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

export interface GetWorkRuleAssignmentInput {
  id: string;
}

/**
 * Function: getWorkRuleAssignment
 * Description: Retrieves a single WorkRuleAssignment generation by its surrogate id,
 * returning the target binding (targetType / targetId), the referenced
 * workRuleId, and effective-dating fields.
 */
export async function run(db: ReadonlyDB<DB>, input: GetWorkRuleAssignmentInput) {
  const workRuleAssignment = await db
    .selectFrom("WorkRuleAssignment")
    .selectAll()
    .where("id", "=", input.id)
    .executeTakeFirst();

  if (!workRuleAssignment) {
    return err(new WorkRuleAssignmentNotFoundError(input.id));
  }

  return ok({ workRuleAssignment });
}