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

import 'package:android_id/android_id.dart';
import 'package:collection/collection.dart';
import 'package:crypto/crypto.dart';
import 'package:device_info_plus/device_info_plus.dart';
import 'package:flutter/foundation.dart';
import 'package:screen_secure/screen_secure.dart';
import 'package:shared_preferences/shared_preferences.dart';

import '../adjust/adjust_events.dart';
import '../api/api_client.dart';
import 'auth_token_store.dart';
import '../api/api_config.dart';
import '../api/proxy_client.dart';
import '../api/services/user_api.dart';
import '../log/app_logger.dart';
import '../referrer/referrer_service.dart';
import '../user/user_state.dart';

/// 用于判断 common_info 是否改变了首页结构（分类栏 / 列表数据源）
class _HomeExtSnapshot {
  _HomeExtSnapshot(this.needWait, this.items);

  final bool? needWait;
  final List<dynamic>? items;

  factory _HomeExtSnapshot.capture() {
    final raw = UserState.extConfigItems.value;
    return _HomeExtSnapshot(
      UserState.needShowVideoMenu.value,
      raw == null ? null : List<dynamic>.from(raw),
    );
  }

  static bool needsFullHomeReload(_HomeExtSnapshot before, _HomeExtSnapshot after) {
    if (before.needWait != after.needWait) return true;
    return !const DeepCollectionEquality().equals(before.items, after.items);
  }
}

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

  static final _log = AppLogger('AuthService');

  static Future<void>? _loginFuture;

  /// 登录是否已完成，用于 UI 控制（如登录中隐藏页面加载指示器）
  static final ValueNotifier<bool> isLoginComplete = ValueNotifier(false);

  /// 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 _logMsg(String msg) {
    _log.d(msg);
  }

  static const _prefsKeyFallbackDeviceId = 'persisted_device_id';

  /// 设备唯一标识（用于 fast_login origin 等）。
  ///
  /// - **Android**：`Settings.Secure.ANDROID_ID`（[`android_id`](https://pub.dev/packages/android_id)）。\
  ///   注意：`device_info_plus` 的 `AndroidDeviceInfo.id` 实为 **`Build.ID`（ROM 构建号）**，同版本机型大量相同，**不能**当设备 ID。
  /// - **iOS**：`identifierForVendor`（同厂商应用间稳定；卸载同厂商全部应用后会变）。
  /// - **其它 / 读失败**：写入 SharedPreferences 的随机 id，保证进程内稳定且极低碰撞概率。
  static Future<String> _getDeviceId() async {
    switch (defaultTargetPlatform) {
      case TargetPlatform.android:
        final androidId = await const AndroidId().getId();
        if (androidId != null && androidId.isNotEmpty) {
          return androidId;
        }
        _logMsg('_getDeviceId: ANDROID_ID 为空，使用本地持久化 fallback');
        return _persistedFallbackDeviceId();
      case TargetPlatform.iOS:
        final ios = await DeviceInfoPlugin().iosInfo;
        final idfv = ios.identifierForVendor;
        if (idfv != null && idfv.isNotEmpty) return idfv;
        return _persistedFallbackDeviceId();
      default:
        return _persistedFallbackDeviceId();
    }
  }

  static Future<String> _persistedFallbackDeviceId() async {
    final prefs = await SharedPreferences.getInstance();
    var id = prefs.getString(_prefsKeyFallbackDeviceId);
    if (id != null && id.isNotEmpty) return id;
    final random = Random.secure();
    final bytes = List<int>.generate(16, (_) => random.nextInt(256));
    id = base64UrlEncode(bytes).replaceAll('=', '');
    await prefs.setString(_prefsKeyFallbackDeviceId, id);
    _logMsg('_getDeviceId: 已生成并持久化 fallback id');
    return id;
  }

