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

type ShiftOrderByField = "date" | "plannedStartAt" | "createdAt";

export interface ListShiftsInput extends PaginationInput<ShiftOrderByField> {}

/**
 * Function: listShifts
 * Description: Returns an unfiltered, paginated list of shifts across all
 * statuses and shiftTypes — the general-purpose listing used by
 * administrative and planning views.
 */
export async function run(db: ReadonlyDB<DB>, input: ListShiftsInput) {
  const limit = input.limit ?? DEFAULT_PAGE_SIZE;
  const offset = input.offset ?? 0;

  if (!Number.isInteger(limit) || limit < 1) {
    return err(new InvalidPaginationError(`limit=${input.limit}`));
  }
  if (!Number.isInteger(offset) || offset < 0) {
    return err(new InvalidPaginationError(`offset=${input.offset}`));
  }

  // A calendar listing reads by date, so `date` stays the default rather than `id`. The `id`
  // tiebreaker is what makes the order total: without it, rows sharing a date come back in
  // whatever order the engine picks and can repeat or vanish across pages.
  const shifts = await db
    .selectFrom("Shift")
    .selectAll()
    .orderBy(input.orderBy ?? "date", input.orderDirection ?? "asc")
    .orderBy("id", "asc")
    .limit(limit + 1)
    .offset(offset)
    .execute();

  return ok(buildPaginatedResult(shifts, limit));
}