MqttMonitor/MqttClient.py

# -*- coding: utf-8 -*-

# Copyright (c) 2018 - 2023 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing a PyQt wrapper around the paho MQTT client.
"""

import paho.mqtt.client as mqtt

from paho.mqtt.packettypes import PacketTypes
from paho.mqtt.properties import Properties
from PyQt6.QtCore import QCoreApplication, QObject, QTimer, pyqtSignal, pyqtSlot

from eric7.Utilities.crypto import pwConvert

from .MqttProtocols import MqttProtocols


class MqttClient(QObject):
    """
    Class implementing a PyQt wrapper around the paho MQTT client.

    @signal onConnectV3(flags, rc) emitted after the client has connected to
        the broker (MQTT v3)
    @signal onConnectV5(flags, rc, packetType, properties emitted after the
        client has connected to the broker (MQTT v5)
    @signal onDisconnectedV3(rc) emitted after the client has disconnected from
        the broker (MQTT v3)
    @signal onDisconnectedV5(rc, packetType) emitted after the client has
        disconnected from the broker (MQTT v5)
    @signal onLog(level, message) emitted to send client log data
    @signal onMessageV3(topic, payload, qos, retain) emitted after a message
        has been received by the client (MQTT v3)
    @signal onMessageV5(topic, payload, qos, retain, properties) emitted after
        a message has been received by the client (MQTT v5)
    @signal onPublish(mid) emitted after a message has been published
    @signal onSubscribeV3(mid, grantedQos) emitted after the client has
        subscribed to some topics (MQTT v3)
    @signal onSubscribeV5(mid, reasonCodes, properties) emitted after the
        client has subscribed to some topics (MQTT v5)
    @signal onUnsubscribeV3(mid) emitted after the client has unsubscribed from
        some topics (MQTT v3)
    @signal onUnsubscribeV5(mid, rc, packetType, properties) emitted after the
        client has unsubscribed from some topics (MQTT v5)
    @signal connectTimeout() emitted to indicate, that a connection attempt
        timed out
    """

    onConnectV3 = pyqtSignal(dict, int)
    onConnectV5 = pyqtSignal(dict, int, int, dict)
    onDisconnectedV3 = pyqtSignal(int)
    onDisconnectedV5 = pyqtSignal(int, int)
    onLog = pyqtSignal(int, str)
    onMessageV3 = pyqtSignal(str, bytes, int, bool)
    onMessageV5 = pyqtSignal(str, bytes, int, bool, dict)
    onPublish = pyqtSignal(int)
    onSubscribeV3 = pyqtSignal(int, tuple)
    onSubscribeV5 = pyqtSignal(int, list, dict)
    onUnsubscribeV3 = pyqtSignal(int)
    onUnsubscribeV5 = pyqtSignal(int, int, int, dict)

    connectTimeout = pyqtSignal()

    DefaultConnectTimeout = 15  # connect timeout in seconds

    LogDebug = 0x01
    LogInfo = 0x02
    LogNotice = 0x04
    LogWarning = 0x08
    LogError = 0x10
    LogDisabled = 0xFF
    LogLevelMap = {
        mqtt.MQTT_LOG_DEBUG: LogDebug,
        mqtt.MQTT_LOG_INFO: LogInfo,
        mqtt.MQTT_LOG_NOTICE: LogNotice,
        mqtt.MQTT_LOG_WARNING: LogWarning,  # __NO-TASK__
        mqtt.MQTT_LOG_ERR: LogError,
    }

    def __init__(
        self,
        clientId="",
        cleanSession=True,
        userdata=None,
        protocol=mqtt.MQTTv311,
        transport="tcp",
        parent=None,
    ):
        """
        Constructor

