From 2fc26764f623255199d61a2bf20a6c1ded845b15 Mon Sep 17 00:00:00 2001
From: Rowa <jrowah@gmail.com>
Date: Tue, 5 Nov 2024 00:16:41 +0300
Subject: [PATCH 1/2] stores and retrieves game state in ets

---
 lib/battle_ship/application.ex |  1 +
 lib/battle_ship/game.ex        | 27 +++++++++++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/lib/battle_ship/application.ex b/lib/battle_ship/application.ex
index 108746f..7c6fc28 100644
--- a/lib/battle_ship/application.ex
+++ b/lib/battle_ship/application.ex
@@ -16,6 +16,7 @@ defmodule BattleShip.Application do
 
     # See https://hexdocs.pm/elixir/Supervisor.html
     # for other strategies and supported options
+    :ets.new(:game_state, [:public, :named_table])
     opts = [strategy: :one_for_one, name: BattleShip.Supervisor]
     Supervisor.start_link(children, opts)
   end
diff --git a/lib/battle_ship/game.ex b/lib/battle_ship/game.ex
index 94b66e1..9ad61b5 100644
--- a/lib/battle_ship/game.ex
+++ b/lib/battle_ship/game.ex
@@ -39,9 +39,8 @@ defmodule BattleShip.Game do
              rules: struct()
            }}
   def init(name) do
-    player1 = %{name: name, board: Board.new(), guesses: Guesses.new()}
-    player2 = %{name: nil, board: Board.new(), guesses: Guesses.new()}
-    {:ok, %{player1: player1, player2: player2, rules: %Rules{}}, @timeout}
+    send(self(), {:set_state, name})
+    {:ok, fresh_state(name)}
   end
 
   @spec add_player(pid(), binary()) :: :error | {:reply, :ok, %{}}
@@ -141,11 +140,25 @@ defmodule BattleShip.Game do
     {:stop, {:shutdown, :timeout}, state_data}
   end
 
+  def handle_info({:set_state, name}, _state_data) do
+    state_data =
+      case :ets.lookup(:game_state, name) do
+        [] -> fresh_state(name)
+        [{_key, state}] -> state
+      end
+
+    :ets.insert(:game_state, {name, state_data})
+    {:noreply, state_data, @timeout}
+  end
+
   defp update_player2_name(state_data, name), do: put_in(state_data.player2.name, name)
 
   defp update_rules(state_data, rules), do: %{state_data | rules: rules}
 
-  defp reply_success(state_data, reply), do: {:reply, reply, state_data, @timeout}
+  defp reply_success(state_data, reply) do
+    :ets.insert(:game_state, {state_data.player1.name, state_data})
+    {:reply, reply, state_data, @timeout}
+  end
 
   defp update_board(state_data, player, board),
     do: Map.update!(state_data, player, fn player -> %{player | board: board} end)
@@ -160,4 +173,10 @@ defmodule BattleShip.Game do
       Guesses.add(guesses, hit_or_miss, coordinate)
     end)
   end
+
+  defp fresh_state(name) do
+    player1 = %{name: name, board: Board.new(), guesses: Guesses.new()}
+    player2 = %{name: nil, board: Board.new(), guesses: Guesses.new()}
+    %{player1: player1, player2: player2, rules: %Rules{}}
+  end
 end

From dd786b9c44ff6680a8acbd65d1292a5736a83f12 Mon Sep 17 00:00:00 2001
From: Rowa <jrowah@gmail.com>
Date: Tue, 5 Nov 2024 00:25:48 +0300
Subject: [PATCH 2/2] cleans up after a game

---
 lib/battle_ship/game.ex            | 7 +++++++
 lib/battle_ship/game_supervisor.ex | 1 +
 2 files changed, 8 insertions(+)

diff --git a/lib/battle_ship/game.ex b/lib/battle_ship/game.ex
index 9ad61b5..9a303a2 100644
--- a/lib/battle_ship/game.ex
+++ b/lib/battle_ship/game.ex
@@ -60,6 +60,13 @@ defmodule BattleShip.Game do
   def guess_coordinate(game, player, row, col) when player in @players,
     do: GenServer.call(game, {:guess_coordinate, player, row, col})
 
+  def terminate({:shutdown, :timeout}, state_data) do
+    :ets.delete(:game_state, state_data.player1.name)
+    :ok
+  end
+
+  def terminate(_reason, _state), do: :ok
+
   def handle_call({:guess_coordinate, player, row, col}, _from, state_data) do
     opponent = opponent(player)
     opponent_board = player_board(state_data, opponent)
diff --git a/lib/battle_ship/game_supervisor.ex b/lib/battle_ship/game_supervisor.ex
index ce5f661..b98e324 100644
--- a/lib/battle_ship/game_supervisor.ex
+++ b/lib/battle_ship/game_supervisor.ex
@@ -12,6 +12,7 @@ defmodule BattleShip.GameSupervisor do
   def start_game(name), do: Supervisor.start_child(GameSupervisor, [name])
 
   def stop_game(name) do
+    :ets.delete(:game_state, name)
     Supervisor.terminate_child(GameSupervisor, pid_from_name(name))
   end