MqttMonitor/MqttMonitorWidget.py

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

# Copyright (c) 2018 - 2022 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing the MQTT Monitor widget.
"""

import collections
import contextlib
import copy
import os

from PyQt6.QtCore import pyqtSlot, Qt, QTimer, QFileInfo, QPoint
from PyQt6.QtGui import QFont, QTextCursor, QBrush, QColor
from PyQt6.QtWidgets import QWidget, QDialog, QMenu

from EricWidgets.EricApplication import ericApp
from EricWidgets import EricMessageBox, EricFileDialog
from EricWidgets.EricPathPicker import EricPathPickerModes

from .Ui_MqttMonitorWidget import Ui_MqttMonitorWidget

from .MqttClient import (
    MqttClient, mqttConnackMessage, mqttErrorMessage, mqttLogLevelString
)
from .MqttReasonCodes import mqttReasonCode
from .MqttProtocols import MqttProtocols

import UI.PixmapCache
import Utilities


class MqttMonitorWidget(QWidget, Ui_MqttMonitorWidget):
    """
    Class implementing the MQTT Monitor widget.
    """
    BrokerStatusTopicPrefix = "$SYS/broker/"
    BrokerStatusTopic = "$SYS/broker/#"
    BrokerStatusTopicLoadPrefix = "$SYS/broker/load/"
    
    def __init__(self, plugin, usesDarkPalette, parent=None):
        """
        Constructor
        
        @param plugin reference to the plug-in object
        @type MqttMonitorPlugin
        @param usesDarkPalette flag indicating the use of a dark application
            palette
        @type bool
        @param parent reference to the parent widget
        @type QWidget
        """
        super().__init__(parent)
        self.setupUi(self)
        
        self.layout().setContentsMargins(0, 3, 0, 0)
        
        self.__plugin = plugin
        self.__iconSuffix = "dark" if usesDarkPalette else "light"
        
        self.__connectedToBroker = False
        self.__brokerStatusTopicSubscribed = False
        
        with contextlib.suppress(AttributeError):
            # backward compatibility
            if not ericApp().usesSmallScreen():
                self.pixmapLabel.setPixmap(UI.PixmapCache.getPixmap(
                    os.path.join("MqttMonitor", "icons",
                                 "mqtt48-{0}".format(self.__iconSuffix))
                ))
        
        self.publishPayloadFilePicker.setMode(
            EricPathPickerModes.OPEN_FILE_MODE)
        self.publishPayloadFilePicker.setFilters(self.tr("All Files (*)"))
        
        self.brokerComboBox.lineEdit().setClearButtonEnabled(True)
        self.publishTopicComboBox.lineEdit().setClearButtonEnabled(True)
        
        self.__messagesFormat = self.messagesEdit.currentCharFormat()
        self.__messagesTopicFormat = self.messagesEdit.currentCharFormat()
        self.__messagesTopicFormat.setFontWeight(QFont.Weight.Bold)
        self.__messagesQosFormat = self.messagesEdit.currentCharFormat()
        self.__messagesQosFormat.setFontItalic(True)
        self.__messagesSubheaderFormat = self.messagesEdit.currentCharFormat()
        self.__messagesSubheaderFormat.setFontUnderline(True)
        
        self.__propertiesFormat = self.propertiesEdit.currentCharFormat()
        self.__propertiesTopicFormat = self.propertiesEdit.currentCharFormat()
        self.__propertiesTopicFormat.setFontWeight(QFont.Weight.Bold)
        self.__propertiesNameFormat = self.propertiesEdit.currentCharFormat()
        self.__propertiesNameFormat.setFontItalic(True)
        
        self.messagesSearchWidget.attachTextEdit(self.messagesEdit)
        self.messagesSearchWidget.setWidthForHeight(False)
        
        self.__isMessageAlternate = False
        self.__isPropertiesAlternate = False
        
        for logLevel in (MqttClient.LogDisabled,
                         MqttClient.LogDebug,
                         MqttClient.LogInfo,
                         MqttClient.LogNotice,
                         MqttClient.LogWarning,
                         MqttClient.LogError):
            self.logLevelComboBox.addItem(mqttLogLevelString(
                logLevel, isMqttLogLevel=False), logLevel)
        self.logLevelComboBox.setCurrentIndex(
            self.logLevelComboBox.count() - 1)
        
        if usesDarkPalette:
            self.__logMessagesBackgrounds = {
                MqttClient.LogDebug: QBrush(QColor("#2f2f2f")),
                MqttClient.LogInfo: QBrush(QColor("#868686")),
                MqttClient.LogNotice: QBrush(QColor("#009900")),
                MqttClient.LogWarning: QBrush(QColor("#999900")),
                MqttClient.LogError: QBrush(QColor("#990000")),
                MqttClient.LogDisabled: QBrush(QColor("#990099")),
                # reuse LogDisabled for unknown log levels
            }
        else:
            self.__logMessagesBackgrounds = {
                MqttClient.LogDebug: QBrush(Qt.GlobalColor.white),
                MqttClient.LogInfo: QBrush(Qt.GlobalColor.lightGray),
                MqttClient.LogNotice: QBrush(Qt.GlobalColor.green),
                MqttClient.LogWarning: QBrush(Qt.GlobalColor.yellow),
                MqttClient.LogError: QBrush(Qt.GlobalColor.red),
                MqttClient.LogDisabled: QBrush(Qt.GlobalColor.magenta)
                # reuse LogDisabled for unknown log levels
            }
        
        self.logSearchWidget.attachTextEdit(self.logEdit)
        self.logSearchWidget.setWidthForHeight(False)
        
        self.brokerWidget.setCurrentIndex(0)
        
        self.__connectionModeProfile = True
        self.__setConnectionMode(True)  # initial mode is 'profile connection'
        self.__populateProfileComboBox()
        
        self.connectButton.setIcon(UI.PixmapCache.getIcon("ircConnect"))
        self.brokerConnectionOptionsButton.setIcon(UI.PixmapCache.getIcon(
            os.path.join("MqttMonitor", "icons",
                         "connectionOptions-{0}".format(self.__iconSuffix))
        ))
        self.__populateBrokerComboBoxes()
        self.brokerStatusLabel.hide()
        self.clearWillButton.setIcon(
            UI.PixmapCache.getIcon("certificateDelete"))
        
        self.subscribeTopicComboBox.lineEdit().setClearButtonEnabled(True)
        self.subscribeTopicComboBox.lineEdit().returnPressed.connect(
            self.on_subscribeButton_clicked)
        self.__populateSubscribeTopicComboBox()
        