        @param clientId ID to be used for the client
        @type str
        @param cleanSession flag indicating to start a clean session
        @type bool
        @param userdata user data
        @type any
        @param protocol version of the MQTT protocol to use
        @type int, one of mqtt.MQTTv31, mqtt.MQTTv311 or mqtt.MQTTv5
        @param transport transport to be used
        @type str, one of "tcp" or "websockets"
        @param parent reference to the parent object
        @type QObject
        """
        QObject.__init__(self, parent=parent)

        self.__loopStarted = False

        self.__connectTimeoutTimer = QTimer(self)
        self.__connectTimeoutTimer.setSingleShot(True)
        self.__connectTimeoutTimer.setInterval(MqttClient.DefaultConnectTimeout * 1000)
        self.__connectTimeoutTimer.timeout.connect(self.__connectTimeout)

        self.onConnectV3.connect(self.__connectTimeoutTimer.stop)
        self.onConnectV5.connect(self.__connectTimeoutTimer.stop)

        self.__cleanSession = cleanSession
        self.__protocol = protocol
        self.__disconnectUserProperties = []

        if protocol == MqttProtocols.MQTTv5:
            cleanSession = None

        self.__mqttClient = mqtt.Client(
            client_id=clientId,
            clean_session=cleanSession,
            userdata=userdata,
            protocol=int(protocol),
            transport=transport,
        )

        self.__initCallbacks(protocol)

    def __initCallbacks(self, protocol):
        """
        Private method to initialize the MQTT callback methods.

        @param protocol MQTT protocol version
        @type MqttProtocols
        """
        if protocol in (MqttProtocols.MQTTv31, MqttProtocols.MQTTv311):
            self.__mqttClient.on_connect = self.__onConnectV3
            self.__mqttClient.on_disconnect = self.__onDisconnectedV3
            self.__mqttClient.on_subscribe = self.__onSubscribeV3
            self.__mqttClient.on_unsubscribe = self.__onUnsubscribeV3
            self.__mqttClient.on_message = self.__onMessageV3
        else:
            self.__mqttClient.on_connect = self.__onConnectV5
            self.__mqttClient.on_disconnect = self.__onDisconnectedV5
            self.__mqttClient.on_subscribe = self.__onSubscribeV5
            self.__mqttClient.on_unsubscribe = self.__onUnsubscribeV5
            self.__mqttClient.on_message = self.__onMessageV5

        self.__mqttClient.on_log = self.__onLog
        self.__mqttClient.on_publish = self.__onPublish

    def __onConnectV3(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        flags,
        rc,
        properties=None,  # noqa: U100
    ):
        """
        Private method to handle the connect to the broker (MQTT v3.1 and v3.1.1).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param flags dictionary containing the response flags sent by the broker
        @type dict
        @param rc result code
        @type int
        @param properties optional properties (defaults to None)
        @type dict (optional)
        """
        self.onConnectV3.emit(flags, rc)

    def __onDisconnectedV3(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        rc,
    ):
        """
        Private method to handle the disconnect from the broker (MQTT v3.1 and v3.1.1).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param rc result code
        @type int
        """
        self.onDisconnectedV3.emit(rc)

    def __onSubscribeV3(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        mid,
        grantedQos,
    ):
        """
        Private method to handle a subscribe event (MQTT v3.1 and v3.1.1).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param mid message ID
        @type int
        @param grantedQos list of granted QoS for each subscription request
        @type list of int
        """
        self.onSubscribeV3.emit(mid, grantedQos)

    def __onUnsubscribeV3(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        mid,
    ):
        """
        Private method to handle an unsubscribe event (MQTT v3.1 and v3.1.1).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param mid message ID
        @type int
        """
        self.onUnsubscribeV3.emit(mid)

    def __onMessageV3(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        message,
    ):
        """
        Private method to handle a new message received from the broker (MQTT v3.1
        and v3.1.1).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param message received message object
        @type paho.mqtt.MQTTMessage
        """
        self.onMessageV3.emit(
            message.topic, message.payload, message.qos, message.retain
        )

    def __onConnectV5(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        flags,
        rc,
        properties=None,
    ):
        """
        Private method to handle the connect to the broker (MQTT v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param flags dictionary containing the response flags sent by the broker
        @type dict
        @param rc reason code
        @type paho.mqtt.ReasonCodes
        @param properties optional properties (defaults to None)
        @type dict (optional)
        """
        self.onConnectV5.emit(
            flags,
            rc.value,
            rc.packetType,
            properties.json() if properties is not None else {},
        )

