import fs from 'fs';
import path from 'path';
import { bundleMDX } from 'mdx-bundler';
import remarkGfm from 'remark-gfm';
import rehypeSlug from 'rehype-slug';

export interface Frontmatter {
  title: string;
  date: string;
  excerpt?: string;
  teaser?: string;
  tags?: string[];
  icon?: string;
  image?: string;
  video?: string;
}

export interface Post {
  slug: string;
  frontmatter: Frontmatter;
  code: string;
}

const contentDirectory = path.join(process.cwd(), 'content');
const datePrefixRegex = /^\d{4}-\d{2}-\d{2}-/;

export function getPostSlugs(type: 'projects' | 'research' | 'teaching' | 'experience') {
  const typeDirectory = path.join(contentDirectory, type);
  if (!fs.existsSync(typeDirectory)) return [];
  return fs.readdirSync(typeDirectory).map(file =>
    file.replace(datePrefixRegex, '').replace(/\.mdx$/, '')
  );
}

export async function getPostBySlug(type: 'projects' | 'research' | 'teaching' | 'experience', slug: string): Promise<Post | null> {
  const typeDirectory = path.join(contentDirectory, type);

  const allFiles = fs.readdirSync(typeDirectory);
  const fileName = allFiles.find(file =>
    file.replace(datePrefixRegex, '').replace(/\.mdx$/, '') === slug
  );

  if (!fileName) {
    console.error(`[MDX] Could not find a file for slug: ${slug} in ${typeDirectory}`);
    return null;
  }

  const fullPath = path.join(typeDirectory, fileName);
  const fileContents = fs.readFileSync(fullPath, 'utf8');

  const dateMatch = fileName.match(/^\d{4}-\d{2}-\d{2}/);
  const dateFromFilename = dateMatch ? dateMatch[0] : new Date().toISOString();

  const { code, frontmatter } = await bundleMDX({
    source: fileContents,
    mdxOptions(options) {
      options.remarkPlugins = [...(options.remarkPlugins ?? []), remarkGfm];
      options.rehypePlugins = [...(options.rehypePlugins ?? []), rehypeSlug];
      return options;
    },
  });

  return {
    slug,
    frontmatter: { ...frontmatter, date: dateFromFilename } as Frontmatter,
    code,
  };
}