from sqlalchemy import func, or_, select, text

from db.models.service_notifications import ServiceNotification
from db.session import UnitOfWork
from schemas.enums import NotificationStatus


async def get_notification_by_id(uow: UnitOfWork, n_id: int) -> ServiceNotification | None:
    stmt = select(ServiceNotification).where(ServiceNotification.id == n_id)
    r = await uow.session.execute(stmt)

    return r.scalar_one_or_none()


async def get_pending_notifications(
    uow: UnitOfWork, batch_size: int = 50
) -> list[ServiceNotification]:
    stmt = (
        select(ServiceNotification)
        .where(
            or_(
                ServiceNotification.status == "pending",
                (
                    (ServiceNotification.status == "dispatched")
                    & (
                        ServiceNotification.dispatched_at
                        < func.now() - text("interval '10 minutes'")
                    )
                ),
            )
        )
        .order_by(ServiceNotification.created_at)
        .with_for_update(skip_locked=True)
        .limit(batch_size)
    )
    r = await uow.session.execute(stmt)

    return list(r.scalars().all())


async def ack_notification(uow: UnitOfWork, n_id: int) -> ServiceNotification | None:
    notification = await get_notification_by_id(uow, n_id)
    if not notification:
        return

    notification.sent_at = func.now()
    notification.status = NotificationStatus.SENT

    return notification


async def mark_notification_as_dispatched(uow: UnitOfWork, n_id: int):
    notification = await get_notification_by_id(uow, n_id)
    if not notification:
        return

    notification.dispatched_at = func.now()
    notification.status = NotificationStatus.DISPATCHED
    notification.attempts += 1

    return notification