    def __onDisconnectedV5(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        rc,
        properties=None,  # noqa: U100
    ):
        """
        Private method to handle the disconnect from the broker (MQTT v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param rc result code or reason code
        @type int or paho.mqtt.ReasonCodes
        @param properties optional properties (defaults to None)
        @type dict (optional)
        """
        if isinstance(rc, int):
            packetType = PacketTypes.DISCONNECT
            resultCode = rc
        else:
            packetType = rc.packetType
            resultCode = rc.value
        self.onDisconnectedV5.emit(resultCode, packetType)

    def __onSubscribeV5(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        mid,
        reasonCodes,
        properties=None,
    ):
        """
        Private method to handle a subscribe event (MQTT v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param mid message ID
        @type int
        @param reasonCodes list of reason code for each subscribed topic
        @type list of paho.mqtt.ReasonCodes
        @param properties optional properties (defaults to None)
        @type dict (optional)
        """
        self.onSubscribeV5.emit(
            mid,
            reasonCodes,
            properties.json() if properties is not None else {},
        )

    def __onUnsubscribeV5(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        mid,
        properties,
        reasonCodes,
    ):
        """
        Private method to handle an unsubscribe event (MQTT v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param mid message ID
        @type int
        @param properties optional properties (defaults to None)
        @type dict (optional)
        @param reasonCodes list of reason code for each unsubscribed topic
        @type list of paho.mqtt.ReasonCodes
        """
        self.onUnsubscribeV5.emit(
            mid,
            reasonCodes.value,
            reasonCodes.packetType,
            properties.json() if properties is not None else {},
        )

    def __onMessageV5(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        message,
    ):
        """
        Private method to handle a new message received from the broker (MQTT v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param message received message object
        @type paho.mqtt.MQTTMessage
        """
        self.onMessageV5.emit(
            message.topic,
            message.payload,
            message.qos,
            message.retain,
            message.properties.json(),
        )

    def __onLog(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        level,
        buf,
    ):
        """
        Private method to handle a log event (MQTT v3.1, v3.1.1 and v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param level severity of the log message
        @type int
        @param buf log message
        @type str
        """
        self.onLog.emit(level, buf)

    def __onPublish(
        self,
        client,  # noqa: U100
        userdata,  # noqa: U100
        mid,
    ):
        """
        Private method to handle the publishing of a message (MQTT v3.1, v3.1.1
        and v5.0).

        @param client reference to the client object
        @type paho.mqtt.Client
        @param userdata user data
        @type Any
        @param mid message ID
        @type int
        """
        self.onPublish.emit(mid)

    @pyqtSlot()
    def __connectTimeout(self):
        """
        Private slot handling a failed connection attempt.
        """
        self.stopLoop()
        self.connectTimeout.emit()

    def setConnectionTimeout(self, timeout):
        """
        Public method to set the connection timeout value.

        @param timeout timeout value to be set in seconds
        @type int
        """
        self.__connectTimeoutTimer.setInterval(timeout * 1000)

    def setMaxInflightMessages(self, inflight=20):
        """
        Public method to set the maximum number of messages with QoS > 0 that
        can be part way through their network flow at once.

        @param inflight maximum number of messages in flight
        @type int
        """
        self.__mqttClient.max_inflight_messages_set(inflight)

    def setMaxQueuedMessages(self, queueSize=0):
        """
        Public method to set the maximum number of messages with QoS > 0 that
        can be pending in the outgoing message queue.

        @param queueSize maximum number of queued messages (0 = unlimited)
        @type int
        """
        self.__mqttClient.max_queued_messages_set(queueSize)

    def setUserCredentials(self, username, password=None):
        """
        Public method to set the user name and optionally the password.

        @param username user name to be set
        @type str
        @param password optional password
        @type str
        """
        self.__mqttClient.username_pw_set(username, password=password)

    def setUserData(self, userdata):
        """
        Public method to set the user data.

        @param userdata user data
        @type any
        """
        self.__mqttClient.user_data_set(userdata)

    def setLastWill(self, topic, payload=None, qos=0, retain=False, properties=None):
        """
        Public method to set the last will of the client.

