"use strict";

const https = require('https');
const Sitemapper = require('sitemapper');
const jsdom = require('jsdom');
const fs = require('fs');

const { JSDOM } = jsdom;

if (!process.argv[2]) {
    console.error('No path to sitemap given');
}

const sitemapUrl = process.argv[2];
const elementSelector = process.argv[3] || 'body';
const removeMultipleNewlines = process.argv[4] || false;

const get = async (url) => {
    console.log('Fetching html from webpage ('+url+')');
    return new Promise((resolve, reject) => {
        https.get(url, res => {
            res.setEncoding('utf8');
            let response = '';
            res.on('data', data => { response += data; });
            res.on('end', () => { resolve(response); });
        }).on('error', error => reject(error));
    });
};

const getUrlsFromSitemap = async (sitemapUrl) => {
    const sitemap = new Sitemapper();
    return await sitemap.fetch(sitemapUrl);
};

const scrapeUrl = async (url) => {
    console.log('Scraping webpage');
    const html = await get(url);

    return getTextFromHtml(html);
};

const getTextFromHtmlNode = (htmlNode) => {

    if (
        htmlNode.tagName === 'STYLE' ||
        htmlNode.tagName === 'style' ||
        htmlNode.nodeType === 8
    ) {
        return '';
    }

    if (htmlNode.tagName === 'BR') {
        return "\n";
    }

    if (htmlNode.nodeType === 3) {
        return htmlNode.textContent.trim();
    }

    let output = '';
    for (let i = 0; i < htmlNode.childNodes.length; i++) {
        output += getTextFromHtmlNode(htmlNode.childNodes[i]);
    }

    if (output) {
        const markdownMap = {
            'H1': '# ',
            'H2': '## ',
            'H3': '### ',
            'H4': '#### ',
            'H5': '#### ',
            'H6': '##### ',
            'LI': '* ',
            'OPTION': '* ',
        };

        if (markdownMap[htmlNode.tagName]) {
            return "\n"+markdownMap[htmlNode.tagName] + output.trim();
        }

        return "\n"+output.trim();
    }

    return '';
};

const getTextFromHtml = (html) => {

    console.log('Getting text from webpage');

    const dom = new JSDOM(html);

    let output = '';
    const containerEl = dom.window.document.querySelector(elementSelector);

    for (let i = 0; i < containerEl.childNodes.length; i++) {
        output += getTextFromHtmlNode(containerEl.childNodes[i]);
    }

    return output;
};

const removeNewlines = (string) => {
    return string.replace(/[\r\n]{2,}/g, "\n");
};

const scrapeUrls = async (urls) => {
    let output = '';
    for (let i = 0; i < urls.length; i++) {
        output += "\n";
        output += '# '+urls[i];
        output += "\n";
        output += await scrapeUrl(urls[i]);
    }
    return output;
};

const writeFile = (filename, content) => {
    console.log('Writing all text to output.txt');
    fs.writeFile(filename, content, (err) => {
        if(err) {
            return console.error(err);
        }
        console.log('The file was saved!');
    });
};

// IIFE
(async function() {
    const urls = await getUrlsFromSitemap(sitemapUrl);

    const content = await scrapeUrls(urls.sites);
    writeFile('output.md', (removeMultipleNewlines ? removeNewlines(content) : content));
})();