Gate Start/Pause/Stop on whether a Sud is loaded and running

Start is enabled only once a schedule is loaded and idle; Pause/Stop
only while it's actually running (RAMPING/HOLDING/WAIT_USER). All
three stay disabled until something arrives on the Sud channel (which
only happens if a SudTask is actually configured server-side), and
get disabled again on disconnect since nothing reported over a dead
connection can still be trusted.

Also drops actionStop's leftover wiring to disconnect() - now that
Stop is meant to stop a running brew, it shouldn't tear down the
websocket connection instead.

client/brewpi_gui.py

@@ -16,6 +16,10 @@ from ws.message import MessageDispatcherSync
 from queue import Queue
 import asyncio
 
+# str(SudState.X) values (as sent in the 'State' message) that count as
+# "running" for enabling/disabling the Start/Pause/Stop toolbar actions.
+SUD_RUNNING_STATES = {"SudState.RAMPING", "SudState.HOLDING", "SudState.WAIT_USER"}
+
 
 def _style_axis(ax):
 	ax.set_facecolor('white')
@@ -164,6 +168,8 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		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.sud_loaded = False
+		self.sud_state = None
 		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')
@@ -179,8 +185,8 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		self.msg_sud.set_recv_handler(self.on_sud_changed)
 
 		self.setupUi(self)
+		self.update_sud_actions()
 		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)
 		self.Slider_pwr_soll.valueChanged.connect(self.on_slider_pwr_soll_changed)
@@ -263,6 +269,17 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 	def on_ws_connect_changed(self, connected):
 		self.connected = connected
 		self.btn_connect.setText("Disconnect" if connected else "Connect")
+		if not connected:
+			# Nothing reported over a dead connection can be trusted anymore.
+			self.sud_loaded = False
+			self.sud_state = None
+			self.update_sud_actions()
+
+	def update_sud_actions(self):
+		running = self.sud_loaded and self.sud_state in SUD_RUNNING_STATES
+		self.actionStart.setEnabled(self.sud_loaded and not running)
+		self.actionPause.setEnabled(running)
+		self.actionStop.setEnabled(running)
 
 	def on_slider_temp_soll_changed(self, value):
 		print("on_slider_temp_soll_changed {}".format(value))
@@ -390,6 +407,9 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 
 	def on_sud_changed(self, msg):
 		print("on_sud_changed {}".format(msg))
+		# Receiving anything at all on this channel means a Sud is loaded
+		# server-side - the schedule it's running may still be coming.
+		self.sud_loaded = True
 		for key in msg:
 			if "Json" in key:
 				if self.sud_download_path:
@@ -400,6 +420,9 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 					self.update_sud_forecast(msg['Json'])
 			elif "Name" in key:
 				self.statusBar().showMessage("Sud schedule updated: {}".format(msg['Name']), 5000)
+			elif "State" in key:
+				self.sud_state = msg['State']
+		self.update_sud_actions()
 
 	def update_sud_forecast(self, doc):
 		try: