json + associations based on game/prize/level/level_prize example

example.rb

class Prize       < Struct.new(:name, :img);           end
class Level       < Struct.new(:name, :order, :image); end
class Achievement < Struct.new(:prize, :level);        end

class Rewarding
  def add(achviement);                 end
  def level_rewards(level_or_order);   end
  def level_for_prize(prize);          end
  def max_rewarding_level;             end
end


class RewardingPresenter # Mapper ?
  def initialize(rewarding)
  end

  def as_json(*)
    hash = {prizes: prizes = [], levels: levels = [], rewards: rewards = []}
    (0..rewarding.max_rewarding_level).each do |level|
      rewarding.level_rewards(level).each do |achv|
        prizes  << achv.prize unless prizes.include?(achv.prize)
        levels  << achv.level unless levels.include?(achv.level)
        rewards << [prizes.index_of(achv.prize), levels.index_of(level.prize)]
      end
    end
    hash
  end
end