import 'dart:convert';
import 'dart:io' show Platform;

import 'package:cupertino_http/cupertino_http.dart';
import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:http/http.dart' as http;

import '../auth/session_store.dart';
import '../config/app_config.dart';
import 'models.dart';

/// 后端账号/支付/授权 API 客户端（契约见 docs/PaymentApi.md）。
/// 后端未部署或请求失败时抛出 [OrderApiException]；登录失效抛出 [SessionExpiredException]，
/// 由 UI 层回登录页。
class OrderApiException implements Exception {
  final String message;
  const OrderApiException(this.message);

  @override
  String toString() => message;
}

/// 登录已失效（后端返回 code 61）：token 过期/被清，UI 应清除会话回登录页
class SessionExpiredException extends OrderApiException {
  const SessionExpiredException() : super('登录已失效，请重新登录');
}

class OrderApi {
  final String baseUrl;
  final SessionStore sessionStore;
  final http.Client _client;

  // iOS 26 对 dart:io 原生 socket 访问本地网络存在拦截 bug（权限已允许仍
  // 拒绝连接），改用 NSURLSession 网络栈（CupertinoClient）绕过；非 Apple
  // 平台回退 IOClient。
  OrderApi({String? baseUrl, required this.sessionStore, http.Client? client})
      : baseUrl = baseUrl ?? AppConfig.apiBaseUrl,
        _client = client ?? _defaultHttpClient();

  static http.Client _defaultHttpClient() {
    if (!kIsWeb && Platform.isIOS) {
      return CupertinoClient.defaultSessionConfiguration();
    }
    return http.Client();
  }

  /// 注册账号；重复注册等业务错误由 [_decode] 抛出
  Future<void> register({
    required String phone,
    required String password,
  }) async {
    final res = await _post('/api/v1/auth/register',
        jsonEncode({'phone': phone, 'password': password}),
        auth: false);
    _decode(res);
  }

  /// 登录，成功返回 token（由调用方存入 SessionStore）
  Future<String> login({
    required String phone,
    required String password,
  }) async {
    final res = await _post('/api/v1/auth/login',
        jsonEncode({'phone': phone, 'password': password}),
        auth: false);
    final json = _decode(res);
    return json['token'] as String;
  }

  /// 创建订单，返回支付参数（微信 prepay 参数或支付宝 orderStr）
  Future<Order> createOrder({
    required String planId,
    required PayChannel channel,
  }) async {
    final body = jsonEncode({'planId': planId, 'channel': channel.name});
    final res = await _post('/api/v1/orders', body);
    final json = _decode(res);
    final params = (json['payParams'] as Map?)?.cast<String, dynamic>() ?? {};
    return Order(
      orderId: json['orderId'] as String,
      wechatParams: params,
      alipayOrderStr: params['orderStr'] as String?,
    );
  }

  /// 客户端支付完成后通知服务端（幂等），服务端据异步回调落授权
  Future<void> confirmOrder(String orderId) async {
    final res =
        await _post('/api/v1/orders/$orderId/confirm', jsonEncode({}));
    _decode(res);
  }

  /// 拉取套餐价格方案（config.yml 静态定价，客户端不硬编码）
  Future<List<Plan>> fetchPlans() async {
    final http.Response res;
    try {
      res = await _client.get(
        Uri.parse('$baseUrl/api/v1/plans'),
        headers: {'Accept': 'application/json', ...await _authHeaders()},
      ).timeout(const Duration(seconds: 15));
    } catch (e) {
      if (e is OrderApiException) rethrow;
      throw OrderApiException('网络请求失败: $e');
    }
    final json = _decode(res);
    return (json['list'] as List)
        .map((e) => Plan.fromJson(e as Map<String, dynamic>))
        .toList();
  }

  /// 查询授权状态（服务端为准）
  Future<LicenseStatus> fetchLicense() async {
    final http.Response res;
    try {
      res = await _client.get(
        Uri.parse('$baseUrl/api/v1/license'),
        headers: {'Accept': 'application/json', ...await _authHeaders()},
      ).timeout(const Duration(seconds: 15));
    } catch (e) {
      if (e is OrderApiException) rethrow;
      throw OrderApiException('网络请求失败: $e');
    }
    final json = _decode(res);
    return LicenseStatus.fromJson(json);
  }

  Future<http.Response> _post(String path, String body,
      {bool auth = true}) async {
    try {
      return await _client
          .post(
            Uri.parse('$baseUrl$path'),
            headers: {
              'Content-Type': 'application/json',
              ...auth ? await _authHeaders() : const <String, String>{},
            },
            body: body,
          )
          .timeout(const Duration(seconds: 15));
    } catch (e) {
      if (e is OrderApiException) rethrow;
      throw OrderApiException('网络请求失败: $e');
    }
  }

  Future<Map<String, String>> _authHeaders() async {
    final token = await sessionStore.readToken();
    if (token == null || token.isEmpty) {
      throw const SessionExpiredException();
    }
    return {'Authorization': 'Bearer $token'};
  }

  Map<String, dynamic> _decode(http.Response res) {
    final Map<String, dynamic> json;
    try {
      json = jsonDecode(res.body) as Map<String, dynamic>;
    } catch (_) {
      throw OrderApiException('服务端响应异常 (${res.statusCode})');
    }
    if (res.statusCode != 200 || json['code'] != 0) {
      final message = json['message'] as String? ?? '服务端错误 (${res.statusCode})';
      if (json['code'] == 61) {
        throw const SessionExpiredException();
      }
      throw OrderApiException(message);
    }
    return json['data'] as Map<String, dynamic>;
  }
}