// lib/services/gnss/gnss_service.dart
import 'dart:async';
import 'package:get/get.dart';
import 'package:nmea/nmea.dart';
import '../../gnss_sentences/gngga.dart';
import 'gnss_connection.dart';
import 'bt_serial_gnss_connection.dart';
import 'ble_gnss_connection.dart';

class GnssService extends GetxService {
  static GnssService get to => Get.find();

  GnssConnection? _connection;

  // Reaktív állapot — a controllerek Obx-szel figyelhetik
  final connectionState = GnssConnectionState.disconnected.obs;
  final activeConnectionType = Rxn<GnssConnectionType>();

  // Parsed NMEA adatok
  final latitude = 0.0.obs;
  final longitude = 0.0.obs;
  final altitude = 0.0.obs;
  final geoidSeparation = 0.0.obs;
  final gpsQuality = 0.obs;
  final utcFix = ''.obs;
  final satelliteCount = 0.obs;
  final hdop = 0.0.obs;

  final NmeaDecoder _decoder = NmeaDecoder();
  StreamSubscription? _nmeaSub;
  StreamSubscription? _stateSub;

  @override
  void onInit() {
    super.onInit();
    _decoder.registerTalkerSentence('GGA', (l) => Gngga(raw: l));
  }

  // ── Kapcsolódás ──────────────────────────────────────────────────

  Future<void> connectBtSerial(String macAddress) async {
    await _disconnect();
    _connection = BtSerialGnssConnection();
    activeConnectionType.value = GnssConnectionType.btSerial;
    await _doConnect(macAddress);
  }

  Future<void> connectBle(
    String deviceId, {
    String? serviceUuid,
    String? txCharUuid,
  }) async {
    await _disconnect();
    _connection = BleGnssConnection(
      serviceUuid: serviceUuid ?? '6e400001-b5b3-f393-e0a9-e50e24dcca9e',
      txCharUuid: txCharUuid ?? '6e400003-b5b3-f393-e0a9-e50e24dcca9e',
    );
    activeConnectionType.value = GnssConnectionType.ble;
    await _doConnect(deviceId);
  }

  Future<void> _doConnect(String address) async {
    _stateSub = _connection!.connectionState.listen((s) {
      connectionState.value = s;
    });
    _nmeaSub = _connection!.nmeaLines.listen(_parseNmea);
    await _connection!.connect(address);
  }

  Future<void> _disconnect() async {
    await _nmeaSub?.cancel();
    await _stateSub?.cancel();
    await _connection?.disconnect();
    _connection?.dispose();
    _connection = null;
  }

  // ── NMEA parsing — egy helyen, nem háromban ──────────────────────

  void _parseNmea(String line) {
    if (!line.startsWith('\$GNGGA') && !line.startsWith('\$GPGGA')) return;

    try {
      final sentence = _decoder.decode(line);
      if (sentence == null || !sentence.valid || sentence is! Gngga) return;
      if (sentence.gpsQualityIndicator == 0) return;

      latitude.value = sentence.latitude;
      longitude.value = sentence.longitude;
      altitude.value = sentence.altitudeAboveMeanSeaLevel;
      geoidSeparation.value = sentence.geoidSeparation;
      gpsQuality.value = sentence.gpsQualityIndicator;
      utcFix.value = sentence.utcOfPositionFix;
      satelliteCount.value = sentence.numberOfSvsInUse;
      hdop.value = sentence.hdop;
    } catch (_) {}
  }

  @override
  void onClose() {
    _disconnect();
    super.onClose();
  }
}