module Bishop

# File lib/bishop.rb, line 6
def illegal(board,x,y)
  possible_moves = []

  7.times do |coord|
    possible_moves += Board.board_safe(
      diagonal(coord) 
    )
  end

  if not(possible_moves.any? {|move| move == [x,y]})
    raise Game::IllegalMove, "#{x},#{y} is not a possible move" 
  elsif board.at(x,y).friend_of?(self)
    raise Game::IllegalMove, "#{x},#{y} is occupied by a friend"
  elsif jumped?(board,x,y) 
    raise Game::IllegalMove, "Bishops cannot jump" 
  else
    :legal_move
  end
end