Minesweeper logic ruby code

minesweeper.rb

class Field
  attr_accessor :field, :dimenstions, :number_of_mines

  def initialize(dimenstions, number_of_mines)
    @dimenstions = dimenstions
    @number_of_mines = number_of_mines
    initialize_free_of_mines_coordinates
    build_field
    fill_field_with_mines
  end

  def open(x, y)
    lose_game if field[x][y].mine?

    field[x][y].open
    reveal(x, y, mines_nearby(x, y))
    if mines_nearby(x, y) == 0
      coordinates_around(x, y) do |i, j|
        open(i, j) unless field[i][j].opened?
      end
    end
  end

  def mines_nearby(x, y)
    count = 0
    coordinates_around(x, y) do |i, j|
      count += 1 if field[i][j].mine?
    end
    count
  end

  private

  attr_accessor :free_of_mines_coordinates

  def coordinates_around(x, y)
    x-1.upto x+1 do |i|
      y-1.upto y+1 do |j|
        if (i < 0 || j < 0) || (i >= dimenstions || j >= dimenstions)
          yield i, j if !(i == x && j == y)
        end
      end
    end
  end

  def initialize_free_of_mines_coordinates
    @free_of_mines_coordinates = Array.new()
    dimenstions.times do |i|
      dimenstions.times do |j|
        @free_of_mines_coordinates << [i, j]
      end
    end
  end

  def build_field(dimenstions, munber_of_mines)
    field = Array.new dimenstions do
                        Array.new dimenstions do
                          Coordinate.new
                        end
                      end

  end

  def fill_field_with_mines
    number_of_mines.times { add_mine_to_field }
  end

  def add_mine_to_field
    coordinate = free_of_mines_coordinates[rand(free_of_mines_coordinates.size - 1)] # [x, y]
    free_of_mines_coordinates.delete(coordinate)

    field[coordinate[0]][coordinate[1]].mine = true
  end
end

class Coordinate
  attr_writer :mine

  def initialize
    @mine = false
    @opened = false
  end

  def mine?
    mine
  end

  def opened?
    opened
  end

  def open
    self.opened = true
  end

  private

  attr_reader :mine
  attr_accessor :opened
end