diff --git a/ruby/.ruby-version b/ruby/.ruby-version
new file mode 100644
index 00000000..35d16fb1
--- /dev/null
+++ b/ruby/.ruby-version
@@ -0,0 +1 @@
+2.5.7
diff --git a/ruby/gilded_rose.rb b/ruby/gilded_rose.rb
index 3b299af0..22638f50 100644
--- a/ruby/gilded_rose.rb
+++ b/ruby/gilded_rose.rb
@@ -1,54 +1,48 @@
 class GildedRose
-
   def initialize(items)
     @items = items
   end
 
-  def update_quality()
+  def update_quality
     @items.each do |item|
-      if item.name != "Aged Brie" and item.name != "Backstage passes to a TAFKAL80ETC concert"
-        if item.quality > 0
-          if item.name != "Sulfuras, Hand of Ragnaros"
-            item.quality = item.quality - 1
-          end
+      next if item.name == 'Sulfuras, Hand of Ragnaros'
+
+      item.sell_in -= 1
+
+      quality_change = case item.name
+      when 'Backstage passes to a TAFKAL80ETC concert'
+        if item.sell_in.negative?
+          item.quality = 0
+          next
         end
-      else
-        if item.quality < 50
-          item.quality = item.quality + 1
-          if item.name == "Backstage passes to a TAFKAL80ETC concert"
-            if item.sell_in < 11
-              if item.quality < 50
-                item.quality = item.quality + 1
-              end
-            end
-            if item.sell_in < 6
-              if item.quality < 50
-                item.quality = item.quality + 1
-              end
-            end
-          end
-        end
-      end
-      if item.name != "Sulfuras, Hand of Ragnaros"
-        item.sell_in = item.sell_in - 1
-      end
-      if item.sell_in < 0
-        if item.name != "Aged Brie"
-          if item.name != "Backstage passes to a TAFKAL80ETC concert"
-            if item.quality > 0
-              if item.name != "Sulfuras, Hand of Ragnaros"
-                item.quality = item.quality - 1
-              end
-            end
-          else
-            item.quality = item.quality - item.quality
-          end
+
+        if item.sell_in >= 10
+          1
+        elsif item.sell_in >= 5
+          2
         else
-          if item.quality < 50
-            item.quality = item.quality + 1
-          end
+          3
         end
+      when 'Conjured Mana Cake'
+        item.sell_in < 0 ? 4 : 2
+      else
+        quality_degradation = item.sell_in < 0 ? 2 : 1
+
+        quality_degradation *= 2 if item.name.start_with?('Conjured')
+
+        quality_degradation
       end
+
+      new_quality = if [
+        'Aged Brie',
+        'Backstage passes to a TAFKAL80ETC concert',
+      ].include?(item.name)
+        item.quality + quality_change
+      else
+        item.quality - quality_change
+      end
+
+      item.quality = [[new_quality, 50].min, 0].max
     end
   end
 end