GildedRose-Refactoring-Kata/python/gilded_rose.py
2025-12-07 18:50:22 +00:00

291 lines
7.9 KiB
Python
Executable File

"""Gilded Rose Refactoring Kata."""
from __future__ import annotations
from abc import ABC, abstractmethod
AGED_BRIE: str = "Aged Brie"
BACKSTAGE_PASSES: str = "Backstage passes to a TAFKAL80ETC concert"
CONJURED: str = "Conjured"
MAX_QUALITY: int = 50
MIN_QUALITY: int = 0
SULFURAS: str = "Sulfuras, Hand of Ragnaros"
SULFURAS_QUALITY: int = 80
class ItemUpdateStrategy(ABC):
"""Abstract base class for item update strategies."""
@abstractmethod
def update_quality(self, item: Item) -> None:
"""Update the quality of the given item according to specific rules.
Parameters
----------
item : Item
The item whose quality is to be updated.
"""
pass
@abstractmethod
def update_sell_in(self, item: Item) -> None:
"""Update the sell_in of the given item according to specific rules.
Parameters
----------
item : Item
The item whose sell_in is to be updated.
"""
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 ItemStrategyFactory:
"""Factory for creating appropriate item update strategies.
Maps item names to their corresponding update strategies.
Centralizes the logic for determining which strategy to use.
"""
def __init__(self) -> None:
"""Initialize the factory with strategy instances."""
self._normal = NormalItemStrategy()
self._aged_brie = AgedBrieStrategy()
self._sulfuras = SulfurasStrategy()
self._backstage = BackstagePassStrategy()
self._conjured = ConjuredItemStrategy()
def get_strategy(self, item_name: str) -> ItemUpdateStrategy:
"""Return the appropriate strategy for the given item name.
Parameters
----------
item_name : str
The name of the item.
Returns
-------
ItemUpdateStrategy
The strategy instance for updating this item type.
"""
if item_name == SULFURAS:
return self._sulfuras
elif item_name == AGED_BRIE:
return self._aged_brie
elif item_name == BACKSTAGE_PASSES:
return self._backstage
elif item_name.startswith(CONJURED):
return self._conjured
else:
return self._normal
class GildedRose:
"""Manages inventory quality updates for the Gilded Rose inn.
Updates item quality and sell_in values acording to specific business rules:
- Normal items degrade in quality over time
- "Aged Brie" increases in quality as it ages
- "Sulfuras" is a legendary item that never changes
- "Backstage passes" increase in quality as concert approaches, drop to 0 after
- Quality is never negative and never exceeds 50 (except Sulfuras at 80)
Goblin will throw a tantrum if the Item class is modified.
"""
def __init__(self, items: list[Item]) -> None:
"""Initialize the GildedRose with a list of items.
Parameters
----------
items : list[Item]
The list of items in the inventory.
"""
self.items = items
self._strategy_factory = ItemStrategyFactory()
def update_quality(self) -> None:
"""Update quality and sell_in for all items according to the business rules."""
for item in self.items:
strategy = self._strategy_factory.get_strategy(item.name)
strategy.update_quality(item)
strategy.update_sell_in(item)
class Item:
"""Represents an item in the Gilded Rose inventory.
This class must not be modidied cuz Goblin said so.
"""
def __init__(self, name: str, sell_in: int, quality: int) -> None:
"""Initialize an item in the Gilded Rose inventory.
Parameters
----------
name : str
The item's name, which determines its update behavior.
sell_in : int
Number of days remaining to sell the item.
quality : int
Current quality value (0-50 for normal items, 80 for Sulfuras).
"""
self.name = name
self.sell_in = sell_in
self.quality = quality
def __repr__(self) -> str:
"""Return a string representation of the item.
Returns
-------
str
A string describing the item with its name, sell_in, and quality.
"""
return f"{self.name}, {self.sell_in}, {self.quality}"