next-sitemap.config.cjs

/* eslint-disable @typescript-eslint/no-require-imports */
const fs = require('fs');
const path = require('path');
/* eslint-enable @typescript-eslint/no-require-imports */

const pathLevelToPriority = {
  0: 1,
  1: 0.9,
  2: 0.8,
  3: 0.7,
};

const EXCLUDED_PATHS = ['/feed.xml'];

const getPathDepthLevel = (urlPath) => {
  if (urlPath === '/') {
    return 0;
  }

  return urlPath.split('/').length - 1;
};

function getContentDate(urlPath) {
  const blogMatch = urlPath.match(/^\/blog\/([^/]+)$/);
  const snippetMatch = urlPath.match(/^\/snippets\/([^/]+)$/);

  let dir;
  let slug;

  if (blogMatch) {
    dir = '_posts';
    slug = blogMatch[1];
  } else if (snippetMatch) {
    dir = '_snippets';
    slug = snippetMatch[1];
  } else {
    return null;
  }

  const filePath = path.join(process.cwd(), dir, `${slug}.md`);

  try {
    const content = fs.readFileSync(filePath, 'utf-8');
    const frontmatter =
      content.match(/^---\r?\n([\s\S]*?)\r?\n---/m)?.[1] ?? '';
    const updateMatch = frontmatter.match(/^updateDate:\s*(.+)$/m);
    const createMatch = frontmatter.match(/^createDate:\s*(.+)$/m);

    const dateStr = updateMatch
      ? updateMatch[1].trim()
      : createMatch
        ? createMatch[1].trim()
        : null;

    if (dateStr) {
      return new Date(dateStr).toISOString();
    }
  } catch (error) {
    if (error?.code !== 'ENOENT') {
      console.error(`Error reading content date for ${urlPath}:`, error);
    }
  }

  return null;
}

/** @type {import("next-sitemap").IConfig} */
module.exports = {
  siteUrl: 'https://shramko.dev',
  generateIndexSitemap: false,
  exclude: EXCLUDED_PATHS,
  transform: async (config, urlPath) => {
    const contentDate = getContentDate(urlPath);

    return {
      loc: urlPath,
      priority: pathLevelToPriority[getPathDepthLevel(urlPath)],
      ...(contentDate && { lastmod: contentDate }),
      alternateRefs: config.alternateRefs ?? [],
    };
  },
};