/*!
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */

const headerIds = new Map<string, number>();

export const getHeaderId = (heading: string): string => {
  const numberOfHeaderOccurrencesInTheDocument = headerIds.get(heading) ?? 0;
  headerIds.set(heading, numberOfHeaderOccurrencesInTheDocument + 1);

  // extract the extended markdown heading id
  // ex:  ## MyHeading {# myId}
  const match = heading.match(/{#([\w-]+)}/);

  let extractedId: string;
  if (match) {
    extractedId = match[1];
  } else {
    extractedId = heading
      .toLowerCase()
      .replace(/<code>(.*?)<\/code>/g, '$1') // remove <code>
      .replace(/<strong>(.*?)<\/strong>/g, '$1') // remove <strong>
      .replace(/<em>(.*?)<\/em>/g, '$1') // remove <em>
      .replace(/\s|\//g, '-') // remove spaces and slashes
      .replace(/gt;|lt;/g, '') // remove escaped < and >
      .replace(/&#\d+;/g, '') // remove HTML entities
      .replace(/[^\p{L}\d\-]/gu, ''); // only keep letters, digits & dashes
  }

  const headerId = numberOfHeaderOccurrencesInTheDocument
    ? `${extractedId}-${numberOfHeaderOccurrencesInTheDocument}`
    : extractedId;

  return headerId;
};

export const resetHeaderIdsOfCurrentDocument = (): void => {
  headerIds.clear();
};