MQTTWrapper

import kotlinx.coroutines.*
import org.eclipse.paho.client.mqttv3.*

class MqttWrapper(
    private val brokerUrl: String,
    private val clientId: String,
    private val callbackScope: CoroutineScope = CoroutineScope(Dispatchers.Main)
) {

    private var mqttClient: MqttClient? = null

    // Variable to hold the latest received MQTT message payload
    var latestMessage: String? = null
        private set

    // Callback to notify when a new message arrives
    var onMessageReceived: ((topic: String, message: String) -> Unit)? = null

    fun connect() {
        try {
            mqttClient = MqttClient(brokerUrl, clientId, null)
            val options = MqttConnectOptions()
            options.isCleanSession = true

            mqttClient?.setCallback(object : MqttCallback {
                override fun connectionLost(cause: Throwable?) {
                    // Handle loss of connection if needed
                }

                override fun messageArrived(topic: String?, message: MqttMessage?) {
                    val msgStr = message?.toString() ?: ""
                    latestMessage = msgStr
                    // Invoke the callback on the main thread
                    callbackScope.launch {
                        onMessageReceived?.invoke(topic ?: "", msgStr)
                    }
                }

                override fun deliveryComplete(token: IMqttDeliveryToken?) {
                    // Optionally handle delivery complete
                }
            })

            mqttClient?.connect(options)

        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }

    fun subscribe(topic: String, qos: Int = 1) {
        try {
            mqttClient?.subscribe(topic, qos)
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }

    fun publish(topic: String, message: String, qos: Int = 1) {
        try {
            val mqttMessage = MqttMessage(message.toByteArray())
            mqttMessage.qos = qos
            mqttClient?.publish(topic, mqttMessage)
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }

    fun disconnect() {
        try {
            mqttClient?.disconnect()
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }
}