refactor: 推进后端分层架构治理

app/application/subscription/search.py

@@ -0,0 +1,82 @@
+"""手工订阅搜索应用用例。"""
+
+from dataclasses import dataclass
+from typing import Callable, Protocol
+
+from app.application.subscription.delete import SubscribeDeletionCandidate
+
+
+@dataclass(frozen=True, slots=True)
+class SubscribeSearchActor:
+    """执行手工订阅搜索的用户身份。"""
+
+    username: str
+    is_superuser: bool
+
+
+class SubscribeSearchRepository(Protocol):
+    """手工订阅搜索所需的最小读取端口。"""
+
+    async def get_candidate(
+            self,
+            subscribe_id: int,
+    ) -> SubscribeDeletionCandidate | None:
+        """读取单条订阅的归属信息。"""
+        ...
+
+    async def list_search_ids(self, username: str, state: str) -> list[int]:
+        """返回用户当前可搜索状态下的订阅编号。"""
+        ...
+
+
+SubscribeSearchScheduler = Callable[[int | None, str | None], None]
+
+
+class SearchSubscriptionsCommand:
+    """按用户权限生成并提交手工订阅搜索任务。"""
+
+    def __init__(
+            self,
+            repository: SubscribeSearchRepository,
+            schedule_search: SubscribeSearchScheduler,
+    ) -> None:
+        """注入订阅读取端口和后台任务提交端口。"""
+        self._repository = repository
+        self._schedule_search = schedule_search
+
+    async def execute(
+            self,
+            actor: SubscribeSearchActor,
+            subscribe_id: int | None = None,
+    ) -> bool:
+        """提交单条或当前用户全部可搜索订阅，返回目标是否存在。"""
+        if subscribe_id is not None:
+            candidate = await self._repository.get_candidate(subscribe_id)
+            if not self._can_access(candidate, actor):
+                return False
+            self._schedule_search(subscribe_id, None)
+            return True
+
+        if actor.is_superuser:
+            self._schedule_search(None, "R")
+            return True
+
+        subscribe_ids = await self._repository.list_search_ids(
+            actor.username,
+            "R",
+        )
+        for current_id in subscribe_ids:
+            self._schedule_search(current_id, None)
+        return True
+
+    @staticmethod
+    def _can_access(
+            candidate: SubscribeDeletionCandidate | None,
+            actor: SubscribeSearchActor,
+    ) -> bool:
+        """沿用订阅读取接口的超级用户和归属用户权限语义。"""
+        if candidate is None:
+            return False
+        if actor.is_superuser:
+            return True
+        return bool(candidate.username) and candidate.username == actor.username