export const DEFAULT_TABLE_PAGE_SIZE_OPTIONS = [5, 10, 20, 50] as const;

export const SHARED_ADMIN_TABLE_PAGE_SIZE_STORAGE_KEY =
  "admin-table-page-size";

type ResolveTablePageSizeArgs = {
  storageKey?: string;
  pageSizeOptions?: readonly number[];
  defaultPageSize: number;
};

function isValidPageSize(pageSize: number, pageSizeOptions?: readonly number[]) {
  if (!Number.isFinite(pageSize) || pageSize <= 0) return false;
  if (!pageSizeOptions || pageSizeOptions.length === 0) return true;
  return pageSizeOptions.includes(pageSize);
}

export function resolveStoredTablePageSize({
  storageKey,
  pageSizeOptions,
  defaultPageSize,
}: ResolveTablePageSizeArgs) {
  if (!isValidPageSize(defaultPageSize, pageSizeOptions)) {
    return pageSizeOptions?.[0] ?? 10;
  }

  if (typeof window === "undefined" || !storageKey) {
    return defaultPageSize;
  }

  try {
    const rawValue = window.localStorage.getItem(storageKey);
    if (!rawValue) return defaultPageSize;

    const parsedValue = Number(rawValue);
    return isValidPageSize(parsedValue, pageSizeOptions)
      ? parsedValue
      : defaultPageSize;
  } catch {
    return defaultPageSize;
  }
}

export function persistTablePageSize(
  storageKey: string | undefined,
  pageSize: number,
  pageSizeOptions?: readonly number[]
) {
  if (typeof window === "undefined" || !storageKey) return;
  if (!isValidPageSize(pageSize, pageSizeOptions)) return;

  try {
    window.localStorage.setItem(storageKey, String(pageSize));
  } catch {
    // Ignore storage failures so pagination keeps working normally.
  }
}