Lambda to provide an RSS feed of Exberliner's daily news blog

berlin-daily-news.js

const { parse } = require('node-html-parser');
const { Feed } = require('feed');
const fetch = require('node-fetch');

const BERLIN_DAILY_NEWS_URL = 'https://www.exberliner.com/english-news-berlin/';

const parseHomeHtml = (html) => {
  const root = parse(html);

  const [description, title] = root.querySelector('title').rawText.split(' - ');
  const nodes = root.querySelectorAll('.hero-head__box');
  const articleLinks = nodes.map((node) => node.getAttribute('href'));

  return { title, description, articleLinks };
};

const parseArticleHtml = (html) => {
  const root = parse(html);

  const headerNodes = root.querySelectorAll('.entry-header > h1, .entry-header > div, .entry-header > p');
  const articleHeader = headerNodes.reduce((acc, node) => {
    if (node.rawTagName === 'h1') {
      acc.title = node.rawText;
    }

    if (node.classNames === 'user-actions') {
      const tempDate = node.childNodes[1].innerText.replace(' -', '').replace(' Uhr', '');
      const d = tempDate.match(/(\d\d)\.(\d\d)\.(\d\d\d\d)(.*)/);
      acc.date = new Date(Date.parse(`${d[3]}.${d[2]}.${d[1]}${d[4]}`));
    }

    if (node.rawTagName === 'p' && node.classList.contains('single-excerpt')) {
      acc.headline = `<p>${node.rawText}</p>`;
    }
    return acc;
  }, {});

  const bodyNodes = root.querySelectorAll('.entry-content > figure, .entry-content > p');
  const article = bodyNodes.reduce((acc, node) => {
    if (node.rawTagName === 'p') {
      if (node.childNodes[0] && !node.childNodes[0].rawTagName) {
        if (!Date.parse(node.innerText)) {
          acc.body += node.toString();
        }
      }
    } else if (node.rawTagName === 'figure') {
      acc.image = node.toString().replace(/src=.*data-src\="(.*?)"/, 'src="$1"');
    }
    return acc;
  }, Object.assign(articleHeader, {body: ''}));

  return article;
};

const generateRssFeed = (title, description, link, articles) => {
  const feed = new Feed({
    title,
    description,
    link,
  });

  articles.forEach((article) => {
    feed.addItem({
      title: article.title,
      description: article.headline + article.image + article.body,
      date: article.date,
      link: article.link,
    });
  });

  return feed.rss2();
};

exports.handler = async (_event) => {
  const date = new Date();
  if (date.getHours() < 8 || date.getHours() > 16 || date.getDay() === 0 || date.getDay() === 6) {
    const response = {
      statusCode: 503,
    };
    return response;
  }

  const news = await fetch(BERLIN_DAILY_NEWS_URL);
  const html = await news.text();
  const { title, description, articleLinks } = parseHomeHtml(html);

  const articles = await Promise.all(articleLinks.map(async (link) => {
    const article = await fetch(link);
    const html = await article.text();
    return Object.assign(parseArticleHtml(html), { link });
  }));

  const rss = generateRssFeed(title, description, BERLIN_DAILY_NEWS_URL, articles);

  const response = {
    statusCode: 200,
    body: rss,
  };
  return response;
};