Class: ChessMate

Inherits:
Object
  • Object
show all
Defined in:
lib/chessmate.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(board: nil, turn: nil, promotable: nil, en_passant: nil, castling: nil, in_check: nil, allow_out_of_turn: nil, move_history: nil, ignore_logging: false) ⇒ ChessMate

Returns a new instance of ChessMate.



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# File 'lib/chessmate.rb', line 25

def initialize(board: nil,
               turn: nil,
               promotable: nil,
               en_passant: nil,
               castling: nil,
               in_check: nil,
               allow_out_of_turn: nil,
               move_history: nil,
               ignore_logging: false)
  @board = board || DEFAULT[:board].map(&:dup)
  @turn = turn || DEFAULT[:turn]
  @promotable = promotable
  @en_passant = en_passant || DeepDup.deep_dup(DEFAULT[:en_passant])
  @castling = castling || DeepDup.deep_dup(DEFAULT[:castling])
  @in_check = in_check || DeepDup.deep_dup(DEFAULT[:in_check])

  @allow_out_of_turn = if allow_out_of_turn.nil?
                         ENV['TEST'] == 'true' || false
                       elsif [true, false].include?(allow_out_of_turn)
                         allow_out_of_turn
                       else
                         false
                       end
  @move_history = move_history || []
  @ignore_logging = ignore_logging
end

Instance Attribute Details

#allow_out_of_turn ⇒ Object (readonly)

Returns the value of attribute allow_out_of_turn.



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# File 'lib/chessmate.rb', line 16

def allow_out_of_turn
  @allow_out_of_turn
end

#board ⇒ Object (readonly)

Returns the value of attribute board.



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# File 'lib/chessmate.rb', line 16

def board
  @board
end

#castling ⇒ Object (readonly)

Returns the value of attribute castling.



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# File 'lib/chessmate.rb', line 16

def castling
  @castling
end

#en_passant ⇒ Object (readonly)

Returns the value of attribute en_passant.



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# File 'lib/chessmate.rb', line 16

def en_passant
  @en_passant
end

#in_check ⇒ Object (readonly)

Returns the value of attribute in_check.



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# File 'lib/chessmate.rb', line 16

def in_check
  @in_check
end

#move_history ⇒ Object (readonly)

Returns the value of attribute move_history.



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# File 'lib/chessmate.rb', line 16

def move_history
  @move_history
end

#promotable ⇒ Object (readonly)

Returns the value of attribute promotable.



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# File 'lib/chessmate.rb', line 16

def promotable
  @promotable
end

#turn ⇒ Object (readonly)

Returns the value of attribute turn.



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# File 'lib/chessmate.rb', line 16

def turn
  @turn
end

Instance Method Details

#any_valid_moves?(color) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chessmate.rb', line 221

def any_valid_moves?(color)
  test_board = @board.map(&:dup)

  test_board.each_with_index do |row, orig_y|
    row.each_with_index do |col, orig_x|
      next unless !col.nil? && col[0] == color

      orig_pos = NotationParser.encode_notation([orig_y, orig_x])
      8.times do |dest_x|
        8.times do |dest_y|
          dest_pos = NotationParser.encode_notation([dest_y, dest_x])
          next unless move(orig_pos, dest_pos, true)
          return true unless in_check_after_move?([orig_y, orig_x], [dest_y, dest_x])
        end
      end
    end
  end

  false
end

#checkmate?(color) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chessmate.rb', line 242

def checkmate?(color)
  piece_color = color.downcase == 'w' ? :white : :black
  !any_valid_moves?(color) && in_check?[piece_color]
end

#draw?(color) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chessmate.rb', line 247

def draw?(color)
  piece_color = color.downcase == 'w' ? :white : :black
  !any_valid_moves?(color) && in_check?[piece_color] == false
end

#in_check?(board = nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chessmate.rb', line 106

def in_check?(board = nil)
  board = board.nil? ? @board : board
  wk_coords = bk_coords = nil

  board.each_with_index do |row, y|
    wk_coords = [y, row.index('WK')] if row.include?('WK')
    bk_coords = [y, row.index('BK')] if row.include?('BK')
  end

  wk_pos = NotationParser.encode_notation(wk_coords) if wk_coords
  bk_pos = NotationParser.encode_notation(bk_coords) if bk_coords

  white_in_check = black_in_check = false
  board.each_with_index do |row, y|
    row.each_with_index do |col, x|
      next if col.nil?

      piece_pos = NotationParser.encode_notation([y, x])
      if col[0] == 'W' && bk_pos
        black_in_check = true if move(piece_pos, bk_pos, test: true)
      elsif col[0] == 'B' && wk_pos
        white_in_check = true if move(piece_pos, wk_pos, test: true)
      end
    end
  end

  { white: white_in_check, black: black_in_check }
end

#in_check_after_move?(orig, dest) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chessmate.rb', line 177

def in_check_after_move?(orig, dest)
  test_board = @board.map(&:dup)

  orig_y, orig_x = orig
  dest_y, dest_x = dest
  piece = test_board[orig_y][orig_x]
  piece_type = test_board[orig_y][orig_x]
  opposite_color = piece_type[0] == 'W' ? :black : :white
  direction = opposite_color == :white ? -1 : 1

  if piece_type[1] == 'P' && @en_passant[opposite_color] == [dest_y + direction, dest_x]
    en_passant = true
    en_passant_coords = [@en_passant[opposite_color][0], @en_passant[opposite_color][1]]
  end

  test_board[en_passant_coords[0]][en_passant_coords[1]] = nil if en_passant

  test_board[orig_y][orig_x] = nil
  test_board[dest_y][dest_x] = piece_type

  piece_color = piece[0]
  king = piece_color + 'K'

  king_coords = nil
  test_board.each_with_index do |row, y|
    king_coords = [y, row.index(king)] if row.include?(king)
  end

  return false if king_coords.nil?