        self.subscribeButton.setIcon(UI.PixmapCache.getIcon("plus"))
        self.subscribeButton.setEnabled(False)
        self.subscribePropertiesButton.setIcon(
            UI.PixmapCache.getIcon("listSelection"))
        self.subscribePropertiesButton.setEnabled(False)
        self.subscribePropertiesButton.setVisible(False)
        
        self.unsubscribeButton.setIcon(UI.PixmapCache.getIcon("minus"))
        self.unsubscribeButton.setEnabled(False)
        self.unsubscribePropertiesButton.setIcon(
            UI.PixmapCache.getIcon("listSelection"))
        self.unsubscribePropertiesButton.setEnabled(False)
        self.unsubscribePropertiesButton.setVisible(False)
        
        self.__initPropertiesEditMenu()
        
        self.__subscribedTopics = []
        self.__topicQueue = {}
        self.__updateUnsubscribeTopicComboBox()
        
        self.__publishedTopics = []
        self.__updatePublishTopicComboBox()
        self.publishButton.setEnabled(False)
        self.publishPropertiesButton.setIcon(
            UI.PixmapCache.getIcon("listSelection"))
        self.publishPropertiesButton.setEnabled(False)
        self.publishPropertiesButton.setVisible(False)
        
        self.__connectionOptions = None
        
        prefix = MqttMonitorWidget.BrokerStatusTopicPrefix
        self.__statusLabelMapping = {
            # broker
            prefix + "version": self.versionLabel,
            prefix + "timestamp": self.timestampLabel,
            prefix + "uptime": self.uptimeLabel,
            prefix + "subscriptions/count": self.subscriptionsLabel,
            # clients
            prefix + "clients/connected": self.clientsConnectedLabel,
            prefix + "clients/disconnected": self.clientsDisconnectedLabel,
            prefix + "clients/expired": self.clientsExpiredLabel,
            prefix + "clients/maximum": self.clientsMaximumLabel,
            prefix + "clients/total": self.clientsTotalLabel,
            # messages
            prefix + "messages/sent": self.messagesSentLabel,
            prefix + "messages/received": self.messagesReceivedLabel,
            prefix + "messages/stored": self.messagesStoredLabel,
            prefix + "store/messages/count": self.messagesStoredLabel,
            prefix + "messages/inflight": self.messagesInflightLabel,
            prefix + "retained messages/count": self.messagesRetainedLabel,
            # publish messages
            prefix + "publish/messages/sent": self.publishMessagesSentLabel,
            prefix + "publish/messages/received":
                self.publishMessagesReceivedLabel,
            prefix + "publish/messages/dropped":
                self.publishMessagesDroppedLabel,
            # traffic
            prefix + "bytes/sent": self.bytesSentLabel,
            prefix + "bytes/received": self.bytesReceivedLabel,
            # load
            prefix + "load/bytes/sent": self.loadBytesSentLabel,
            prefix + "load/bytes/received": self.loadBytesReceivedLabel,
            prefix + "load/messages/sent": self.loadMessagesSentLabel,
            prefix + "load/messages/received": self.loadMessagesReceivedLabel,
            prefix + "load/publish/sent": self.loadPublishSentLabel,
            prefix + "load/publish/received": self.loadPublishReceivedLabel,
            prefix + "load/publish/dropped": self.loadPublishDroppedLabel,
            prefix + "load/connections": self.loadConnectionsLabel,
            prefix + "load/sockets": self.loadSocketsLabel,
        }
        
        self.__statusLoadValues = collections.defaultdict(
            self.__loadDefaultDictFactory)
    
    def __createClient(self, clientId="", cleanSession=None,
                       protocol=None):
        """
        Private method to instantiate a MQTT client for a given protocol.
        
        @param clientId ID to be used for the client
        @type str
        @param cleanSession flag indicating to start a clean session
        @type bool
        @param protocol MQTT protocol version to be used (defaults to None)
        @type MqttProtocols or int (optional)
        @return created and connected MQTT client object
        @rtype MqttClient
        """
        if protocol is None:
            protocol = self.__plugin.getPreferences("DefaultProtocol")
        
        client = MqttClient(clientId=clientId, cleanSession=cleanSession,
                            protocol=protocol)
        
        # connect the MQTT client signals
        client.onConnectV3.connect(self.__brokerConnected)
        client.onConnectV5.connect(self.__brokerConnected)
        client.onDisconnectedV3.connect(self.__brokerDisconnected)
        client.onDisconnectedV5.connect(self.__brokerDisconnected)
        client.onLog.connect(self.__clientLog)
        client.onMessageV3.connect(self.__messageReceived)
        client.onMessageV5.connect(self.__messageReceived)
        client.onPublish.connect(self.__messagePublished)
        client.onSubscribeV3.connect(self.__topicSubscribed)
        client.onSubscribeV5.connect(self.__topicSubscribedV5)
        client.onUnsubscribeV3.connect(self.__topicUnsubscribed)
        client.onUnsubscribeV5.connect(self.__topicUnsubscribedV5)
        
        client.connectTimeout.connect(self.__connectTimeout)
        
        return client
    
    def __initPropertiesEditMenu(self):
        """
        Private method to create the properties output context menu.
        """
        self.__propertiesEditMenu = QMenu(self)
        self.__copyPropertiesAct = self.__propertiesEditMenu.addAction(
            UI.PixmapCache.getIcon("editCopy"),
            self.tr("Copy"), self.propertiesEdit.copy)
        self.__propertiesEditMenu.addSeparator()
        self.__selectAllPropertiesAct = self.__propertiesEditMenu.addAction(
            UI.PixmapCache.getIcon("editSelectAll"),
            self.tr("Select All"), self.propertiesEdit.selectAll)
        self.__propertiesEditMenu.addSeparator()
        self.__clearPropertiesAct = self.__propertiesEditMenu.addAction(
            UI.PixmapCache.getIcon("editDelete"),
            self.tr("Clear"), self.propertiesEdit.clear)
        
        self.propertiesEdit.copyAvailable.connect(
            self.__copyPropertiesAct.setEnabled)
        
        self.__copyPropertiesAct.setEnabled(False)
    
    #######################################################################
    ## Slots handling MQTT related signals
    #######################################################################
    
    @pyqtSlot(dict, int)
    @pyqtSlot(dict, int, int, dict)
    def __brokerConnected(self, flags, rc, packetType=None, properties=None):
        """
        Private slot to handle being connected to a broker.
        
