quetre/fetchers/answersFetcher.js

/* eslint-disable no-useless-catch */
////////////////////////////////////////////////////////
//                      IMPORTS
////////////////////////////////////////////////////////
import * as cheerio from 'cheerio';
import getAxiosInstance from '../utils/getAxiosInstance.js';
import AppError from '../utils/AppError.js';

////////////////////////////////////////////////////////
//                     FUNCTION
////////////////////////////////////////////////////////
/**
 * makes a call to quora.com(with the resourceStr appended) and returns parsed JSON containing the data about the resource requested.
 * @param {string} resourceStr a string after the baseURL
 * @param {string} lang additional options
 * @returns JSON containing the result
 */
const answersFetcher = async (resourceStr, lang) => {
  try {
    const axiosInstance = getAxiosInstance(lang);
    const res = await axiosInstance.get(encodeURIComponent(resourceStr));
    const $ = cheerio.load(res.data);

    const rawData = { question: null, answers: [], related: [], answerCount: 0 };

    // there are about 9-10 script tags containing data we need
    $('body script').each((i, el) => {
      const text = $(el).html();
      const matches = text.match(/\.push\((".*")\);/); // data is contained like: someProp.push("<data>");

      if (!matches) return;

      // brittle logic, but works
      const matchedPart = JSON.parse(JSON.parse(matches[1])).data;

      // only question block has this word
      if (typeof matchedPart.question?.viewerHasAnswered !== 'undefined') {
        rawData.question = matchedPart.question;

        // primary answer block
      } else if (matchedPart.question?.answers?.edges?.[0].node.answer?.content) {
        rawData.answers.push(matchedPart.question.answers.edges[0].node.answer);

        // other answer blocks
      } else if (
        // eslint-disable-next-line no-underscore-dangle
        matchedPart.node?.__typename === 'QuestionAnswerItem2'
      ) {
        rawData.answers.push(matchedPart.node.answer);

        // related questions block contains both answer count and related questions
      } else if (matchedPart.bottomRelatedQuestionsInfo) {
        rawData.related = matchedPart.bottomRelatedQuestionsInfo.relatedQuestions;
        rawData.answerCount = matchedPart.answerCount;
      }
    });

    if (!rawData.question) throw new AppError("couldn't retrieve data", 500);

    return rawData;
  } catch (err) {
    const statusCode = err.response?.status;
    if (statusCode === 404) throw new AppError('Not found', 404);
    else if (statusCode === 429 || statusCode === 403)
      throw new AppError(
        'Quora is rate limiting this instance. Try another or host your own.',
        503
      );
    else throw err;
  }
};

////////////////////////////////////////////////////////
//                     EXPORTS
////////////////////////////////////////////////////////
export default answersFetcher;