Updated inventory modification code

ruby/gilded_rose.rb

@@ -1,56 +1,74 @@
 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
-        end
+      case item.name
+      when "Aged Brie"
+        update_aged_brie(item)
+      when "Backstage passes to a TAFKAL80ETC concert"
+        update_backstage_passes(item)
+      when "Sulfuras, Hand of Ragnaros"
+        next # Sulfuras remains unchanged, move to the next item
+      when "Conjured Mana Cake"
+        update_conjured(item)
       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
-        else
-          if item.quality < 50
-            item.quality = item.quality + 1
-          end
-        end
+        update_normal_item(item)
       end
     end
   end
+
+  private
+
+  def update_aged_brie(item)
+    decrease_sell_in(item)
+    increase_quality(item, 2)
+  end
+
+  def update_backstage_passes(item)
+    decrease_sell_in(item)
+    if item.sell_in > 0
+      if item.sell_in <= 5
+        increase_quality(item, 3)
+      elsif item.sell_in <= 10
+        increase_quality(item, 2)
+      else
+        increase_quality(item, 1)
+      end
+    else
+      item.quality = 0
+    end
+  end
+
+  def increase_quality(item, amount)
+    item.quality = [item.quality + amount, 50].min
+  end
+
+  def update_normal_item(item)
+    decrease_quality(item)
+    decrease_quality(item) if expired?(item)
+    decrease_sell_in(item)
+  end
+
+  def update_conjured(item)
+    decrease_quality(item, 2)
+    decrease_quality(item, 2) if expired?(item)
+    decrease_sell_in(item)
+  end
+
+  def decrease_quality(item, rate = 1)
+    item.quality -= rate if item.quality > 0
+  end
+
+  def decrease_sell_in(item)
+    item.sell_in -= 1
+  end
+
+  def expired?(item)
+    item.sell_in <= 0
+  end
 end
 
 class Item
@@ -62,7 +80,7 @@ class Item
     @quality = quality
   end
 
-  def to_s()
+  def to_s
     "#{@name}, #{@sell_in}, #{@quality}"
   end
 end