def test_can_castle(self):
"""
Test that a king can perform a castle
:return:
"""
board = ChessBoard()
# Check from white perspective
board['a1'] = Rook(Color.WHITE)
board['e1'] = King(Color.WHITE)
board['h1'] = Rook(Color.WHITE)
self.assertTrue(board.can_castle(Color.WHITE, MoveDirection.LEFT),
'King should be able to castle')
self.assertTrue(board.can_castle(Color.WHITE, MoveDirection.RIGHT),
'King should be able to castle')
# Check from black perspective
board['a8'] = Rook(Color.BLACK)
board['e8'] = King(Color.BLACK)
board['h8'] = Rook(Color.BLACK)
self.assertTrue(board.can_castle(Color.BLACK, MoveDirection.LEFT),
'King should be able to castle')
self.assertTrue(board.can_castle(Color.BLACK, MoveDirection.RIGHT),
'King should be able to castle')
class ChessGame(db.Model):
"""
Create new chess game
"""
__tablename__ = 'game'
id = db.Column(db.Integer, primary_key=True)
fen = db.Column(db.String(100))
white_player_id = db.Column(db.Integer, db.ForeignKey('players.id'))
black_player_id = db.Column(db.Integer, db.ForeignKey('players.id'))
is_over = db.Column(db.Boolean, default=False)
white_player = db.relationship("Player", foreign_keys=white_player_id)
black_player = db.relationship("Player", foreign_keys=black_player_id)
score = db.relationship("GameScore", uselist=False, back_populates="game")
def __init__(self, fen=None, **kwargs):
"""
Generate a ChessGame object.
:param fen: string
Fen notation string to initialize game.
:param kwargs:
"""
super().__init__(**kwargs)
self.fen = fen if fen else 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq -'
fen = Fen(self.fen, validate=False)
self._board = ChessBoard(fen)
@property
def board(self):
return self._board
@board.setter
def board(self, board):
self._board = board
def get_legal_moves(self, position):
"""
Retrieve possible legal moves for a piece on a position.
:param position: string
Algebraic notation position.
:return:
"""
try:
ChessHelper.validate_position(position)
except InvalidPositionError as e:
# Maybe log error here
# Reraise exception either way
raise
else:
return self._board.get_legal_moves(position)
def move_piece(self, start_position, end_position):
"""
Move a piece from start_position to end_position.
:param start_position:
:param end_position:
:return:
"""
try:
ChessHelper.validate_position(start_position)
ChessHelper.validate_position(end_position)
except InvalidPositionError as e:
# Maybe log error here
# Reraise exception either way
raise
else:
current_fen = Fen(self.fen)
current_player = current_fen.current_player
next_player = Color.WHITE if current_player == Color.BLACK else Color.BLACK
move_result = MoveResult()
# If moving a pawn to the end of the board, dont update anything on the board.
# Instead, just return the pawn promote info.
if self.can_promote_pawn(start_position, end_position):
player = self._get_player_by_color(current_player)
promote_info = {
'player': player,
'promote_types': self.get_pawn_promote_types()
}
move_result.pawn_promote_info = promote_info
return move_result
move_result.update_positions = self._board.move_piece(
start_position, end_position)
# Determine which directions castling is possible for.
castle_info = {Color.BLACK: [], Color.WHITE: []}
for color in [Color.WHITE, Color.BLACK]:
for direction in [MoveDirection.LEFT, MoveDirection.RIGHT]:
if self._board.can_castle(color, direction):
castle_info[color].append(direction)
# Generate and save fen string after move
next_fen = Fen()
next_fen_str = next_fen.generate_fen(
self._board.get_board_pieces(), next_player,
castle_info[Color.WHITE], castle_info[Color.BLACK],
self._board.get_enpassant_position())
self.fen = next_fen_str
# If checkmate or draw, set game over flag. Also create game_score object and fill
# the move results object.
is_checkmate = self._board.is_checkmate(next_player)
is_stalemate = self._board.is_stalemate(next_player)
if is_checkmate or is_stalemate:
self.is_over = True
if is_checkmate:
if current_player == Color.WHITE:
self.score = GameScore(game=self, white_score=1)
player_in_checkmate = self.black_player
player_in_checkmate.color = Color.BLACK
else:
self.score = GameScore(game=self, black_score=1)
player_in_checkmate = self.white_player
player_in_checkmate.color = Color.WHITE
move_result.king_in_checkmate = player_in_checkmate
else:
self.score = GameScore(game=self,
white_score=0.5,
black_score=0.5)
move_result.draw = True
# If it is check, add info to move_result.
is_check = self._board.is_check(next_player)
if is_check:
if current_player == Color.WHITE:
player_in_check = self._get_player_by_color(Color.BLACK)
else:
player_in_check = self._get_player_by_color(Color.WHITE)
move_result.king_in_check = player_in_check
return move_result
@property
def current_player(self):
"""
Retrieve the current player
:return Player:
Player object with color set.
"""
fen = Fen(self.fen)
current_player_color = fen.current_player
current_player = self.white_player if current_player_color == Color.WHITE else self.black_player
# Dynamically add color field so UI can know player info and color.
if current_player:
current_player.color = Color.WHITE if current_player_color == Color.WHITE else Color.BLACK
return current_player
def promote_pawn(self, start_position, end_position, piece_type):
"""
Promote a pawn to another piece type.
:param start_position: string
Algebraic notation for pawn position.
:param end_position: string
Algebraic notation for destination position.
