const {DateTime} = require("luxon");
const fs = require("fs");
const pluginRss = require("@11ty/eleventy-plugin-rss");
const pluginSyntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
const sanitizeHtml = require('sanitize-html');

module.exports = function (eleventyConfig) {
  eleventyConfig.addPlugin(pluginRss);
  eleventyConfig.addPlugin(pluginSyntaxHighlight, {
    alwaysWrapLineHighlights: false
  });
  eleventyConfig.setDataDeepMerge(true);

  eleventyConfig.addLayoutAlias("post", "layouts/post.njk");

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

  eleventyConfig.addFilter('dateFromTimestamp', timestamp => {
    return DateTime.fromISO(timestamp, {zone: 'utc'}).toJSDate()
  });

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

  // 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);
  });

  // Webmentions Filter
  eleventyConfig.addFilter('webmentionsForUrl', (webmentions, url) => {
    const allowedTypes = ['mention-of', 'in-reply-to']
    const allowedHTML = {
      allowedTags: ['b', 'i', 'em', 'strong', 'a'],
      allowedAttributes: {
        a: ['href']
      }
    }

    const clean = entry => {
      const {content} = entry
      if (content && content['content-type'] === 'text/html') {
        content.value = sanitizeHTML(content.value, allowedHTML)
      }
      return entry
    };

    return webmentions
      .filter(entry => entry['wm-target'] === url)
      .filter(entry => allowedTypes.includes(entry['wm-property']))
      .filter(entry => !!entry.content)
      .map(clean)
  });

  eleventyConfig.addNunjucksFilter('split', (str, seperator) => {
    return str.split(seperator);
  });

  eleventyConfig.addNunjucksFilter('sanitize', (str) => sanitizeHtml(str, {
    allowedTags: [ 'p', 'b', 'strong', 'i', 'em', 'blockquote', 'a' ],
  }));

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

  eleventyConfig.addPassthroughCopy("img");
  eleventyConfig.addPassthroughCopy("css");
  eleventyConfig.addPassthroughCopy("js");
  eleventyConfig.addPassthroughCopy("demos");
  eleventyConfig.addPassthroughCopy("fonts");
  eleventyConfig.addPassthroughCopy({"static": "/"})
  /* Markdown Plugins */
  let markdownIt = require("markdown-it");
  let markdownItAnchor = require("markdown-it-anchor");
  let options = {
    html: true,
    breaks: true,
    linkify: true
  };
  let opts = {
    permalink: true,
    permalinkClass: "direct-link",
    permalinkSymbol: "#"
  };

  eleventyConfig.setLibrary("md", markdownIt(options)
    .use(markdownItAnchor, opts)
  );

  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();
        });
      }
    }
  });

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

    // If your site lives in a different subdirectory, change this.
    // Leading or trailing slashes are all normalized away, so don’t worry about it.
    // If you don’t have a subdirectory, use "" or "/" (they do the same thing)
    // This is only used for URLs (it does not affect your file structure)
    pathPrefix: "/",

    markdownTemplateEngine: "liquid",
    htmlTemplateEngine: "njk",
    dataTemplateEngine: "njk",
    passthroughFileCopy: true,
    dir: {
      input: ".",
      includes: "_includes",
      data: "_data",
      output: "_site"
    }
  };
};
