"""Single billing service module. Stripe is the only impl — no provider
abstraction. Account row is canonical local state; Stripe is canonical
remote state; the webhook handler bridges the two."""
from datetime import datetime, timezone, timedelta
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.subscription import Subscription


TRIAL_DAYS = 14


class BillingService:
    @staticmethod
    async def start_trial(db: AsyncSession, account_id) -> Subscription:
        """Idempotent. Creates a trialing Subscription on Pro for the account if
        one doesn't exist; otherwise returns the existing row."""
        result = await db.execute(
            select(Subscription).where(Subscription.account_id == account_id)
        )
        existing = result.scalar_one_or_none()
        if existing is not None:
            return existing

        sub = Subscription(
            account_id=account_id,
            plan="pro",
            status="trialing",
            current_period_start=datetime.now(timezone.utc),
            current_period_end=datetime.now(timezone.utc) + timedelta(days=TRIAL_DAYS),
        )
        db.add(sub)
        await db.commit()
        await db.refresh(sub)
        return sub