        @param flags flags set for the connection
        @type dict
        @param rc CONNACK result code or MQTTv5 reason code
        @type int
        @param packetType packet type as reported by the client
        @type int
        @param properties dictionary containing the received connection
            properties
        @type dict
        """
        self.brokerStatusLabel.hide()
        
        if rc == 0:
            self.__connectedToBroker = True
            self.__connectionOptions = None
        
        try:
            sessionPresent = flags["session present"] == 1
        except KeyError:
            sessionPresent = False
        
        msg = (
            mqttReasonCode(rc, packetType)
            if packetType is not None else
            mqttConnackMessage(rc)
        )
        if sessionPresent:
            msg = self.tr("{0} - Session still present").format(msg)
        self.__flashBrokerStatusLabel(msg)
        
        if properties:
            self.__showProperties("Connect", properties)
        
        self.connectButton.setEnabled(True)
        if rc == 0:
            self.__connectedToBroker = True
            self.__connectionOptions = None
            
            self.connectButton.setIcon(
                UI.PixmapCache.getIcon("ircDisconnect"))
            
            self.subscribeGroup.setEnabled(True)
            self.subscribePropertiesButton.setVisible(
                self.__client.getProtocol() == MqttProtocols.MQTTv5)
            self.unsubscribeGroup.setEnabled(True)
            self.unsubscribePropertiesButton.setVisible(
                self.__client.getProtocol() == MqttProtocols.MQTTv5)
            self.publishGroup.setEnabled(True)
            self.brokerStatusButton.setEnabled(True)
            self.publishPropertiesButton.setVisible(
                self.__client.getProtocol() == MqttProtocols.MQTTv5)
            
            self.__statusLoadValues.clear()
            self.__clearBrokerStatusLabels()
            self.__setBrokerStatusSubscribed(False)
        else:
            self.__client.stopLoop()
    
    @pyqtSlot()
    def __connectTimeout(self):
        """
        Private slot handling a timeout during a connection attempt.
        """
        self.__flashBrokerStatusLabel(self.tr("Connection timed out"))
        self.__setConnectButtonState()
    
    @pyqtSlot(int)
    @pyqtSlot(int, int)
    def __brokerDisconnected(self, rc, packetType=None):
        """
        Private slot to handle a disconnection from the broker.
        
        @param rc MQTT error result code
        @type int
        @param packetType packet type as reported by the client
        @type int
        """
        self.__connectedToBroker = False
        
        # ensure, the client loop is stopped
        self.__client.stopLoop()
        
        msg = (
            # MQTT v5
            mqttReasonCode(rc, packetType)
            if packetType is not None else
            # MQTT v3
            (
                mqttErrorMessage(rc)
                if rc > 0 else
                self.tr("Connection to Broker shut down cleanly.")
            )
        )
        self.__flashBrokerStatusLabel(msg)
        
        self.connectButton.setIcon(UI.PixmapCache.getIcon("ircConnect"))
        self.__setConnectButtonState()

        self.__subscribedTopics = []
        self.__topicQueue = {}
        self.__updateUnsubscribeTopicComboBox()
        self.__updatePublishTopicComboBox()
        
        self.subscribeGroup.setEnabled(False)
        self.subscribePropertiesButton.setVisible(False)
        self.unsubscribeGroup.setEnabled(False)
        self.unsubscribePropertiesButton.setVisible(False)
        self.publishGroup.setEnabled(False)
        self.publishPropertiesButton.setVisible(False)
        self.brokerStatusButton.setEnabled(False)
        
        self.__statusLoadValues.clear()
    
    @pyqtSlot(int, str)
    def __clientLog(self, level, message):
        """
        Private slot to handle the receipt of a log message.
        
        @param level log level
        @type int
        @param message log message
        @type str
        """
        with contextlib.suppress(KeyError):
            if MqttClient.LogLevelMap[level] < self.logLevelComboBox.itemData(
                    self.logLevelComboBox.currentIndex()):
                return
        
        scrollbarValue = self.logEdit.verticalScrollBar().value()
        
        textCursor = self.logEdit.textCursor()
        if not self.logEdit.document().isEmpty():
            textCursor.movePosition(QTextCursor.MoveOperation.End)
            self.logEdit.setTextCursor(textCursor)
            self.logEdit.insertPlainText("\n")
        
        textBlockFormat = textCursor.blockFormat()
        try:
            textBlockFormat.setBackground(
                self.__logMessagesBackgrounds[MqttClient.LogLevelMap[level]])
        except KeyError:
            textBlockFormat.setBackground(
                self.__logMessagesBackgrounds[MqttClient.LogDisabled])
        textCursor.setBlockFormat(textBlockFormat)
        textCursor.movePosition(QTextCursor.MoveOperation.End)
        self.logEdit.setTextCursor(textCursor)
        
        txt = self.tr("{0}: {1}").format(mqttLogLevelString(level), message)
        self.logEdit.insertPlainText(Utilities.filterAnsiSequences(txt))
        
        if self.followLogMessagesCheckBox.isChecked():
            self.logEdit.ensureCursorVisible()
        else:
            self.logEdit.verticalScrollBar().setValue(scrollbarValue)
    
    @pyqtSlot(str, bytes, int, bool)
    @pyqtSlot(str, bytes, int, bool, dict)
    def __messageReceived(self, topic, payload, qos, retain, properties=None):
        """
        Private slot to handle the receipt of a message.
        
        @param topic topic of the message
        @type str
        @param payload payload (i.e. data) of the message
        @type bytes
        @param qos quality of service indicator
        @type int
        @param retain flag indicating a retained message
        @type bool
        @param properties properties sent with the message (MQTT v5)
        @type Properties
        """
        if topic.startswith(MqttMonitorWidget.BrokerStatusTopicPrefix):
            # handle broker status messages
            self.__handleBrokerStatusMessage(topic, payload)
        else:
            self.__appendMessage(topic, payload, qos, retain,
                                 properties=properties)
    
    @pyqtSlot(int)
    def __messagePublished(self, mid):
        """
        Private slot to handle a message being published.
        
        @param mid ID of the published message
        @type int
        """
        # nothing to show for this
        pass
    
    @pyqtSlot(int)
    def __topicSubscribed(self, mid):
        """
        Private slot to handle being subscribed to topics (MQTT v3.1,
        MQTT v3.1.1).
        
