import http from 'node:http';
import { request as httpRequest } from 'node:http';

const listenHost = process.env.IMGPROXY_COMPAT_HOST || '10.10.0.2';
const listenPort = Number(process.env.IMGPROXY_COMPAT_PORT || 20081);
const upstream = new URL(process.env.IMGPROXY_UPSTREAM || 'http://127.0.0.1:20082');

function convertPath(url) {
  if (url === '/health') return '/health';
  const pathname = url.split('?')[0] || '/';
  const match = pathname.match(/^(?:\/[^/]+)?\/unsafe\/(\d+)x(\d+)\/(\d+)\/([a-z0-9]+)\/(.+)$/i);
  if (!match) return pathname;
  const [, width, height, quality, format, encodedSource] = match;
  let source;
  source = encodedSource;
  for (let i = 0; i < 3; i += 1) {
    try {
      const decoded = decodeURIComponent(source);
      if (decoded === source) break;
      source = decoded;
    } catch {
      break;
    }
  }
  if (source.startsWith('local://') && !source.startsWith('local:///')) {
    source = `local:///${source.slice('local://'.length)}`;
  }
  return `/unsafe/rs:fit:${width}:${height}/q:${quality}/plain/${source}@${format}`;
}

const server = http.createServer((req, res) => {
  const upstreamPath = convertPath(req.url || '/');
  const options = {
    hostname: upstream.hostname,
    port: upstream.port || 80,
    method: req.method,
    path: upstreamPath,
    headers: {
      ...req.headers,
      host: upstream.host,
    },
  };
  const proxy = httpRequest(options, (upstreamRes) => {
    res.writeHead(upstreamRes.statusCode || 502, upstreamRes.headers);
    upstreamRes.pipe(res);
  });
  proxy.on('error', (err) => {
    res.writeHead(502, { 'content-type': 'text/plain' });
    res.end(`imgproxy compat proxy error: ${err.message}`);
  });
  req.pipe(proxy);
});

server.listen(listenPort, listenHost, () => {
  console.log(`imgproxy compat proxy listening on ${listenHost}:${listenPort}, upstream ${upstream.href}`);
});