#292: Publish HA discovery on HA reconnection

Author: nanomad

configuration/__init__.py

@@ -37,6 +37,7 @@ def __init__(self):
         self.ha_discovery_enabled: bool = True
         self.ha_discovery_prefix: str = 'homeassistant'
         self.ha_show_unavailable: bool = True
+        self.ha_lwt_topic: str = 'homeassistant/status'
         self.charge_dynamic_polling_min_percentage: float = 1.0
         self.publish_raw_api_data: bool = False
 

handlers/vehicle.py

@@ -47,7 +47,10 @@ def __init__(
             True
         )
         self.vehicle_state = vehicle_state
-        self.ha_discovery = HomeAssistantDiscovery(vehicle_state, vin_info, config)
+        if self.configuration.ha_discovery_enabled:
+            self.__ha_discovery = HomeAssistantDiscovery(vehicle_state, vin_info, config)
+        else:
+            self.__ha_discovery = None
 
         self.__setup_abrp(config, vin_info)
         self.__setup_osmand(config, vin_info)
@@ -114,8 +117,7 @@ async def handle_vehicle(self) -> None:
                         exc_info=e
                     )
                 finally:
-                    if self.configuration.ha_discovery_enabled:
-                        self.ha_discovery.publish_ha_discovery_messages()
+                    self.publish_ha_discovery_messages(force=False)
             else:
                 # car not active, wait a second
                 await asyncio.sleep(1.0)
@@ -464,6 +466,10 @@ def __get_command_topics(self, topic: str) -> tuple[str, str]:
         result_topic = global_topic_removed.removesuffix(SET_SUFFIX).removesuffix('/') + '/' + RESULT_SUFFIX
         return set_topic, result_topic
 
+    def publish_ha_discovery_messages(self, *, force: bool = False):
+        if self.__ha_discovery is not None:
+            self.__ha_discovery.publish_ha_discovery_messages(force=force)
+
 
 class VehicleHandlerLocator(ABC):
 

integrations/home_assistant/discovery.py

@@ -96,15 +96,15 @@ def __init__(self, vehicle_state: VehicleState, vin_info: VinInfo, configuration
         )
         self.published = False
 
-    def publish_ha_discovery_messages(self):
-        if self.published:
-            LOG.debug("Skipping Home Assistant discovery messages as it was already published")
-            return
-
+    def publish_ha_discovery_messages(self, *, force: bool = False):
         if not self.__vehicle_state.is_complete():
             LOG.debug("Skipping Home Assistant discovery messages as vehicle state is not yet complete")
             return
 
+        if self.published and not force:
+            LOG.debug("Skipping Home Assistant discovery messages as it was already published")
+            return
+        
         self.__publish_ha_discovery_messages_real()
         self.published = True
 

mqtt_gateway.py

@@ -159,6 +159,16 @@ def get_vehicle_handler(self, vin: str) -> Optional[VehicleHandler]:
     def vehicle_handlers(self) -> dict[str, VehicleHandler]:
         return self.__vehicle_handlers
 
+    @override
+    async def on_mqtt_global_command_received(self, *, topic: str, payload: str):
+        match topic:
+            case self.configuration.ha_lwt_topic:
+                if payload == 'online':
+                    for (_, h) in self.vehicle_handlers.items():
+                        h.publish_ha_discovery_messages(force=True)
+            case _:
+                LOG.error(f'Received unknown global command {topic}: {payload}')
+
     @override
     async def on_mqtt_command_received(self, *, vin: str, topic: str, payload: str) -> None:
         vehicle_handler = self.get_vehicle_handler(vin)

publisher/core.py

@@ -8,7 +8,11 @@
 
 INVALID_MQTT_CHARS = re.compile(r'[+#*$>]')
 
+
 class MqttCommandListener(ABC):
+    async def on_mqtt_global_command_received(self, *, topic: str, payload: str):
+        raise NotImplementedError("Should have implemented this")
+
     async def on_mqtt_command_received(self, *, vin: str, topic: str, payload: str) -> None:
         raise NotImplementedError("Should have implemented this")
 

publisher/mqtt_publisher.py

@@ -83,6 +83,10 @@ def __on_connect(self, _client, _flags, rc, _properties) -> None:
                     LOG.debug(f'Subscribing to MQTT topic {charging_station.connected_topic}')
                     self.vin_by_charger_connected_topic[charging_station.connected_topic] = charging_station.vin
                     self.client.subscribe(charging_station.connected_topic)
+            if self.configuration.ha_discovery_enabled:
+                self.client.subscribe(
+                    self.configuration.ha_lwt_topic
+                )
             self.keepalive()
         else:
             if rc == gmqtt.constants.CONNACK_REFUSED_BAD_USERNAME_PASSWORD:
@@ -120,6 +124,9 @@ async def __on_message_real(self, *, topic: str, payload: str) -> None:
                 LOG.debug(f'Vehicle with vin {vin} is connected to its charging station')
             else:
                 LOG.debug(f'Vehicle with vin {vin} is disconnected from its charging station')
+        elif topic == self.configuration.ha_lwt_topic:
+            if self.command_listener is not None:
+                await self.command_listener.on_mqtt_global_command_received(topic=topic, payload=payload)
         else:
             vin = self.get_vin_from_topic(topic)
             if self.command_listener is not None:

tests/test_mqtt_publisher.py

@@ -14,6 +14,10 @@
 
 
 class TestMqttPublisher(unittest.IsolatedAsyncioTestCase, MqttCommandListener):
+    @override
+    async def on_mqtt_global_command_received(self, *, topic: str, payload: str):
+        pass
+
     @override
     async def on_mqtt_command_received(self, *, vin: str, topic: str, payload: str) -> None:
         self.received_vin = vin