        @param mid ID of the subscribe request
        @type int
        """
        if mid in self.__topicQueue:
            topic = self.__topicQueue.pop(mid)
            self.__subscribedTopics.append(topic)
            self.__addTopicToRecent(topic)
            
            self.__updateUnsubscribeTopicComboBox()
            self.__updatePublishTopicComboBox()
    
    @pyqtSlot(int, list, dict)
    def __topicSubscribedV5(self, mid, reasonCodes, properties):
        """
        Private slot to handle being subscribed to topics (MQTT v5).
        
        @param mid ID of the subscribe request
        @type int
        @param reasonCodes list of reason codes, one for each topic
        @type list of ReasonCodes
        @param properties dictionary containing the received subscribe
            properties
        @type dict
        """
        msg = mqttReasonCode(reasonCodes[0].value, reasonCodes[0].packetType)
        self.__flashBrokerStatusLabel(msg)
        
        if properties:
            self.__showProperties("Subscribe", properties)
        
        self.__topicSubscribed(mid)
    
    @pyqtSlot(int)
    def __topicUnsubscribed(self, mid):
        """
        Private slot to handle being unsubcribed from a topic (MQTT v3.1,
        MQTT v3.1.1).
        
        @param mid ID of the unsubscribe request
        @type int
        """
        if mid in self.__topicQueue:
            topic = self.__topicQueue.pop(mid)
            with contextlib.suppress(ValueError):
                self.__subscribedTopics.remove(topic)
                self.__updateUnsubscribeTopicComboBox()
                self.__updatePublishTopicComboBox()
    
    @pyqtSlot(int, int, int, dict)
    def __topicUnsubscribedV5(self, mid, rc, packetType, properties):
        """
        Private slot to handle being unsubscribed to topics (MQTT v5).
        
        @param mid ID of the subscribe request
        @type int
        @param rc MQTTv5 reason code
        @type int
        @param packetType packet type as reported by the client
        @type int
        @param properties dictionary containing the received subscribe
            properties
        @type dict
        """
        msg = mqttReasonCode(rc, packetType)
        self.__flashBrokerStatusLabel(msg)
        
        if properties:
            self.__showProperties("Unsubscribe", properties)
        
        self.__topicUnsubscribed(mid)
    
    #######################################################################
    ## Slots handling UI interactions
    #######################################################################
    
    @pyqtSlot()
    def __flashBrokerStatusLabel(self, message):
        """
        Private slot to show the broker status label with some text for
        5 seconds.
        
        @param message message to be shown
        @type str
        """
        self.brokerStatusLabel.setText(message)
        self.brokerStatusLabel.show()
        QTimer.singleShot(5000, self.brokerStatusLabel.hide)
    
    @pyqtSlot()
    def on_modeButton_clicked(self):
        """
        Private slot to switch between connection profiles and direct
        connection mode.
        """
        self.__setConnectionMode(not self.__connectionModeProfile)
    
    @pyqtSlot(str)
    def on_profileComboBox_currentIndexChanged(self, profileName):
        """
        Private slot handling the change of the selected profile.
        
        @param profileName name of the selected profile
        @type str
        """
        self.__setConnectButtonState()
    
    @pyqtSlot(str)
    def on_brokerComboBox_editTextChanged(self, host):
        """
        Private slot to handling entering or selecting a broker host name.
        
        @param host host name of the broker
        @type str
        """
        self.__setConnectButtonState()
    
    @pyqtSlot()
    def on_brokerConnectionOptionsButton_clicked(self):
        """
        Private slot to show a dialog to modify connection options or a
        dialog to edit connection profiles.
        """
        if self.__connectionModeProfile:
            from .MqttConnectionProfilesDialog import (
                MqttConnectionProfilesDialog
            )
            profileName = self.profileComboBox.currentText()
            dlg = MqttConnectionProfilesDialog(
                self.__plugin.getPreferences("BrokerProfiles"),
                currentProfile=profileName, parent=self)
            if dlg.exec() == QDialog.DialogCode.Accepted:
                profilesDict = dlg.getProfiles()
                self.__plugin.setPreferences("BrokerProfiles", profilesDict)
                self.__populateProfileComboBox()
        else:
            from .MqttConnectionOptionsDialog import (
                MqttConnectionOptionsDialog
            )
            dlg = MqttConnectionOptionsDialog(
                self.__connectionOptions, parent=self)
            if dlg.exec() == QDialog.DialogCode.Accepted:
                self.__connectionOptions = dlg.getConnectionOptions()
                if self.__connectionOptions["TlsEnable"]:
                    port = self.brokerPortComboBox.currentText().strip()
                    if port == "1883":
                        # it is default non-encrypted port => set to TLS port
                        self.brokerPortComboBox.setEditText("8883")
                else:
                    port = self.brokerPortComboBox.currentText().strip()
                    if port == "8883":
                        # it is default TLS port => set to non-encrypted port
                        self.brokerPortComboBox.setEditText("1883")
    
    @pyqtSlot()
    def on_connectButton_clicked(self):
        """
        Private slot to handle a connect or disconnect request.
        """
        if self.__connectedToBroker:
            self.__client.disconnectFromServer()
        else:
            if self.__connectionModeProfile:
                self.__profileConnectToBroker()
            else:
                self.__directConnectToBroker()
    
    @pyqtSlot()
    def on_subscribePropertiesButton_clicked(self):
        """
        Private slot to edit the subscribe user properties.
        """
        topic = self.subscribeTopicComboBox.currentText()
        self.__editProperties(
            "subscribe",
            self.tr("SUBSCRIBE: User Properties for '{0}'").format(topic),
            topic
        )
    
    @pyqtSlot(str)
    def on_subscribeTopicComboBox_editTextChanged(self, topic):
        """
        Private slot to handle a change of the entered topic.
        
        @param topic entered topic text
        @type str
        """
        self.subscribeButton.setEnabled(bool(topic))
        self.subscribePropertiesButton.setEnabled(bool(topic))
    
    @pyqtSlot()
    def on_subscribeButton_clicked(self):
        """
        Private slot to subscribe to the entered topic.
        """
        topic = self.subscribeTopicComboBox.currentText()
        qos = self.subscribeQosSpinBox.value()
        if topic:
            if topic.startswith(MqttMonitorWidget.BrokerStatusTopicPrefix):
                EricMessageBox.warning(
                    self,
                    self.tr("Subscribe to Topic"),
                    self.tr("Subscriptions to the Status topic '$SYS' shall"
                            " be done on the 'Status' tab."))
            else:
                properties = (
                    self.__plugin.getPreferences("SubscribeProperties")
                    .get(topic, [])
                    if self.__client.getProtocol() == MqttProtocols.MQTTv5 else
                    None
                )
                result, mid = self.__client.subscribe(
                    topic, qos=qos, properties=properties)
                self.__topicQueue[mid] = topic
    
    @pyqtSlot()
    def on_unsubscribePropertiesButton_clicked(self):
        """
        Private slot to edit the unsubscribe user properties.
        """
        topic = self.unsubscribeTopicComboBox.currentText()
        self.__editProperties(
            "unsubscribe",
            self.tr("UNSUBSCRIBE: User Properties for '{0}'").format(topic),
            topic
        )
    
    @pyqtSlot(str)
    def on_unsubscribeTopicComboBox_currentIndexChanged(self, topic):
        """
        Private slot to handle the selection of a topic to unsubscribe from.
        
