sorty.rb

Shoes.app(:width => 200, :height => 70 * 4 + 40) do
  background black
  colors = [red, blue, green, yellow]
  people = ["steve","ed","nick","tom"]
  @next_color = colors.cycle
  @next_color.next

  @previous_color = colors.cycle
  (colors.length - 1).times { @previous_color.next }

  def names_n_colors(people, colors)
    clear do
      background black
      names_n_colors = colors.zip(people).map do |color, person|
        flow(:height => 70, :width => 200) do
          border color, :strokewidth => 2
          my_label = subtitle person, :stroke => white
          fill @previous_color.next
          rotate(90)
          a = arrow(104, 5, 30)
          a.click { names_n_colors(swap_previous(people, person), colors)  }
          fill @next_color.next
          rotate(180)
          a = arrow(90, 45, 30)
          a.click { names_n_colors(swap_next(people, person), colors)  }
        end
      end

      button "ok!"
    end
  end

  def swap_previous(array, item)
    idx = array.index(item)
    array[(idx-1) % array.length],array[idx] = array[idx],array[(idx-1) % array.length]
    array
  end
  def swap_next(array, item)
    idx = array.index(item)
    array[(idx+1) % array.length],array[idx] = array[idx],array[(idx+1) % array.length]
    array
  end
  names_n_colors(people, colors)
end