From 3271c2459179ae2e831c65fdab706488627968f6 Mon Sep 17 00:00:00 2001
From: Vasu Bhatia <git@vbh.ai>
Date: Sun, 7 Dec 2025 18:31:53 +0000
Subject: [PATCH] Implement specific strategy classes for all item types

---
 python/gilded_rose.py | 145 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)

diff --git a/python/gilded_rose.py b/python/gilded_rose.py
index 96d5424a..effb7d74 100755
--- a/python/gilded_rose.py
+++ b/python/gilded_rose.py
@@ -38,6 +38,151 @@ class ItemUpdateStrategy(ABC):
         """
         pass
 
+class NormalItemStrategy(ItemUpdateStrategy):
+    """Strategy for normal items that degrade in quality over time."""
+
+    def update_quality(self, item: Item) -> None:
+        """Decrease quality by 1 before sell date, by 2 after.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        degradation: int = 2 if item.sell_in < 0 else 1
+        item.quality = max(MIN_QUALITY, item.quality - degradation)
+
+    def update_sell_in(self, item: Item) -> None:
+        """Decrease sell_in by 1 each day.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        item.sell_in -= 1
+
+
+class AgedBrieStrategy(ItemUpdateStrategy):
+    """Strategy for Aged Brie that increases in quality over time."""
+
+    def update_quality(self, item: Item) -> None:
+        """Increase quality by 1 before sell date, by 2 after.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        increase: int = 2 if item.sell_in < 0 else 1
+        item.quality = min(MAX_QUALITY, item.quality + increase)
+
+    def update_sell_in(self, item: Item) -> None:
+        """Decrease sell_in by 1 each day.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        item.sell_in -= 1
+
+
+class SulfurasStrategy(ItemUpdateStrategy):
+    """Strategy for Sulfuras, a legendary item that never changes."""
+
+    def update_quality(self, item: Item) -> None:
+        """Sulfuras quality never changes.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update (no actual change occurs).
+
+        """
+        pass
+
+    def update_sell_in(self, item: Item) -> None:
+        """Sulfuras never needs to be sold.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update (no actual change occurs).
+
+        """
+        pass
+
+
+class BackstagePassStrategy(ItemUpdateStrategy):
+    """Strategy for Backstage passes with tiered quality appreciation."""
+
+    def update_quality(self, item: Item) -> None:
+        """Update quality based on days until concert.
+
+        Quality increases by:
+        - 1 when more than 10 days remain
+        - 2 when 6-10 days remain
+        - 3 when 1-5 days remain
+        - drops to 0 after concert (sell_in < 0)
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        if item.sell_in < 0:
+            item.quality = 0
+        elif item.sell_in <= 5:
+            item.quality = min(MAX_QUALITY, item.quality + 3)
+        elif item.sell_in <= 10:
+            item.quality = min(MAX_QUALITY, item.quality + 2)
+        else:
+            item.quality = min(MAX_QUALITY, item.quality + 1)
+
+    def update_sell_in(self, item: Item) -> None:
+        """Decrease sell_in by 1 each day.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        item.sell_in -= 1
+
+
+class ConjuredItemStrategy(ItemUpdateStrategy):
+    """Strategy for Conjured items that degrade twice as fast as normal items."""
+
+    def update_quality(self, item: Item) -> None:
+        """Decrease quality by 2 before sell date, by 4 after.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        degradation = 4 if item.sell_in < 0 else 2
+        item.quality = max(MIN_QUALITY, item.quality - degradation)
+
+    def update_sell_in(self, item: Item) -> None:
+        """Decrease sell_in by 1 each day.
+
+        Parameters
+        ----------
+        item : Item
+            The item to update.
+
+        """
+        item.sell_in -= 1
+
 class GildedRose:
     """Manages inventory quality updates for the Gilded Rose inn.