feat: add factory_Reset, reconfigure_settings endpoints for sensors

lib/localiser/domain/sensors.ex

@@ -54,9 +54,28 @@ defmodule Localiser.Domain.Sensors do
     |> Repo.update()
   end
 
+  def factory_reset(%Sensor{} = sensor) do
+    Localiser.MQTT.Connection.publish(cmd_topic(sensor), Jason.encode!(%{action: "factory_reset"}))
+    {:ok, sensor}
+  end
+
+  # Pushes new WiFi and/or MQTT broker settings to the sensor. The sensor will
+  # apply the changes and restart. All keys are optional — omit any you don't
+  # want to change. Valid keys: "ssid", "password", "mqtt_host", "mqtt_port".
+  def reconfigure_settings(%Sensor{} = sensor, config) do
+    payload = Map.merge(
+      %{"action" => "reconfigure_settings"},
+      Map.new(config, fn
+        {"mqtt_broker", v} -> {"mqtt_host", v}
+        entry -> entry
+      end)
+    )
+    Localiser.MQTT.Connection.publish(cmd_topic(sensor), Jason.encode!(payload))
+    {:ok, sensor}
+  end
+
   def delete_sensor(%Sensor{} = sensor) do
-    topic = "localiser/sensor/#{sensor.sensor_id}/cmd"
-    Localiser.MQTT.Connection.publish(topic, Jason.encode!(%{command: "factory_reset"}))
+    factory_reset(sensor)
     Repo.delete(sensor)
   end
 
@@ -164,6 +183,8 @@ defmodule Localiser.Domain.Sensors do
     end
   end
 
+  defp cmd_topic(sensor), do: "localiser/sensor/#{sensor.sensor_id}/cmd"
+
   defp populate_floor_coords(%Sensor{room: nil} = sensor), do: sensor
 
   defp populate_floor_coords(%Sensor{room: room} = sensor) do