import { NextResponse } from 'next/server';
import fs from 'fs';
import path from 'path';
import matter from 'gray-matter';
import { remark } from 'remark';
import gfm from 'remark-gfm';
import remarkRehype from 'remark-rehype';
import rehypeRaw from 'rehype-raw';
import rehypeStringify from 'rehype-stringify';

const postsDirectory = path.join(process.cwd(), 'posts');

const pinnedPath = path.join(postsDirectory, 'pinned.json');
let pinnedSlugs: string[] = [];
if (fs.existsSync(pinnedPath)) {
  try {
    pinnedSlugs = JSON.parse(fs.readFileSync(pinnedPath, 'utf8'));
  } catch {}
}

// Function to get file creation date
function getFileCreationDate(filePath: string): Date {
  const stats = fs.statSync(filePath);
  return stats.birthtime;
}

async function getPostByPath(filePath: string, relPath: string) {
  const fileContents = fs.readFileSync(filePath, 'utf8');
  const { data, content } = matter(fileContents);
  const createdAt = getFileCreationDate(filePath);
  const processedContent = await remark()
    .use(gfm)
    .use(remarkRehype, { allowDangerousHtml: true })
    .use(rehypeRaw)
    .use(rehypeStringify)
    .process(content);
  return {
    type: 'post',
    slug: relPath.replace(/\.md$/, ''),
    title: data.title,
    date: data.date,
    tags: data.tags || [],
    summary: data.summary,
    content: processedContent.toString(),
    createdAt: createdAt.toISOString(),
    pinned: pinnedSlugs.includes(relPath.replace(/\.md$/, '')),
  };
}

async function readPostsDir(dir: string, relDir = ''): Promise<any[]> {
  const entries = fs.readdirSync(dir, { withFileTypes: true });
  const folders: any[] = [];
  const posts: any[] = [];
  for (const entry of entries) {
    const fullPath = path.join(dir, entry.name);
    const relPath = relDir ? path.join(relDir, entry.name) : entry.name;
    if (entry.isDirectory()) {
      const children = await readPostsDir(fullPath, relPath);
      folders.push({ type: 'folder', name: entry.name, path: relPath, children });
    } else if (entry.isFile() && entry.name.endsWith('.md')) {
      posts.push(await getPostByPath(fullPath, relPath));
    }
  }
  // Sort posts by creation date (newest first)
  posts.sort((a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime());
  // Folders first, then posts
  return [...folders, ...posts];
}

export async function GET() {
  try {
    const tree = await readPostsDir(postsDirectory);
    return NextResponse.json(tree);
  } catch (error) {
    return NextResponse.json({ error: 'Fehler beim Laden der Beiträge' }, { status: 500 });
  }
}