Translate moves into display format

lib/chess/moves.ex

@@ -2,6 +2,7 @@ defmodule Chess.Moves do
   @moduledoc false
 
   alias Chess.Board
+  alias Chess.Store.Move
 
   alias Chess.Moves.Pieces.Pawn
   alias Chess.Moves.Pieces.Bishop
@@ -10,6 +11,12 @@ defmodule Chess.Moves do
   alias Chess.Moves.Pieces.Queen
   alias Chess.Moves.Pieces.King
 
+  def transform(moves) do
+    moves
+    |> Enum.map(fn(move) -> Move.translate(move) end)
+    |> Enum.chunk_every(2)
+  end
+
   def available(board, {file, rank}) do
     piece =
       board

lib/chess/store/move.ex

@@ -27,5 +27,13 @@ defmodule Chess.Store.Move do
     |> validate_required(required_attrs())
   end
 
+  def translate(move) do
+    [
+      <<97 + move.from.file, 49 + move.from.rank>>,
+      <<97 + move.to.file, 49 + move.to.rank>>
+    ]
+    |> Enum.join("-")
+  end
+
   defp required_attrs, do: ~w[game_id from to piece]a
 end

test/chess/moves_test.exs

@@ -0,0 +1,34 @@
+defmodule Chess.MovesTest do
+  @moduledoc false
+
+  use Chess.DataCase
+
+  describe "moves" do
+    alias Chess.Store.Move
+    alias Chess.Moves
+
+    test "tranforms a list of moves" do
+      moves = [
+        %Move{
+          from: %{file: 4, rank: 1},
+          to: %{file: 4, rank: 3},
+        },
+        %Move{
+          from: %{file: 4, rank: 6},
+          to: %{file: 4, rank: 4},
+        },
+        %Move{
+          from: %{file: 1, rank: 0},
+          to: %{file: 2, rank: 2},
+        },
+      ]
+
+      expected_result = [
+        ["e2-e4", "e7-e5"],
+        ["b1-c3"],
+      ]
+
+      assert Moves.transform(moves) == expected_result
+    end
+  end
+end

test/chess/store/move_test.exs

@@ -77,5 +77,15 @@ defmodule Chess.MoveTest do
 
       refute changeset.valid?
     end
+
+
+    test "translates a move" do
+      move = %Move{
+        from: %{file: 4, rank: 1},
+        to: %{file: 4, rank: 3},
+      }
+
+      assert Move.translate(move) == "e2-e4"
+    end
   end
 end