Show game state on the board

assets/css/_board.scss

@@ -49,6 +49,35 @@
   &.player-is-black.white-to-move::before {
     top: 2%;
   }
+
+  .board-rank-labels,
+  .board-file-labels {
+    display: none;
+  }
+
+  &.player-is-white {
+    .board-rank-labels {
+      display: flex;
+      flex-direction: column-reverse;
+    }
+
+    .board-file-labels {
+      display: flex;
+      flex-direction: row;
+    }
+  }
+
+  &.player-is-black {
+    .board-rank-labels {
+      display: flex;
+      flex-direction: column;
+    }
+
+    .board-file-labels {
+      display: flex;
+      flex-direction: row-reverse;
+    }
+  }
 }
 
 .board-rank-labels {
@@ -59,26 +88,6 @@
   width: 5%;
 }
 
-.board.player-is-white {
-  .board-rank-labels {
-    flex-direction: column-reverse;
-  }
-
-  .board-file-labels {
-    flex-direction: row;
-  }
-}
-
-.board.player-is-black {
-  .board-rank-labels {
-    flex-direction: column;
-  }
-
-  .board-file-labels {
-    flex-direction: row-reverse;
-  }
-}
-
 .board-file-labels {
   display: flex;
   height: 5%;
@@ -87,6 +96,14 @@
   width: 90%;
 }
 
+.board-game-state {
+  bottom: 0;
+  color: white;
+  height: 5%;
+  position: absolute;
+  width: 90%;
+}
+
 .board-label {
   align-items: center;
   display: flex;

assets/js/components/chess-board.js

@@ -4,6 +4,8 @@ import { connect } from "react-redux";
 import classNames from "classnames";
 
 import ChessBoardSquare from "./chess-board-square";
+import RankLabels from "./rank-labels";
+import FileLabels from "./file-labels";
 
 class ChessBoard extends React.Component {
   componentWillMount() {
@@ -72,6 +74,12 @@ class ChessBoard extends React.Component {
     });
   }
 
+  get gameState() {
+    const { store } = this.props;
+    console.log(store.getState().state);
+    return store.getState().state;
+  }
+
   get boardClass() {
     const turn = this.getTurn();
     const player = this.getPlayer();
@@ -79,43 +87,19 @@ class ChessBoard extends React.Component {
     return classNames("board", turn + "-to-move", "player-is-" + player);
   }
 
-  get rankLabels() {
-    return [1, 2, 3, 4, 5, 6, 7, 8];
-  }
-
-  get fileLabels() {
-    return ["a", "b", "c", "d", "e", "f", "g", "h"];
-  }
-
-  renderRankLabels() {
-    return _.map(this.rankLabels, (rankLabel) => {
-      return (
-        <div key={rankLabel} className="board-label">{rankLabel}</div>
-      );
-    });
-  }
-
-  renderFileLabels() {
-    return _.map(this.fileLabels, (fileLabel) => {
-      return (
-        <div key={fileLabel} className="board-label">{fileLabel}</div>
-      );
-    });
-  }
-
   render() {
     return (
       <div className={this.boardClass}>
-        <div className="board-rank-labels">
-          {this.renderRankLabels()}
-        </div>
-        <div className="board-file-labels">
-          {this.renderFileLabels()}
-        </div>
+        <RankLabels />
+        <FileLabels />
 
         <div className="board-body">
           {this.renderSquares()}
         </div>
+
+        <div className="board-game-state">
+          {this.gameState}
+        </div>
       </div>
     );
   }

assets/js/components/file-labels.js

@@ -0,0 +1,31 @@
+import React from "react";
+import _ from "lodash";
+import classNames from "classnames";
+
+class FileLabels extends React.Component {
+  constructor(props) {
+    super(props);
+  }
+
+  get fileLabels() {
+    return ["a", "b", "c", "d", "e", "f", "g", "h"];
+  }
+
+  renderFileLabels() {
+    return _.map(this.fileLabels, (fileLabel) => {
+      return (
+        <div key={fileLabel} className="board-label">{fileLabel}</div>
+      );
+    });
+  }
+
+  render() {
+    return (
+      <div className="board-file-labels">
+        {this.renderFileLabels()}
+      </div>
+    );
+  }
+}
+
+export default FileLabels;

assets/js/components/rank-labels.js

@@ -0,0 +1,31 @@
+import React from "react";
+import _ from "lodash";
+import classNames from "classnames";
+
+class RankLabels extends React.Component {
+  constructor(props) {
+    super(props);
+  }
+
+  get rankLabels() {
+    return [1, 2, 3, 4, 5, 6, 7, 8];
+  }
+
+  renderRankLabels() {
+    return _.map(this.rankLabels, (rankLabel) => {
+      return (
+        <div key={rankLabel} className="board-label">{rankLabel}</div>
+      );
+    });
+  }
+
+  render() {
+    return (
+      <div className="board-rank-labels">
+        {this.renderRankLabels()}
+      </div>
+    );
+  }
+}
+
+export default RankLabels;

