api: implement Server-Sent-Events on top of mqtt parameters

api/src/dooris_api/ccujack.py

@@ -72,6 +72,7 @@ class CCUJackClient:
     locks: LockData
     param_values: Dict[str, Any]
     task_process_messages: asyncio.Task
+    data_updated: asyncio.Event
 
     def __init__(self, base_uri: str, auth: BasicAuth, mqtt_conn: str):
         self.http = ClientSession(
@@ -84,6 +85,7 @@ class CCUJackClient:
         self.locks = None
         self.param_values = dict()
         self.task_process_messages = None
+        self.data_updated = asyncio.Event()
 
     async def connect_mqtt(self):
         await self.mqtt.connect()
@@ -99,10 +101,10 @@ class CCUJackClient:
     async def find_locks(self):
         logger.debug("Inspecting lock devices present in CCUJack")
 
-        # iterate through the CCUJACK API to find all devices
         async with self.http.get("/device") as resp:
             devices = CCUDeviceList.model_validate(await resp.json())
 
+            # inspect CCUJACK for locks
             device_infos = await asyncio.gather(
                 *[
                     self._inspect_ccu_device(i)
@@ -111,17 +113,22 @@ class CCUJackClient:
                 ]
             )
 
-            self.locks = [i for i in device_infos if i[0].type == DEVICE_TYPE_LOCK]
-
-        # update active mqtt subscriptions
-        mqtt_topics = set()
-        for i_lock, lock_channels in self.locks:
-            for i_channel, channel_params in lock_channels:
-                for i_param in channel_params:
-                    mqtt_topics.add(
-                        f"device/status/{i_lock.address}/{i_channel.index}/{i_param.id}"
-                    )
-        await self.mqtt.update_subscriptions(mqtt_topics)
+            # save the result
+            new_locks = [i for i in device_infos if i[0].type == DEVICE_TYPE_LOCK]
+            if new_locks != self.locks:
+                self.locks = new_locks
+                self.data_updated.set()
+                self.data_updated.clear()
+                
+                # update active mqtt subscriptions based on newly discovered devices
+                mqtt_topics = set()
+                for i_lock, lock_channels in self.locks:
+                    for i_channel, channel_params in lock_channels:
+                        for i_param in channel_params:
+                            mqtt_topics.add(
+                                f"device/status/{i_lock.address}/{i_channel.index}/{i_param.id}"
+                            )
+                await self.mqtt.update_subscriptions(mqtt_topics)
 
     async def process_mqt_messages(self):
         while True:
@@ -134,9 +141,12 @@ class CCUJackClient:
                     f"Got new value from MQTT for parameter {param_name}: {param_value}"
                 )
                 self.param_values[param_name] = param_value
+                self.data_updated.set()
 
             except Exception as e:
                 logger.exception(f"could not process incoming mqtt message: {e}")
+            finally:
+                self.data_updated.clear()
 
     async def query_param_value(self, address: str) -> CCUValue:
         if address in self.param_values: