import 'dart:async';
import 'package:flutter/material.dart';
import '../data/models/kline_candle.dart';
import '../data/services/kline_service.dart';
import '../data/services/kline_websocket_service.dart';

/// K线状态管理
class KlineProvider extends ChangeNotifier {
  final KlineService _klineService;
  final KlineWebSocketService _wsService;

  KlineProvider(this._klineService, this._wsService);

  List<KlineCandle> _candles = [];
  KlineCandle? _currentCandle;
  String _interval = '1h';
  String _coinCode = '';
  bool _isLoading = false;
  bool _isLoadingMore = false;
  bool _isConnected = false;
  String? _error;

  StreamSubscription<KlineCandle>? _wsSubscription;
  Timer? _pollingTimer;

  // Getters
  List<KlineCandle> get candles => _candles;
  KlineCandle? get currentCandle => _currentCandle;
  String get interval => _interval;
  String get coinCode => _coinCode;
  bool get isLoading => _isLoading;
  bool get isLoadingMore => _isLoadingMore;
  bool get isConnected => _isConnected;
  String? get error => _error;

  /// 加载某个币种的K线数据
  Future<void> loadCoin(String coinCode, {String? interval}) async {
    _coinCode = coinCode;
    if (interval != null) _interval = interval;
    _candles = [];
    _currentCandle = null;
    _error = null;
    _isLoading = true;
    notifyListeners();

    try {
      // 1. 获取历史K线
      final response = await _klineService.fetchHistory(
        coinCode: _coinCode,
        interval: _interval,
        limit: 200,
      );
      if (response.success && response.data != null) {
        _candles = response.data!;
      }

      // 2. 获取当前K线
      final currentResponse = await _klineService.fetchCurrentCandle(
        coinCode: _coinCode,
        interval: _interval,
      );
      if (currentResponse.success && currentResponse.data != null) {
        _currentCandle = currentResponse.data;
      }

      // 3. 连接 WebSocket
      _connectWebSocket();

      _isLoading = false;
      notifyListeners();
    } catch (e) {
      _error = '加载K线数据失败: $e';
      _isLoading = false;
      notifyListeners();
    }
  }

  /// 切换周期
  Future<void> changeInterval(String newInterval) async {
    if (newInterval == _interval) return;

    _interval = newInterval;
    _candles = [];
    _currentCandle = null;

    // 重新加载
    await loadCoin(_coinCode, interval: newInterval);
  }

  /// 加载更多历史数据（分页）
  Future<void> loadMore() async {
    if (_isLoadingMore || _candles.isEmpty) return;
    _isLoadingMore = true;
    notifyListeners();

    try {
      final oldestTime = _candles.first.closeTime;
      final response = await _klineService.fetchHistory(
        coinCode: _coinCode,
        interval: _interval,
        limit: 200,
        before: oldestTime,
      );
      if (response.success && response.data != null) {
        _candles = [...response.data!, ..._candles];
      }
    } catch (_) {}

    _isLoadingMore = false;
    notifyListeners();
  }

  void _connectWebSocket() {
    // 取消之前的订阅
    _wsSubscription?.cancel();
    _wsService.unsubscribe(_coinCode);

    // 订阅新币种
    _wsService.connect();
    _wsSubscription = _wsService.subscribe(_coinCode).listen(
      _onTick,
      onError: (_) => _startPolling(),
      onDone: () => _startPolling(),
    );

    _isConnected = _wsService.isConnected;
    notifyListeners();
  }

  void _onTick(KlineCandle tick) {
    if (tick.interval != _interval) return;

    _isConnected = true;

    if (tick.isClosed) {
      // 收盘 tick → 添加到历史列表
      _candles.add(tick);
      _currentCandle = null;

      // 停止轮询（如果之前在轮询）
      _pollingTimer?.cancel();
      _pollingTimer = null;
    } else {
      // 进行中的 tick → 更新当前K线
      _currentCandle = tick;
    }

    notifyListeners();
  }

  /// WebSocket 断连时降级为 HTTP 轮询
  void _startPolling() {
    _isConnected = false;
    notifyListeners();

    _pollingTimer?.cancel();
    _pollingTimer = Timer.periodic(
      const Duration(seconds: 5),
      (_) => _pollCurrentCandle(),
    );
  }

  Future<void> _pollCurrentCandle() async {
    try {
      final response = await _klineService.fetchCurrentCandle(
        coinCode: _coinCode,
        interval: _interval,
      );
      if (response.success && response.data != null) {
        _currentCandle = response.data;
        notifyListeners();
      }
    } catch (_) {}
  }

  @override
  void dispose() {
    _wsSubscription?.cancel();
    _wsService.unsubscribe(_coinCode);
    _pollingTimer?.cancel();
    super.dispose();
  }
}