/**
 * Categories file dumps and playlists by topic, in two sets apart, one of each
 * {@link CategoryKind}, and give each topic its own page. This module types
 * them for the server and the client, with the bodies that create and change
 * them. Those who hold `category:manage` manage both sets on `/manage`. The
 * client lists them in its `CategoriesProvider`.
 *
 * @module
 */

/**
 * Lists what a category files: a dump category files dumps, a playlist
 * category playlists. Each kind is a set of its own, whose slugs and names are
 * unique within it.
 */
export const CATEGORY_KINDS = ["dump", "playlist"] as const;

/** One of the {@link CATEGORY_KINDS}. */
export type CategoryKind = typeof CATEGORY_KINDS[number];

/**
 * Checks whether `value` is one of the {@link CATEGORY_KINDS}, for the
 * category validator and the rows the category service reads.
 */
export function isCategoryKind(value: unknown): value is CategoryKind {
  return (CATEGORY_KINDS as readonly unknown[]).includes(value);
}

/**
 * Returned by the category routes. A dump category's feed lives at `/<slug>`
 * on the client, a playlist category's at `/playlists/<slug>`, and a dump or
 * playlist names its categories by `id` in `categoryIds`.
 */
export interface Category {
  id: string;
  /** What it files. It never changes. */
  kind: CategoryKind;
  slug: string;
  name: string;
  /** Sorts the categories, lowest first. */
  position: number;
  createdAt: Date;
  updatedAt?: Date;
}

/**
 * Passed to `POST /api/categories`. The slug must be free within its kind, and
 * a dump category's not reserved by a route.
 */
export interface CreateCategoryRequest {
  kind: CategoryKind;
  slug: string;
  name: string;
  /** 0 when left out. */
  position?: number;
}

/**
 * Passed to `PUT /api/categories/:id`. A field left out keeps its value, and
 * the kind is kept.
 */
export interface UpdateCategoryRequest {
  slug?: string;
  name?: string;
  position?: number;
}