add game supervisor

lib/battle_ship/application.ex

@@ -10,7 +10,8 @@ defmodule BattleShip.Application do
     children = [
       # Starts a worker by calling: BattleShip.Worker.start_link(arg)
       # {BattleShip.Worker, arg}
-      {Registry, keys: :unique, name: Registry.Game}
+      {Registry, keys: :unique, name: Registry.Game},
+      {BattleShip.GameSupervisor, []}
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

lib/battle_ship/game_supervisor.ex

@@ -0,0 +1,23 @@
+defmodule BattleShip.GameSupervisor do
+  @moduledoc false
+  use Supervisor
+
+  alias __MODULE__
+  alias BattleShip.Game
+
+  def start_link(_options), do: Supervisor.start_link(GameSupervisor, :ok, name: GameSupervisor)
+
+  def init(:ok), do: Supervisor.init([Game], strategy: :simple_one_for_one)
+
+  def start_game(name), do: Supervisor.start_child(GameSupervisor, [name])
+
+  def stop_game(name) do
+    Supervisor.terminate_child(GameSupervisor, pid_from_name(name))
+  end
+
+  defp pid_from_name(name) do
+    name
+    |> Game.via_tuple()
+    |> GenServer.whereis()
+  end
+end