/**
 * The `follows` table: its row type and its guard.
 *
 * @module
 */

import type { SQLOutputValue } from "node:sqlite";

/**
 * A row of the `follows` table: one user following either another user or a
 * playlist.
 */
export interface FollowRow {
  /** The follow's id. */
  id: string;
  /** The id of the user following. */
  follower_id: string;
  /** The id of the user followed, when it is a user. */
  followed_user_id: string | null;
  /** The id of the playlist followed, when it is a playlist. */
  followed_playlist_id: string | null;
  /** When the follow began. */
  created_at: string;
  /** Any other column the query selects. */
  [key: string]: SQLOutputValue;
}

/** Checks whether `obj` is a {@link FollowRow}. */
export function isFollowRow(
  obj: unknown,
): obj is FollowRow {
  return !!obj && typeof obj === "object" &&
    "id" in obj && typeof obj.id === "string" &&
    "follower_id" in obj && typeof obj.follower_id === "string" &&
    "created_at" in obj && typeof obj.created_at === "string" &&
    "followed_user_id" in obj && (obj.followed_user_id === null ||
      typeof obj.followed_user_id === "string") &&
    "followed_playlist_id" in obj && (obj.followed_playlist_id === null ||
      typeof obj.followed_playlist_id === "string");
}