import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:get/get.dart';
import 'package:intaleq_maps/intaleq_maps.dart';

import '../models/friendly_unit.dart';

/// ============================================================================
/// [LocalNetworkTrackerService] - محرك التتبع المحلي للوحدات (Blue Force Tracking)
/// ============================================================================
/// English:
/// Uses UDP Broadcast (Port 4545) to transmit and receive live GPS coordinates
/// of friendly forces over a localized tactical MANET or Wi-Fi mesh network,
/// entirely offline with zero dependency on cellular data.
///
/// العربية:
/// محرك التتبع المحلي عبر شبكات الراديو أو الواي فاي (Mesh/MANET). 
/// يستخدم بروتوكول UDP Broadcast لإرسال واستقبال إحداثيات القوات الصديقة
/// وعرضها على خريطة القائد ميدانياً بدون إنترنت.
/// ============================================================================
class LocalNetworkTrackerService extends GetxService {
  static const int broadcastPort = 4545;
  
  // My Device Info
  final String myDeviceId = 'DEV_${DateTime.now().millisecondsSinceEpoch.toString().substring(7)}';
  final String myCallsign = 'Alpha-1 (Commander)';
  final UnitRole myRole = UnitRole.commander;

  // Rx Map of all active friendly units nearby
  final RxMap<String, FriendlyUnit> friendlyUnits = <String, FriendlyUnit>{}.obs;

  RawDatagramSocket? _socket;
  Timer? _broadcastTimer;
  Timer? _cleanupTimer;

  // The last known GPS position of this device
  LatLng? _currentPosition;
  double _currentHeading = 0.0;

  void updateMyPosition(LatLng pos, double heading) {
    _currentPosition = pos;
    _currentHeading = heading;
  }

  Future<LocalNetworkTrackerService> init() async {
    await _startListening();
    _startBroadcasting();
    _startCleanupRoutine();
    return this;
  }

  /// 1. Start Listening for UDP Packets from other radios/tablets
  Future<void> _startListening() async {
    try {
      _socket = await RawDatagramSocket.bind(InternetAddress.anyIPv4, broadcastPort);
      _socket?.broadcastEnabled = true;

      _socket?.listen((RawSocketEvent event) {
        if (event == RawSocketEvent.read) {
          final datagram = _socket?.receive();
          if (datagram != null) {
            _processIncomingPacket(datagram.data);
          }
        }
      });
      debugPrint('🟢 Local BFT Listener started on port $broadcastPort');
    } catch (e) {
      debugPrint('🔴 Local BFT Listener error: $e');
    }
  }

  /// 2. Process incoming JSON position reports
  void _processIncomingPacket(List<int> data) {
    try {
      final jsonStr = utf8.decode(data);
      final map = jsonDecode(jsonStr);
      final unit = FriendlyUnit.fromJson(map);

      // Ignore our own broadcast loops
      if (unit.deviceId == myDeviceId) return;

      // Update the reactive map
      friendlyUnits[unit.deviceId] = unit;
    } catch (e) {
      // Ignore malformed packets
    }
  }

  /// 3. Broadcast our position to the local network every 3 seconds
  void _startBroadcasting() {
    _broadcastTimer = Timer.periodic(const Duration(seconds: 3), (timer) {
      if (_currentPosition == null || _socket == null) return;

      final me = FriendlyUnit(
        deviceId: myDeviceId,
        callsign: myCallsign,
        position: _currentPosition!,
        heading: _currentHeading,
        role: myRole,
        lastSeen: DateTime.now(),
      );

      final data = utf8.encode(jsonEncode(me.toJson()));
      
      try {
        // Send to universal broadcast address. 
        // In a real tactical mesh network (TrellisWare/Silvus), 
        // multicast or specific subnet broadcast is used.
        _socket?.send(data, InternetAddress('255.255.255.255'), broadcastPort);
      } catch (e) {
        // Broadcast failed (e.g. no network interface active)
      }
    });
  }

  /// 4. Cleanup old units (Remove units not seen for 30 seconds)
  void _startCleanupRoutine() {
    _cleanupTimer = Timer.periodic(const Duration(seconds: 10), (timer) {
      final now = DateTime.now();
      final deadKeys = <String>[];
      
      friendlyUnits.forEach((key, unit) {
        if (now.difference(unit.lastSeen).inSeconds > 30) {
          deadKeys.add(key);
        }
      });

      for (var key in deadKeys) {
        friendlyUnits.remove(key);
      }
    });
  }

  @override
  void onClose() {
    _broadcastTimer?.cancel();
    _cleanupTimer?.cancel();
    _socket?.close();
    super.onClose();
  }
}