init: inital commit

lib/localiser/localisation/room/server.ex

@@ -0,0 +1,75 @@
+defmodule Localiser.Localisation.Room.Server do
+  use GenServer
+
+  @pubsub Localiser.PubSub
+
+  defstruct [:id, :name, :offset_x, :offset_y, :width, :height, occupants: MapSet.new()]
+
+  def start_link(room) do
+    GenServer.start_link(__MODULE__, room, name: via(room.id))
+  end
+
+  def via(room_id) do
+    {:via, Registry, {Localiser.Registry, {:room, room_id}}}
+  end
+
+  def tag_entered(room_id, tag_id) do
+    GenServer.cast(via(room_id), {:tag_entered, tag_id})
+  end
+
+  def tag_left(room_id, tag_id) do
+    GenServer.cast(via(room_id), {:tag_left, tag_id})
+  end
+
+  def get_occupants(room_id) do
+    GenServer.call(via(room_id), :get_occupants)
+  end
+
+  @impl true
+  def init(room) do
+    state = %__MODULE__{
+      id: room.id,
+      name: room.name,
+      offset_x: room.offset_x || 0.0,
+      offset_y: room.offset_y || 0.0,
+      width: room.width || 0.0,
+      height: room.height || 0.0
+    }
+
+    {:ok, state}
+  end
+
+  @impl true
+  def handle_cast({:tag_entered, tag_id}, state) do
+    new_occupants = MapSet.put(state.occupants, tag_id)
+
+    if new_occupants != state.occupants do
+      broadcast(state.id, new_occupants)
+    end
+
+    {:noreply, %{state | occupants: new_occupants}}
+  end
+
+  def handle_cast({:tag_left, tag_id}, state) do
+    new_occupants = MapSet.delete(state.occupants, tag_id)
+
+    if new_occupants != state.occupants do
+      broadcast(state.id, new_occupants)
+    end
+
+    {:noreply, %{state | occupants: new_occupants}}
+  end
+
+  @impl true
+  def handle_call(:get_occupants, _from, state) do
+    {:reply, state.occupants, state}
+  end
+
+  defp broadcast(room_id, occupants) do
+    Phoenix.PubSub.broadcast(
+      @pubsub,
+      "room:#{room_id}",
+      {:room_occupancy_changed, room_id, occupants}
+    )
+  end
+end