        @param topic topic the will message should be published on
        @type str
        @param payload message to send as a will
        @type str, bytes, int or float
        @param qos quality of service level to use for the will
        @type int, one of 0, 1 or 2
        @param retain flag indicating to set as the "last known good"/retained
            message for the will topic
        @type bool
        @param properties list of user properties to be sent with the
            last will message
        @type list of tuple of (str, str)
        """
        self.__mqttClient.will_set(
            topic, payload=payload, qos=qos, retain=retain, properties=properties
        )

    def clearLastWill(self):
        """
        Public method to remove a will that was previously configured with
        setLastWill().
        """
        self.__mqttClient.will_clear()

    def setTLS(self, caCerts=None, certFile=None, keyFile=None):
        """
        Public method to enable secure connections and set the TLS parameters.

        @param caCerts path to the Certificate Authority certificates file
        @type str
        @param certFile PEM encoded client certificate file
        @type str
        @param keyFile PEM encoded private key file
        @type str
        @return tuple containing a success flag and the error string of the
            paho-mqtt library
        @rtype tuple of (bool, str)
        """
        try:
            self.__mqttClient.tls_set(
                ca_certs=caCerts, certfile=certFile, keyfile=keyFile
            )
            return True, ""
        except (FileNotFoundError, ValueError) as err:
            return False, str(err)

        return False, "unspecific error occurred"

    def getProtocol(self):
        """
        Public method to get the MQTT protocol version.

        @return MQTT protocol version in use
        @rtype int
        """
        return self.__protocol

    def startLoop(self):
        """
        Public method to start the MQTT client loop.
        """
        self.__mqttClient.loop_start()
        self.__loopStarted = True

    def stopLoop(self):
        """
        Public method to stop the MQTT client loop.
        """
        self.__mqttClient.loop_stop()
        self.__loopStarted = False

    def connectToServer(
        self,
        host,
        port=1883,
        keepalive=60,
        bindAddress="",
        properties=None,
        clearWill=False,
    ):
        """
        Public method to connect to a remote MQTT broker.

        @param host host name or IP address of the remote broker
        @type str
        @param port network port of the server host to connect to (default:
            1883, using TLS: 8883)
        @type int
        @param keepalive maximum period in seconds allowed between
            communications with the broker
        @type int
        @param bindAddress IP address of a local network interface to bind
            this client to
        @type str
        @param properties list of user properties to be sent with the
            subscription
        @type list of tuple of (str, str)
        @param clearWill flag indicating to clear the last will previously set
        @type bool
        """
        if clearWill:
            self.clearLastWill()

        props = (
            self.__createPropertiesObject(PacketTypes.CONNECT, properties)
            if properties
            else None
        )
        self.__mqttClient.connect_async(
            host,
            port=port,
            keepalive=keepalive,
            bind_address=bindAddress,
            clean_start=self.__cleanSession,
            properties=props,
        )

        self.__connectTimeoutTimer.start()

        if not self.__loopStarted:
            self.startLoop()

    def connectToServerWithOptions(
        self, host, port=1883, bindAddress="", options=None, clearWill=False
    ):
        """
        Public method to connect to a remote MQTT broker.

        @param host host name or IP address of the remote broker
        @type str
        @param port network port of the server host to connect to (default:
            1883, using TLS: 8883)
        @type int
        @param bindAddress IP address of a local network interface to bind
            this client to
        @type str
        @param options dictionary containing the connection options. This
            dictionary should contain the keys "ClientId", "ConnectionTimeout",
            "Keepalive", "CleanSession", "Username", "Password", "WillTopic",
            "WillMessage", "WillQos", "WillRetain", "WillProperties",
            "TlsEnable", "TlsCaCert", "TlsClientCert", "TlsClientKey",
            "UserProperties".
        @type dict
        @param clearWill flag indicating to clear the last will previously set
        @type bool
        """
        if options:
            parametersDict = self.defaultConnectionOptions()
            parametersDict.update(options)

            self.setConnectionTimeout(parametersDict["ConnectionTimeout"])

            # step 1: set username and password
            if parametersDict["Username"]:
                if parametersDict["Password"]:
                    self.setUserCredentials(
                        parametersDict["Username"],
                        pwConvert(parametersDict["Password"], encode=False),
                    )
                else:
                    self.setUserCredentials(parametersDict["Username"])

