From 8efe8ea391d76b65a5075f413930636422d88b6d Mon Sep 17 00:00:00 2001
From: Dan Barber <github@danbarber.me>
Date: Thu, 19 Jan 2017 12:21:46 +0000
Subject: [PATCH] Add tests and logic for basic rook movement

---
 test/models/moves_test.exs | 22 ++++++++++++++++++++++
 web/models/moves.ex        | 27 ++++++++++++++++++++++++++-
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/test/models/moves_test.exs b/test/models/moves_test.exs
index 33457dc..5c68b6b 100644
--- a/test/models/moves_test.exs
+++ b/test/models/moves_test.exs
@@ -33,6 +33,28 @@ defmodule Chess.MovesTest do
     assert moves == expected_moves
   end
 
+  test "rooks can move horizontally or vertically" do
+    board = %{ "4,5" => %{type: :rook, colour: :white} }
+    moves = Moves.available(board, {4, 5})
+
+    expected_moves = Enum.sort([
+      {4, 0}, {4, 1}, {4, 2}, {4, 3}, {4, 4}, {4, 6}, {4, 7},
+      {0, 5}, {1, 5}, {2, 5}, {3, 5}, {5, 5}, {6, 5}, {7, 5}, 
+    ])
+    assert moves == expected_moves
+  end
+
+  test "rook cannot move further than the edge" do
+    board = %{ "0,0" => %{type: :rook, colour: :white} }
+    moves = Moves.available(board, {0, 0})
+
+    expected_moves = Enum.sort([
+      {0, 1}, {0, 2}, {0, 3}, {0, 4}, {0, 5}, {0, 6}, {0, 7},
+      {1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}, {6, 0}, {7, 0}, 
+    ])
+    assert moves == expected_moves
+  end
+
   def board do
     Chess.Board.default
   end
diff --git a/web/models/moves.ex b/web/models/moves.ex
index c66fc3f..1732fea 100644
--- a/web/models/moves.ex
+++ b/web/models/moves.ex
@@ -15,7 +15,32 @@ defmodule Chess.Moves do
           _ -> [{file, rank - 1}]
         end
       %{type: :rook} ->
-        []
+        rook_moves(board, square)
     end
   end
+
+  defp rook_moves(board, square) do
+    {file, rank} = square
+    moves = []
+
+    moves = cond do
+      file > 0 -> moves ++ Enum.map((file - 1)..0, fn (f) -> {f, rank} end)
+      true -> moves
+    end
+    moves = cond do
+      file < 7 -> moves ++ Enum.map((file + 1)..7, fn (f) -> {f, rank} end)
+      true -> moves
+    end
+
+    moves = cond do
+      rank > 0 -> moves ++ Enum.map((rank - 1)..0, fn (r) -> {file, r} end)
+      true -> moves
+    end
+    moves = cond do
+      rank < 7 -> moves ++ Enum.map((rank + 1)..7, fn (r) -> {file, r} end)
+      true -> moves
+    end
+
+    Enum.sort(moves)
+  end
 end