Data loss prevention

const DEBUG = true;
const SOME_HOOK_SERVER = 'https://webhook.flow-wolf.io/hook';

/**
 * Alert a data breach by posting to a webhook server
 */
function postDataBreach(request) {
  return fetch(SOME_HOOK_SERVER, {
    method: 'POST',
    body: JSON.stringify(body),
    headers: {
      'content-type': 'application/json;charset=UTF-8',
    },
    body: JSON.stringify({
      ip: request.headers.get('cf-connecting-ip'),
      time: Date.now(),
      request: request,
    }),
  });
}

/**
 * Define personal data with regular expressions.
 * Respond with block if credit card data, and strip
 * emails and phone numbers from the response.
 * Execution will be limited to MIME type "text/*".
 */
async function handleRequest(request) {
  const response = await fetch(request);

  // Return origin response, if response wasn’t text
  const contentType = response.headers.get('content-type') || '';
  if (!contentType.toLowerCase().includes('text/')) {
    return response;
  }

  let text = await response.text();

  // When debugging replace the response
  // from the origin with an email
  text = DEBUG ? text.replace('You may use this', 'me@example.com may use this') : text;

  const sensitiveRegexsMap = {
    creditCard: String.raw`\b(?:4[0-9]{12}(?:[0-9]{3})?|(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|6(?:011|5[0-9]{2})[0-9]{12}|(?:2131|1800|35\d{3})\d{11})\b`,
    email: String.raw`\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b`,
    phone: String.raw`\b07\d{9}\b`,
  };

  for (const kind in sensitiveRegexsMap) {
    const sensitiveRegex = new RegExp(sensitiveRegexsMap[kind], 'ig');
    const match = await sensitiveRegex.test(text);
    if (match) {
      // Alert a data breach
      await postDataBreach(request);

      // Respond with a block if credit card,
      // otherwise replace sensitive text with `*`s
      return kind === 'creditCard'
        ? new Response(kind + ' found\nForbidden\n', {
            status: 403,
            statusText: 'Forbidden',
          })
        : new Response(text.replace(sensitiveRegex, '**********'), response);
    }
  }
  return new Response(text, response);
}

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request));
});