assets/js/reducers/chess-board.js

@@ -13,6 +13,7 @@ const chessBoardReducer = (state = defaultState, action) => {
       return Immutable.fromJS(state)
         .set("board", action.board)
         .set("turn", action.turn)
+        .set("state", action.state)
         .set("selectedSquare", null)
         .set("moves", [])
         .toJS();

assets/js/store/actions.js

@@ -16,6 +16,7 @@ export const setGame = (data) => {
     type: SET_GAME,
     board: data.board,
     turn: data.turn,
+    state: data.state,
   };
 };
 

assets/js/store/default-state.js

@@ -3,6 +3,7 @@ const defaultState = {
 
   player: null,
   turn: null,
+  state: null,
 
   moves: [],
 

lib/chess/game_state.ex

@@ -5,16 +5,48 @@ defmodule Chess.GameState do
   alias Chess.Moves
   alias Chess.Moves.Piece
 
+  def state(board, colour) do
+    cond do
+      player_checkmated?(board, colour) ->
+        "checkmate"
+      player_stalemated?(board, colour) ->
+        "stalemate"
+      king_in_check?(board, colour) ->
+        "check"
+      true -> nil
+    end
+  end
+
   def player_checkmated?(board, colour) do
+    king_in_check?(board, colour) &&
+      player_cannot_move?(board, colour)
+  end
+
+  def player_stalemated?(board, colour) do
+    !king_in_check?(board, colour) &&
+      player_cannot_move?(board, colour)
+  end
+
+  def king_in_check?(board, colour) do
+    king =
+      board
+      |> Board.search(%{"type" => "king", "colour" => colour})
+      |> List.first
+
+    board
+    |> Piece.attacked?(king)
+  end
+
+  def player_cannot_move?(board, colour) do
     board
     |> Board.search(%{"colour" => colour})
     |> Enum.all?(fn({file, rank}) ->
       board
-      |> cannot_escape_check?({file, rank})
+      |> piece_cannot_move?({file, rank})
     end)
   end
 
-  def cannot_escape_check?(board, {file, rank}) do
+  def piece_cannot_move?(board, {file, rank}) do
     piece =
       board
       |> Board.piece({file, rank})
@@ -27,14 +59,4 @@ defmodule Chess.GameState do
       |> king_in_check?(piece["colour"])
     end)
   end
-
-  def king_in_check?(board, colour) do
-    king =
-      board
-      |> Board.search(%{"type" => "king", "colour" => colour})
-      |> List.first
-
-    board
-    |> Piece.attacked?(king)
-  end
 end

lib/chess/store/game.ex

@@ -15,6 +15,7 @@ defmodule Chess.Store.Game do
   schema "games" do
     field :board, :map, default: Board.default()
     field :turn, :string, default: "white"
+    field :state, :string
 
     belongs_to :user, Chess.Store.User
     belongs_to :opponent, Chess.Store.User, references: :id
@@ -34,6 +35,7 @@ defmodule Chess.Store.Game do
     struct
     |> cast(params, required_attrs())
     |> validate_king_in_check(struct, params)
+    |> check_game_state(struct, params)
   end
 
   def change_turn("black"), do: "white"
@@ -49,6 +51,11 @@ defmodule Chess.Store.Game do
       or_where: game.opponent_id == ^user_id
   end
 
+  def check_game_state(changeset, _struct, params) do
+    changeset
+    |> put_change(:state, GameState.state(params.board, params.turn))
+  end
+
   def validate_king_in_check(changeset, %Game{turn: turn}, %{board: board}) do
     if GameState.king_in_check?(board, turn) do
       changeset

lib/chess_web/channels/game_channel.ex

@@ -22,7 +22,8 @@ defmodule ChessWeb.GameChannel do
     payload = %{
       player: player(socket, game),
       board: Board.transform(game.board),
-      turn: game.turn
+      turn: game.turn,
+      state: game.state
     }
 
     socket
@@ -81,7 +82,8 @@ defmodule ChessWeb.GameChannel do
   def send_update(game) do
     payload = %{
       board: Board.transform(game.board),
-      turn: game.turn
+      turn: game.turn,
+      state: game.state
     }
     ChessWeb.Endpoint.broadcast("game:#{game.id}", "game:update", payload)
   end

priv/repo/migrations/20180407190333_add_state_to_game.exs

@@ -0,0 +1,9 @@
+defmodule Chess.Repo.Migrations.AddStateToGame do
+  use Ecto.Migration
+
+  def change do
+    alter table("games") do
+      add :state, :string
+    end
+  end
+end

test/chess/game_state_test.exs

@@ -91,4 +91,14 @@ defmodule Chess.GameStateTest do
 
     refute GameState.player_checkmated?(board, "white")
   end
+
+  test "game can be stalemated" do
+    board = %{
+      "0,0" => %{"type" => "king", "colour" => "white"},
+      "1,2" => %{"type" => "rook", "colour" => "black"},
+      "2,1" => %{"type" => "rook", "colour" => "black"},
+    }
+
+    assert GameState.player_stalemated?(board, "white")
+  end
 end