Add Service and MqttSubscriber classes

- Create utils dir and move utils.py there

motor_passo/utils/mqtt_subscriber.py

@@ -0,0 +1,51 @@
+import paho.mqtt.client as mqtt
+
+from motor_passo.utils.service import Service
+
+
+class MqttSubscriber(Service):
+
+    def __init__(self, broker_host, broker_port):
+        super().__init__(name="mqtt_listener")
+        self.broker_host = broker_host
+        self.broker_port = broker_port
+        self._client = mqtt.Client()
+        self._client.on_connect = self._on_connect
+        self._client.on_message = self._on_message
+        self._client.on_disconnect = self._on_disconnect
+        self._cbs: dict[str, callable] = {}
+
+    def run(self) -> None:
+        self.client.connect(self.broker_host, self.broker_port, 60)
+        self.client.loop_start()
+
+    def subscribe(self, topic: str, cb: callable) -> None:
+        self._cbs[topic] = cb
+
+        if self._client.is_connected():
+            self._client.subscribe(topic)
+
+    def _on_connect(self, client, userdata, flags, rc) -> None:
+        self._l.debug(f"Conectado com resultado {str(rc)}")
+
+        for topic in self._cbs.keys():
+            client.subscribe(topic)
+
+    def _on_disconnect(self, client, userdata, rc) -> None:
+        self._l.debug(f"Desconectado, código {str(rc)}")
+        # Start the loop again in case of an unexpected disconnection
+        client.loop_start()
+
+    def _on_message(self, client, userdata, message) -> None:
+        payload = message.payload.decode("utf-8")
+        self._l.debug(f"Mensagem recebida no tópico: {message.topic}")
+
+        if message.topic not in self._cbs:
+            self._l.debug(f"Mensagem no tópico {message.topic} não tratada")
+            return
+
+        try:
+            self._cbs[message.topic](message.topic, payload)
+        except Exception:
+            self._l.exception(
+                f"Falha ao processar mensagem no tópico {message.topic}")