.eleventy.js

const { DateTime } = require("luxon");
const pluginRss = require("@11ty/eleventy-plugin-rss");
const pluginSyntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
const pluginNavigation = require("@11ty/eleventy-navigation");
const pluginSEO = require('eleventy-plugin-seo');
const markdownIt = require("markdown-it");
const markdownItAnchor = require("markdown-it-anchor");
const lodash = require('lodash');

module.exports = function(eleventyConfig) {
  let markdownLibrary = markdownIt({
    html: true,
    breaks: true,
    linkify: true
  }).use(markdownItAnchor, {
    permalink: true,
    permalinkClass: "direct-link",
    permalinkSymbol: "#"
  });

  eleventyConfig.addPlugin(pluginRss);
  eleventyConfig.addPlugin(pluginSyntaxHighlight);
  eleventyConfig.addPlugin(pluginNavigation);
  eleventyConfig.addPlugin(pluginSEO);
  
  eleventyConfig.addShortcode('removeTrailingSlash', string => string.replace(/\/$/, ''));

  eleventyConfig.setDataDeepMerge(true);

  eleventyConfig.addLayoutAlias("replace", "replace.html");
  eleventyConfig.addLayoutAlias("base", "base.html");

  eleventyConfig.addFilter("readableDate", dateObj => {
    return DateTime.fromJSDate(dateObj, {zone: 'utc'}).toFormat("dd LLL yyyy");
  });

  eleventyConfig.addCollection('replace', (collectionAPI) => 
    collectionAPI.getFilteredByGlob('./replace/*.md')
  );

  // https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-date-string
  eleventyConfig.addFilter('htmlDateString', (dateObj) => {
    return DateTime.fromJSDate(dateObj, {zone: 'utc'}).toFormat('yyyy-LL-dd');
  });

  eleventyConfig.addPairedShortcode('infobox', content => 
    `<div class="info-box">${markdownLibrary.render(content)}</div>`
  );

  eleventyConfig.addShortcode('get', function (object, path) {
    return lodash.get(object, path);
  });

  eleventyConfig.addShortcode('env', function () {
    return process.env.NODE_ENV || 'development';
  });

  eleventyConfig.addPairedShortcode('takeaway', content => 
      `<div class="take-away">${content}</div>`
  );

  eleventyConfig.addPairedShortcode('centertext', content => 
    `<div class="centered-text">${content}</div>`
  );

//   eleventyConfig.addShortcode('isDefined', function ())

  // Get the first `n` elements of a collection.
  eleventyConfig.addFilter("head", (array, n) => {
    if( n < 0 ) {
      return array.slice(n);
    }

    return array.slice(0, n);
  });

//   eleventyConfig.addCollection("tagList", require("./_11ty/getTagList"));

  eleventyConfig.addPassthroughCopy("img");
  eleventyConfig.addPassthroughCopy("styling");
  eleventyConfig.addPassthroughCopy("assets");

  /* Markdown Overrides */
  eleventyConfig.setLibrary("md", markdownLibrary);

  // Browsersync Overrides
  eleventyConfig.setBrowserSyncConfig({
    callbacks: {
      ready: function(err, browserSync) {
        // const content_404 = fs.readFileSync('_site/404.html');

        // browserSync.addMiddleware("*", (req, res) => {
        //   // Provides the 404 content without redirect.
        //   res.write(content_404);
        //   res.end();
        // });
      },
    },
    ui: false,
    ghostMode: false
  });

  return {
    templateFormats: [
      "md",
      "html",
      "liquid",
      "pug",
      "njk"
    ],

    // If your site lives in a different subdirectory, change this.
    // Leading or trailing slashes are all normalized away, so don’t worry about those.

    // If you don’t have a subdirectory, use "" or "/" (they do the same thing)
    // This is only used for link URLs (it does not affect your file structure)
    // Best paired with the `url` filter: https://www.11ty.io/docs/filters/url/

    // You can also pass this in on the command line using `--pathprefix`
    // pathPrefix: "/",

    markdownTemplateEngine: "liquid",
    htmlTemplateEngine: "liquid",
    dataTemplateEngine: "liquid",

    // These are all optional, defaults are shown:
    dir: {
      input: "./",
      includes: "_includes/",
      layouts: "_includes/layouts/",
      data: "_data",
      output: "_site"
    }
  };
};