import { Node } from 'prosemirror-model';

/**
 * The distinct target slugs of every `[[wikilink]]` and every `![[embed]]`
 * (transclusion, issue #135) in a document (issue #47). Used server-side to
 * maintain the `page_links` index on every content change, so backlinks and
 * phantom (missing-target) links can be queried — an embed is semantically a
 * reference, so it registers as a link too. Order of first appearance is
 * preserved; duplicates are collapsed.
 */
export function extractWikilinkSlugs(doc: Node): string[] {
  const slugs: string[] = [];
  const seen = new Set<string>();
  doc.descendants((node) => {
    if (node.type.name === 'wikilink' || node.type.name === 'transclusion') {
      const slug = node.attrs.targetSlug as string;
      if (slug && !seen.has(slug)) {
        seen.add(slug);
        slugs.push(slug);
      }
    }
  });
  return slugs;
}