const { xml2json, json2xml } = require('xml-js');
const { readFileSync, writeFileSync } = require('fs');

const postIds = require('./postIds').map(id => Number(id));
const xml = JSON.parse(xml2json(readFileSync('./export.xml')));

const comments = xml.elements.filter(element => element.type === 'comment');
const rss = xml.elements.find(element => element.name === 'rss');
const channel = rss.elements.find(element => element.name === 'channel');
const nonItems = channel.elements.filter(element => element.name !== 'item');

const matchingItems = channel.elements.filter(element => {
  return element.name === 'item' && element.elements.some(element => {
    return element.elements && element.elements.some(element => {
      return postIds.includes(Number(element.text));
    });
  });
});

const matched = {
  ...xml,
  elements: [
    ...comments,
    {
      ...rss,
      elements: [
        {
          ...channel,
          elements: [
            ...nonItems,
            ...matchingItems
          ]
        }
      ]
    }
  ]
}

writeFileSync('./matched.xml', json2xml(matched, { spaces: 2 }));