text: /**
   * Copyright 2019 Google LLC
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  const through = require('through2');
  const path = require('path');
  const PluginError = require('plugin-error');
  const Vinyl = require('vinyl');
  const lunr = require('lunr');
  const s = require('string');
  const fm = require('front-matter');
  const { getSection, getUrlFromPath } = require('../helpers/url');
  
  module.exports = function(options) {
    const buffer = [];
    let firstFile;
    const locale = options.locale;
  
    // Lunr and through require use of `this`, so need to disable linting for these items.
    /* eslint-disable no-invalid-this */
  
    return through.obj(
      function(file, enc, cb) {
        let pageIndex;
  
        if (file.isStream()) {
          this.emit('error', new PluginError('lunr-index', 'Streaming not supported'));
          return cb();
        }
  
        if (file.path.includes('style-guide')) {
          return cb();
        }
  
        if (!firstFile) {
          firstFile = file;
        }
  
        try {
          const { attributes, body } = fm(file.contents.toString());
  
          pageIndex = {
            title: attributes.title,
            tags: attributes.tags,
            metadesc: attributes.metadesc,
            href: getUrlFromPath(file.path),
            section: getSection(getUrlFromPath(file.path)),
            content: s(body)
              .stripTags()
              .stripPunctuation().s,
          };
        } catch (err) {
          this.emit('error', new PluginError('lunr-index', err));
          return cb();
        }
        if (pageIndex) {
          buffer.push(pageIndex);
        }
        cb();
      },
      function(cb) {
        if (!firstFile) {
          return cb();
        }
  
        const idx = lunr(function() {
          this.ref('href');
          this.field('title');
          this.field('content');
          this.field('tags');
  
          buffer.forEach(function(doc) {
            this.add(doc);
          }, this);
        });
  
        const previews = {};
        buffer.forEach(function(doc) {
          previews[doc.href] = {
            title: doc.title,
            tags: doc.tags,
            metadesc: doc.metadesc,
            section: doc.section,
            href: doc.href,
          };
        });
  
        const indexFile = new Vinyl({
          base: firstFile.base,
          cwd: firstFile.cwd,
          path: path.join(firstFile.base, `index-${locale}.json`),
          /* eslint new-cap: [1, {"newIsCapExceptions": ["Buffer.from"]}]*/
          contents: new Buffer.from(JSON.stringify(idx)),
        });
        const previewsFile = new Vinyl({
          base: firstFile.base,
          cwd: firstFile.cwd,
          path: path.join(firstFile.base, `preview-${locale}.json`),
          /* eslint new-cap: [1, {"newIsCapExceptions": ["Buffer.from"]}]*/
          contents: new Buffer.from(JSON.stringify(previews)),
        });
        this.push(previewsFile);
        this.push(indexFile);
        cb();
      },
    );
  };
  