#bluebird #promise #parser

parser.js

const cheerio = require("cheerio")
const Promise = require("bluebird")
const request = Promise.promisify(require("request"))
const csvStringify = require('csv-stringify')
const fs = require('fs')

const URL = 'https://dou.ua/forums'
request(URL)
	.then(topics)
	.mapSeries(topic => request(topic.url).then(res => topicContents(res, topic)))
	.then(data => data.map(item => Object.values(item)))
	.then(writeFileCsv)
	.catch(err => {
		console.log("Error", err)
	})

function topics(res) {
	const $ = cheerio.load(res.body);
	return $("div.b-forum-articles article > h2 > a:first-child")
		.map((i, link) => ({
			title: link.attribs.title,
			url: link.attribs.href,
			commentsCount: 0
		}))
		.toArray()
}

function topicContents(res, topic) {
	const $ = cheerio.load(res.body)
	const commentsCount = parseInt($('#lblCommentsCount').text())
	topic.commentsCount = Number.isNaN(commentsCount) ? 0 : commentsCount
	return topic
}

function writeFileCsv(data) {
	csvStringify(data, {
			delimiter: ';',
			header: true,
			formatters: {
				date: it => moment(it).format('YYYY-MM-DD'),
				bool: it => it ? 'X' : '',
			},
		},
		(err, output) => {
			fs.writeFileSync(getNameFile('./tmp/some-parse'), output, err => {
				if (err) {
					console.log('Some error occurred - file either not saved or corrupted file saved.', err)
				} else {
					console.log('It\'s saved!')
				}
			})
		}
	)
}

function getNameFile(prefix) {
	return [
		prefix,
		new Date().getFullYear(),
		new Date().getMonth() + 1,
		new Date().getDate(),
		new Date().getHours(),
	].join('-') + '.csv'
}