from sqlalchemy import select, update, func

from market.models.market import CartItem


async def adopt_session_cart_for_user(session, user_id: int, session_id: str | None) -> None:
    """
    When a user logs in or registers:
    - If there are cart items for this anonymous session, take them over.
    - Replace any existing cart items for this user with the anonymous cart.
    """

    if not session_id:
        return

    # 1) Find anonymous cart items for this session
    result = await session.execute(
        select(CartItem)
        .where(
            CartItem.deleted_at.is_(None),
            CartItem.user_id.is_(None),
            CartItem.session_id == session_id,
        )
    )
    anon_items = result.scalars().all()
    if not anon_items:
        # nothing to adopt
        return

    # 2) Soft-delete any existing cart for this user
    await session.execute(
        update(CartItem)
        .where(
            CartItem.deleted_at.is_(None),
            CartItem.user_id == user_id,
        )
        .values(deleted_at=func.now())
    )

    # 3) Reassign anonymous cart items to the user
    for ci in anon_items:
        ci.user_id = user_id
        # optional: you can keep the session_id as well, but user_id will take precedence
        # ci.session_id = session_id

    # No explicit commit here; caller's transaction will handle it