            # step 2: set last will data
            if not clearWill and parametersDict["WillTopic"]:
                if parametersDict["WillMessage"]:
                    willMessage = parametersDict["WillMessage"]
                else:
                    # empty message to clear the will
                    willMessage = None
                props = (
                    self.__createPropertiesObject(
                        PacketTypes.WILLMESSAGE, parametersDict["WillProperties"]
                    )
                    if (
                        parametersDict["WillProperties"]
                        and self.__protocol == MqttProtocols.MQTTv5
                    )
                    else None
                )
                self.setLastWill(
                    parametersDict["WillTopic"],
                    payload=willMessage,
                    qos=parametersDict["WillQos"],
                    retain=parametersDict["WillRetain"],
                    properties=props,
                )

            # step 3: set TLS parameters
            if parametersDict["TlsEnable"]:
                if parametersDict["TlsCaCert"] and parametersDict["TlsClientCert"]:
                    # use self signed client certificate
                    self.setTLS(
                        caCerts=parametersDict["TlsCaCert"],
                        certFile=parametersDict["TlsClientCert"],
                        keyFile=parametersDict["TlsClientKey"],
                    )
                elif parametersDict["TlsCaCert"]:
                    # use CA certificate file
                    self.setTLS(caCerts=parametersDict["TlsCaCert"])
                else:
                    # use default TLS configuration
                    self.setTLS()

            # step 4: get the connect user properties
            if self.__protocol == MqttProtocols.MQTTv5:
                try:
                    userProperties = parametersDict["UserProperties"]
                    properties = userProperties["connect"][:]
                    self.__disconnectUserProperties = (
                        userProperties["connect"][:]
                        if userProperties["use_connect"]
                        else userProperties["disconnect"][:]
                    )
                except KeyError:
                    properties = None
            else:
                properties = None
            # step 4: connect to server
            self.__cleanSession = parametersDict["CleanSession"]
            self.connectToServer(
                host,
                port=port,
                keepalive=parametersDict["Keepalive"],
                properties=properties,
                clearWill=clearWill,
            )
        else:
            keepalive = self.defaultConnectionOptions()["Keepalive"]
            self.connectToServer(
                host,
                port=port,
                keepalive=keepalive,
                bindAddress=bindAddress,
                clearWill=clearWill,
            )

    @classmethod
    def defaultConnectionOptions(cls):
        """
        Class method to get a connection options dictionary with default
        values.

        @return dictionary containing the default connection options. It has
            the keys "ClientId", "Protocol", "ConnectionTimeout", "Keepalive",
            "CleanSession", "Username", "Password", "WillTopic", "WillMessage",
            "WillQos", "WillRetain", "WillProperties", "TlsEnable",
            "TlsCaCert", "TlsClientCert", "TlsClientKey", "UserProperties".
        @rtype dict
        """
        from PluginMqttMonitor import mqttPluginObject

        return {
            "ClientId": "ERIC7_MQTT_MONITOR_CLIENT",
            "Protocol": mqttPluginObject.getPreferences("DefaultProtocol"),
            "ConnectionTimeout": MqttClient.DefaultConnectTimeout,
            "Keepalive": 60,
            "CleanSession": True,
            "Username": "",
            "Password": "",
            "WillTopic": "",
            "WillMessage": "",
            "WillQos": 0,
            "WillRetain": False,
            "WillProperties": [],
            "TlsEnable": False,
            "TlsCaCert": "",
            "TlsClientCert": "",
            "TlsClientKey": "",
            "UserProperties": {
                "connect": [],
                "disconnect": [],
                "use_connect": True,
            },
        }

    def reconnectToServer(self):
        """
        Public method to reconnect the client with the same parameters.
        """
        self.__connectTimeoutTimer.start()

        self.__mqttClient.reconnect()

        if not self.__loopStarted:
            self.startLoop()

    def disconnectFromServer(self):
        """
        Public method to disconnect the client from the remote broker.
        """
        self.__connectTimeoutTimer.stop()

        props = (
            self.__createPropertiesObject(
                PacketTypes.DISCONNECT, self.__disconnectUserProperties
            )
            if self.__disconnectUserProperties
            else None
        )
        self.__mqttClient.disconnect(properties=props)

    def subscribe(self, topic, qos=0, properties=None):
        """
        Public method to subscribe to topics with quality of service.

