const http2 = require('http2');
const fs = require('fs');
const path = require('path');
const zlib = require('zlib');
const brotli = require('brotli'); // npm package

const PORT = 3032;
const BROTLI_QUALITY = 11; // slow, but we're caching so who cares
const STATIC_DIRECTORY = path.resolve(__dirname, '../dist/');
const cache = {};

/*
 -- To generate keys  --
openssl req -x509 -newkey rsa:2048 -nodes -sha256 -subj '/CN=localhost' \
 -keyout localhost-privkey.pem -out localhost-cert.pem
*/
const server = http2.createSecureServer({
  key: fs.readFileSync(path.resolve(__dirname, './localhost-privkey.pem')),
  cert: fs.readFileSync(path.resolve(__dirname, './localhost-cert.pem')),
});

const getStaticFile = (fileName, useBrotli) => {
  const cacheKey = `${fileName}-${useBrotli}`; // we must cache gzipped and brotli responses separately
  if (cacheKey in cache) return cache[cacheKey];

  const fileBuffer = fs.readFileSync(path.resolve(STATIC_DIRECTORY, fileName.replace(/^\//, '')));
  const compressedFile = useBrotli
    ? brotli.compress(fileBuffer, { quality: BROTLI_QUALITY })
    : zlib.gzipSync(fileBuffer.toString());
  cache[cacheKey] = compressedFile;

  return compressedFile;
};

const getItemAtPath = ({ path, useBrotli }) => {
  const notFoundResponse = {
    body: `<h1>No ${path} for you!</h1>`,
    responseHeader: {
      ':status': 404,
    },
  };

  try {
    const commonHeader = {
      'Content-Encoding': useBrotli ? 'br' : 'gzip',
      ':status': 200,
    };

    if (path === '/') {
      return {
        body: getStaticFile('index.html', useBrotli),
        responseHeader: {
          ...commonHeader,
          'content-type': 'text/html',
        },
      };
    }

    if (path.endsWith('.js')) {
      return {
        body: getStaticFile(path, useBrotli),
        responseHeader: {
          ...commonHeader,
          'Cache-Control': 'max-age=31536000',
          'content-type': 'application/javascript',
        },
      };
    }

    if (path.endsWith('.css')) {
      return {
        body: getStaticFile(path, useBrotli),
        responseHeader: {
          ...commonHeader,
          'Cache-Control': 'max-age=31536000',
          'content-type': 'text/css',
        },
      };
    }

    return notFoundResponse;
  } catch (err) {
    return notFoundResponse;
  }
}

server.on('stream', (stream, headers) => {
  const { body, responseHeader } = getItemAtPath({
    path: headers[':path'],
    useBrotli: headers['accept-encoding'].includes('br'),
  })

  stream.respond(responseHeader);
  stream.end(body);
});

server.listen(PORT);

console.info(`Server is probably ready on https://localhost:${PORT}`);