  /// 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();
  }

  /// 根据 extConfig.safe_area 启用/禁用系统截屏防护
  static Future<void> _applyScreenSecure(bool? safeArea) async {
    if (defaultTargetPlatform != TargetPlatform.android &&
        defaultTargetPlatform != TargetPlatform.iOS) {
      return;
    }
    try {
      await ScreenSecure.init(screenshotBlock: false, screenRecordBlock: false);
      if (safeArea == true) {
        await ScreenSecure.enableScreenshotBlock();
        await ScreenSecure.enableScreenRecordBlock();
        _logMsg('safe_area=true: 已启用截屏/录屏防护');
      } else {
        await ScreenSecure.disableScreenshotBlock();
        await ScreenSecure.disableScreenRecordBlock();
        _logMsg('safe_area=$safeArea: 已关闭截屏/录屏防护');
      }
    } on ScreenSecureException catch (e) {
      _logMsg('ScreenSecure 设置失败: ${e.message}');
    }
  }

  /// 系统相册/相机 Activity 返回后，若开启了截屏防护（[UserState.safeArea]），部分机型会黑屏卡死甚至重启。
  /// 在整段选图流程外包一层：临时关闭防护，结束后按当前配置恢复。
  static Future<T> runWithNativeMediaPicker<T>(Future<T> Function() action) async {
    if (defaultTargetPlatform != TargetPlatform.android &&
        defaultTargetPlatform != TargetPlatform.iOS) {
      return await action();
    }
    try {
      await ScreenSecure.disableScreenshotBlock();
      await ScreenSecure.disableScreenRecordBlock();
      _logMsg('native media picker: ScreenSecure released');
    } on ScreenSecureException catch (e) {
      _logMsg('native media picker: disable failed: ${e.message}');
    }
    try {
      return await action();
    } finally {
      await _applyScreenSecure(UserState.safeArea.value);
    }
  }

  /// 将 common_info 响应保存到全局，并解析 surge 中的 lucky（是否开启三方支付）
  static void _saveCommonInfoToState(Map<String, dynamic> data) {
    final reveal = data['reveal'] as int?;
    if (reveal != null) UserState.setCredits(reveal);
    final realm = data['realm'] as String?;
    if (realm != null && realm.isNotEmpty) UserState.setAvatar(realm);
    final terminal = data['terminal'] as String?;
    if (terminal != null && terminal.isNotEmpty) {
      UserState.setUserName(terminal);
    }
    final navigate = data['navigate'] as String?;
    if (navigate != null) UserState.setNavigate(navigate);

    final surgeStr = data['surge'] as String?;
    if (surgeStr != null && surgeStr.isNotEmpty) {
      try {
        final surge = json.decode(surgeStr) as Map<String, dynamic>?;
        if (surge != null) {
          final enable = surge['lucky'] as bool?;
          UserState.setEnableThirdPartyPayment(enable);
          // extConfig：need_wait = 是否展示 Video 菜单，safe_area = 是否防止截屏，items = 图片列表（见 docs/extConfig.md）
          final needWait = surge['need_wait'] as bool?;
          final safeArea = surge['safe_area'] as bool?;
          final items = surge['items'] as List<dynamic>?;
          UserState.setExtConfig(
            needShowVideoMenuValue: needWait,
            safeAreaValue: safeArea,
            items: items,
          );
          _applyScreenSecure(safeArea);
        }
      } catch (e) {
        _logMsg('surge JSON 解析失败: $e');
      }
    }
  }

  /// 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;

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

    try {
      // 极短让步：避免个别机型刚起进程时网络栈未就绪；过长会拖慢冷启动
      await Future<void>.delayed(const Duration(milliseconds: 400));

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

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

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

      await AuthTokenStore.restoreToApiClient();
      if (ApiClient.instance.proxy.userToken != null &&
          ApiClient.instance.proxy.userToken!.isNotEmpty) {
        _logMsg('init: 已用本地 token 注入请求头，本次 fast_login 将携带 knight');
      }

      ApiResponse? res;
      for (var i = 0; i < maxRetries; i++) {
        if (i > 0) {
          _logMsg('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) {
          _logMsg('init: 第 ${i + 1} 次请求失败: $e');
          if (i == maxRetries - 1) rethrow;
        }
      }

      if (res == null) return;

      _logMsg('init: 登录结果 code=${res.code} msg=${res.msg}');
      _logMsg('init: 登录响应 data=${res.data}');