        @param topic single topic to subscribe to or a tuple with a topic
            and a QoS or a list of tuples with a topic and a QoS each
        @type str or tuple of (str, int) or list of tuple of (str, int)
        @param qos quality of service
        @type int, one of 0, 1 or 2
        @param properties list of user properties to be sent with the
            subscription
        @type list of tuple of (str, str)
        @return tuple containing the result code and the message ID
        @rtype tuple of (int, int)
        """
        props = (
            self.__createPropertiesObject(PacketTypes.SUBSCRIBE, properties)
            if properties
            else None
        )
        return self.__mqttClient.subscribe(topic, qos=qos, properties=props)

    def unsubscribe(self, topic, properties=None):
        """
        Public method to unsubscribe topics.

        @param topic topic or list of topics to unsubscribe
        @type str or list of str
        @param properties list of user properties to be sent with the
            subscription
        @type list of tuple of (str, str)
        @return tuple containing the result code and the message ID
        @rtype tuple of (int, int)
        """
        props = (
            self.__createPropertiesObject(PacketTypes.UNSUBSCRIBE, properties)
            if properties
            else None
        )
        return self.__mqttClient.unsubscribe(topic, properties=props)

    def publish(self, topic, payload=None, qos=0, retain=False, properties=None):
        """
        Public method to publish to a topic.

        @param topic topic to publish to
        @type str
        @param payload data to be published
        @type str, bytes, int or float
        @param qos quality of service
        @type int, one of 0, 1 or 2
        @param retain flag indicating to set as the "last known good"/retained
            message for the topic
        @type bool
        @param properties list of user properties to be sent with the
            subscription
        @type list of tuple of (str, str)
        @return message info object
        @rtype mqtt.MQTTMessageInfo
        """
        props = (
            self.__createPropertiesObject(PacketTypes.PUBLISH, properties)
            if properties
            else None
        )
        return self.__mqttClient.publish(
            topic, payload=payload, qos=qos, retain=retain, properties=props
        )

    def __createPropertiesObject(self, packetType, properties):
        """
        Private method to assemble the MQTT v5 properties object.

        @param packetType type of the MQTT packet
        @type PacketTypes (= int)
        @param properties list of user properties
        @type list of tuple of (str, str)
        @return MQTT v5 properties object
        @rtype Properties
        """
        props = Properties(packetType)
        props.UserProperty = properties
        return props


def mqttConnackMessage(connackCode):
    """
    Module function to get the string associated with a CONNACK result.

    @param connackCode result code of the connection request
    @type int
    @return textual representation for the result code
    @rtype str
    """
    if connackCode == mqtt.CONNACK_ACCEPTED:
        return QCoreApplication.translate("MqttConnackMessage", "Connection Accepted.")
    elif connackCode == mqtt.CONNACK_REFUSED_PROTOCOL_VERSION:
        return QCoreApplication.translate(
            "MqttConnackMessage", "Connection Refused: unacceptable protocol version."
        )
    elif connackCode == mqtt.CONNACK_REFUSED_IDENTIFIER_REJECTED:
        return QCoreApplication.translate(
            "MqttConnackMessage", "Connection Refused: identifier rejected."
        )
    elif connackCode == mqtt.CONNACK_REFUSED_SERVER_UNAVAILABLE:
        return QCoreApplication.translate(
            "MqttConnackMessage", "Connection Refused: broker unavailable."
        )
    elif connackCode == mqtt.CONNACK_REFUSED_BAD_USERNAME_PASSWORD:
        return QCoreApplication.translate(
            "MqttConnackMessage", "Connection Refused: bad user name or password."
        )
    elif connackCode == mqtt.CONNACK_REFUSED_NOT_AUTHORIZED:
        return QCoreApplication.translate(
            "MqttConnackMessage", "Connection Refused: not authorised."
        )
    else:
        return QCoreApplication.translate(
            "MqttConnackMessage", "Connection Refused: unknown reason."
        )


def mqttErrorMessage(mqttErrno):
    """
    Module function to get the error string associated with an MQTT error
    number.

