const path = require("path");
const glob = require("glob");
const fs = require("fs");
const axios = require("axios");

// If you use Dotenv you can include your .env variables uncommenting the following line
// require("dotenv").config();

// Make sure any symlinks in the project folder are resolved:
// https://github.com/facebookincubator/create-react-app/issues/637
const appDirectory = fs.realpathSync(process.cwd());
const resolveApp = relativePath => path.resolve(appDirectory, relativePath);

// SITE_ROOT is the domain of your app
// Update example.com with your domain or set the env variable
const SITE_ROOT = process.env.SITE_ROOT || "https://example.com";

// SOURCE is where are stored all pages files
// By default it tracks all files in the pages folder
// without considering the ones starting with `_` (e.g. _document.js and _app.js)
const SOURCE =
  process.env.SOURCE || path.join(resolveApp("pages"), "/**/!(_*).js");

// API_SOURCE is the endpoint of you api
// Update example.com/api with your endpoint or set the env variable
const API_SOURCE = process.env.API_SOURCE || "https://example.com/api";

// DESTINATION is where the real file is exported
// By default is .next/static/sitemap.xml
const DESTINATION =
  process.env.DESTINATION ||
  path.join(resolveApp(".next/static"), "sitemap.xml");


const createSitemap = () => {
  
  /**
   * STEP 1: Store all static pages url
   **/
  let diskPages = glob.sync(SOURCE);
  let xml = "";
  xml += '<?xml version="1.0" encoding="UTF-8"?>';
  xml += '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">';

  diskPages.forEach(page => {
    let stats = fs.statSync(page);
    let modDate = new Date(stats.mtime);
    let lastMod = `${modDate.getFullYear()}-${(
      "0" +
      (modDate.getMonth() + 1)
    ).slice(-2)}-${("0" + modDate.getDate()).slice(-2)}`;

    page = page.replace(resolveApp("pages"), "");
    page = page.replace(/.js$/, "");
    page = `${SITE_ROOT}${page}`;

    if (page.match(/.*\/index$/)) {
      page = page.replace(/(.*)index$/, "$1");
    }

    xml += "<url>";
    xml += `<loc>${page}</loc>`;
    xml += `<lastmod>${lastMod}</lastmod>`;
    xml += `<changefreq>always</changefreq>`;
    xml += `<priority>0.5</priority>`;
    xml += "</url>";
  });
  
  /**
   * STEP 2: Store all dynamic pages url
   * In the following snippet we gather all products available
   * TODO: Add <lastmod>${lastMod}</lastmod> tag and set priority order
   **/
  return axios
    .post(API_SOURCE, {
      query: `{
        productList: {
          product: {
            slug
          }
        } 
      }`
    })
    .then(resp => {
      let { productList } = resp.data;
      productList.forEach((product, index) => {
        xml += "<url><loc>";
        xml += `${SITE_ROOT}/products/${product.slug}`;
        xml +=
          "</loc><changefreq>always</changefreq><priority>0.5</priority></url>";
        if (index === productList.length - 1) {
          xml += "</urlset>";
        }
      });
      return xml;
    })
    .catch(error => {
      console.log(error.message, error.name);
    });
};

module.exports = { DESTINATION, createSitemap };