import 'dart:convert';

import 'package:analytics_sdk/utils/device_fingerprint_util.dart';
import 'package:analytics_sdk/utils/logger.dart';
import 'package:crypto/crypto.dart';
import 'package:flutter/foundation.dart';

/// SDK 全局上下文：持有所有公共字段、提供 event_id 计算。
///
/// 作为 SDK 内部的单一状态来源（SSOT），所有事件构造时从此处读取公共字段。
/// 不对外暴露，接入方无需直接使用。
class SdkContext {
  /// SDK 版本号（写死，与 pubspec.yaml 保持一致）
  static const String kSdkVersion = '1.4.6';

  /// appVersion 公共字段默认值。
  /// 接入方未传 `appVersion`、或 release 模式下传入非法值时均使用该值，
  /// 保证事件 payload 与 `AnalyticsSdk.getParams()` 返回值保持一致。
  static const String kDefaultAppVersion = '1.0.0';

  /// 客户端事件签名规则版本。
  static const String kEventSignatureVersion = '2.0.0';

  static String _eventSignatureHmacKey = '';
  static String _eventSignatureVersion = kEventSignatureVersion;

  static String? _appId;
  static String? _channel;
  static String? _uid;
  static String? _appVersion;
  static String? _device;
  static String? _deviceId;
  static String? _deviceBrand;
  static String? _deviceModel;
  static String? _userAgent;
  static String? _systemName;
  static String? _systemVersion;
  static String? _deviceFingerprint;
  static String _fingerprintVersion = DeviceFingerprintUtil.kVersion;
  static Map<String, dynamic> _environmentFields = _defaultEnvironmentFields();

  /// SID 提供者（由 AnalyticsSdk.init() 注入）。
  /// 调用时同时返回当前 SID 并记录用户行为，避免 entity 层直接依赖 SessionManager。
  static String Function()? sidProvider;

  /// 配置公共字段
  ///
  /// 所有参数均为可选，非 null 值才会覆盖现有值。
  /// 通常在 [AnalyticsSdk.init] 中调用，也可在 init 之后按需更新。
  /// deviceFingerprint / fingerprintVersion 不再支持从外部传入。
  static void configure({
    String? appId,
    String? channel,
    String? uid,
    String? appVersion,
    String? device,
    String? deviceId,
    String? deviceBrand,
    String? deviceModel,
    String? userAgent,
    String? systemName,
    String? systemVersion,
    String? deviceFingerprint,
    String? fingerprintVersion,
    Map<String, dynamic>? environmentFields,
  }) {
    if (appId != null) _appId = appId;
    if (channel != null) _channel = channel;
    if (uid != null) _uid = uid;
    if (appVersion != null) {
      if (RegExp(r'^\d+\.\d+\.\d+$').hasMatch(appVersion)) {
        _appVersion = appVersion;
      } else if (kDebugMode) {
        Logger.analyticsSdk('appVersion 格式不正确，应为 x.y.z，当前值：$appVersion，已忽略',
            level: LogLevel.error);
      } else {
        _appVersion = kDefaultAppVersion;
      }
    }
    if (device != null) _device = device;
    if (deviceId != null) _deviceId = deviceId;
    if (deviceBrand != null) _deviceBrand = deviceBrand;
    if (deviceModel != null) _deviceModel = deviceModel;
    if (userAgent != null) _userAgent = userAgent;
    if (systemName != null) _systemName = systemName;
    if (systemVersion != null) _systemVersion = systemVersion;
    if (environmentFields != null) {
      _environmentFields = {
        ..._defaultEnvironmentFields(),
        ..._normalizeEnvironmentFields(environmentFields),
      };
    }
  }

  /// SDK 内部调用：重置自动生成的设备指纹状态。
  static void resetGeneratedDeviceFingerprint() {
    _deviceFingerprint = null;
    _fingerprintVersion = DeviceFingerprintUtil.kVersion;
  }

