class Product
  attr_reader :days_remaining, :quality

  def initialize(days_remaining:, quality:)
    @days_remaining = days_remaining
    @quality = quality
  end

  def tick; end

  private

  attr_writer :days_remaining, :quality
end

class NormalItem < Product
  def tick
    self.days_remaining = days_remaining - 1
    if days_remaining > 0
      self.quality = quality > 1 ? quality - 1 : 0
    else
      self.quality = quality > 2 ? quality - 2 : 0
    end
  end
end

class ConjuredManaCake < Product
  def tick
    self.days_remaining = days_remaining - 1
    if days_remaining > 0
      self.quality = quality > 1 ? quality - 2 : 0
    else
      self.quality = quality > 3 ? quality - 4 : 0
    end
  end
end

class AgedBrie < Product
  def tick
    self.days_remaining = days_remaining - 1
    if days_remaining > 0
      self.quality = quality < 50 ? quality + 1 : 50
    else
      self.quality = quality < 49 ? quality + 2 : 50
    end
  end
end

class BackstagePasses < Product
  def tick
    self.days_remaining = days_remaining - 1
    if days_remaining > 9
      self.quality = quality < 50 ? quality + 1 : 50
    elsif days_remaining > 4
      self.quality = quality < 50 ? quality + 2 : 50
    elsif days_remaining >= 0
      self.quality = quality < 50 ? quality + 3 : 50
    else
      self.quality = 0
    end
  end
end

class GildedRose
  PRODUCT = {
    'Conjured Mana Cake' => 'ConjuredManaCake',
    'Aged Brie' => 'AgedBrie',
    'Backstage passes to a TAFKAL80ETC concert' => 'BackstagePasses',
    'Normal Item' => 'NormalItem'
  }.freeze

  attr_reader :product

  def initialize(name:, days_remaining:, quality:)
    @product = product_by(name).new(days_remaining: days_remaining, quality: quality)
  end

  def tick
    product.tick
  end

  def days_remaining
    product.days_remaining
  end

  def quality
    product.quality
  end

  private

  def product_by(name)
    Object.const_get(PRODUCT[name] || 'Product')
  end
end