.eleventy.js

module.exports = function(eleventyConfig) {
  eleventyConfig.setUseGitIgnore(false);

  // Date filter
  eleventyConfig.addFilter("date", require("./lib/filters/dates.js") );
  eleventyConfig.addFilter("isoDate", require("./lib/filters/isoDate.js") );

  // Generate assets
  eleventyConfig.addPassthroughCopy({ "src/img": "img" });
  eleventyConfig.addPassthroughCopy({ "src/txt": "txt" });
  eleventyConfig.addPassthroughCopy({ "src/pdf": "pdf" });

  // Smart quotes filter
  const smartypants = require("smartypants");
  eleventyConfig.addFilter("smart", str => smartypants.smartypants(str, 'qDe'));

  // Markdown Plugins
  var uslug = require('uslug');
  var uslugify = s => uslug(s);
  var anchor = require('markdown-it-anchor');
  var markdownIt = require("markdown-it");
  eleventyConfig.setLibrary("md", markdownIt({
    html: true,
    typographer: true
  }).use(anchor, {slugify: uslugify, tabIndex: false}));
  var mdIntro = markdownIt({
    typographer: true
  });
  eleventyConfig.addFilter("markdown", markdown => mdIntro.render(markdown));

  const slugify = require("slugify");
  eleventyConfig.addFilter("slugify", str => {
    return slugify(str, {
      customReplacements: [
        ['+', ' plus '],
        ['@', ' at ']
      ],
      remove: /[*~.,–—()'"‘’“”!?:;]/g,
      lower: true
    });
  });

  // Code syntax highlighting
  const syntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
  eleventyConfig.addPlugin(syntaxHighlight, {
    templateFormats: ["njk", "md"]
  });

  // RSS
  const pluginRss = require("@11ty/eleventy-plugin-rss");
  eleventyConfig.addPlugin(pluginRss);

  // List all topics for a type of content
  eleventyConfig.addFilter("getTopics", (arr) => {
    const notRendered = ['all', 'post', 'research', 'software', 'other'];
    const topics = arr.map(post => post.data.tags).flat().filter(d => !notRendered.includes(d)).sort();
    const uniqueTopics = [...new Set(topics)];
    return uniqueTopics;
  });

  // List all tags
  eleventyConfig.addFilter("tags", collection => {
    const notRendered = ['all', 'post', 'research', 'software', 'other'];
    return Object.keys(collection)
      .filter(d => !notRendered.includes(d))
      .sort();
  });

  // List tags belonging to a page
  eleventyConfig.addFilter("tagsOnPage", tags => {
    const notRendered = ['all', 'post', 'research', 'software', 'other'];
    return tags
      .filter(d => !notRendered.includes(d))
      .sort();
  });

  // Sort by order in front matter
  eleventyConfig.addFilter("ordered", collection => {
    return collection.sort((a, b) => a.data.order - b.data.order);
  });

  // Add limit for output
  eleventyConfig.addFilter("limit", (arr, limit) => {
    return arr.slice(0, limit);
  });

  // Remove current post from output
  eleventyConfig.addFilter("removeCurrent", (arr, title) => {
    return arr.filter(item => {
      return item.url && item.data.title !== title;
    });
  });

  // Get all the years that blog posts were posted
  eleventyConfig.addFilter("getYears", (arr) => {
    const dates = arr.map(post => post.date.getFullYear());
    const uniqueYears = [...new Set(dates)];
    return uniqueYears;
  });

  // Filter items by year
  eleventyConfig.addFilter("filterByYear", (arr, year) => {
    return arr.filter(item => {
      return item.date.getFullYear() == year;
    })
  });

  // Get current year for footer
  eleventyConfig.addFilter("getCurrentYear", () => new Date().getFullYear());

  // Get current date
  eleventyConfig.addFilter("getCurrentDate", () => {
    const today = new Date();
    const dd = String(today.getDate()).padStart(2, '0');
    const mm = String(today.getMonth() + 1).padStart(2, '0');
    const yyyy = today.getFullYear();
    return yyyy + '/' + mm + '/' + dd;
  });

  // Select type filter
  eleventyConfig.addFilter("selectattr", function (arr, attr, value) {
    return arr.filter((item) => item.data[attr] === value);
  });

  // Reject type filter
  eleventyConfig.addFilter("rejectattr", function (arr, attr, value) {
    return arr.filter((item) => item.data[attr] !== value);
  });

  // Localhost server config
  eleventyConfig.setServerOptions({
    port: 3000,
  });

  return {
    dir: {
      input: "src/site",
      output: "dist",
      includes: "_includes",
      layouts: "_layouts"
    },
    templateFormats : ["njk", "html", "md", "txt", "webmanifest", "ico"],
    htmlTemplateEngine : "njk",
    markdownTemplateEngine : "njk"
  };
};