import { err, ok, type CommandContext } from "@tailor-platform/erp-kit/core";
import type { Transaction } from "../generated/kysely-tailordb";
import { AccrualPlanNotFoundError, PlanAlreadyRetiredError } from "../lib/errors.generated";

export interface RetireAccrualPlanInput {
  id: string;
  /** Retirement date set as effectiveEnd on the current open generation; defaults to today. */
  effectiveEnd?: Date;
}

/**
 * Function: retireAccrualPlan
 * Description: Closes the current open generation of an AccrualPlan when
 * the plan is discontinued, preserving all prior generations so that past
 * grants remain historically explainable.
 */
export async function run(db: Transaction, input: RetireAccrualPlanInput, _ctx: CommandContext) {
  const { id } = input;

  const current = await db
    .selectFrom("AccrualPlan")
    .selectAll()
    .where("id", "=", id)
    .forUpdate()
    .executeTakeFirst();
  if (!current) {
    return err(new AccrualPlanNotFoundError(id));
  }
  if (current.effectiveEnd !== null) {
    return err(new PlanAlreadyRetiredError(id));
  }

  const effectiveEnd = input.effectiveEnd ?? new Date();
  const accrualPlan = await db
    .updateTable("AccrualPlan")
    .set({ effectiveEnd })
    .where("id", "=", id)
    .returningAll()
    .executeTakeFirstOrThrow();

  return ok({ accrualPlan });
}