        @param topic topic text
        @type str
        """
        self.unsubscribeButton.setEnabled(bool(topic))
        self.unsubscribePropertiesButton.setEnabled(bool(topic))
    
    @pyqtSlot()
    def on_unsubscribeButton_clicked(self):
        """
        Private slot to unsubscribe from the selected topic.
        """
        topic = self.unsubscribeTopicComboBox.currentText()
        if topic:
            properties = (
                self.__plugin.getPreferences("SubscribeProperties")
                .get(topic, [])
                if self.__client.getProtocol() == MqttProtocols.MQTTv5 else
                None
            )
            result, mid = self.__client.unsubscribe(
                topic, properties=properties)
            self.__topicQueue[mid] = topic
    
    @pyqtSlot()
    def on_publishPropertiesButton_clicked(self):
        """
        Private slot to edit the publish user properties.
        """
        topic = self.publishTopicComboBox.currentText()
        self.__editProperties(
            "publish",
            self.tr("PUBLISH: User Properties for '{0}'").format(topic),
            topic
        )
    
    @pyqtSlot(str)
    def on_publishTopicComboBox_editTextChanged(self, topic):
        """
        Private slot to handle changes of the publish topic name.
        
        @param topic topic text
        @type str
        """
        self.publishButton.setEnabled(bool(topic))
        self.publishPropertiesButton.setEnabled(bool(topic))
    
    @pyqtSlot()
    def on_publishButton_clicked(self):
        """
        Private slot to publish the entered message.
        """
        topic = self.publishTopicComboBox.currentText()
        qos = self.publishQosSpinBox.value()
        retain = self.publishRetainCheckBox.isChecked()
        payloadFile = self.publishPayloadFilePicker.text()
        if (
            bool(payloadFile) and
            os.path.exists(payloadFile) and
            os.path.getsize(payloadFile) <= 268435455
        ):
            # payload size limit is 268,435,455 bytes
            try:
                with open(payloadFile, "rb") as f:
                    payloadStr = f.read()
            except EnvironmentError as err:
                EricMessageBox.critical(
                    self,
                    self.tr("Read Payload from File"),
                    self.tr("""<p>The file <b>{0}</b> could not be read."""
                            """ Aborting...</p><p>Reason: {1}</p>""").format(
                        payloadFile, str(err)))
                return
        else:
            payloadStr = self.publishPayloadEdit.toPlainText()
            if not payloadStr:
                # use empty string together with the retain flag to clean
                # a retained message by sending None instead
                payloadStr = None
        properties = (
            self.__plugin.getPreferences("PublishProperties").get(topic, [])
            if self.__client.getProtocol() == MqttProtocols.MQTTv5 else
            None
        )
        
        msgInfo = self.__client.publish(
            topic, payload=payloadStr, qos=qos, retain=retain,
            properties=properties)
        if msgInfo.rc == 0:
            if topic not in self.__publishedTopics:
                self.__publishedTopics.append(topic)
            self.__updatePublishTopicComboBox(resetTopic=False)
            if self.clearPublishCheckBox.isChecked():
                self.on_publishClearButton_clicked()
    
    @pyqtSlot()
    def on_publishClearRetainedButton_clicked(self):
        """
        Private slot to clear the retained messages for the topic.
        """
        topic = self.publishTopicComboBox.currentText()
        properties = (
            self.__plugin.getPreferences("PublishProperties").get(topic, [])
            if self.__client.getProtocol() == MqttProtocols.MQTTv5 else
            None
        )
        
        msgInfo = self.__client.publish(
            topic, payload=None, retain=True, properties=properties)
        if msgInfo.rc == 0:
            if topic not in self.__publishedTopics:
                self.__publishedTopics.append(topic)
            self.__updatePublishTopicComboBox(resetTopic=False)
    
    @pyqtSlot()
    def on_publishClearButton_clicked(self):
        """
        Private slot to clear the publish data fields.
        """
        self.publishTopicComboBox.clearEditText()
        self.publishPayloadEdit.clear()
        self.publishQosSpinBox.setValue(0)
        self.publishRetainCheckBox.setChecked(False)
        self.publishPayloadFilePicker.clear()
    
    @pyqtSlot(str)
    def on_publishPayloadFilePicker_textChanged(self, path):
        """
        Private slot handling a change of path of the payload file.
        
        @param path path of the payload file
        @type str
        """
        self.publishPayloadEdit.setEnabled(not bool(path))
    
    @pyqtSlot(QPoint)
    def on_propertiesEdit_customContextMenuRequested(self, pos):
        """
        Private slot to show the context menu for the properties output.
        
        @param pos the position of the mouse pointer
        @type QPoint
        """
        self.__propertiesEditMenu.popup(self.propertiesEdit.mapToGlobal(pos))
    
    @pyqtSlot()
    def on_brokerStatusButton_clicked(self):
        """
        Private slot to subscribe or unsubscribe the broker status topic.
        """
        if self.__brokerStatusTopicSubscribed:
            # unsubscribe status topic
            rc, _ = self.__client.unsubscribe(
                MqttMonitorWidget.BrokerStatusTopic)
            if rc == 0:
                # successfully sent
                self.__setBrokerStatusSubscribed(False)
        else:
            # subscribe status topic
            rc, _ = self.__client.subscribe(
                MqttMonitorWidget.BrokerStatusTopic)
            if rc == 0:
                # successfully sent
                self.__setBrokerStatusSubscribed(True)
    
    @pyqtSlot(int)
    def on_messagesEdit_blockCountChanged(self, newBlockCount):
        """
        Private slot handling changes of received messages.
        
