import type { RequestHandler } from './$types';
import { error } from '@sveltejs/kit';
import { createReadStream, existsSync, statSync } from 'node:fs';
import { join, basename, extname } from 'node:path';

const IMAGE_DIR = process.env.IMAGE_DIR ?? './data/images';

const MIME: Record<string, string> = {
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.png': 'image/png',
  '.webp': 'image/webp',
  '.gif': 'image/gif',
  '.avif': 'image/avif',
  '.ico': 'image/x-icon',
  '.svg': 'image/svg+xml'
};

export const GET: RequestHandler = ({ params }) => {
  const filename = basename(params.filename ?? '');
  if (!filename || filename.includes('..')) error(400, { message: 'Invalid filename' });
  const full = join(IMAGE_DIR, filename);
  if (!existsSync(full)) error(404, { message: 'Not found' });

  const st = statSync(full);
  const ext = extname(filename).toLowerCase();
  const mime = MIME[ext] ?? 'application/octet-stream';

  const stream = createReadStream(full);
  return new Response(stream as unknown as ReadableStream, {
    status: 200,
    headers: {
      'content-type': mime,
      'content-length': String(st.size),
      'cache-control': 'public, max-age=86400, immutable'
    }
  });
};