Toggle Connect/Disconnect on the same button once connected

MessageDispatcherSync gains an optional on_connect_changed(bool)
callback, fired from the websocket client's background loop once the
connection is actually live/lost, so the button only flips state on a
real connection change rather than optimistically on click.

client/brewpi_gui.py

@@ -160,7 +160,9 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		loop = asyncio.new_event_loop()
 		asyncio.set_event_loop(loop)
 		self.msg_dispatch = MessageDispatcherSync(auto_subscribe=True)
+		self.msg_dispatch.on_connect_changed = self.on_ws_connect_changed
 		self.ws_client = WsClient(listener=self.msg_dispatch, loop=loop)
+		self.connected = False
 		self.msg_pot = self.msg_dispatch.msgio_get('Pot')
 		self.msg_sensor = self.msg_dispatch.msgio_get('Sensor')
 		self.msg_heater = self.msg_dispatch.msgio_get('Heater')
@@ -176,7 +178,7 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		self.msg_sud.set_recv_handler(self.on_sud_changed)
 
 		self.setupUi(self)
-		self.btn_connect.clicked.connect(self.connect)
+		self.btn_connect.clicked.connect(self.on_btn_connect_clicked)
 		self.actionStop.triggered.connect(self.disconnect)
 		self.actionSudDownload.triggered.connect(self.on_action_sud_download)
 		self.actionSudUpload.triggered.connect(self.on_action_sud_upload)
@@ -246,6 +248,16 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 	def disconnect(self):
 		self.ws_client.disconnect()
 
+	def on_btn_connect_clicked(self):
+		if self.connected:
+			self.disconnect()
+		else:
+			self.connect()
+
+	def on_ws_connect_changed(self, connected):
+		self.connected = connected
+		self.btn_connect.setText("Disconnect" if connected else "Connect")
+
 	def on_slider_temp_soll_changed(self, value):
 		print("on_slider_temp_soll_changed {}".format(value))
 		self.msg_tempctrl.send({'Soll': {'Temp': value}})