Refactor homekit_controller entity update to work more like update coordinator (#32670)

* Clean up use of get_characteristic_types

* Get rid of get_hk_char_value helper

* Get rid of _update_fn callbacks

* Call async_write_has_state directly as async_state_changed doesnt do anything any more

homeassistant/components/homekit_controller/switch.py

@@ -32,30 +32,17 @@ async def async_setup_entry(hass, config_entry, async_add_entities):
 class HomeKitSwitch(HomeKitEntity, SwitchDevice):
     """Representation of a Homekit switch."""
 
-    def __init__(self, *args):
-        """Initialise the switch."""
-        super().__init__(*args)
-        self._on = None
-        self._outlet_in_use = None
-
     def get_characteristic_types(self):
         """Define the homekit characteristics the entity cares about."""
         return [CharacteristicsTypes.ON, CharacteristicsTypes.OUTLET_IN_USE]
 
-    def _update_on(self, value):
-        self._on = value
-
-    def _update_outlet_in_use(self, value):
-        self._outlet_in_use = value
-
     @property
     def is_on(self):
         """Return true if device is on."""
-        return self._on
+        return self.service.value(CharacteristicsTypes.ON)
 
     async def async_turn_on(self, **kwargs):
         """Turn the specified switch on."""
-        self._on = True
         characteristics = [{"aid": self._aid, "iid": self._chars["on"], "value": True}]
         await self._accessory.put_characteristics(characteristics)
 
@@ -67,5 +54,6 @@ class HomeKitSwitch(HomeKitEntity, SwitchDevice):
     @property
     def device_state_attributes(self):
         """Return the optional state attributes."""
-        if self._outlet_in_use is not None:
-            return {OUTLET_IN_USE: self._outlet_in_use}
+        outlet_in_use = self.service.value(CharacteristicsTypes.OUTLET_IN_USE)
+        if outlet_in_use is not None:
+            return {OUTLET_IN_USE: outlet_in_use}