export const dynamic = "force-dynamic";

import { NextResponse } from 'next/server';
import fs from 'fs';
import path from 'path';
import matter from 'gray-matter';
import { marked } from 'marked';
import DOMPurify from 'dompurify';
import { JSDOM } from 'jsdom';
import hljs from 'highlight.js';
import { getPostsDirectory } from '@/lib/postsDirectory';

const postsDirectory = getPostsDirectory();

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

// Function to generate ID from text (matches frontend logic)
function generateId(text: string): string {
  return text
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '');
}

const renderer = new marked.Renderer();

// Custom heading renderer to add IDs
renderer.heading = (text, level) => {
  const id = generateId(text);
  return `<h${level} id="${id}">${text}</h${level}>`;
};

renderer.code = (code, infostring, escaped) => {
  const lang = (infostring || '').match(/\S*/)?.[0];
  const highlighted = lang && hljs.getLanguage(lang)
    ? hljs.highlight(code, { language: lang }).value
    : hljs.highlightAuto(code).value;
  const langClass = lang ? `language-${lang}` : '';
  return `<pre><code class="hljs ${langClass}">${highlighted}</code></pre>`;
};

marked.setOptions({
  gfm: true,
  breaks: true,
  renderer,
});

async function getPostBySlug(slug: string) {
  const realSlug = slug.replace(/\.md$/, '');
  const fullPath = path.join(postsDirectory, `${realSlug}.md`);
  const fileContents = fs.readFileSync(fullPath, 'utf8');
  const { data, content } = matter(fileContents);
  const createdAt = getFileCreationDate(fullPath);

  let processedContent = '';
  try {
    // Convert markdown to HTML
    const rawHtml = marked.parse(content);

    // Create a DOM window for DOMPurify
    const window = new JSDOM('').window;
    const purify = DOMPurify(window);

    // Sanitize the HTML
    processedContent = purify.sanitize(rawHtml as string, {
      ALLOWED_TAGS: [
        'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
        'p', 'a', 'ul', 'ol', 'li', 'blockquote',
        'pre', 'code', 'em', 'strong', 'del',
        'hr', 'br', 'img', 'table', 'thead', 'tbody',
        'tr', 'th', 'td', 'div', 'span', 'iframe'
      ],
      ALLOWED_ATTR: [
        'class', 'id', 'style',
        'href', 'target', 'rel',
        'src', 'alt', 'title', 'width', 'height',
        'frameborder', 'allowfullscreen'
      ],
      ALLOWED_URI_REGEXP: /^(?:(?:(?:f|ht)tps?|mailto|tel|callto|cid|xmpp):|[^a-z]|[a-z+.\-]+(?:[^a-z+.\-:]|$))/i
    });
  } catch (err) {
    console.error(`Error processing markdown for slug "${realSlug}":`, err);
    // Return a more informative error message in the content
    processedContent = `<div class="error-message">
      <p>Error processing markdown content. Please check the console for details.</p>
      <pre>${err instanceof Error ? err.message : 'Unknown error'}</pre>
    </div>`;
  }

  return {
    slug: realSlug,
    title: data.title,
    date: data.date,
    tags: data.tags || [],
    summary: data.summary,
    content: processedContent,
    createdAt: createdAt.toISOString(),
    author: (process.env.NEXT_PUBLIC_BLOG_OWNER || 'Anonymous') + "'s",
  };
}

export async function GET(
  request: Request,
  { params }: { params: { slug: string[] | string } }
) {
  try {
    const slugArr = Array.isArray(params.slug) ? params.slug : [params.slug];
    const slugPath = slugArr.join('/');
    const post = await getPostBySlug(slugPath);
    return NextResponse.json(post);
  } catch (error) {
    console.error('Error loading post:', error);
    return NextResponse.json(
      { 
        error: 'Error loading post',
        details: error instanceof Error ? error.message : 'Unknown error'
      }, 
      { status: 500 }
    );
  }
}