refactor: move state mutation logic to when method, simplify set/update methods

domain/marketplace/classified_ad.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 from dataclasses import dataclass, field, replace
 from decimal import Decimal
+from typing import Self
 
 from domain.framework.entity import Entity
 from domain.marketplace.classified_ad_id import ClassifiedAdId
@@ -53,31 +54,26 @@ class ClassifiedAd(Entity):
                 f"Cannot publish classified ad with missing or invalid: {', '.join(errors)}"
             )
 
-    def request_to_publish(self):
-        self._ensure_valid_state()
+    def when(self, event: DomainEvent) -> Self:
+        match event:
+            case ClassifiedAdTitleChanged():
+                return replace(self, title=ClassifiedAdTitle(title=event.title))
+            case ClassifiedAdTextUpdated():
+                return replace(self, text=ClassifiedAdText(text=event.ad_text))
+            case ClassifiedAdPriceUpdated():
+                return replace(self, price=Price(amount=event.price))
+            case ClassifiedAdSentForReview():
+                return replace(self, state=ClassifiedAdState.PendingReview)
+        return self
 
-        updated = replace(self, state=ClassifiedAdState.PendingReview)
-        return updated.apply(
-            ClassifiedAdSentForReview(id=self.id.value)
-        )
+    def request_to_publish(self):
+        return self.apply(ClassifiedAdSentForReview(id=self.id.value))
 
     def set_title(self, title: ClassifiedAdTitle) -> ClassifiedAd:
-        updated = replace(self, title=title)
-        updated._ensure_valid_state()
-        return updated.apply(
-            ClassifiedAdTitleChanged(id=self.id.value, title=title.title)
-        )
+        return self.apply(ClassifiedAdTitleChanged(id=self.id.value, title=title.title))
 
     def update_text(self, text: ClassifiedAdText) -> ClassifiedAd:
-        updated = replace(self, text=text)
-        updated._ensure_valid_state()
-        return updated.apply(
-            ClassifiedAdTextUpdated(id=self.id.value, ad_text=text.text)
-        )
+        return self.apply(ClassifiedAdTextUpdated(id=self.id.value, ad_text=text.text))
 
     def update_price(self, price: Price) -> ClassifiedAd:
-        updated = replace(self, price=price)
-        updated._ensure_valid_state()
-        return updated.apply(
-            ClassifiedAdPriceUpdated(id=self.id.value, price=price.amount)
-        )
+        return self.apply(ClassifiedAdPriceUpdated(id=self.id.value, price=price.amount))