  /// SDK 内部调用：写入已生成的设备指纹。
  static void configureGeneratedDeviceFingerprint(String deviceFingerprint) {
    final normalized = deviceFingerprint.trim();
    _deviceFingerprint = normalized.isEmpty ? null : normalized;
    _fingerprintVersion = DeviceFingerprintUtil.kVersion;
  }

  /// 更新用户 ID（登录或切换账号时调用）
  static void setUid(String newUid) {
    _uid = newUid;
  }

  /// 更新渠道（渠道变更时调用）
  static void setChannel(String channel) {
    _channel = channel;
  }

  /// 增量更新系统、网络、硬件和浏览器环境快照字段。
  ///
  /// 用于网络、电量、充电状态等运行期可能变化的字段刷新。
  static void updateEnvironmentFields(Map<String, dynamic> fields) {
    if (fields.isEmpty) return;
    _environmentFields = {
      ..._environmentFields,
      ..._normalizeEnvironmentFields(fields),
    };
  }

  /// 配置客户端事件签名密钥。
  ///
  /// 密钥来自加密配置解密后的 `signKey`，不写入事件、payload、日志或缓存。
  static void configureEventSignature({
    String? signKey,
    String? version,
  }) {
    if (signKey != null) {
      _eventSignatureHmacKey = signKey.trim();
    }
    final normalizedVersion = version?.trim();
    if (normalizedVersion != null && normalizedVersion.isNotEmpty) {
      _eventSignatureVersion = normalizedVersion;
    }
  }

  /// 重置所有公共字段为 null（SDK 重新初始化时使用）
  ///
  /// 与 [configure] 不同，此方法会将所有字段清为 null，
  /// 而 configure 中传 null 表示"不修改"。
  static void reset() {
    _appId = null;
    _channel = null;
    _uid = null;
    _appVersion = null;
    _device = null;
    _deviceId = null;
    _deviceBrand = null;
    _deviceModel = null;
    _userAgent = null;
    _systemName = null;
    _systemVersion = null;
    _deviceFingerprint = null;
    _fingerprintVersion = DeviceFingerprintUtil.kVersion;
    _environmentFields = _defaultEnvironmentFields();
    _eventSignatureHmacKey = '';
    _eventSignatureVersion = kEventSignatureVersion;
    sidProvider = null;
  }

  // ──────── Getters（调试 / 外部复用） ────────────────────────────────────

  static String? get appId => _appId;
  static String? get channel => _channel;
  static String? get uid => _uid;
  static String? get appVersion => _appVersion;
  static String? get deviceId => _deviceId;
  static String? get deviceBrand => _deviceBrand;
  static String? get deviceModel => _deviceModel;
  static String get deviceFingerprint => _deviceFingerprint ?? '';
  static String get fingerprintVersion => _fingerprintVersion;
  static Map<String, dynamic> get environmentFields =>
      Map<String, dynamic>.from(_environmentFields);

  /// 获取设备公共字段（供产品方在服务端上报事件时复用）
  ///
  /// 返回的 Map 包含：sid、device、device_id、device_brand、device_model、
  /// user_agent、system_name、system_version、device_fingerprint、fp_version。
  /// 未配置的字段返回空字符串。
  static Map<String, String> getDeviceCommonFields() {
    String sid = '';
    try {
      sid = sidProvider?.call() ?? '';
    } catch (_) {
      // 未初始化或 SID 获取异常时保持为空，确保该读取 API 不抛异常。
    }

    return {
      'sid': sid,
      'device': _device ?? '',
      'device_id': _deviceId ?? '',
      'device_brand': _deviceBrand ?? '',
      'device_model': _deviceModel ?? '',
      'user_agent': _userAgent ?? '',
      'system_name': _systemName ?? '',
      'system_version': _systemVersion ?? '',
      'device_fingerprint': _deviceFingerprint ?? '',
      'fp_version': _fingerprintVersion,
    };
  }

