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

type CompanyHolidayOrderByField = "holidayDate";

export interface ListCompanyHolidaysInput extends PaginationInput<CompanyHolidayOrderByField> {
  /** Restricts results to a single HolidayCalendar. */
  calendarId?: string;
  /** Restricts results to entries whose holidayDate falls within this calendar year. */
  year?: number;
  /** Restricts results to entries whose holidayDate is on or after this date. */
  startDate?: Date;
  /** Restricts results to entries whose holidayDate is on or before this date. */
  endDate?: Date;
}

/**
 * Function: listCompanyHolidays
 * Description: Returns a paginated list of holiday-calendar entries,
 * optionally filtered by date range or year. Omitting a filter returns the
 * full calendar, paginated. Supports calendar browsing and admin review of
 * registered holidays.
 */
export async function run(db: ReadonlyDB<DB>, input: ListCompanyHolidaysInput) {
  const limit = input.limit ?? DEFAULT_PAGE_SIZE;
  const offset = input.offset ?? 0;
  const orderBy = input.orderBy ?? "id";
  const orderDirection = input.orderDirection ?? "asc";

  let query = db.selectFrom("CompanyHoliday").selectAll();

  if (input.calendarId !== undefined) {
    query = query.where("calendarId", "=", input.calendarId);
  }

  if (input.year !== undefined) {
    const startOfYear = new Date(Date.UTC(input.year, 0, 1));
    const startOfNextYear = new Date(Date.UTC(input.year + 1, 0, 1));
    query = query
      .where("holidayDate", ">=", startOfYear)
      .where("holidayDate", "<", startOfNextYear);
  }

  if (input.startDate !== undefined) {
    query = query.where("holidayDate", ">=", input.startDate);
  }

  if (input.endDate !== undefined) {
    query = query.where("holidayDate", "<=", input.endDate);
  }

  const companyHolidays = await query
    .orderBy(orderBy, orderDirection)
    .limit(limit + 1)
    .offset(offset)
    .execute();

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