text: /**
   * Copyright (c) Facebook, Inc. and its affiliates.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   */
  
  const toString = require('mdast-util-to-string');
  const visit = require('unist-util-visit');
  const escapeHtml = require('escape-html');
  
  // https://github.com/syntax-tree/mdast#heading
  function toValue(node) {
    if (node && node.type) {
      switch (node.type) {
        case 'text':
          return escapeHtml(node.value);
        case 'heading':
          return node.children.map(toValue).join('');
        case 'inlineCode':
          return `<code>${escapeHtml(node.value)}</code>`;
        case 'emphasis':
          return `<em>${node.children.map(toValue).join('')}</em>`;
        case 'strong':
          return `<strong>${node.children.map(toValue).join('')}</strong>`;
        case 'delete':
          return `<del>${node.children.map(toValue).join('')}</del>`;
        default:
      }
    }
  
    return toString(node);
  }
  
  // Visit all headings. We `slug` all headings (to account for
  // duplicates), but only take h2 and h3 headings.
  function search(node) {
    const headings = [];
    let current = -1;
    let currentDepth = 0;
  
    const onHeading = (child, index, parent) => {
      const value = toString(child);
  
      if (parent !== node || !value || child.depth > 3 || child.depth < 2) {
        return;
      }
  
      const entry = {
        value: toValue(child),
        id: child.data.id,
        children: [],
      };
  
      if (!headings.length || currentDepth >= child.depth) {
        headings.push(entry);
        current += 1;
        currentDepth = child.depth;
      } else {
        headings[current].children.push(entry);
      }
    };
  
    visit(node, 'heading', onHeading);
  
    return headings;
  }
  
  module.exports = search;
  