  /// 获取系统、网络、硬件和浏览器环境快照字段。
  ///
  /// 仅供 SDK 内部构建 `sdk_init` 启动快照和少量汇总事件使用，普通事件公共字段
  /// 不再重复携带这些环境快照。
  static Map<String, dynamic> getEnvironmentSnapshotFields() {
    return Map<String, dynamic>.from(_environmentFields);
  }

  /// 给 SDK 客户端事件补充外层签名字段。
  ///
  /// 历史版本曾把轻量环境签名写入 payload；这里会清理这些保留字段，
  /// 避免同一事件同时出现新旧两套签名。
  static Map<String, dynamic> attachDeviceEnvIfNeeded(
    Map<String, dynamic> event,
  ) {
    final eventName = event['event']?.toString() ?? '';
    final isServerOnlyEvent = _serverOnlyEvents.contains(eventName);
    final result = Map<String, dynamic>.from(event);
    final existingPayload = result['payload'];
    final existingDeviceEnv = result.remove('device_env');

    if (existingPayload is Map || existingPayload == null) {
      final payload = <String, dynamic>{
        if (existingPayload is Map)
          ...Map<String, dynamic>.from(existingPayload),
        if (existingDeviceEnv is Map)
          ...Map<String, dynamic>.from(existingDeviceEnv),
      };
      payload.removeWhere(
          (key, _) => _reservedPayloadSignatureFields.contains(key));
      result['payload'] = payload;
    }

    if (!isServerOnlyEvent && _eventSignatureHmacKey.isNotEmpty) {
      final eventForSignature = Map<String, dynamic>.from(result);
      result['event_sig_version'] = _eventSignatureVersion;
      result['event_sig'] = _eventSignature(eventForSignature);
    }
    return result;
  }

  /// 生成公共字段 Map
  ///
  /// 包含所有客户端事件上报所需的公共字段：
  /// event、channel、app_id、uid、sid、client_ts、
  /// device、device_id、device_brand、device_model、
  /// user_agent、system_name、system_version、
  /// device_fingerprint、fp_version、sdk_version、app_version。
  ///
  /// 本方法永远不会抛出异常。
  static Map<String, dynamic> generateCommonFields(String event) {
    final now = DateTime.now();
    final clientTs = now.millisecondsSinceEpoch ~/ 1000;

    String sid;
    try {
      sid = sidProvider?.call() ?? 'fallback_${now.millisecondsSinceEpoch}';
    } catch (_) {
      sid = 'fallback_${now.millisecondsSinceEpoch}';
    }

    return {
      'event': event,
      'channel': _channel ?? '',
      'app_id': _appId ?? '',
      'uid': _uid ?? '',
      'sid': sid,
      'client_ts': clientTs,
      'device': _device ?? '',
      'device_id': _deviceId ?? '',
      'device_brand': _deviceBrand ?? '',
      'device_model': _deviceModel ?? '',
      'user_agent': _userAgent ?? '',
      'system_name': _systemName ?? '',
      'system_version': _systemVersion ?? '',
      'device_fingerprint': _deviceFingerprint ?? '',
      'fp_version': _fingerprintVersion,
      'sdk_version': kSdkVersion,
      'app_version': _appVersion ?? kDefaultAppVersion,
    };
  }

  /// 根据字段列表生成 event_id
  ///
  /// 计算规则：
  /// 1. 对每个字段值单独做 MD5
  /// 2. 将所有 MD5 用 `|` 拼接
  /// 3. 对拼接结果再做一次 MD5，作为最终 event_id
  ///
  /// **注意**：`device_fingerprint` 不参与 event_id 计算。
  /// 本方法永远不会抛出异常，失败时返回基于时间戳的备选 ID。
  static String generateEventId(List<String> fields) {
    try {
      final fieldDigests = <String>[];
      for (final value in fields) {
        final v = value;
        final bytes = utf8.encode(v);
        final digest = md5.convert(bytes);
        fieldDigests.add(digest.toString());
      }