      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);
          await AuthTokenStore.write(token);
          _logMsg('init: 已设置 userToken 并写入本地');
        } else {
          _logMsg('init: 响应中无 reevaluate (userToken)，保留原本地 token（若有）');
        }
        // equip = 服务端 firstRegister（见 docs/user_login.md），为 true/1 时上报注册事件
        final equipRaw = data?['equip'];
        final equipFirstRegister = equipRaw == true ||
            equipRaw == 1 ||
            equipRaw == '1' ||
            (equipRaw is String && equipRaw.toLowerCase() == 'true');
        if (equipFirstRegister) {
          AdjustEvents.trackRegister();
          final prefs = await SharedPreferences.getInstance();
          await prefs.setString(
            'adjust_register_date',
            DateTime.now().toIso8601String().substring(0, 10),
          );
          _logMsg('init: equip=true 首次注册，已上报 register');
        }
        final credits = data?['reveal'] as int?;
        if (credits != null) {
          UserState.setCredits(credits);
          _logMsg('init: 已同步积分 $credits');
        }
        final uid = data?['asset'] as String?;
        if (uid != null && uid.isNotEmpty) {
          UserState.setUserId(uid);
          _logMsg('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);
        }
        final countryCode = data?['navigate'] as String?;
        if (countryCode != null) {
          UserState.setNavigate(countryCode);
        }

        // 3. 归因与 common_info：后台执行，不阻塞 loginComplete（避免服务端慢/挂起导致一直卡在启动遮罩）
        unawaited(_runPostLoginReferrerWork(uid!, deviceId));
      } else {
        _logMsg('init: 登录失败');
      }
    } catch (e, st) {
      _logMsg('init: 异常 $e');
      _logMsg('init: 堆栈 $st');
    } finally {
      if (!completer.isCompleted) {
        completer.complete();
        isLoginComplete.value = true;
      }
    }
  }

  static bool _applyCommonInfoAndDidHomeStructureChange(ApiResponse commonRes) {
    if (!commonRes.isSuccess || commonRes.data == null) return false;
    final commonData = commonRes.data as Map<String, dynamic>?;
    if (commonData == null) return false;
    final before = _HomeExtSnapshot.capture();
    _saveCommonInfoToState(commonData);
    final after = _HomeExtSnapshot.capture();
    final changed = _HomeExtSnapshot.needsFullHomeReload(before, after);
    if (changed) {
      _logMsg('common_info 已更新，need_wait/items 相对上次有结构性变化');
    }
    _logMsg('common_info 响应已应用');
    return changed;
  }

  /// 依次上报 android_adjust、gg（均等待服务端返回，成败都继续）；结束后统一拉 common_info 更新 extConfig
  static Future<void> _reportBothReferrersAndRefreshCommonInfo(
    String uid,
    String deviceId,
  ) async {
    final adjustDigest = await ReferrerService.getAdjustReferrerDigest();
    final ggDigest = await ReferrerService.getGgReferrerDigest();

    final rAdjust = await UserApi.referrer(
      sentinel: ApiConfig.appId,
      asset: uid,
      digest: adjustDigest,
      origin: deviceId,
      accolade: 'android_adjust',
    );
    if (rAdjust.isSuccess) {
      _logMsg('referrer(android_adjust) 成功');
    } else {
      _logMsg(
          'referrer(android_adjust) 失败: code=${rAdjust.code} msg=${rAdjust.msg}');
    }

    final rGg = await UserApi.referrer(
      sentinel: ApiConfig.appId,
      asset: uid,
      digest: ggDigest,
      origin: deviceId,
      accolade: 'gg',
    );
    if (rGg.isSuccess) {
      _logMsg('referrer(gg) 成功');
    } else {
      _logMsg('referrer(gg) 失败: code=${rGg.code} msg=${rGg.msg}');
    }

    final commonRes = await UserApi.getCommonInfo(
      sentinel: ApiConfig.appId,
      asset: uid,
    );
    if (_applyCommonInfoAndDidHomeStructureChange(commonRes)) {
      UserState.requestHomeFullReload();
    } else if (!commonRes.isSuccess) {
      _logMsg(
          'common_info 失败: code=${commonRes.code} msg=${commonRes.msg}');
    }
  }

  static Future<void> _runPostLoginReferrerWork(String uid, String deviceId) async {
    try {
      await _reportBothReferrersAndRefreshCommonInfo(uid, deviceId);
    } catch (e, _) {
      _logMsg('referrer/common_info 后台任务失败: $e');
    }
  }
}