feat(chat): add context and use it in live view

lib/slax/chat.ex

@@ -0,0 +1,23 @@
+defmodule Slax.Chat do
+  @moduledoc """
+  Context to handle with chat details.
+  """
+
+  import Ecto.Query
+
+  alias Slax.Chat.Room
+  alias Slax.Repo
+
+  def get_first_room! do
+    query = from(r in Room, limit: 1)
+    Repo.one(query)
+  end
+
+  def get_room!(id) do
+    Repo.get!(Room, id)
+  end
+
+  def list_rooms do
+    Repo.all(Room)
+  end
+end

lib/slax_web/live/chat_room_live.ex

@@ -2,7 +2,7 @@ defmodule SlaxWeb.ChatRoomLive do
   @moduledoc false
   use SlaxWeb, :live_view
 
-  alias Slax.Repo
+  alias Slax.Chat
   alias Slax.Chat.Room
 
   @impl Phoenix.LiveView
@@ -42,7 +42,7 @@ defmodule SlaxWeb.ChatRoomLive do
 
   @impl Phoenix.LiveView
   def mount(_params, _session, socket) do
-    rooms = Repo.all(Room)
+    rooms = Chat.list_rooms()
 
     {:ok, assign(socket, hide_topic?: false, rooms: rooms)}
   end
@@ -52,10 +52,10 @@ defmodule SlaxWeb.ChatRoomLive do
     room =
       case Map.fetch(params, "id") do
         {:ok, id} ->
-          Repo.get(Room, id)
+          Chat.get_room!(id)
 
         :error ->
-          List.first(socket.assigns.rooms)
+          Chat.get_first_room!()
       end
 
     {:noreply, assign(socket, hide_topic?: false, room: room)}