import { Node } from 'prosemirror-model';

/**
 * The distinct user ids mentioned in a document (issue #150) — the input for
 * the derived `page_mentions` rows and the mention notifications (#151).
 * Mentions without a resolved user id (e.g. from a Markdown import) are
 * purely visual and excluded.
 */
export function extractMentionUserIds(doc: Node): string[] {
  const ids = new Set<string>();
  doc.descendants((node) => {
    if (node.type.name === 'mention') {
      const userId = node.attrs.userId as string;
      if (userId) ids.add(userId);
    }
  });
  return [...ids];
}