slugger.mjs

'use strict';

import { DEPRECATION_HEADING_REGEX } from '../constants.mjs';

/**
 * Creates a stateful slugger for legacy anchor links.
 *
 * Generates underscore-separated slugs in the form `{apiStem}_{text}`,
 * appending `_{n}` for duplicates to preserve historical anchor compatibility.
 *
 * Headings matching the `DEP####:` pattern return just the deprecation code
 * (e.g., `DEP0001`) as the anchor, matching the behavior of the old tooling
 * and preserving existing external links.
 *
 * @returns {(text: string, apiStem: string) => string}
 */
export const createLegacySlugger =
  (counters = {}) =>
  (text, apiStem) => {
    const depMatch = DEPRECATION_HEADING_REGEX.exec(text);

    if (depMatch) {
      return depMatch[1];
    }

    const id = `${apiStem}_${text}`
      .toLowerCase()
      .replace(/^[^a-z0-9]+|[^a-z0-9]+$/g, '')
      .replace(/[^a-z0-9]+/g, '_')
      .replace(/^\d/, '_$&');

    counters[id] ??= -1;
    const count = ++counters[id];
    return count > 0 ? `${id}_${count}` : id;
  };