library-api.ts

import { APIGatewayProxyHandler } from 'aws-lambda';
import 'source-map-support/register';
import axios from 'axios';
import * as cheerio from 'cheerio';
import LIBRARY_SEARCH_URL from './endpoint';

const SELECTORS = {
  RESULT_ENTRIES: '.results_cell',
  TITLE_LINK: '.displayDetailLink',
  THUMBNAIL: '.thumbnail img',
  AUTHOR_NAME: '.INITIAL_AUTHOR_SRCH'
}

function queryLibrary(queryStr) {
  const url = new URL(LIBRARY_SEARCH_URL);
  url.search = `qu=${queryStr.replace(' ', '+')}`;
  return axios.get(url.href);
}

function extractEntries(html) {
  const $ = cheerio.load(html);
  const results = $(SELECTORS.RESULT_ENTRIES);
  const entries = [];
  results.each((_, elem) => {
    const rawThumbnailSrc = $(SELECTORS.THUMBNAIL, elem).attr('src');
    const thumbnailSrc = rawThumbnailSrc.match('no_image.png') ? '' : rawThumbnailSrc;
    const authorText = $(SELECTORS.AUTHOR_NAME, elem).text();
    const authorName = authorText.replace('by', '').trim();
    const result = {
      title: $(SELECTORS.TITLE_LINK, elem).text(),
      thumbnail: thumbnailSrc,
      author: authorName
    };
    entries.push(result);
  });
  return entries;
}

export const query: APIGatewayProxyHandler = async (event, _context) => {
  if (!event.queryStringParameters || !event.queryStringParameters.q) {
    return {
      statusCode: 400,
      body: JSON.stringify({
        message: 'No query provided'
      }),
    };
  }

  const res = await queryLibrary(event.queryStringParameters.q);
  const resHTML = res.data;
  const entries = extractEntries(resHTML);

  return {
    statusCode: 200,
    body: JSON.stringify({
      entries
    })
  };
}