import fs from "fs";
import { join } from "path";
import matter from "gray-matter";

const docsDirectory = join(process.cwd(), "src/_docs");

export function getDocSlugs() {
  return fs.readdirSync(docsDirectory);
}

export function getDocBySlug(slug: string, fields: string[] = []) {
  const realSlug = slug.replace(/\.md$/, "");
  const fullPath = join(docsDirectory, `${realSlug}.md`);
  const fileContents = fs.readFileSync(fullPath, "utf8");
  const { data, content } = matter(fileContents);

  type Items = {
    [key: string]: string;
  };

  const items: Items = {};

  // Ensure only the minimal needed data is exposed
  fields.forEach((field) => {
    if (field === "slug") {
      items[field] = realSlug;
    }
    if (field === "content") {
      items[field] = content;
    }

    if (typeof data[field] !== "undefined") {
      items[field] = data[field];
    }
  });

  return items;
}

export function getAllDocs(fields: string[] = []) {
  const slugs = getDocSlugs();
  const docs = slugs
    .map((slug) => getDocBySlug(slug, fields))
    // sort docs by date in descending order
    .sort((doc1, doc2) => (doc1.date > doc2.date ? -1 : 1));
  return docs;
}