feat: add current room occupancy endpoint

lib/localiser/web/controllers/tag_controller.ex

@@ -2,12 +2,21 @@ defmodule Localiser.Web.Controllers.TagController do
   use Phoenix.Controller, formats: [:json]
   use OpenApiSpex.ControllerSpecs
 
-  alias Localiser.Domain.Tags
+  alias Localiser.Domain.{Rooms, Tags}
+  alias Localiser.Localisation.Tag.Filter, as: TagFilter
   alias Localiser.Web.Schemas
 
   tags ["Tags"]
   security [%{"bearerAuth" => []}]
 
+  operation :occupancy,
+    summary: "Get every tag's current room",
+    responses: [
+      ok: {"Tag occupancy list", "application/json",
+           %OpenApiSpex.Schema{type: :array, items: Schemas.TagOccupancy}},
+      unauthorized: {"Unauthorized", "application/json", Schemas.Error}
+    ]
+
   operation :index,
     summary: "List all tags",
     responses: [
@@ -50,6 +59,18 @@ defmodule Localiser.Web.Controllers.TagController do
       unauthorized: {"Unauthorized", "application/json", Schemas.Error}
     ]
 
+  def occupancy(conn, _params) do
+    tag_to_room = build_tag_to_room_map()
+
+    result =
+      Tags.list_tags()
+      |> Enum.map(fn tag ->
+        %{id: tag.id, tag_id: tag.tag_id, name: tag.name, room_id: Map.get(tag_to_room, tag.tag_id)}
+      end)
+
+    json(conn, result)
+  end
+
   def index(conn, _params) do
     json(conn, Enum.map(Tags.list_tags(), &render_tag/1))
   end
@@ -94,6 +115,20 @@ defmodule Localiser.Web.Controllers.TagController do
     send_resp(conn, :no_content, "")
   end
 
+  defp build_tag_to_room_map do
+    Rooms.list_rooms()
+    |> Enum.flat_map(fn room ->
+      occupants =
+        case Registry.lookup(Localiser.Registry, {:room, room.id}) do
+          [{pid, _}] -> GenServer.call(pid, :get_occupants)
+          []         -> MapSet.new()
+        end
+
+      Enum.map(MapSet.to_list(occupants), &{&1, room.id})
+    end)
+    |> Map.new()
+  end
+
   defp render_tag(tag) do
     live = TagFilter.get_live_state(tag.tag_id)
 

lib/localiser/web/router.ex

@@ -71,6 +71,7 @@ defmodule Localiser.Web.Router do
 
     resources "/floors", FloorController, except: [:new, :edit]
     resources "/floors/:floor_id/rooms", RoomController, except: [:new, :edit]
+    get "/tags/occupancy", TagController, :occupancy
     resources "/tags", TagController, except: [:new, :edit]
 
     # Sensors

lib/localiser/web/schemas.ex

@@ -67,11 +67,13 @@ defmodule Localiser.Web.Schemas do
     OpenApiSpex.schema(%{
       title: "Tag", type: :object,
       properties: %{
-        id:     %Schema{type: :integer},
+        id:        %Schema{type: :integer},
-        tag_id: %Schema{type: :string},
+        tag_id:    %Schema{type: :string},
-        name:   %Schema{type: :string}
+        name:      %Schema{type: :string},
+        room_id:   %Schema{type: :integer, nullable: true},
+        last_seen: %Schema{type: :string, format: :"date-time", nullable: true}
       },
-      required: [:id, :tag_id, :name]
+      required: [:id, :tag_id, :name, :room_id, :last_seen]
     })
   end
 
@@ -303,6 +305,20 @@ defmodule Localiser.Web.Schemas do
     })
   end
 
+  defmodule TagOccupancy do
+    require OpenApiSpex
+    OpenApiSpex.schema(%{
+      title: "TagOccupancy", type: :object,
+      properties: %{
+        id:      %Schema{type: :integer},
+        tag_id:  %Schema{type: :string},
+        name:    %Schema{type: :string},
+        room_id: %Schema{type: :integer, nullable: true}
+      },
+      required: [:id, :tag_id, :name, :room_id]
+    })
+  end
+
   defmodule TagParams do
     require OpenApiSpex
     OpenApiSpex.schema(%{