From a66bc2655ba6edc4169a4d7809895829a65bc356 Mon Sep 17 00:00:00 2001
From: Dan Barber <github@danbarber.me>
Date: Fri, 25 May 2018 15:16:29 -0400
Subject: [PATCH] Abstract out channel queries

---
 lib/chess/game_state.ex                |  2 +-
 lib/chess/repo/queries.ex              | 28 ++++++++++++++++++++++++++
 lib/chess_web/channels/game_channel.ex | 23 ++++++++-------------
 3 files changed, 37 insertions(+), 16 deletions(-)
 create mode 100644 lib/chess/repo/queries.ex

diff --git a/lib/chess/game_state.ex b/lib/chess/game_state.ex
index 6211b4a..610128e 100644
--- a/lib/chess/game_state.ex
+++ b/lib/chess/game_state.ex
@@ -38,7 +38,7 @@ defmodule Chess.GameState do
       |> Board.search(%{"type" => "king", "colour" => colour})
       |> List.first
 
-    if king == nil do
+    if is_nil(king) do
       raise "There is no #{colour} king!"
     end
 
diff --git a/lib/chess/repo/queries.ex b/lib/chess/repo/queries.ex
new file mode 100644
index 0000000..aa4ecde
--- /dev/null
+++ b/lib/chess/repo/queries.ex
@@ -0,0 +1,28 @@
+defmodule Chess.Repo.Queries do
+  @moduledoc false
+
+  import Ecto.Query
+
+  alias Chess.Repo
+  alias Chess.Store.Game
+
+  def game_for_info(user_id, game_id) do
+    user_id
+    |> Game.for_user_id()
+    |> preload([:moves, :user, :opponent])
+    |> Repo.get!(game_id)
+  end
+
+  def game_with_moves(user_id, game_id) do
+    user_id
+    |> Game.for_user_id()
+    |> preload(:moves)
+    |> Repo.get!(game_id)
+  end
+
+  def game_for_user(user_id, game_id) do
+    user_id
+    |> Game.for_user_id()
+    |> Repo.get!(game_id)
+  end
+end
diff --git a/lib/chess_web/channels/game_channel.ex b/lib/chess_web/channels/game_channel.ex
index a69a56d..856501d 100644
--- a/lib/chess_web/channels/game_channel.ex
+++ b/lib/chess_web/channels/game_channel.ex
@@ -3,10 +3,11 @@ defmodule ChessWeb.GameChannel do
 
   use ChessWeb, :channel
 
-  alias Chess.Store.Game
   alias Chess.Board
-  alias Chess.Moves
   alias Chess.MoveList
+  alias Chess.Moves
+  alias Chess.Repo.Queries
+  alias Chess.Store.Game
 
   def join("game:" <> game_id, _params, socket) do
     send(self(), {:after_join, game_id})
@@ -17,11 +18,7 @@ defmodule ChessWeb.GameChannel do
   def handle_info({:after_join, game_id}, socket) do
     game =
       socket.assigns.current_user_id
-      |> Game.for_user_id()
-      |> preload(:moves)
-      |> preload(:user)
-      |> preload(:opponent)
-      |> Repo.get!(game_id)
+      |> Queries.game_for_info(game_id)
 
     payload = %{
       player: player(socket, game),
@@ -42,9 +39,7 @@ defmodule ChessWeb.GameChannel do
     move_params = convert_params(params)
 
     socket.assigns.current_user_id
-    |> Game.for_user_id()
-    |> preload(:moves)
-    |> Repo.get!(socket.assigns.game_id)
+    |> Queries.game_with_moves(socket.assigns.game_id)
     |> Moves.make_move(move_params)
     |> case do
       {:ok, _} ->
@@ -65,8 +60,7 @@ defmodule ChessWeb.GameChannel do
   ) do
     game =
       socket.assigns.current_user_id
-      |> Game.for_user_id()
-      |> Repo.get!(socket.assigns.game_id)
+      |> Queries.game_for_user(socket.assigns.game_id)
 
     moves = Moves.available(game.board, {
       String.to_integer(file),
@@ -90,9 +84,7 @@ defmodule ChessWeb.GameChannel do
   def send_update(socket) do
     game =
       socket.assigns.current_user_id
-      |> Game.for_user_id()
-      |> preload(:moves)
-      |> Repo.get!(socket.assigns.game_id)
+      |> Queries.game_with_moves(socket.assigns.game_id)
 
     payload = %{
       board: Board.transform(game.board),
@@ -100,6 +92,7 @@ defmodule ChessWeb.GameChannel do
       state: game.state,
       moves: MoveList.transform(game.moves),
     }
+
     ChessWeb.Endpoint.broadcast("game:#{game.id}", "game:update", payload)
   end