wacom: remove state-based decision of whether to listen or register

Previously, we set self._mode and used that to determine what connection to
attempt. This can sometimes lead to a device attempting to register in
response to a listen() request (and vice versa).

Make this dependent on the caller arguments only. So when listen() is
requested do exactly that and generate the right exception if the device is in
the wrong mode.

Fixes #79 (multiple patches required)

tuhi/base.py

@@ -139,7 +139,10 @@ class TuhiDevice(GObject.Object):
             self._wacom_device.connect('notify::uuid', self._on_uuid_updated, bluez_device)
             self._wacom_device.connect('battery-status', self._on_battery_status, bluez_device)
 
-        self._wacom_device.start(not self.registered)
+        if not self.registered:
+            self._wacom_device.start_register()
+        else:
+            self._wacom_device.start_listen()
 
     def _on_bluez_device_disconnected(self, bluez_device):
         logger.debug(f'{bluez_device.address}: disconnected')

tuhi/wacom.py

@@ -47,6 +47,12 @@ class Protocol(enum.Enum):
     INTUOS_PRO = 'intuos-pro'
 
 
+@enum.unique
+class DeviceMode(enum.Enum):
+    REGISTER = 1
+    LISTEN = 2
+
+
 def signed_char_to_int(v):
     return int.from_bytes([v], byteorder='little', signed=True)
 
@@ -803,16 +809,18 @@ class WacomDevice(GObject.Object):
         logger.info('registration completed')
         self.notify('uuid')
 
-    def run(self):
+    def _run(self, *args, **kwargs):
         if self._is_running:
             logger.error(f'{self._device.address}: already synching, ignoring this request')
             return
 
+        mode = args[0]
+
         logger.debug(f'{self._device.address}: starting')
         self._is_running = True
         exception = None
         try:
-            if self._register_mode:
+            if mode == DeviceMode.REGISTER:
                 self.register_device()
             else:
                 assert self._wacom_protocol is not None
@@ -821,11 +829,13 @@ class WacomDevice(GObject.Object):
             logger.error(f'**** Exception: {e} ****')
             exception = e
         finally:
-            self._register_mode = False
             self._is_running = False
             self.emit('done', exception)
 
-    def start(self, register_mode):
-        self._register_mode = register_mode
-        self.thread = threading.Thread(target=self.run)
+    def start_listen(self):
+        self.thread = threading.Thread(target=self._run, args=(DeviceMode.LISTEN,))
+        self.thread.start()
+
+    def start_register(self):
+        self.thread = threading.Thread(target=self._run, args=(DeviceMode.REGISTER,))
         self.thread.start()