Move piece getter to board module

lib/chess/board.ex

@@ -9,6 +9,10 @@ defmodule Chess.Board do
     end)
   end
 
+  def piece(board, {file, rank}) do
+    board["#{file},#{rank}"]
+  end
+
   def move_piece(board, move_params) do
     [from_file, from_rank] = move_params["from"]
     [to_file, to_rank] = move_params["to"]

lib/chess/moves.ex

@@ -1,6 +1,8 @@
 defmodule Chess.Moves do
   @moduledoc false
 
+  alias Chess.Board
+
   alias Chess.Moves.Pieces.Pawn
   alias Chess.Moves.Pieces.Bishop
   alias Chess.Moves.Pieces.Knight
@@ -9,7 +11,9 @@ defmodule Chess.Moves do
   alias Chess.Moves.Pieces.King
 
   def available(board, {file, rank}) do
-    piece = board["#{file},#{rank}"]
+    piece =
+      board
+      |> Board.piece({file, rank})
 
     case piece do
       %{"type" => "pawn"} ->

lib/chess/moves/generator.ex

@@ -6,10 +6,13 @@ defmodule Chess.Moves.Generator do
   like this.
   """
 
+  alias Chess.Board
+
   # `movement` is either a vector (bishop, rook, queen)
   # or a pattern (king, knight)
   def moves(board, {file, rank}, movement) do
-    board["#{file},#{rank}"]
+    board
+    |> Board.piece({file, rank})
     |> Map.get("colour")
     |> _moves(board, {file, rank}, movement)
   end
@@ -52,12 +55,17 @@ defmodule Chess.Moves.Generator do
   end
 
   defp can_capture_piece?(colour, board, {file, rank}) do
-    piece = board["#{file},#{rank}"]
+    piece =
+      board
+      |> Board.piece({file, rank})
+
     piece && piece["colour"] != colour
   end
 
   defp obstruction?(colour, board, {file, rank}) do
-    piece = board["#{file},#{rank}"]
+    piece =
+      board
+      |> Board.piece({file, rank})
     piece && piece["colour"] == colour
   end
 end

lib/chess/moves/piece.ex

@@ -1,9 +1,13 @@
 defmodule Chess.Moves.Piece do
   @moduledoc false
 
+  alias Chess.Board
   alias Chess.Moves.Generator
   alias Chess.Moves.Pieces.Knight
 
+  def find(board, piece) do
+  end
+
   def attacked?(board, {file, rank}) do
     attacked_by_rook_or_queen?(board, {file, rank}) ||
       attacked_by_bishop_or_queen?(board, {file, rank}) ||
@@ -48,7 +52,9 @@ defmodule Chess.Moves.Piece do
   end
 
   defp match_piece(board, {file, rank}, piece_type) do
-    piece = board["#{file},#{rank}"]
+    piece =
+      board
+      |> Board.piece({file, rank})
 
     piece["type"] == piece_type
   end

lib/chess/moves/pieces/pawn.ex

@@ -1,20 +1,24 @@
 defmodule Chess.Moves.Pieces.Pawn do
   @moduledoc false
 
+  alias Chess.Board
+
   def moves(board, {file, rank}) do
     normal_moves(board, {file, rank}) ++
       capture_moves(board, {file, rank})
   end
 
   defp normal_moves(board, {file, rank}) do
-    board["#{file},#{rank}"]
+    board
+    |> Board.piece({file, rank})
     |> Map.get("colour")
     |> _moves(board, {file, rank})
   end
 
   defp capture_moves(board, {file, rank}) do
     colour =
-      board["#{file},#{rank}"]
+      board
+      |> Board.piece({file, rank})
       |> Map.get("colour")
 
     colour
@@ -62,7 +66,10 @@ defmodule Chess.Moves.Pieces.Pawn do
   end
 
   defp can_capture_piece?(colour, board, {file, rank}) do
-    piece = board["#{file},#{rank}"]
+    piece =
+      board
+      |> Board.piece({file, rank})
+
     piece && piece["colour"] != colour
   end