const fs = require('fs').promises;
const { resolve } = require('path');

const {promisify} = require('util');
const frontMatterParser = require('parser-front-matter');

const parse = promisify(frontMatterParser.parse.bind(frontMatterParser));

// https://stackoverflow.com/questions/5827612/node-js-fs-readdir-recursive-directory-search
async function getFiles(dir) {
  const dirents = await fs.readdir(dir, { withFileTypes: true });
  const files = await Promise.all(dirents.map((dirent) => {
    const res = resolve(dir, dirent.name);
    return dirent.isDirectory() ? getFiles(res) : res;
  }));
  return Array.prototype.concat(...files);
}

async function loadPostsWithFrontMatter(postsDirectoryPath) {
  const postNames = await getFiles(postsDirectoryPath);
  const posts = await Promise.all(
    // could be .DS_Store stuff found using recursive function above... 
    postNames.filter(name => name.endsWith('.md')).map(async fileName => {
      const fileContent = await fs.readFile(fileName, 'utf8');
      const {content, data} = await parse(fileContent);
      return {
        content: content.slice(0, 3000),
        ...data
      };
    })
  );
  return posts;
}

const lunrjs = require('lunr');

function makeIndex(posts) {
  return lunrjs(function() {
    this.ref('title');
    this.field('title');
    this.field('content');
    this.field('tags');
    posts.forEach(p => {
      this.add(p);
    });
  });
}

async function run() {
  const posts = await loadPostsWithFrontMatter(`${__dirname}/content/post`);
  const essays = await loadPostsWithFrontMatter(`${__dirname}/content/essays`);
  const index = makeIndex(posts.concat(essays));
  console.log(JSON.stringify(index));
}

run()
  .then(() => process.exit(0))
  .catch(error => {
    console.error(error);
    process.exit(1);
  });