import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'dart:math';
import 'package:flutter/foundation.dart';
import 'package:mqtt_client/mqtt_client.dart';
import 'package:mqtt_client/mqtt_server_client.dart';

class MqttService {
  late MqttServerClient client;
  final String server = '5.75.197.180';
  final int port = 1883;
  final StreamController<Map<String, dynamic>> _messageStreamController =
      StreamController.broadcast();

  Stream<Map<String, dynamic>> get messages => _messageStreamController.stream;

  bool get isConnected => client.connectionStatus?.state == MqttConnectionState.connected;

  Future<void> connect(String token) async {
    final String clientId =
        'nest-' + Random().nextInt(0xFFFFFF).toRadixString(16).padLeft(6, '0');
    final String username = 'ignored';
    final String password = token;

    client = MqttServerClient.withPort(server, clientId, port);
    client.logging(on: true);
    client.keepAlivePeriod = 60;
    client.autoReconnect = true;
    client.setProtocolV311();

    debugPrint('--- [MQTT] Attempting to connect...');
    debugPrint('--- [MQTT] Server: $server:$port');
    debugPrint('--- [MQTT] ClientID: $clientId');

    final connMessage = MqttConnectMessage()
        .withClientIdentifier(clientId)
        .startClean()
        .authenticateAs(username, password);

    client.connectionMessage = connMessage;

    client.onConnected = () {
      debugPrint('✅ [MQTT] Connected successfully.');
      client.updates!.listen((List<MqttReceivedMessage<MqttMessage>> c) {
        final MqttPublishMessage recMess = c[0].payload as MqttPublishMessage;
        
        final String payload =
            MqttPublishPayload.bytesToStringAsString(recMess.payload.message);

        debugPrint('<<<<< [MQTT] Received Data <<<<<');
        debugPrint('<<<<< [MQTT] Topic: ${c[0].topic}');
        debugPrint('<<<<< [MQTT] Payload as String: $payload'); 
        debugPrint('<<<<< ======================== <<<<<');

        try {
          final Map<String, dynamic> jsonPayload = json.decode(payload);
          _messageStreamController.add(jsonPayload);
        } catch (e) {
          debugPrint("❌ [MQTT] Error decoding received JSON: $e");
        }
      });
    };

    client.onDisconnected = () {
      debugPrint('❌ [MQTT] Disconnected.');
    };
    
    client.onAutoReconnect = () {
      debugPrint('↪️ [MQTT] Auto-reconnecting...');
    };

    client.onAutoReconnected = () {
        debugPrint('✅ [MQTT] Auto-reconnected successfully.');
    };

    client.onSubscribed = (String topic) {
      debugPrint('✅ [MQTT] Subscribed to topic: $topic');
    };
    
    client.pongCallback = () {
        debugPrint('🏓 [MQTT] Ping response received');
    };

    try {
      await client.connect();
    } on NoConnectionException catch (e) {
        debugPrint('❌ [MQTT] Connection failed - No Connection Exception: $e');
        client.disconnect();
    } on SocketException catch (e) {
        debugPrint('❌ [MQTT] Connection failed - Socket Exception: $e');
        client.disconnect();
    } catch (e) {
      debugPrint('❌ [MQTT] Connection failed - General Exception: $e');
      client.disconnect();
    }
  }

  void subscribe(String topic) {
    if (isConnected) {
      client.subscribe(topic, MqttQos.atLeastOnce);
    } else {
      debugPrint("⚠️ [MQTT] Cannot subscribe. Client is not connected.");
    }
  }

  void publish(String topic, Map<String, dynamic> message) {
    if (isConnected) {
      final builder = MqttClientPayloadBuilder();
      final payloadString = json.encode(message);
      builder.addString(payloadString);

      debugPrint('>>>>> [MQTT] Publishing Data >>>>>');
      debugPrint('>>>>> [MQTT] Topic: $topic');
      debugPrint('>>>>> [MQTT] Payload: $payloadString');
      debugPrint('>>>>> ======================= >>>>>');

      client.publishMessage(topic, MqttQos.atLeastOnce, builder.payload!);
    } else {
        debugPrint("⚠️ [MQTT] Cannot publish. Client is not connected.");
    }
  }

  void dispose() {
    debugPrint("--- [MQTT] Disposing MQTT Service.");
    _messageStreamController.close();
    client.disconnect();
  }
}