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

export interface GetShiftPatternInput {
  shiftPatternId: string;
}

/**
 * Function: getShiftPattern
 * Retrieves a single ShiftPattern by id, with its segments included from the
 * embedded `segments` array (ADR-022), ordered by sequence.
 */
export async function run(db: ReadonlyDB<DB>, input: GetShiftPatternInput) {
  const shiftPattern = await db
    .selectFrom("ShiftPattern")
    .selectAll()
    .where("id", "=", input.shiftPatternId)
    .executeTakeFirst();

  if (!shiftPattern) {
    return err(new ShiftPatternNotFoundError(input.shiftPatternId));
  }

  const segments = [...(shiftPattern.segments ?? [])].sort((a, b) => a.sequence - b.sequence);

  return ok({ shiftPattern, segments });
}