import { and, eq, lte, desc, subscriptionPlans, type Db } from "@parking/db";
import type { SubscriptionPlan } from "@parking/shared";

// Subscription-plan pricing. The PURE span math (periodsBetween / priceSubscriptionSpan
// / addMonths) lives in @parking/shared so it's unit-tested alongside the tariff fee
// function; here we add the DB-backed plan-version resolver. A plan is admin-composed,
// versioned config (like a tariff) — the operator SELLS from it and never types a
// price. See wiki/entities/subscription.md.
export { periodsBetween, priceSubscriptionSpan, addMonths } from "@parking/shared";

/** Resolve the plan VERSION in force for `planId` at `asOf`: the latest active row
 *  with effectiveFrom ≤ asOf (the tariff-resolve pattern). null when none applies. */
export function resolvePlanVersion(db: Db, planId: string, asOf: string): SubscriptionPlan | null {
  const row = db
    .select()
    .from(subscriptionPlans)
    .where(
      and(
        eq(subscriptionPlans.planId, planId),
        eq(subscriptionPlans.active, true),
        lte(subscriptionPlans.effectiveFrom, asOf),
      ),
    )
    .orderBy(desc(subscriptionPlans.effectiveFrom))
    .limit(1)
    .get();
  return row ? (row as SubscriptionPlan) : null;
}