/**
 * A dump is what users post: a link or a file, with a title and a note. This
 * module types it as the API sends it, with its link preview and the bodies
 * that create and edit it. The backend's `dump-service.ts` produces these types
 * and the frontend's dump pages and create form consume them.
 *
 * @module
 */

/**
 * Names the kind of link a {@link RichContent} previews: a site the player
 * plays its own way, or `generic` for any other page, this site's included.
 */
export type RichContentType = "youtube" | "bandcamp" | "soundcloud" | "generic";

/**
 * Built by a provider of `rich-content-service.ts` when a link is posted or
 * previewed, and stored with the dump as JSON. The frontend's
 * `RichContentCard` and player read it.
 */
export interface RichContent {
  /** The player picks how to play the link by it. */
  type: RichContentType;
  url: string;
  siteName?: string;
  title?: string;
  description?: string;
  /**
   * A real preview image (og:image, a large content image, a video still).
   * Never a favicon — an absent value means "this page offers no artwork",
   * which is what makes the generated placeholder possible.
   */
  thumbnailUrl?: string;
  /** Used as the placeholder's glyph. */
  faviconUrl?: string;
  /** The page's declared brand color, normalized to `#rrggbb`. */
  accentColor?: string;
  /**
   * The player a YouTube, Bandcamp or SoundCloud link plays in, framed by the
   * frontend.
   */
  embedUrl?: string;
}

/**
 * Returned by every endpoint that answers dumps, and pushed to clients by the
 * `dump_created` and `dump_updated` socket messages. A URL dump has `url` and
 * `richContent`, a file dump the `file…` fields. A private dump reaches its
 * poster only.
 */
export interface Dump {
  id: string;
  kind: "url" | "file";
  title: string;
  /**
   * Names the dump in its page's path, `dumpPath` (`shared/paths.ts`) building
   * it with {@link ownerUsername}. Made from the title on creation, it changes
   * only when edited, and is unique among its poster's dumps.
   */
  slug: string;
  /** The poster's note on the dump, in Markdown. */
  comment?: string;
  userId: string;
  /** The poster's current name, which the dump's path starts with. */
  ownerUsername: string;
  createdAt: Date;
  updatedAt?: Date;
  url?: string;
  richContent?: RichContent;
  fileName?: string;
  fileMime?: string;
  fileSize?: number;
  voteCount: number;
  /** Deleted comments are not counted. */
  commentCount: number;
  isPrivate: boolean;
  /** Set when the poster uploaded a custom thumbnail. */
  thumbnailMime?: string;
  categoryIds?: string[];
}

/**
 * Returned by `GET /api/dumps?url=` for each dump already posted with the
 * link being typed, and shown by the create form's `DuplicateNotice`. It holds
 * only what the notice displays and links to.
 */
export interface DumpUrlMatch {
  id: string;
  slug: string;
  title: string;
  /** The poster's username. */
  ownerUsername: string;
  createdAt: Date;
  voteCount: number;
  commentCount: number;
}

/**
 * Returned by `GET /api/remote/preview` to the create form, which shows it before the
 * link is posted.
 */
export interface LinkPreview {
  /**
   * False when the page couldn't be fetched. `richContent` is then a stub
   * holding the host name, and this flag is how the form tells a dead link
   * from a page with no preview.
   */
  reached: boolean;
  /**
   * Null only for a link that doesn't parse, which the route rejects before
   * fetching anyway.
   */
  richContent: RichContent | null;
}

/**
 * Passed by the create form to `POST /api/dumps` as a JSON body, to post a
 * link. A file is posted as a multipart form instead.
 */
export interface CreateUrlDumpRequest {
  url: string;
  /** Replaces the title read from the page, when the poster edited it. */
  title?: string;
  comment?: string;
  isPrivate?: boolean;
  categoryIds?: string[];
}

/**
 * Passed to `PUT /api/dumps/:dumpId` by the edit page, and by the dump page's
 * inline title edit. A field left out stays as it is.
 */
export interface UpdateDumpRequest {
  /** Ignored for a file dump. A changed link has its preview fetched again. */
  url?: string;
  title?: string;
  /**
   * A new slug, which the edit page's slug field sends. A title change never
   * changes the slug by itself.
   */
  slug?: string;
  /** `null` removes the note. */
  comment?: string | null;
  isPrivate?: boolean;
  /** Replaces the current categories. */
  categoryIds?: string[];
}

/**
 * Returns a file dump's version, which the file and thumbnail URLs carry as
 * `?v=`: the frontend's `dumpFileUrl` and `dumpThumbnailUrl`, and the digest's
 * thumbnails. It changes whenever the file may have, so the file and thumbnail
 * routes cache a URL naming the current one for good and revalidate any other.
 * Without its dates, a dump gets a version no route serves as current.
 */
export function dumpFileVersion(
  dump: { fileSize?: number; createdAt?: Date; updatedAt?: Date },
): string {
  const at = dump.updatedAt ?? dump.createdAt;
  return `${dump.fileSize ?? 0}-${at ? at.getTime() : 0}`;
}