import 'dart:async';
import 'package:flutter/services.dart';

/// PDA服务类，用于处理扫描和RFID功能
class PdaService {
  static const MethodChannel _methodChannel = MethodChannel(
    'com.vber.chicken_farm/pda_scanner',
  );

  static const EventChannel _eventChannel = EventChannel(
    'com.vber.chicken_farm/pda_scanner_event',
  );

  static final PdaService _instance = PdaService._internal();
  factory PdaService() => _instance;
  PdaService._internal();

  StreamSubscription? _scanSubscription;
  final StreamController<String?> _scanResultController =
      StreamController<String?>.broadcast();

  /// 扫描条形码/二维码
  Future<void> scanBarcode() async {
    try {
      await _methodChannel.invokeMethod('scanBarcode');
    } on PlatformException catch (e) {
      print("扫描失败: ${e.message}");
    }
  }

  /// 读取RFID
  Future<String?> readRfid() async {
    try {
      final String? rfid = await _methodChannel.invokeMethod('readRfid');
      return rfid;
    } on PlatformException catch (e) {
      print("读取RFID失败: ${e.message}");
      return null;
    }
  }

  /// 写入RFID
  Future<String?> writeRfid(String data) async {
    try {
      final String? result = await _methodChannel.invokeMethod('writeRfid', {
        'data': data,
      });
      return result;
    } on PlatformException catch (e) {
      print("写入RFID失败: ${e.message}");
      return null;
    }
  }

  /// 监听扫描结果
  Stream<String?> get scanResults => _scanResultController.stream;

  /// 开始监听扫描结果
  void startListeningScanResults() {
    _scanSubscription = _eventChannel.receiveBroadcastStream().listen(
      (dynamic result) {
        _scanResultController.sink.add(result as String?);
      },
      onError: (dynamic error) {
        print("接收扫描结果出错: $error");
        _scanResultController.sink.add(null);
      },
    );
  }

  /// 停止监听扫描结果
  void stopListeningScanResults() {
    _scanSubscription?.cancel();
    _scanSubscription = null;
  }

  /// 释放资源
  void dispose() {
    stopListeningScanResults();
    _scanResultController.close();
  }
}