      final joined = fieldDigests.join('|');
      final finalDigest = md5.convert(utf8.encode(joined));
      return finalDigest.toString();
    } catch (e) {
      try {
        final content = fields.join('|');
        return 'h${(content.hashCode & 0x7FFFFFFF).toRadixString(16)}';
      } catch (_) {
        return 't${DateTime.now().millisecondsSinceEpoch}';
      }
    }
  }

  static Map<String, dynamic> _defaultEnvironmentFields() => {
        'language': '',
        'timezone': '',
        'package_name': '',
        'screen_width': -1,
        'screen_height': -1,
        'screen_dpi': -1,
        'device_pixel_ratio': -1,
        'orientation': '',
        'screen_brightness': -1,
        'volume': -1,
        'is_screen_on': -1,
        'network_type': 'unknown',
        'battery_level': -1,
        'is_charging': -1,
        'battery_state': 'unknown',
        'cpu_cores': -1,
        'device_memory_gb': -1,
        'browser_name': '',
        'browser_version': '',
        'cookie_enabled': -1,
        'local_storage_enabled': -1,
        'touch_support': -1,
        'max_touch_points': -1,
        'color_depth': -1,
        'is_pwa': -1,
      };

  static Map<String, dynamic> _normalizeEnvironmentFields(
    Map<String, dynamic> fields,
  ) {
    final normalized = Map<String, dynamic>.from(fields);
    if (normalized.containsKey('device_pixel_ratio')) {
      normalized['device_pixel_ratio'] =
          _normalizeDevicePixelRatio(normalized['device_pixel_ratio']);
    }
    return normalized;
  }

  static int _normalizeDevicePixelRatio(dynamic value) {
    if (value == null) return -1;
    final ratio =
        value is num ? value.toDouble() : double.tryParse(value.toString());
    if (ratio == null || !ratio.isFinite) return -1;
    if (ratio > 10) return ratio.round();
    return (ratio * 100).round();
  }

  static const Set<String> _serverOnlyEvents = {
    'user_register',
    'user_login',
    'realtime_online',
    'order_created',
    'order_paid',
    'coin_consume',
    'video_status_change',
  };

  static const Set<String> _reservedPayloadSignatureFields = {
    'sdk_type',
    'client_type',
    'id_type',
    'event_sig',
    'event_sig_version',
    'security_key_version',
    'sign_algorithm',
    'sign_ts',
  };

  static String _eventSignature(
    Map<String, dynamic> event,
  ) {
    try {
      if (_eventSignatureHmacKey.isEmpty) return '';
      final factors = [
        event['event']?.toString() ?? '',
        event['event_id']?.toString() ?? '',
        event['app_id']?.toString() ?? '',
        event['client_ts']?.toString() ?? '',
        event['device_fingerprint']?.toString() ?? '',
      ];
      final signatureInput = factors.join('|');
      final signature = Hmac(sha256, utf8.encode(_eventSignatureHmacKey))
          .convert(utf8.encode(signatureInput))
          .toString();
      Logger.analyticsSdk(
        'event_sig input="$signatureInput" '
        'event_sig=$signature '
        'event_sig_version=$_eventSignatureVersion',
      );
      return signature;
    } catch (_) {
      return '';
    }
  }

  /// 从公共字段 Map 和业务特有字段列表生成 event_id。
  ///
  /// 本方法永远不会抛出异常。
  static String generateEventIdFromCommonFields(
      Map<String, dynamic> commonFields, List<String> extraFields) {
    return generateEventId([
      commonFields['event'] as String? ?? '',
      commonFields['app_id'] as String? ?? '',
      commonFields['channel'] as String? ?? '',
      commonFields['uid'] as String? ?? '',
      commonFields['device'] as String? ?? '',
      commonFields['device_id'] as String? ?? '',
      commonFields['device_brand'] as String? ?? '',
      commonFields['device_model'] as String? ?? '',
      (commonFields['client_ts'] ?? '').toString(),
      commonFields['sid'] as String? ?? '',
      ...extraFields,
    ]);
  }
}