        @param newBlockCount (ignored)
        @type int
        """
        enable = not self.messagesEdit.document().isEmpty()
        self.saveMessagesButton.setEnabled(enable)
        self.clearMessagesButton.setEnabled(enable)
    
    @pyqtSlot()
    def on_saveMessagesButton_clicked(self):
        """
        Private slot to save the received messages.
        """
        fn, selectedFilter = EricFileDialog.getSaveFileNameAndFilter(
            self,
            self.tr("Save Messages"),
            "",
            self.tr("Messages Files (*.txt);;All Files (*)"),
            "",
            EricFileDialog.DontConfirmOverwrite)
        
        if fn:
            if fn.endswith("."):
                fn = fn[:-1]
            
            ext = QFileInfo(fn).suffix()
            if not ext:
                ex = selectedFilter.split("(*")[1].split(")")[0]
                if ex:
                    fn += ex
            if QFileInfo(fn).exists():
                res = EricMessageBox.yesNo(
                    self,
                    self.tr("Save Messages"),
                    self.tr("<p>The file <b>{0}</b> already exists."
                            " Overwrite it?</p>").format(fn),
                    icon=EricMessageBox.Warning)
                if not res:
                    return
            
            fn = Utilities.toNativeSeparators(fn)
            try:
                with open(fn, "w") as f:
                    f.write(self.messagesEdit.toPlainText())
            except EnvironmentError as err:
                EricMessageBox.critical(
                    self,
                    self.tr("Save Messages"),
                    self.tr("""<p>The file <b>{0}</b> could not be written."""
                            """</p><p>Reason: {1}</p>""").format(
                        fn, str(err)))
    
    @pyqtSlot(int)
    def on_logEdit_blockCountChanged(self, newBlockCount):
        """
        Private slot handling changes of received messages.
        
        @param newBlockCount (ignored)
        @type int
        """
        enable = not self.logEdit.document().isEmpty()
        self.saveLogMessagesButton.setEnabled(enable)
        self.clearLogMessagesButton.setEnabled(enable)
    
    @pyqtSlot()
    def on_saveLogMessagesButton_clicked(self):
        """
        Private slot to save the log messages.
        """
        fn, selectedFilter = EricFileDialog.getSaveFileNameAndFilter(
            self,
            self.tr("Save Log Messages"),
            "",
            self.tr("Log Files (*.log);;All Files (*)"),
            "",
            EricFileDialog.DontConfirmOverwrite)
        
        if fn:
            if fn.endswith("."):
                fn = fn[:-1]
            
            ext = QFileInfo(fn).suffix()
            if not ext:
                ex = selectedFilter.split("(*")[1].split(")")[0]
                if ex:
                    fn += ex
            if QFileInfo(fn).exists():
                res = EricMessageBox.yesNo(
                    self,
                    self.tr("Save Log Messages"),
                    self.tr("<p>The file <b>{0}</b> already exists."
                            " Overwrite it?</p>").format(fn),
                    icon=EricMessageBox.Warning)
                if not res:
                    return
            
            fn = Utilities.toNativeSeparators(fn)
            try:
                with open(fn, "w") as f:
                    f.write(self.logEdit.toPlainText())
            except EnvironmentError as err:
                EricMessageBox.critical(
                    self,
                    self.tr("Save Log Messages"),
                    self.tr("""<p>The file <b>{0}</b> could not be written."""
                            """</p><p>Reason: {1}</p>""").format(
                        fn, str(err)))
    
    #######################################################################
    ## Utility methods
    #######################################################################
    
    def __setBrokerStatusSubscribed(self, subscribed):
        """
        Private method to set the subscription status for the broker status
        topics.
        
        @param subscribed subscription status for the broker status topics
        @type bool
        """
        self.__brokerStatusTopicSubscribed = subscribed
        if subscribed:
            self.brokerStatusButton.setText(self.tr("Unsubscribe"))
            self.brokerStatusButton.setToolTip(
                self.tr("Press to deactivate the status display"))
        else:
            self.brokerStatusButton.setText(self.tr("Subscribe"))
            self.brokerStatusButton.setToolTip(
                self.tr("Press to activate the status display"))
    
    def __addBrokerToRecent(self, host, port):
        """
        Private method to add a host name to the list of recently connected
        brokers.
        
        @param host host name of broker
        @type str
        @param port port number of the connection
        @type int
        """
        brokerList = self.__plugin.getPreferences("RecentBrokersWithPort")
        hostAndPort = [host, port]
        if hostAndPort in brokerList:
            brokerList.remove(hostAndPort)
        brokerList.insert(0, hostAndPort)
        # limit the most recently used entries
        maxBrokers = self.__plugin.getPreferences("RecentBrokersNumber")
        brokerList = brokerList[:maxBrokers]
        self.__plugin.setPreferences("RecentBrokersWithPort", brokerList)
        
        self.__populateBrokerComboBoxes()
    
    def __populateBrokerComboBoxes(self):
        """
        Private method to populate the broker name and port combo boxes.
        """
        brokerPortList = self.__plugin.getPreferences("RecentBrokersWithPort")
        
        # step 1: clear combo boxes
        self.brokerComboBox.clear()
        self.brokerPortComboBox.clear()
        
        # step 2a: populate the broker name list
        currentBroker = brokerPortList[0][0] if brokerPortList else ""
        brokerSet = {b[0].strip() for b in brokerPortList}
        self.brokerComboBox.addItems(sorted(brokerSet))
        index = self.brokerComboBox.findText(currentBroker)
        self.brokerComboBox.setCurrentIndex(index)
        
        # step 2b: populate the broker ports list
        currentPort = brokerPortList[0][1] if brokerPortList else 1883
        currentPortStr = "{0:5}".format(currentPort)
        portsSet = {b[1] for b in brokerPortList}
        portsSet.update({1883, 8883})
        self.brokerPortComboBox.addItems(
            sorted("{0:5}".format(p) for p in portsSet))
        index = self.brokerPortComboBox.findText(currentPortStr)
        self.brokerPortComboBox.setCurrentIndex(index)
        
        # step 3: update the connect button state
        self.__setConnectButtonState()
    
    def __populateProfileComboBox(self):
        """
        Private method to populate the profiles selection box.
        """
        profilesDict = self.__plugin.getPreferences("BrokerProfiles")
        mostRecentProfile = self.__plugin.getPreferences("MostRecentProfile")
        
        self.profileComboBox.clear()
        self.profileComboBox.addItems(sorted(profilesDict.keys()))
        if mostRecentProfile:
            index = self.profileComboBox.findText(mostRecentProfile)
            if index >= 0:
                self.profileComboBox.setCurrentIndex(index)
        
        self.__setConnectButtonState()
    
    def __addTopicToRecent(self, topic):
        """
        Private method to add a topic to the list of recently subscribed
        topics.
        
