board class for tic tac toe

board.rb

class Board
  def initialize(grid=[[nil, nil, nil], [nil, nil, nil], [nil, nil, nil]])
    @grid = grid
  end
  
  def grid
    @grid
  end
  
  def place_mark(position, symbol)
    row = position[0]
    column = position[1]
    @grid[row][column] = symbol
  end
  
  def empty?(position)
    row = position[0]
    column = position[1]
    @grid[row][column].nil?
  end
  
  def place_marks(positions, symbol)
    postions.each do |position|
      place_mark(position, symbol)
    end
  end
  
  def over?
    if @grid.flatten.count(nil) == 0 
      true
    elsif winner == :X || winner == :O
      true
    else
      false
    end
  end
  
  def sets
    return nil if @grid.flatten.count(nil) == 0
    row_set = []
    if @grid.any?{|row| row.count(:X) == 3}
      row_set << grid.select{|row| row.count(:X) == 3}
    elsif @grid.any?{|row| row.count(:O) == 3}
      row_set << grid.select{|row| row.count(:X) == 3}
    end
    return row_set.flatten.pop unless row_set.flatten.empty?
    
    first_column = []
    second_column = []
    third_column = []

    @grid.each do |row|
      first_column << row[0]
      second_column << row[1]
      third_column << row[2]
    end
    
    diagonal_set_backslash = [@grid[0][0], @grid[1][1], @grid[2][2]]
    diagonal_set_forward = [@grid[0][2], @grid[1][1], @grid[2][0]]
    
    if first_column.count(:O) == 3 || first_column.count(:X) == 3
      first_column.flatten.pop
    elsif second_column.count(:O) == 3 || second_column.count(:X) == 3
      second_column.flatten.pop
    elsif third_column.count(:O) == 3 || third_column.count(:X) == 3
      third_column.flatten.pop
    elsif diagonal_set_backslash.count(:O) == 3 || diagonal_set_backslash.count(:X) == 3
      diagonal_set_backslash.flatten.pop
    elsif diagonal_set_forward.count(:O) == 3 || diagonal_set_forward.count(:X)
      diagonal_set_forward.flatten.pop
    end
  end
  
  def winner
    sets
  end
end



  def preps_grid_for_rendering(board)
    sets = board.map do |row| 
        row = row.map do |slot|
          slot = " " if slot.nil?
        end
    end
    #grid = grid.gsub(" ", nil)
    sets
  end
  
  def display(board)
    rows = preps_grid_for_rendering(board)
    puts " | 0 | 1 | 2 "
    puts "  ___________"
    puts "0| #{rows[0][0]} | #{rows[0][1]} | #{rows[0][2]}"
    puts "1| #{rows[1][0]} | #{rows[1][1]} | #{rows[1][2]}"
    puts "2| #{rows[2][0]} | #{rows[2][1]} | #{rows[2][2]}"
  end