feat: cron worker for renewal notifs

services/notifications.py

@@ -0,0 +1,64 @@
+import asyncio
+from datetime import UTC, datetime, timedelta
+from typing import TYPE_CHECKING
+
+from sqlalchemy import select
+from sqlalchemy.dialects.postgresql import insert
+
+from config import cfg
+from db.models import ServiceNotification, Subscription
+from db.session import async_session
+from schemas.enums import NotificationType
+
+if TYPE_CHECKING:
+    from sqlalchemy.ext.asyncio import AsyncSession
+
+
+async def collect_subscription_notifications(
+    session: "AsyncSession", now: datetime | None = None
+) -> int:
+    now = now or datetime.now(UTC)
+    periods = (
+        (NotificationType.SEVEN_DAYS, now + timedelta(days=3), now + timedelta(days=7)),
+        (NotificationType.THREE_DAYS, now + timedelta(days=1), now + timedelta(days=3)),
+        (NotificationType.ONE_DAY, now, now + timedelta(days=1)),
+        (NotificationType.EXPIRED, None, now),
+    )
+    created = 0
+
+    for notification_type, starts_at, ends_at in periods:
+        conditions = [Subscription.expires_at <= ends_at]
+        if starts_at is not None:
+            conditions.append(Subscription.expires_at > starts_at)
+
+        subscriptions = await session.scalars(select(Subscription).where(*conditions))
+        rows = [
+            {
+                "subscription_id": subscription.id,
+                "notify_type": notification_type,
+                "sub_expires_at": subscription.expires_at,
+            }
+            for subscription in subscriptions
+        ]
+        if not rows:
+            continue
+
+        stmt = insert(ServiceNotification).values(rows)
+        stmt = stmt.on_conflict_do_nothing(constraint="uq_subscription_notification")
+        result = await session.execute(stmt)
+        created += result.rowcount or 0
+
+    await session.commit()
+    return created
+
+
+async def run_subscription_notifications() -> None:
+    interval = cfg.notification_scan_interval * 60
+    while True:
+        try:
+            async with async_session() as session:
+                await collect_subscription_notifications(session)
+        except Exception:
+            # A failed iteration must not stop subsequent notification checks.
+            pass
+        await asyncio.sleep(interval)