import 'dart:async';
import 'dart:convert';

import 'package:crypto/crypto.dart';
import 'package:device_info_plus/device_info_plus.dart';
import 'package:flutter/foundation.dart';

import '../api/api_client.dart';
import '../api/proxy_client.dart';
import '../api/services/user_api.dart';
import '../referrer/referrer_service.dart';
import '../user/user_state.dart';

/// 认证服务：APP 启动时执行快速登录
class AuthService {
  AuthService._();

  static const _tag = '[AuthService]';

  static Future<void>? _loginFuture;

  /// 登录完成后的 Future，需鉴权接口应 await 此 Future 再请求
  static Future<void> get loginComplete =>
      _loginFuture ?? Future<void>.value();

  static void _log(String msg) {
    debugPrint('$_tag $msg');
  }

  /// 获取设备 ID（Android: androidId, iOS: identifierForVendor, Web:  fallback）
  static Future<String> _getDeviceId() async {
    final deviceInfo = DeviceInfoPlugin();
    switch (defaultTargetPlatform) {
      case TargetPlatform.android:
        final android = await deviceInfo.androidInfo;
        return android.id;
      case TargetPlatform.iOS:
        final ios = await deviceInfo.iosInfo;
        return ios.identifierForVendor ?? 'ios-unknown';
      default:
        return 'device-${DateTime.now().millisecondsSinceEpoch}';
    }
  }

  /// 计算 sign：MD5(deviceId) 大写 32 位
  static String _computeSign(String deviceId) {
    final bytes = utf8.encode(deviceId);
    final digest = md5.convert(bytes);
    return digest.toString().toUpperCase();
  }

  /// APP 启动时调用快速登录
  /// 启动时网络可能未就绪，会延迟后重试
  static Future<void> init() async {
    if (_loginFuture != null) return _loginFuture!;
    final completer = Completer<void>();
    _loginFuture = completer.future;

    _log('init: 开始快速登录');
    const maxRetries = 3;
    const retryDelay = Duration(seconds: 2);

    try {
      // 等待网络就绪（浏览器能访问但 App 报错时，多为启动时网络未初始化）
      await Future<void>.delayed(const Duration(seconds: 2));

      final deviceId = await _getDeviceId();
      _log('init: deviceId=$deviceId');

      final sign = _computeSign(deviceId);
      _log('init: sign=$sign');

      final crest = await ReferrerService.getReferrer();
      if (crest != null && crest.isNotEmpty) {
        _log('init: crest(referrer)=$crest');
      }

      ApiResponse? res;
      for (var i = 0; i < maxRetries; i++) {
        if (i > 0) {
          _log('init: 第 ${i + 1} 次重试，等待 ${retryDelay.inSeconds}s...');
          await Future<void>.delayed(retryDelay);
        }
        try {
          res = await UserApi.fastLogin(
            origin: deviceId,
            resolution: sign,
            digest: crest ?? '',
            crest: crest,
          );
          break;
        } catch (e) {
          _log('init: 第 ${i + 1} 次请求失败: $e');
          if (i == maxRetries - 1) rethrow;
        }
      }

      if (res == null) return;

      _log('init: 登录结果 code=${res.code} msg=${res.msg}');

      if (res.isSuccess && res.data != null) {
        final data = res.data as Map<String, dynamic>?;
        final token = data?['reevaluate'] as String?;
        if (token != null && token.isNotEmpty) {
          ApiClient.instance.setUserToken(token);
          _log('init: 已设置 userToken');
        } else {
          _log('init: 响应中无 reevaluate (userToken)');
        }
        final credits = data?['reveal'] as int?;
        if (credits != null) {
          UserState.setCredits(credits);
          _log('init: 已同步积分 $credits');
        }
        final uid = data?['asset'] as String?;
        if (uid != null && uid.isNotEmpty) {
          UserState.setUserId(uid);
          _log('init: 已设置 userId');
        }
        final avatarUrl = data?['realm'] as String?;
        if (avatarUrl != null && avatarUrl.isNotEmpty) {
          UserState.setAvatar(avatarUrl);
        }
        final name = data?['terminal'] as String?;
        if (name != null && name.isNotEmpty) {
          UserState.setUserName(name);
        }
      } else {
        _log('init: 登录失败');
      }
    } catch (e, st) {
      _log('init: 异常 $e');
      _log('init: 堆栈 $st');
    } finally {
      if (!completer.isCompleted) completer.complete();
    }
  }
}