Refactoring

Signed-off-by: Jean-Maxime <jm.fillau@gmail.com>

python/gilded_rose.py

@@ -1,5 +1,8 @@
 # -*- coding: utf-8 -*-
 
+from dataclasses import dataclass
+from typing import ClassVar, Dict, Type
+
 class GildedRose(object):
 
     def __init__(self, items):
@@ -7,34 +10,8 @@ class GildedRose(object):
 
     def update_quality(self):
         for item in self.items:
-            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
-            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
-                        if item.sell_in < 6:
-                            if item.quality < 50:
-                                item.quality = item.quality + 1
-            if item.name != "Sulfuras, Hand of Ragnaros":
-                item.sell_in = item.sell_in - 1
-            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
-                    else:
-                        item.quality = item.quality - item.quality
-                else:
-                    if item.quality < 50:
-                        item.quality = item.quality + 1
-
+            updater = ItemUpdater.update_for(item)
+            updater.update()
 
 class Item:
     def __init__(self, name, sell_in, quality):
@@ -44,3 +21,67 @@ class Item:
 
     def __repr__(self):
         return "%s, %s, %s" % (self.name, self.sell_in, self.quality)
+
+@dataclass()
+class ItemUpdater:
+
+    item: Item
+
+    _registry: ClassVar[Dict[str, Type["ItemUpdater"]]] = {}
+
+    @classmethod
+    def register(cls, name: str):
+        def deco(subcls: Type["ItemUpdater"]) -> Type["ItemUpdater"]:
+            cls._registry[name] = subcls
+            return subcls
+        return deco
+
+    @classmethod
+    def update_for(cls, item: Item) -> "ItemUpdater":
+        updater_cls = cls._registry.get(item.name, cls)
+        return updater_cls(item)
+
+
+    def update(self):
+        self.item.sell_in = self.item.sell_in - 1
+
+        if self.item.quality > 0:
+            self.item.quality = self.item.quality - 1
+
+        if self.item.sell_in < 0 and self.item.quality > 0:
+            self.item.quality = self.item.quality - 1
+
+
+@ItemUpdater.register("Aged Brie")
+class AgedBrieUpdater(ItemUpdater):
+
+    def update(self):
+        if self.item.quality < 50:
+            self.item.quality = self.item.quality + 1
+
+        self.item.sell_in = self.item.sell_in - 1
+
+        if self.item.sell_in < 0:
+            if self.item.quality < 50:
+                self.item.quality = self.item.quality + 1
+
+@ItemUpdater.register("Sulfuras, Hand of Ragnaros")
+class SulfurasUpdater(ItemUpdater):
+
+    def update(self):
+        pass # Legendary item, never changes
+
+@ItemUpdater.register("Backstage passes to a TAFKAL80ETC concert")
+class BackstagePassUpdater(ItemUpdater):
+
+    def update(self):
+        if self.item.sell_in < 1:
+            self.item.quality = 0  # Concert passed, quality drops to 0
+        elif self.item.sell_in < 6:
+            self.item.quality = min(50, self.item.quality + 3)  # 5 days or less: +3
+        elif self.item.sell_in < 11:
+            self.item.quality = min(50, self.item.quality + 2)  # 10 days or less: +2
+        else:
+            self.item.quality = min(50, self.item.quality + 1)  # More than 10 days: +1
+
+        self.item.sell_in = self.item.sell_in - 1