        @param topic subscribed topic
        @type str
        """
        topicsList = self.__plugin.getPreferences("RecentTopics")
        if topic in topicsList:
            topicsList.remove(topic)
        topicsList.insert(0, topic)
        # limit the most recently used entries
        maxTopics = self.__plugin.getPreferences("RecentTopicsNumber")
        topicsList = topicsList[:maxTopics]
        self.__plugin.setPreferences("RecentTopics", topicsList)
        
        self.__populateSubscribeTopicComboBox()
    
    def __populateSubscribeTopicComboBox(self):
        """
        Private method to populate the subscribe topic combo box.
        """
        topicsList = self.__plugin.getPreferences("RecentTopics")
        
        self.subscribeTopicComboBox.clear()
        self.subscribeTopicComboBox.addItems(sorted(topicsList))
        self.subscribeTopicComboBox.clearEditText()
    
    def __updateUnsubscribeTopicComboBox(self):
        """
        Private method to update the unsubcribe topic combo box.
        """
        self.unsubscribeTopicComboBox.clear()
        self.unsubscribeTopicComboBox.addItems(sorted(self.__subscribedTopics))
        self.unsubscribeButton.setEnabled(
            bool(self.__subscribedTopics))
        self.unsubscribePropertiesButton.setEnabled(
            bool(self.__subscribedTopics))
    
    def __updatePublishTopicComboBox(self, resetTopic=True):
        """
        Private method to update the publish topic combo box.
        
        @param resetTopic flag indicating to reset the topic
        @type bool
        """
        currentTopic = self.publishTopicComboBox.currentText()
        self.publishTopicComboBox.clear()
        self.publishTopicComboBox.addItems(
            list(set(self.__publishedTopics + self.__subscribedTopics)))
        if resetTopic:
            self.publishTopicComboBox.clearEditText()
        else:
            topicIndex = self.publishTopicComboBox.findText(currentTopic)
            self.publishTopicComboBox.setCurrentIndex(topicIndex)
    
    def __appendMessage(self, topic, payload, qos, retain, properties=None):
        """
        Private method to append a received message to the output.
        
        @param topic topic of the received message
        @type str
        @param payload payload of the received message
        @type bytes
        @param qos quality of service indicator (0, 1, 2)
        @type int
        @param retain flag indicating a retained message
        @type bool
        @param properties properties sent with the message (MQTT v5)
        @type dict
        """
        scrollbarValue = self.messagesEdit.verticalScrollBar().value()
        
        textCursor = self.messagesEdit.textCursor()
        if not self.messagesEdit.document().isEmpty():
            textCursor.movePosition(QTextCursor.MoveOperation.End)
            self.messagesEdit.setTextCursor(textCursor)
            self.messagesEdit.insertPlainText("\n")
        
        textBlockFormat = textCursor.blockFormat()
        if self.__isMessageAlternate:
            textBlockFormat.setBackground(
                self.messagesEdit.palette().alternateBase())
        else:
            textBlockFormat.setBackground(
                self.messagesEdit.palette().base())
        textCursor.setBlockFormat(textBlockFormat)
        textCursor.movePosition(QTextCursor.MoveOperation.End)
        self.messagesEdit.setTextCursor(textCursor)
        
        self.messagesEdit.setCurrentCharFormat(self.__messagesTopicFormat)
        self.messagesEdit.insertPlainText(topic + "\n")
        
        self.messagesEdit.setCurrentCharFormat(self.__messagesQosFormat)
        self.messagesEdit.insertPlainText(self.tr("QoS: {0}\n").format(qos))
        
        if retain:
            self.messagesEdit.setCurrentCharFormat(self.__messagesQosFormat)
            self.messagesEdit.insertPlainText(self.tr("Retained Message\n"))
        
        if properties:
            self.messagesEdit.setCurrentCharFormat(
                self.__messagesSubheaderFormat)
            self.messagesEdit.insertPlainText(self.tr("Properties:\n"))
            self.messagesEdit.setCurrentCharFormat(self.__messagesFormat)
            for name, value in sorted(properties.items()):
                self.messagesEdit.insertPlainText(
                    self.tr("{0}: {1}\n", "property name, property value")
                    .format(name, value)
                )
        
        self.messagesEdit.setCurrentCharFormat(self.__messagesSubheaderFormat)
        self.messagesEdit.insertPlainText(self.tr("Message:\n"))
        payloadStr = str(payload, encoding="utf-8", errors="replace")
        payloadStr = Utilities.filterAnsiSequences(payloadStr)
        self.messagesEdit.setCurrentCharFormat(self.__messagesFormat)
        if payloadStr:
            self.messagesEdit.insertPlainText(payloadStr)
        else:
            self.messagesEdit.insertPlainText(self.tr("<empty>"))
        
        if self.followMessagesCheckBox.isChecked():
            self.messagesEdit.ensureCursorVisible()
        else:
            self.messagesEdit.verticalScrollBar().setValue(scrollbarValue)
        
        self.__isMessageAlternate = not self.__isMessageAlternate
    
    def __handleBrokerStatusMessage(self, topic, payload):
        """
        Private method to handle a status message of the broker.
        
        @param topic topic of the received message
        @type str
        @param payload payload of the received message
        @type bytes
        """
        payloadStr = str(payload, encoding="utf-8", errors="replace").strip()
        topic = topic.strip()
        
        if topic.startswith(MqttMonitorWidget.BrokerStatusTopicLoadPrefix):
            self.__handleBrokerLoadStatusMessage(topic, payloadStr)
        else:
            with contextlib.suppress(KeyError):
                label = self.__statusLabelMapping[topic]
                label.setText(payloadStr)
    
    def __handleBrokerLoadStatusMessage(self, topic, payloadStr):
        """
        Private method to append a received message to the output.
        
        @param topic topic of the received message
        @type str
        @param payloadStr string representation of the payload of the
            received message
        @type str
        """
        subtopic, topicElement = topic.rsplit("/", 1)
        self.__statusLoadValues[subtopic][topicElement] = payloadStr
        
        with contextlib.suppress(KeyError):
            label = self.__statusLabelMapping[subtopic]
            label.setText("{0} / {1} / {2}".format(
                self.__statusLoadValues[subtopic]["1min"],
                self.__statusLoadValues[subtopic]["5min"],
                self.__statusLoadValues[subtopic]["15min"],
            ))
    
    def __clearBrokerStatusLabels(self):
        """
        Private method to clear the broker status labels.
        """
        for statusLabelKey in self.__statusLabelMapping:
            label = (
                "- / - / -"
                if statusLabelKey.startswith(
                    MqttMonitorWidget.BrokerStatusTopicLoadPrefix) else
                "-"
            )
            self.__statusLabelMapping[statusLabelKey].setText(label)
    
    def __loadDefaultDictFactory(self):
        """
        Private method to populate non-existing load items.
        
