customize current ruby code

ruby/gilded_rose.rb

@@ -4,52 +4,66 @@ class GildedRose
     @items = items
   end
 
-  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
-      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
-      end
+  def update_quality
+    @items.each { |item| update_item(item) }
+  end
+
+  private
+
+  def update_item(item)
+    validate_item(item)
+    case item.name
+    when "Aged Brie"
+      update_aged_brie(item)
+    when "Sulfuras, Hand of Ragnaros"
+      item.quality = 80 # Ensure quality remains 80
+    when "Backstage passes to a TAFKAL80ETC concert"
+      update_backstage_passes(item)
+    else
+      update_standard_item(item)
     end
+    item.sell_in -= 1 unless item.name == "Sulfuras, Hand of Ragnaros"
+    handle_expired(item)
+  end
+
+  def validate_item(item)
+    raise StandardError, "Invalid sell_in value" unless item.sell_in.is_a?(Integer)
+    raise StandardError, "Invalid quality value" unless item.quality.is_a?(Integer)
+  end
+
+  def update_aged_brie(item)
+    increase_quality(item)
+  end
+
+  def update_backstage_passes(item)
+    increase_quality(item)
+    increase_quality(item) if item.sell_in <= 10
+    increase_quality(item) if item.sell_in <= 5
+  end
+
+  def update_standard_item(item)
+    decrease_quality(item)
+  end
+
+  def handle_expired(item)
+    return unless item.sell_in < 0
+
+    case item.name
+    when "Aged Brie"
+      increase_quality(item)
+    when "Backstage passes to a TAFKAL80ETC concert"
+      item.quality = 0
+    else
+      decrease_quality(item) unless item.name == "Sulfuras, Hand of Ragnaros"
+    end
+  end
+
+  def increase_quality(item)
+    item.quality += 1 if item.quality < 50
+  end
+
+  def decrease_quality(item)
+    item.quality -= 1 if item.quality > 0
   end
 end