from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.point_ledger import PointLedger


async def grant_points(
    db: AsyncSession,
    user_id: int,
    change: int,
    reason: str,
    ref_type: str | None = None,
    ref_id: int | None = None,
) -> PointLedger:
    last_entry = await db.execute(
        select(PointLedger)
        .where(PointLedger.user_id == user_id)
        .order_by(PointLedger.id.desc())
        .limit(1)
    )
    last = last_entry.scalar_one_or_none()
    current_balance = last.balance if last else 0

    ledger = PointLedger(
        user_id=user_id,
        change=change,
        balance=current_balance + change,
        reason=reason,
        ref_type=ref_type,
        ref_id=ref_id,
    )
    db.add(ledger)
    await db.flush()
    return ledger