diff --git a/lib/gilded_rose.dart b/lib/gilded_rose.dart
index 5c87d3a..2322c6e 100644
--- a/lib/gilded_rose.dart
+++ b/lib/gilded_rose.dart
@@ -17,55 +17,73 @@ class GildedRose {
   GildedRose(this.items);
 
   void updateQuality() {
-    for (var i = 0; i < items.length; i++) {
-      if (items[i].name != 'Aged Brie' &&
-          items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-        if (items[i].quality > 0) {
-          if (items[i].name != 'Sulfuras, Hand of Ragnaros') {
-            items[i].quality = items[i].quality - 1;
-          }
-        }
+    for (final item in items) {
+      if (item.name == 'Sulfuras, Hand of Ragnaros') {
+        _updateSulfuras(item);
+      } else if (item.name == 'Aged Brie') {
+        _updateAgedBrie(item);
+      } else if (item.name == 'Backstage passes to a TAFKAL80ETC concert') {
+        _updateBackstagePasses(item);
       } else {
-        if (items[i].quality < 50) {
-          items[i].quality = items[i].quality + 1;
-
-          if (items[i].name == 'Backstage passes to a TAFKAL80ETC concert') {
-            if (items[i].sellIn < 11) {
-              if (items[i].quality < 50) {
-                items[i].quality = items[i].quality + 1;
-              }
-            }
-
-            if (items[i].sellIn < 6) {
-              if (items[i].quality < 50) {
-                items[i].quality = items[i].quality + 1;
-              }
-            }
-          }
-        }
-      }
-
-      if (items[i].name != 'Sulfuras, Hand of Ragnaros') {
-        items[i].sellIn = items[i].sellIn - 1;
-      } 
-
-      if (items[i].sellIn < 0) {
-        if (items[i].name != 'Aged Brie') {
-          if (items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-            if (items[i].quality > 0) {
-              if (items[i].name != 'Sulfuras, Hand of Ragnaros') {
-                items[i].quality = items[i].quality - 1;
-              }
-            }
-          } else {
-            items[i].quality = items[i].quality - items[i].quality;
-          }
-        } else {
-          if (items[i].quality < 50) {
-            items[i].quality = items[i].quality + 1;
-          }
-        }
+        _updateNormalItem(item);
       }
     }
   }
+
+  void _updateNormalItem(Item item) {
+    // Quality decreases by 1 each day
+    if (item.quality > 0) {
+      item.quality -= 1;
+    }
+
+    item.sellIn -= 1;
+
+    // After sell-by date, quality degrades twice as fast
+    if (item.sellIn < 0 && item.quality > 0) {
+      item.quality -= 1;
+    }
+  }
+
+  void _updateAgedBrie(Item item) {
+    // Quality increases as it ages
+    if (item.quality < 50) {
+      item.quality += 1;
+    }
+
+    item.sellIn -= 1;
+
+    // After sell-by date, quality increases twice as fast
+    if (item.sellIn < 0 && item.quality < 50) {
+      item.quality += 1;
+    }
+  }
+
+  void _updateBackstagePasses(Item item) {
+    // Quality increases as concert approaches
+    if (item.quality < 50) {
+      item.quality += 1;
+
+      // 10 days or less: +2 quality/day
+      if (item.sellIn < 11 && item.quality < 50) {
+        item.quality += 1;
+      }
+
+      // 5 days or less: +3 quality/day
+      if (item.sellIn < 6 && item.quality < 50) {
+        item.quality += 1;
+      }
+    }
+
+    item.sellIn -= 1;
+
+    // After concert, quality drops to 0
+    if (item.sellIn < 0) {
+      item.quality = 0;
+    }
+  }
+
+  void _updateSulfuras(Item item) {
+    // Legendary item never changes
+    // Quality always 80, sellIn never decreases
+  }
 }