        @return default dictionary entry
        @rtype dict
        """
        return {
            "1min": "-",
            "5min": "-",
            "15min": "-",
        }
    
    def __setConnectionMode(self, profileMode):
        """
        Private method to set the connection mode.
        
        @param profileMode flag indicating the profile connection mode
        @type bool
        """
        self.__connectionModeProfile = profileMode
        if profileMode:
            self.modeButton.setIcon(UI.PixmapCache.getIcon(
                os.path.join("MqttMonitor", "icons",
                             "profiles-{0}".format(self.__iconSuffix))
            ))
        else:
            self.modeButton.setIcon(UI.PixmapCache.getIcon(
                os.path.join("MqttMonitor", "icons",
                             "quickopen-{0}".format(self.__iconSuffix))
            ))
        
        self.profileComboBox.setVisible(profileMode)
        self.brokerConnectionWidget.setVisible(not profileMode)
        self.__setConnectButtonState()
    
    def __setConnectButtonState(self):
        """
        Private method to set the enabled state of the connect button.
        """
        if self.__connectionModeProfile:
            self.connectButton.setEnabled(
                bool(self.profileComboBox.currentText()))
        else:
            self.connectButton.setEnabled(
                bool(self.brokerComboBox.currentText()))
    
    def __directConnectToBroker(self):
        """
        Private method to connect to the broker with entered data.
        """
        host = self.brokerComboBox.currentText()
        port = self.brokerPortComboBox.currentText().strip()
        try:
            port = int(port)
        except ValueError:
            # use standard port at 1883
            port = 1883
        if host:
            self.brokerStatusLabel.setText(
                self.tr("Connecting to {0}:{1} ...").format(
                    host, port))
            self.brokerStatusLabel.show()
            
            self.__addBrokerToRecent(host, port)
            self.connectButton.setEnabled(False)
            
            if self.clearWillButton.isChecked():
                clearWill = True
                self.clearWillButton.setChecked(False)
            else:
                clearWill = False
            
            if self.__connectionOptions is None:
                self.__client = self.__createClient()
                self.__client.connectToServer(
                    host, port=port, clearWill=clearWill)
            else:
                self.__client = self.__createClient(
                    clientId=self.__connectionOptions["ClientId"],
                    cleanSession=self.__connectionOptions["CleanSession"],
                    protocol=self.__connectionOptions["Protocol"]
                )
                self.__client.connectToServerWithOptions(
                    host, port=port, options=self.__connectionOptions,
                    clearWill=clearWill)
    
    def __profileConnectToBroker(self):
        """
        Private method to connect to the broker with selected profile.
        """
        profileName = self.profileComboBox.currentText()
        if profileName:
            self.__plugin.setPreferences("MostRecentProfile", profileName)
            
            profilesDict = self.__plugin.getPreferences("BrokerProfiles")
            connectionProfile = copy.deepcopy(profilesDict[profileName])
            host = connectionProfile["BrokerAddress"]
            port = connectionProfile["BrokerPort"]
            try:
                protocol = connectionProfile["Protocol"]
            except KeyError:
                protocol = MqttProtocols(
                    self.__plugin.getPreferences("DefaultProtocol"))
            
            self.brokerStatusLabel.setText(
                self.tr("Connecting to {0}:{1} ...").format(
                    host, port))
            self.brokerStatusLabel.show()
            
            self.connectButton.setEnabled(False)
            
            if self.clearWillButton.isChecked():
                clearWill = True
                self.clearWillButton.setChecked(False)
            else:
                clearWill = False
            
            self.__client = self.__createClient(
                clientId=connectionProfile["ClientId"],
                cleanSession=connectionProfile["CleanSession"],
                protocol=protocol
            )
            self.__client.connectToServerWithOptions(
                host, port=port, options=connectionProfile,
                clearWill=clearWill)
    
    def __showProperties(self, typeStr, properties):
        """
        Private method to display the received properties in the properties
        pane.
        
        @param typeStr message type
        @type str
        @param properties dictionary containing the relevant properties
        @type dict
        """
        textCursor = self.propertiesEdit.textCursor()
        if not self.propertiesEdit.document().isEmpty():
            textCursor.movePosition(QTextCursor.MoveOperation.End)
            self.propertiesEdit.setTextCursor(textCursor)
        
        textBlockFormat = textCursor.blockFormat()
        if self.__isPropertiesAlternate:
            textBlockFormat.setBackground(
                self.propertiesEdit.palette().alternateBase())
        else:
            textBlockFormat.setBackground(
                self.propertiesEdit.palette().base())
        textCursor.setBlockFormat(textBlockFormat)
        textCursor.movePosition(QTextCursor.MoveOperation.End)
        self.propertiesEdit.setTextCursor(textCursor)
        
        self.propertiesEdit.setCurrentCharFormat(self.__propertiesTopicFormat)
        self.propertiesEdit.insertPlainText(typeStr + "\n")
        
        for name, value in sorted(properties.items()):
            self.propertiesEdit.setCurrentCharFormat(
                self.__propertiesNameFormat)
            self.propertiesEdit.insertPlainText("{0}: ".format(name))
            self.propertiesEdit.setCurrentCharFormat(self.__propertiesFormat)
            self.propertiesEdit.insertPlainText("{0}\n".format(str(value)))
        
        self.propertiesEdit.ensureCursorVisible()
        
        self.__isPropertiesAlternate = not self.__isPropertiesAlternate
    
    def __editProperties(self, propertiesType, header, key):
        """
        Private method to edit user properties of a given type.
        
        @param propertiesType properties type (one of 'subscribe',
            'unsubscribe', 'publish')
        @type str
        @param header header to be shown in the edit dialog
        @type str
        @param key key to retrieve the right properties
        @type str
        """
        from .MqttUserPropertiesEditor import MqttUserPropertiesEditorDialog
        
        preferencesKey = "{0}Properties".format(propertiesType.capitalize())
        properties = self.__plugin.getPreferences(preferencesKey)
        dlg = MqttUserPropertiesEditorDialog(
            header, properties.get(key, []), self)
        if dlg.exec() == QDialog.DialogCode.Accepted:
            properties[key] = dlg.getProperties()
            self.__plugin.setPreferences(preferencesKey, properties)