/** A column a list is sorted by, and which way. */
export interface ListSort<Key extends string> {
  by: Key;
  order: 'asc' | 'desc';
}

/**
 * The sort after a click on a column: the same column turns the other
 * way; another starts the way it reads best (names A to Z, counts and
 * dates biggest and newest first).
 *
 * @param {ListSort} current   - The sort now.
 * @param {string}   by        - The column clicked.
 * @param {string[]} ascending - The columns that start A to Z.
 * @returns {ListSort}
 */
export const nextSort = <Key extends string>(
  current: ListSort<Key>,
  by: Key,
  ascending: readonly Key[]
): ListSort<Key> =>
  current.by === by
    ? { by, order: current.order === 'asc' ? 'desc' : 'asc' }
    : { by, order: ascending.includes(by) ? 'asc' : 'desc' };