  king_pos = NotationParser.encode_notation(king_coords)

  test_board.each_with_index do |row, y|
    row.each_with_index do |col, x|
      next unless !col.nil? && col[0] != piece_color

      piece_pos = NotationParser.encode_notation([y, x])
      return true if move(piece_pos, king_pos, true, test_board)
    end
  end

  false
end

#move(orig, dest, test = false, test_board = nil) ⇒ Object 



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# File 'lib/chessmate.rb', line 135

def move(orig, dest, test = false, test_board = nil)
  return false if @promotable

  orig_pos = NotationParser.parse_notation(orig)
  dest_pos = NotationParser.parse_notation(dest)

  return false if orig_pos.nil? || dest_pos.nil?

  orig_y = orig_pos[0]
  orig_x = orig_pos[1]

  piece = @board[orig_y][orig_x]
  piece_type = piece[1]
  allowed_turn = piece[0] == 'W' ? :odd? : :even?

  return false unless @allow_out_of_turn || @turn.send(allowed_turn) || test

  board = test_board.nil? ? @board : test_board
  valid_move = case piece_type
               when 'P'
                 Pawn.move_is_valid?(orig_pos, dest_pos, board, @en_passant.dup)
               when 'R'
                 Rook.move_is_valid?(orig_pos, dest_pos, board)
               when 'B'
                 Bishop.move_is_valid?(orig_pos, dest_pos, board)
               when 'N'
                 Knight.move_is_valid?(orig_pos, dest_pos, board)
               when 'Q'
                 Queen.move_is_valid?(orig_pos, dest_pos, board)
               when 'K'
                 King.move_is_valid?(orig_pos, dest_pos, board, @castling.dup)
               else
                 false
               end
  unless test
    in_check_after_move = in_check_after_move?(orig_pos, dest_pos)
    update(orig_pos, dest_pos) if valid_move && !test && !in_check_after_move
  end

  valid_move && !in_check_after_move
end

#promote!(square, piece) ⇒ Object 



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# File 'lib/chessmate.rb', line 260

def promote!(square, piece)
  square_y = square[0]
  square_x = square[1]

  old_piece = @board[square_y][square_x]
  return nil if old_piece.nil? || @promotable != [square_y, square_x]

  case piece.downcase
  when 'rook'
    piece_type = 'R'
  when 'knight'
    piece_type = 'N'
  when 'bishop'
    piece_type = 'B'
  when 'queen'
    piece_type = 'Q'
  else
    return nil
  end

  @board[square_y][square_x] = old_piece[0] + piece_type
  @promotable = nil

  return if @ignore_logging

  logger = ChessLogger.new(nil, nil, nil, promotion_type: piece_type, history: @move_history)
  @move_history[-1] += logger.log_promotion
end

#promote?(square) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chessmate.rb', line 252

def promote?(square)
  square_y = square[0]
  square_x = square[1]
  piece_color = @board[square_y][square_x][0]
  promote_column = piece_color.downcase == 'w' ? 1 : 6
  promote_column == square_y
end

#update(orig, dest = nil) ⇒ Object 



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# File 'lib/chessmate.rb', line 52

def update(orig, dest = nil)
  orig_y, orig_x = orig
  dest_y, dest_x = dest
  piece_type = @board[orig_y][orig_x]
  piece_color = piece_type[0] == 'W' ? :white : :black
  opposite_color = piece_type[0] == 'W' ? :black : :white
  direction = opposite_color == :white ? -1 : 1

  @en_passant[piece_color] = nil if @en_passant[piece_color]

  case piece_type[1]
  when 'P'
    @en_passant[piece_color] = dest if (orig_y - dest_y).abs > 1
    if @en_passant[opposite_color] == [dest_y + direction, dest_x]
      en_passant = true
      en_passant_coords = @en_passant[opposite_color]
    end
  when 'K'
    @castling[piece_color].keys.each do |side|
      @castling[piece_color][side] = false
    end
    if (orig_x - dest_x).abs == 2
      castle = true
      old_rook_x_position = orig_x < dest_x ? 7 : 0
      new_rook_x_position = orig_x < dest_x ? 5 : 3
    end
  when 'R'
    if [0, 7].include?(orig_x)
      direction = orig_x == 7 ? :kingside : :queenside
      @castling[piece_color][direction] = false
    end
  end

  @board[en_passant_coords[0]][en_passant_coords[1]] = nil if en_passant

  if castle
    @board[orig_y][old_rook_x_position] = nil
    @board[orig_y][new_rook_x_position] = piece_type[0] + 'R'
  end

  @promotable = dest if piece_type[1] == 'P' && promote?(orig)

  unless @ignore_logging
    logger = ChessLogger.new(orig, dest, @board)
    @move_history << logger.log_move
  end

  @board[orig_y][orig_x] = nil
  @board[dest_y][dest_x] = piece_type

  @in_check = in_check?
  @turn += 1
end