:param piece_type: Type
Value from Type enum
:return:
"""
try:
ChessHelper.validate_position(start_position)
ChessHelper.validate_position(end_position)
except InvalidPositionError as e:
# Maybe log error here
# Reraise exception either way
raise
else:
if piece_type not in self.get_pawn_promote_types():
raise PieceTypeError(
piece_type, 'Cannot promote pawn to supplied piece type')
if self._board[start_position] is None:
raise EmptyPositionError(start_position)
# TODO confirm pawn on second to last row
piece = self._board[start_position]
piece_class = {
Type.ROOK: Rook,
Type.KNIGHT: Knight,
Type.BISHOP: Bishop,
Type.QUEEN: Queen
}
self._board[start_position] = piece_class[piece_type](piece.color)
return self.move_piece(start_position, end_position)
def get_winner(self):
"""
Return winner of game.
:return:
"""
# Check if score obj exist. If so, return winner
pass
@classmethod
def get_pawn_promote_types(cls):
"""
Retrieve the piece types a pawn can promote to.
:return: Type[]
"""
return [Type.ROOK, Type.KNIGHT, Type.BISHOP, Type.QUEEN]
def can_promote_pawn(self, start_position, end_position):
"""
Test if pawn promotion is possible for the provided position.
:param start_position: string
Algebraic notation position.
:param end_position: string
Algebraic notation position.
:return:
"""
try:
ChessHelper.validate_position(start_position)
ChessHelper.validate_position(end_position)
except InvalidPositionError as e:
# Maybe log error here
# Reraise exception either way
raise
else:
if self._board[start_position] is None:
return False
piece = self._board[start_position]
if piece.type != Type.PAWN:
return False
_, start_row = self._board.position_to_row_and_column(
start_position, piece.color)
_, end_row = self._board.position_to_row_and_column(
end_position, piece.color)
if start_row == self._board.get_dimension(
) - 2 and end_row == self._board.get_dimension() - 1:
return True
return False
def save_to_db(self):
"""
Save game to db.
:return:
"""
db.session.add(self)
db.session.commit()
def delete_from_db(self):
"""
Delete this game from the db.
:return:
"""
db.session.delete(self)
db.session.commit()
def to_dict(self):
"""
Return dictionary for game.
:return:
"""
current_player = self.current_player
white_player = self.white_player
black_player = self.black_player
return {
'game_id': self.id,
'current_player':
current_player.to_dict() if current_player else None,
'white_player': white_player.to_dict() if white_player else None,
'black_player': black_player.to_dict() if black_player else None,
'game_over': self.is_over,
'board': {
position: piece.to_dict()
for position, piece in self.board.get_board_pieces().items()
if piece
}
}
@classmethod
def load_by_id(cls, game_id):
game = cls.query.get(game_id)
if game:
game.board = ChessBoard(Fen(game.fen))
return game
def _get_player_by_color(self, color):
"""
Retrieve the player associated with the provided color.
:param color: Color
:return: Player
"""
if color == Color.WHITE:
player = self.white_player
player.color = Color.WHITE
else:
player = self.black_player
player.color = Color.BLACK
return player
def __str__(self):
return str(self._board)
def test_cannot_castle(self):
"""
Test cases where a king cannot castle.
Expected result is king cannot castle through check, from check, into check, after moving, if
the rook has moved.
:return:
"""
# Check case where king would pass through check
board = ChessBoard()
board['a1'] = Rook(Color.WHITE)
board['e1'] = King(Color.WHITE)
board['d5'] = Rook(Color.BLACK)
expected_moves = ['e2', 'f1', 'f2']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# King in check
board.move_piece('d5', 'e5')
expected_moves = ['d1', 'd2', 'f1', 'f2']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# King ends in check
board.move_piece('e5', 'c5')
expected_moves = ['d1', 'd2', 'e2', 'f1', 'f2']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# Check after king moves
board = ChessBoard()
board['a1'] = Rook(Color.WHITE)
board['e1'] = King(Color.WHITE)
board.move_piece('e1', 'd1')
expected_moves = ['c1', 'c2', 'd2', 'e1', 'e2']
legal_moves = board.get_legal_moves('d1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# Check after left rook moves
board = ChessBoard()
board['a1'] = Rook(Color.WHITE)
board['e1'] = King(Color.WHITE)
board.move_piece('a1', 'b1')
expected_moves = ['d1', 'd2', 'e2', 'f1', 'f2']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# Check after right rook moves
board = ChessBoard()
board['e1'] = King(Color.WHITE)
board['h1'] = Rook(Color.WHITE)
board.move_piece('h1', 'h2')
expected_moves = ['d1', 'd2', 'e2', 'f1', 'f2']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# Check with both rooks after right rook moves
board = ChessBoard()
board['a1'] = Rook(Color.WHITE)
board['e1'] = King(Color.WHITE)
board['h1'] = Rook(Color.WHITE)
board.move_piece('h1', 'h2')
expected_moves = ['c1', 'd1', 'd2', 'e2', 'f1', 'f2']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# Check with both rooks after right rook moves
board = ChessBoard()
board['a1'] = Rook(Color.WHITE)
board['e1'] = King(Color.WHITE)
board['h1'] = Rook(Color.WHITE)
board.move_piece('a1', 'b1')
expected_moves = ['d1', 'd2', 'e2', 'f1', 'f2', 'g1']
legal_moves = board.get_legal_moves('e1')
legal_moves.sort()
self.assertListEqual(expected_moves, legal_moves,
'Expected moves does not match actual')
# Confirm cannot castle even if king and rooks back in starting positions
fen = Fen('r3k2r/8/8/8/8/8/8/8 b - -')
board = ChessBoard(fen)
can_castle_left = board.can_castle(Color.BLACK, MoveDirection.LEFT)
can_castle_right = board.can_castle(Color.BLACK, MoveDirection.RIGHT)
self.assertFalse(can_castle_left,
'King should not be able to castle left')
self.assertFalse(can_castle_right,
'King should not be able to castle right')
