import 'package:dio/dio.dart';

import 'package:yx_tracking_flutter/src/config/analytics_config.dart';
import 'package:yx_tracking_flutter/src/model/system_dim_info.dart';
import 'package:yx_tracking_flutter/src/network/http_client.dart';
import 'package:yx_tracking_flutter/src/storage/config_storage.dart';
import 'package:yx_tracking_flutter/src/storage/sqflite_config_storage.dart';
import 'package:yx_tracking_flutter/src/util/logger.dart';

/// Phase 2：配置拉取与缓存管理。
class ConfigManager {
  /// 创建配置管理器。
  ConfigManager({
    required this.config,
    this.refreshInterval = const Duration(hours: 12),
    ConfigStorage? storage,
    HttpClient? httpClient,
  })  : _httpClient = httpClient ?? HttpClient(config),
        _storage = storage ?? SqfliteConfigStorage();

  /// SDK 配置。
  final AnalyticsConfig config;

  /// 配置刷新间隔。
  final Duration refreshInterval;

  final HttpClient _httpClient;
  final ConfigStorage _storage;

  SystemDimInfo? _current;

  /// 当前缓存的配置（可能为空）。
  SystemDimInfo? get currentConfig => _current;

  /// 初始化本地缓存。
  Future<void> init() async {
    await _storage.init();
    _current = await _storage.loadSystemDimInfo();
    if (_current != null) {
      final eventCount = _current!.eventDefinitions.length;
      final tagCount = _current!.tagDefinitions.length;
      Logger.info(
        '已加载本地配置缓存: events=$eventCount, tags=$tagCount',
      );
    }
  }

  /// 拉取并缓存配置。
  Future<void> fetchAndCacheConfig({bool force = false}) async {
    if (!force && _shouldSkipFetch()) {
      final last = _current?.lastFetchedAt;
      Logger.info('配置未过期，跳过拉取: lastFetchedAt=$last');
      return;
    }

    try {
      final response = await _httpClient.get<dynamic>(
        config.getSystemAllDimInfoUri.toString(),
        queryParameters: <String, dynamic>{'systemCode': config.systemCode},
      );

      final payload = _extractPayloadMap(response.data);
      if (payload == null) {
        Logger.warn('配置拉取成功但响应结构无法解析，已忽略');
        return;
      }

      final version = response.headers.value('etag') ??
          response.headers.value('x-config-version');
      final info = SystemDimInfo.fromResponse(payload, version: version);

      await _storage.saveSystemDimInfo(info);
      _current = info;

      final eventCount = info.eventDefinitions.length;
      final tagCount = info.tagDefinitions.length;
      Logger.info(
        '配置拉取并缓存成功: events=$eventCount, tags=$tagCount',
      );
    } on DioException catch (e, st) {
      Logger.error('配置拉取失败（DioException）', e, st);
    } on Object catch (e, st) {
      Logger.error('配置拉取失败（未知异常）', e, st);
    }
  }

  /// 强制刷新配置。
  Future<void> forceRefresh() => fetchAndCacheConfig(force: true);

  /// 释放资源。
  Future<void> dispose() => _storage.dispose();

  bool _shouldSkipFetch() {
    final current = _current;
    if (current == null) {
      return false;
    }
    final age = DateTime.now().difference(current.lastFetchedAt);
    return age < refreshInterval;
  }

  Map<String, dynamic>? _extractPayloadMap(dynamic data) {
    final root = _asStringKeyMap(data);
    if (root == null) {
      return null;
    }

    if (_looksLikeDimInfo(root)) {
      return root;
    }

    for (final key in const <String>['data', 'result', 'payload']) {
      final nested = _asStringKeyMap(root[key]);
      if (nested != null && _looksLikeDimInfo(nested)) {
        return nested;
      }
    }

    Logger.warn('配置响应结构无法识别，已忽略');
    return null;
  }

  bool _looksLikeDimInfo(Map<String, dynamic> map) {
    return map.containsKey('systemEventTypes') ||
        map.containsKey('systemCustonTas') ||
        map.containsKey('systemCustomTags');
  }

  Map<String, dynamic>? _asStringKeyMap(dynamic value) {
    if (value is Map<String, dynamic>) {
      return value;
    }
    if (value is Map) {
      return value.map((k, v) => MapEntry(k.toString(), v));
    }
    return null;
  }
}