/**
 * Notifications tell a user when someone follows them or their playlists,
 * upvotes, comments, likes or mentions them, or posts where they follow. This
 * module types the ones `api/services/notification-service.ts` makes, and the
 * data each kind carries. The client's `/notifications` page lists them and
 * turns each into a sentence and a link.
 *
 * @module
 */

/**
 * Says which of the `…Data` interfaces a notification's `data` is. Each value
 * has one `notify…` trigger in `notification-service.ts`.
 */
export type NotificationType =
  | "playlist_followed"
  | "user_followed"
  | "user_dump_posted"
  | "playlist_dump_added"
  | "dump_upvoted"
  | "user_mentioned"
  | "dump_commented"
  | "comment_liked";

/**
 * Carried by a `playlist_followed` notification, sent to a playlist's owner.
 */
export interface PlaylistFollowedData {
  followerId: string;
  followerUsername: string;
  playlistId: string;
  playlistTitle: string;
}

/** Carried by a `user_followed` notification, sent to the user followed. */
export interface UserFollowedData {
  followerId: string;
  followerUsername: string;
}

/**
 * Carried by a `user_dump_posted` notification, sent to the followers of a
 * user who posted a public dump.
 */
export interface UserDumpPostedData {
  dumperId: string;
  dumperUsername: string;
  dumpId: string;
  dumpTitle: string;
}

/**
 * Carried by a `playlist_dump_added` notification, sent to the followers of a
 * public playlist when a public dump is added to it.
 */
export interface PlaylistDumpAddedData {
  dumpId: string;
  dumpTitle: string;
  playlistId: string;
  playlistTitle: string;
}

/** Carried by a `dump_upvoted` notification, sent to the dump's poster. */
export interface DumpUpvotedData {
  voterId: string;
  voterUsername: string;
  dumpId: string;
  dumpTitle: string;
}

/**
 * Carried by a `user_mentioned` notification, sent to a user @mentioned in a
 * comment, a dump, a playlist's description or a chat message.
 */
export interface UserMentionedData {
  mentionerId: string;
  mentionerUsername: string;
  contextType: "comment" | "dump" | "playlist" | "chat";
  /** The id of the comment, dump, playlist or chat message. */
  contextId: string;
  /**
   * The title of the dump or playlist, or of the dump a comment is under;
   * empty for the chat.
   */
  contextTitle: string;
  /**
   * Set only for a comment. It names the dump the comment is under, which the
   * notification's link opens.
   */
  dumpId?: string;
}

/** Carried by a `dump_commented` notification, sent to the dump's poster. */
export interface DumpCommentedData {
  commenterId: string;
  commenterUsername: string;
  commentId: string;
  dumpId: string;
  dumpTitle: string;
}

/** Carried by a `comment_liked` notification, sent to the comment's author. */
export interface CommentLikedData {
  likerId: string;
  likerUsername: string;
  commentId: string;
  dumpId: string;
  dumpTitle: string;
}

/**
 * A snapshot taken when the notification is made: a name or title changed
 * later still shows the old one. The notification's `type` says which member
 * it is.
 */
export type NotificationData =
  | PlaylistFollowedData
  | UserFollowedData
  | UserDumpPostedData
  | PlaylistDumpAddedData
  | DumpUpvotedData
  | UserMentionedData
  | DumpCommentedData
  | CommentLikedData;

/**
 * Pushed to its user's sockets in a `notification_created` message when it is
 * made, and returned by `GET /api/notifications`.
 */
export interface Notification {
  id: string;
  userId: string;
  type: NotificationType;
  data: NotificationData;
  read: boolean;
  createdAt: Date;
}