import type { FileMeta, Session } from "../types/session";

export const BASE_W = 595;
export const BASE_H = 842;

export function getSelectedPhotos(session: Session | null | undefined): FileMeta[] {
  if (!session) return [];
  const all = session.uploads?.photos ?? [];
  const selectedOrder = session.selected_photo_ids ?? [];
  const byId = new Map(all.map((photo) => [photo.id, photo]));
  const selected = selectedOrder
    .map((id) => byId.get(id))
    .filter(Boolean) as FileMeta[];
  return selected.length ? selected : all;
}

export function getPhotosForPage(
  session: Session | null | undefined,
  pageIndex: number,
  perPage = 1,
): FileMeta[] {
  const selected = getSelectedPhotos(session);
  const start = pageIndex * perPage;
  return selected.slice(start, start + perPage);
}

export function formatDocNumber(session: Session | null | undefined): string {
  if (!session?.id) return "REP-00000000";
  return `REP-${session.id.slice(0, 8).toUpperCase()}`;
}