feat: auto-refresh calendar subscriptions

backend/calendar_router.py

@@ -1,4 +1,4 @@
-from datetime import UTC, datetime, timedelta
+from datetime import datetime, timedelta
 from uuid import UUID
 from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 
@@ -9,8 +9,9 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from . import calendar as calendar_service
 from .auth import current_user
+from .calendar_refresh import refresh_subscription_cache
 from .db import get_db
-from .models import CalendarSubscription, User, utcnow
+from .models import CalendarSubscription, User
 
 router = APIRouter(prefix="/api/v1", tags=["calendar"])
 MAX_WINDOW = timedelta(days=366)
@@ -90,37 +91,6 @@ async def _owned(db: AsyncSession, user_id: UUID, subscription_id: UUID) -> Cale
     return row
 
 
-async def _refresh(db: AsyncSession, row: CalendarSubscription) -> None:
-    try:
-        result = await __import__("asyncio").to_thread(
-            calendar_service.fetch_calendar, row.url, etag=row.etag, last_modified=row.last_modified
-        )
-        if result.not_modified:
-            if not row.ics_cache:
-                raise HTTPException(502, "calendar returned not modified without cache")
-        elif result.content is not None:
-            # Parse before replacing a known-good cache.
-            calendar_service.parse_ics_events(
-                result.content,
-                row.name,
-                row.color,
-                datetime.now(UTC) - timedelta(days=1),
-                datetime.now(UTC) + timedelta(days=1),
-                "UTC",
-            )
-            row.ics_cache = result.content.decode("utf-8-sig")
-            row.etag = result.etag
-            row.last_modified = result.last_modified
-        row.refreshed_at = utcnow()
-        row.last_error = None
-    except Exception as exc:
-        row.last_error = exc.detail if isinstance(exc, HTTPException) else str(exc)
-        if not row.ics_cache:
-            await db.rollback()
-            raise HTTPException(502, row.last_error) from exc
-    await db.commit()
-
-
 @router.get("/calendar-subscriptions", response_model=list[SubscriptionOut])
 async def list_subscriptions(user: User = Depends(current_user), db: AsyncSession = Depends(get_db)):
     rows = (await db.scalars(select(CalendarSubscription).where(
@@ -139,7 +109,7 @@ async def create_subscription(
     row = CalendarSubscription(user_id=user.id, **payload.model_dump())
     db.add(row)
     await db.flush()
-    await _refresh(db, row)
+    await refresh_subscription_cache(db, row)
     await db.refresh(row)
     return _out(row)
 
@@ -183,7 +153,7 @@ async def refresh_subscription(
     db: AsyncSession = Depends(get_db),
 ):
     row = await _owned(db, user.id, subscription_id)
-    await _refresh(db, row)
+    await refresh_subscription_cache(db, row)
     await db.refresh(row)
     return _out(row)
 
@@ -209,7 +179,7 @@ async def calendar_events(
     sources = []
     for row in rows:
         if not row.ics_cache:
-            await _refresh(db, row)
+            await refresh_subscription_cache(db, row)
         try:
             parsed = calendar_service.parse_ics_events(
                 row.ics_cache or "", row.name, row.color, start, end, user.timezone,