import 'dart:async';
import 'package:flutter/material.dart';
import '../data/models/coin.dart';
import '../data/models/order_book.dart';
import '../data/services/market_service.dart';
import '../data/services/trade_service.dart';

/// 交易頁狀態管理 — 輪詢價格 + 訂單簿
class TradeProvider extends ChangeNotifier {
  final MarketService _marketService;
  // ignore: unused_field
  final TradeService _tradeService;

  TradeProvider(this._marketService, this._tradeService);

  Coin? _selectedCoin;
  OrderBookDepth _depth = const OrderBookDepth(asks: [], bids: [], spread: 0, spreadPercent: 0);
  bool _isLoadingDepth = false;
  String? _error;

  Timer? _pollTimer;
  static const _pollInterval = Duration(seconds: 5);

  Coin? get selectedCoin => _selectedCoin;
  OrderBookDepth get depth => _depth;
  bool get isLoadingDepth => _isLoadingDepth;
  String? get error => _error;

  /// 实时模拟价格（从 depth 轮询获取）
  double get currentPrice => _depth.currentPrice;
  double get change24h => _depth.change24h;
  double get high24h => _depth.high24h;
  double get low24h => _depth.low24h;
  double get volume24h => _depth.volume24h;

  /// 交易时段状态
  String get tradingStatus => _depth.tradingStatus;
  double? get targetLow => _depth.targetLow;
  double? get targetHigh => _depth.targetHigh;
  double? get targetClose => _depth.targetClose;
  bool get isTradable => tradingStatus == 'trading';

  void selectCoin(Coin coin) {
    if (_selectedCoin?.code == coin.code) return;
    _selectedCoin = coin;
    _depth = const OrderBookDepth(asks: [], bids: [], spread: 0, spreadPercent: 0);
    _error = null;
    notifyListeners();
    startPolling();
  }

  void clearSelection() {
    _selectedCoin = null;
    _depth = const OrderBookDepth(asks: [], bids: [], spread: 0, spreadPercent: 0);
    stopPolling();
    notifyListeners();
  }

  void startPolling() {
    stopPolling();
    _fetchDepth();
    _pollTimer = Timer.periodic(_pollInterval, (_) => _fetchDepth());
  }

  void stopPolling() {
    _pollTimer?.cancel();
    _pollTimer = null;
  }

  Future<void> _fetchDepth() async {
    if (_selectedCoin == null) return;
    final response = await _marketService.getDepth(_selectedCoin!.code);
    if (!response.success || response.data == null) return;

    _depth = OrderBookDepth.fromJson(response.data!);
    notifyListeners();
  }

  /// 刷新幣種價格（從 MarketProvider 的列表中找到最新價）
  void updateCoinPrice(Coin updatedCoin) {
    if (_selectedCoin?.code == updatedCoin.code) {
      _selectedCoin = updatedCoin;
      notifyListeners();
    }
  }

  @override
  void dispose() {
    stopPolling();
    super.dispose();
  }
}