text: const { DateTime } = require("luxon");
  const fs = require("fs");
  const pluginRss = require("@11ty/eleventy-plugin-rss");
  const pluginSyntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
  const pluginNavigation = require("@11ty/eleventy-navigation");
  const markdownIt = require("markdown-it");
  const markdownItAnchor = require("markdown-it-anchor");
  const embeds = require("eleventy-plugin-embed-everything");
  const readingTime = require("eleventy-plugin-reading-time");
  const lazyImagesPlugin = require("eleventy-plugin-lazyimages");
  const typesetPlugin = require("eleventy-plugin-typeset");
  const footnotes = require("eleventy-plugin-footnotes");
  
  module.exports = function (eleventyConfig) {
    // Add plugins
    eleventyConfig.addPlugin(pluginRss);
    eleventyConfig.addPlugin(pluginSyntaxHighlight);
    eleventyConfig.addPlugin(pluginNavigation);
    eleventyConfig.addPlugin(embeds, {
      twitter: {
        options: {
          theme: "dark",
        }
      }
    });
    eleventyConfig.addPlugin(readingTime);
    eleventyConfig.addPlugin(lazyImagesPlugin);
    eleventyConfig.addPlugin(typesetPlugin());
    eleventyConfig.addPlugin(footnotes, { title: "feet notes" });
  
    // https://www.11ty.dev/docs/data-deep-merge/
    eleventyConfig.setDataDeepMerge(true);
  
    // Alias `layout: post` to `layout: layouts/post.njk`
    eleventyConfig.addLayoutAlias("post", "layouts/post.njk");
  
    eleventyConfig.addFilter("readableDate", (dateObj) => {
      return DateTime.fromJSDate(dateObj, { zone: "utc" }).toFormat(
        "dd LLL yyyy"
      );
    });
  
    // 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");
    });
  
    // Get the first `n` elements of a collection.
    eleventyConfig.addFilter("head", (array, n) => {
      if (!Array.isArray(array) || array.length === 0) {
        return [];
      }
      if (n < 0) {
        return array.slice(n);
      }
  
      return array.slice(0, n);
    });
  
    // Return the smallest number argument
    eleventyConfig.addFilter("min", (...numbers) => {
      return Math.min.apply(null, numbers);
    });
  
    function filterTagList(tags) {
      return (tags || []).filter(
        (tag) => ["all", "nav", "post", "posts"].indexOf(tag) === -1
      );
    }
  
    eleventyConfig.addFilter("filterTagList", filterTagList);
  
    // markdown-it powers
    eleventyConfig.addFilter("markdownify", (markdown) => {
      const md = markdownIt({
        html: true,
        breaks: true,
        linkify: true,
      }).use(markdownItAnchor, {
        permalink: true,
        permalinkClass: "direct-link",
        permalinkSymbol: "#",
      });
  
      return md.render(markdown);
    });
  
    // Split URL into paths and add <a>s
    eleventyConfig.addFilter("addLinks", (url) => {
      let paths = url.split("/");
      let links = [];
      for (let i = 0; i < paths.length; i++) {
        let path = paths.slice(0, i + 1).join("/");
        links.push(`<a href="${path}">${paths[i]}</a>`);
      }
      console.log(links.join(" / "));
      return links.join(" / ");
    });
  
    // Create an array of all tags
    eleventyConfig.addCollection("tagList", function (collection) {
      let tagSet = new Set();
      collection.getAll().forEach((item) => {
        (item.data.tags || []).forEach((tag) => tagSet.add(tag));
      });
  
      return filterTagList([...tagSet]);
    });
  
    // Copy the `img` and `css` folders to the output
    eleventyConfig.addPassthroughCopy("img");
    eleventyConfig.addPassthroughCopy("css");
  
    // Customize Markdown library and settings:
    let markdownLibrary = markdownIt({
      html: true,
      breaks: true,
      linkify: true,
    }).use(markdownItAnchor, {
      permalink: markdownItAnchor.permalink.ariaHidden({
        placement: "after",
        class: "direct-link",
        symbol: "#",
        level: [1, 2, 3, 4],
      }),
      slugify: eleventyConfig.getFilter("slug"),
    });
    eleventyConfig.setLibrary("md", markdownLibrary);
  
    // Override Browsersync defaults (used only with --serve)
    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.writeHead(404, { "Content-Type": "text/html; charset=UTF-8" });
            res.write(content_404);
            res.end();
          });
        },
      },
      ui: false,
      ghostMode: false,
    });
  
    eleventyConfig.addPassthroughCopy("./_redirects");
  
    return {
      // Control which files Eleventy will process
      // e.g.: *.md, *.njk, *.html, *.liquid
      templateFormats: ["md", "njk", "html", "liquid"],
  
      // -----------------------------------------------------------------
      // If your site deploys to a subdirectory, change `pathPrefix`.
      // Don’t worry about leading and trailing slashes, we normalize these.
  
      // 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.dev/docs/filters/url/
  
      // You can also pass this in on the command line using `--pathprefix`
  
      // Optional (default is shown)
      pathPrefix: "/",
      // -----------------------------------------------------------------
  
      // Pre-process *.md files with: (default: `liquid`)
      markdownTemplateEngine: "njk",
  
      // Pre-process *.html files with: (default: `liquid`)
      htmlTemplateEngine: "njk",
  
      // Opt-out of pre-processing global data JSON files: (default: `liquid`)
      dataTemplateEngine: false,
  
      // These are all optional (defaults are shown):
      dir: {
        input: ".",
        includes: "_includes",
        data: "_data",
        output: "_site",
      },
      passthroughFileCopy: true,
    };
  };
  