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

export interface GetAccrualPlanInput {
  id: string;
}

/**
 * Function: getAccrualPlan
 * Description: Resolves a single AccrualPlan generation by its surrogate id,
 * returning the generation regardless of whether it is the current
 * (effectiveEnd IS NULL) generation or a closed historical one.
 */
export async function run(db: ReadonlyDB<DB>, input: GetAccrualPlanInput) {
  const accrualPlan = await db
    .selectFrom("AccrualPlan")
    .selectAll()
    .where("id", "=", input.id)
    .executeTakeFirst();

  if (!accrualPlan) {
    return err(new AccrualPlanNotFoundError(input.id));
  }

  return ok({ accrualPlan });
}