import 'dart:async';
import 'dart:io';
import 'package:beacon_scanner/beacon_scanner.dart';
import 'package:flutter/foundation.dart';
import 'package:geolocator/geolocator.dart';
import 'package:mymuseum_visitapp/Models/beaconSection.dart';
import 'package:mymuseum_visitapp/Models/visitContext.dart';
import 'package:mymuseum_visitapp/Services/assistantService.dart';
import 'package:mymuseum_visitapp/Services/Glasses/glasses_orchestrator.dart';
import 'package:mymuseum_visitapp/constants.dart';

/// Point de déclenchement géographique pour le TTS automatique.
class GeoTriggerPoint {
  final String id;
  final double latitude;
  final double longitude;
  final double radiusMeters;

  const GeoTriggerPoint({
    required this.id,
    required this.latitude,
    required this.longitude,
    this.radiusMeters = 20.0,
  });
}

/// Déclenche automatiquement une réponse TTS de l'assistant quand :
/// - Le visiteur entre dans le rayon d'un GeoTriggerPoint (GPS)
/// - Un beacon BLE est détecté à proximité (< [beaconProximityMeters])
///
/// Le mode proactif doit être activé dans [VisitAppContext.proactiveModeEnabled]
/// pour que les déclenchements soient actifs.
class GeoBeaconTriggerService {
  GeoBeaconTriggerService._();
  static final GeoBeaconTriggerService instance = GeoBeaconTriggerService._();

  static const double beaconProximityMeters = 3.0;
  static const int cooldownMillis = 30000; // 30s entre deux triggers du même point

  VisitAppContext? _visitAppContext;
  AssistantService? _assistantService;

  StreamSubscription<Position>? _geoSub;
  StreamSubscription<ScanResult>? _beaconSub;

  final List<GeoTriggerPoint> _geoPoints = [];
  final Set<String> _triggeredIds = {};
  final Map<String, int> _lastTriggerTime = {};

  bool _running = false;

  /// Lance le service.
  /// [geoPoints] : points de déclenchement GPS (à peupler depuis la configuration).
  Future<void> start({
    required VisitAppContext visitAppContext,
    List<GeoTriggerPoint> geoPoints = const [],
  }) async {
    if (_running) return;
    if (!Platform.isAndroid && !Platform.isIOS) return;

    _visitAppContext = visitAppContext;
    _assistantService = AssistantService(visitAppContext: visitAppContext);
    _geoPoints
      ..clear()
      ..addAll(geoPoints);
    _running = true;

    await _startGeoTracking();
    await _startBeaconTracking();

    debugPrint('[GeoBeaconTriggerService] Started — ${_geoPoints.length} geo points, beacons active');
  }

  Future<void> stop() async {
    await _geoSub?.cancel();
    await _beaconSub?.cancel();
    _geoSub = null;
    _beaconSub = null;
    _running = false;
    debugPrint('[GeoBeaconTriggerService] Stopped');
  }

  /// Recharge les GeoTriggerPoints (appeler après un changement de configuration).
  void updateGeoPoints(List<GeoTriggerPoint> points) {
    _geoPoints
      ..clear()
      ..addAll(points);
    _triggeredIds.clear();
  }

  // ── GPS ─────────────────────────────────────────────────────────────────────

  Future<void> _startGeoTracking() async {
    final permission = await Geolocator.checkPermission();
    if (permission == LocationPermission.denied ||
        permission == LocationPermission.deniedForever) {
      debugPrint('[GeoBeaconTriggerService] Location permission not granted');
      return;
    }

    _geoSub = Geolocator.getPositionStream(
      locationSettings: const LocationSettings(
        accuracy: LocationAccuracy.high,
        distanceFilter: 5,
      ),
    ).listen(_onPosition);
  }

  void _onPosition(Position position) {
    if (!_isProactiveModeActive()) return;

    for (final point in _geoPoints) {
      final dist = Geolocator.distanceBetween(
        position.latitude,
        position.longitude,
        point.latitude,
        point.longitude,
      );
      if (dist <= point.radiusMeters && _canTrigger(point.id)) {
        _trigger(
          triggerId: point.id,
          prompt: 'Tu es un guide audio de musée. '
              'Le visiteur vient d\'entrer dans la zone "${point.id}". '
              'Accueille-le et donne-lui une brève information de bienvenue en 2 phrases.',
        );
      }
    }
  }

  // ── Beacons ──────────────────────────────────────────────────────────────────

  Future<void> _startBeaconTracking() async {
    final ctx = _visitAppContext;
    if (ctx?.beaconSections == null || ctx!.beaconSections!.isEmpty) return;

    final regions = <Region>[
      if (Platform.isIOS)
        Region(
          identifier: 'GlassesBeacon',
          beaconId: IBeaconId(proximityUUID: 'FDA50693-A4E2-4FB1-AFCF-C6EB07647825'),
        )
      else
        Region(identifier: 'GlassesBeacon'),
    ];

    try {
      _beaconSub = BeaconScanner.instance
          .ranging(regions)
          .listen((ScanResult result) => _onBeaconResult(result));
    } catch (e) {
      debugPrint('[GeoBeaconTriggerService] Beacon scan error: $e');
    }
  }

  void _onBeaconResult(ScanResult result) {
    if (!_isProactiveModeActive()) return;
    final ctx = _visitAppContext;
    if (ctx?.beaconSections == null) return;

    for (final beacon in result.beacons) {
      if (beacon.accuracy > beaconProximityMeters) continue;

      final match = ctx!.beaconSections!.firstWhere(
        (bs) =>
            bs != null &&
            bs.minorBeaconId == beacon.id.minorId &&
            bs.configurationId == ctx.configuration?.id,
        orElse: () => null,
      );

      if (match?.sectionId != null && _canTrigger(match!.sectionId!)) {
        _trigger(
          triggerId: match.sectionId!,
          prompt: 'Tu es un guide audio de musée. '
              'Le visiteur est juste devant l\'œuvre ou l\'espace lié au point d\'intérêt "${match.sectionId}". '
              'Donne une présentation courte et engageante en 2-3 phrases.',
        );
      }
    }
  }

  // ── Déclenchement commun ─────────────────────────────────────────────────────

  bool _canTrigger(String id) {
    final now = DateTime.now().millisecondsSinceEpoch;
    final last = _lastTriggerTime[id] ?? 0;
    return (now - last) >= cooldownMillis;
  }

  bool _isProactiveModeActive() {
    return _visitAppContext?.proactiveModeEnabled == true &&
        _visitAppContext?.glassesEnabled == true;
  }

  Future<void> _trigger({
    required String triggerId,
    required String prompt,
  }) async {
    _lastTriggerTime[triggerId] = DateTime.now().millisecondsSinceEpoch;
    debugPrint('[GeoBeaconTriggerService] Trigger: $triggerId');

    try {
      final response = await _assistantService!.chat(
        message: prompt,
        configurationId: _visitAppContext?.configuration?.id,
      );

      if (response.reply.isNotEmpty) {
        final lang = _visitAppContext?.language ?? 'FR';
        await activeOrchestrator?.ttsEngine.speak(
          response.reply,
          languageCode: _toLangCode(lang),
        );
      }
    } catch (e) {
      debugPrint('[GeoBeaconTriggerService] Trigger error for $triggerId: $e');
    }
  }

  String _toLangCode(String lang) {
    switch (lang.toUpperCase()) {
      case 'FR': return 'fr-FR';
      case 'NL': return 'nl-NL';
      case 'EN': return 'en-US';
      case 'DE': return 'de-DE';
      default:   return 'fr-FR';
    }
  }

  void dispose() {
    stop();
  }
}