import 'dart:math';

import '../../../../core/logging/logger.dart';
import '../../../../core/network/api_problem.dart';
import '../apis/divination_api.dart';
import '../models/divination_backend_models.dart';
import '../models/divination_params.dart';

class DivinationRunService {
  const DivinationRunService({required DivinationApi api}) : _api = api;

  final DivinationApi _api;
  static final Logger _logger = getLogger('features.divination.run_service');

  Future<PointsBalanceData> getPointsBalance() {
    return _api.getPointsBalance();
  }

  Future<DivinationRunAggregate> run({
    required DivinationParams params,
    required List<YaoType> yaoStates,
    void Function()? onDerived,
    void Function()? onTextMessageEnd,
  }) async {
    final threadId = _uuidV4();
    final runId = 'run_${DateTime.now().millisecondsSinceEpoch}';
    await _api.enqueueRun(
      params: params,
      yaoStates: yaoStates,
      threadId: threadId,
      runId: runId,
    );

    DerivedDivinationData? derived;
    String signLevel = '';
    String summary = '';
    List<String> conclusion = const <String>[];
    List<String> focusPoints = const <String>[];
    List<String> advice = const <String>[];
    List<String> keywords = const <String>[];
    String answer = '';

    await for (final event in _api.streamEvents(
      threadId: threadId,
      runId: runId,
    )) {
      final type = event['type'] as String? ?? '';
      _logger.debug(
        message: 'Received run SSE event',
        extra: <String, dynamic>{
          'threadId': threadId,
          'runId': runId,
          'type': type,
        },
      );
      if (type == 'DIVINATION_DERIVED') {
        final payload = event['divination'];
        if (payload is! Map<String, dynamic>) {
          throw const FormatException('DIVINATION_DERIVED 缺少 divination 结构');
        }
        derived = DerivedDivinationData.fromJson(payload);
        onDerived?.call();
        continue;
      }
      if (type == 'TEXT_MESSAGE_END') {
        signLevel = _requiredString(event, 'sign_level');
        summary = _requiredString(event, 'summary');
        conclusion = _requiredStringList(event, 'conclusion');
        focusPoints = _requiredStringList(event, 'focus_points');
        advice = _requiredStringList(event, 'advice');
        keywords = _requiredStringList(event, 'keywords');
        answer = _requiredString(event, 'answer');
        onTextMessageEnd?.call();
        continue;
      }
      if (type == 'RUN_ERROR') {
        _logger.warning(
          message: 'Run ended with RUN_ERROR event',
          extra: <String, dynamic>{
            'threadId': threadId,
            'runId': runId,
            'code': event['code'],
            'detail': event['detail'],
            'message': event['message'],
          },
        );
        throw ApiProblem(
          status: 500,
          title: 'Run failed',
          detail: event['detail'] as String? ?? '解卦失败',
          code: event['code'] as String?,
        );
      }
      if (type == 'RUN_FINISHED') {
        break;
      }
    }

    if (derived == null) {
      _logger.warning(
        message: 'Missing DIVINATION_DERIVED before RUN_FINISHED',
        extra: <String, dynamic>{'threadId': threadId, 'runId': runId},
      );
      throw const FormatException('未收到 DIVINATION_DERIVED 事件');
    }

    return DivinationRunAggregate(
      derived: derived,
      signLevel: signLevel,
      summary: summary,
      conclusion: conclusion,
      focusPoints: focusPoints,
      advice: advice,
      keywords: keywords,
      answer: answer,
    );
  }

  String _requiredString(Map<String, dynamic> json, String key) {
    final value = json[key];
    if (value is! String || value.isEmpty) {
      throw FormatException('缺少字段: $key');
    }
    return value;
  }

  List<String> _requiredStringList(Map<String, dynamic> json, String key) {
    final raw = json[key];
    if (raw is! List<dynamic>) {
      throw FormatException('缺少列表字段: $key');
    }
    return raw
        .map((item) {
          if (item is! String || item.isEmpty) {
            throw FormatException('字段 $key 存在非法项');
          }
          return item;
        })
        .toList(growable: false);
  }

  String _uuidV4() {
    final random = Random.secure();
    final bytes = List<int>.generate(16, (_) => random.nextInt(256));
    bytes[6] = (bytes[6] & 0x0f) | 0x40;
    bytes[8] = (bytes[8] & 0x3f) | 0x80;
    String toHex(int b) => b.toRadixString(16).padLeft(2, '0');
    final b = bytes.map(toHex).toList(growable: false);
    return '${b[0]}${b[1]}${b[2]}${b[3]}-${b[4]}${b[5]}-${b[6]}${b[7]}-${b[8]}${b[9]}-${b[10]}${b[11]}${b[12]}${b[13]}${b[14]}${b[15]}';
  }
}