    @param mqttErrno result code of a MQTT request
    @type int
    @return textual representation of the result code
    @rtype str
    """
    if mqttErrno == mqtt.MQTT_ERR_SUCCESS:
        return QCoreApplication.translate("MqttErrorMessage", "No error.")
    elif mqttErrno == mqtt.MQTT_ERR_NOMEM:
        return QCoreApplication.translate("MqttErrorMessage", "Out of memory.")
    elif mqttErrno == mqtt.MQTT_ERR_PROTOCOL:
        return QCoreApplication.translate(
            "MqttErrorMessage",
            "A network protocol error occurred when communicating with" " the broker.",
        )
    elif mqttErrno == mqtt.MQTT_ERR_INVAL:
        return QCoreApplication.translate(
            "MqttErrorMessage", "Invalid function arguments provided."
        )
    elif mqttErrno == mqtt.MQTT_ERR_NO_CONN:
        return QCoreApplication.translate(
            "MqttErrorMessage", "The client is not currently connected."
        )
    elif mqttErrno == mqtt.MQTT_ERR_CONN_REFUSED:
        return QCoreApplication.translate(
            "MqttErrorMessage", "The connection was refused."
        )
    elif mqttErrno == mqtt.MQTT_ERR_NOT_FOUND:
        return QCoreApplication.translate(
            "MqttErrorMessage", "Message not found (internal error)."
        )
    elif mqttErrno == mqtt.MQTT_ERR_CONN_LOST:
        return QCoreApplication.translate(
            "MqttErrorMessage", "The connection was lost."
        )
    elif mqttErrno == mqtt.MQTT_ERR_TLS:
        return QCoreApplication.translate("MqttErrorMessage", "A TLS error occurred.")
    elif mqttErrno == mqtt.MQTT_ERR_PAYLOAD_SIZE:
        return QCoreApplication.translate("MqttErrorMessage", "Payload too large.")
    elif mqttErrno == mqtt.MQTT_ERR_NOT_SUPPORTED:
        return QCoreApplication.translate(
            "MqttErrorMessage", "This feature is not supported."
        )
    elif mqttErrno == mqtt.MQTT_ERR_AUTH:
        return QCoreApplication.translate("MqttErrorMessage", "Authorisation failed.")
    elif mqttErrno == mqtt.MQTT_ERR_ACL_DENIED:
        return QCoreApplication.translate("MqttErrorMessage", "Access denied by ACL.")
    elif mqttErrno == mqtt.MQTT_ERR_UNKNOWN:
        return QCoreApplication.translate("MqttErrorMessage", "Unknown error.")
    elif mqttErrno == mqtt.MQTT_ERR_ERRNO:
        return QCoreApplication.translate("MqttErrorMessage", "Error defined by errno.")
    elif mqttErrno == mqtt.MQTT_ERR_QUEUE_SIZE:
        return QCoreApplication.translate("MqttErrorMessage", "Message queue full.")
    else:
        return QCoreApplication.translate("MqttErrorMessage", "Unknown error.")


def mqttLogLevelString(mqttLogLevel, isMqttLogLevel=True):
    """
    Module function to get the log level string associated with a log level.

    @param mqttLogLevel log level of the paho-mqtt client
    @type int
    @param isMqttLogLevel flag indicating a MQTT log level is given (if
        False it is the MqttClient variant, i.e. Debug being lowest)
    @type bool
    @return textual representation of the log level
    @rtype str
    """
    if isMqttLogLevel:
        try:
            logLevel = MqttClient.LogLevelMap[mqttLogLevel]
        except KeyError:
            return QCoreApplication.translate("MqttLogLevelString", "Unknown")
    else:
        logLevel = mqttLogLevel

    if logLevel == MqttClient.LogInfo:
        return QCoreApplication.translate("MqttLogLevelString", "Info")
    elif logLevel == MqttClient.LogNotice:
        return QCoreApplication.translate("MqttLogLevelString", "Notice")
    elif logLevel == MqttClient.LogWarning:
        return QCoreApplication.translate("MqttLogLevelString", "Warning")
    elif logLevel == MqttClient.LogError:
        return QCoreApplication.translate("MqttLogLevelString", "Error")
    elif logLevel == MqttClient.LogDebug:
        return QCoreApplication.translate("MqttLogLevelString", "Debug")
    elif logLevel == MqttClient.LogDisabled:
        return QCoreApplication.translate("MqttLogLevelString", "Logging Disabled")
    else:
        return QCoreApplication.translate("MqttLogLevelString", "Unknown")