final retryResponse = await Dio(BaseOptions(baseUrl: baseUrl)).fetch(opts);
            return handler.resolve(retryResponse);
          }
        } catch (e) { log('[ApiClient] token刷新失败: $e'); }
      }
      await _client.clearTokens();
    }
    handler.next(err);
  }
}