Function getSourceUrl

src/url.js:493–526

(url)

 * @return {string}
 */
export function getSourceUrl(url) {
  url = urlAsLocation(url);

  // Not a proxy URL - return the URL itself.
  if (!isProxyOrigin(url)) {
    return url.href;
  }

  // A proxy URL.
  // Example path that is being matched here.
  // https://cdn.ampproject.org/c/s/www.origin.com/foo/
  // The /s/ is optional and signals a secure origin.
  const path = url.pathname.split('/');
  const prefix = path[1];
  userAssert(
    SERVING_TYPE_PREFIX.has(prefix),
    'Unknown path prefix in url %s',
    url.href
  );
  const domainOrHttpsSignal = path[2];
  const origin =
    domainOrHttpsSignal == 's'
      ? 'https://' + decodeURIComponent(path[3])
      : 'http://' + decodeURIComponent(domainOrHttpsSignal);
  // Sanity test that what we found looks like a domain.
  userAssert(origin.indexOf('.') > 0, 'Expected a . in origin %s', origin);
  path.splice(1, domainOrHttpsSignal == 's' ? 3 : 2);
  return (
    origin +
    path.join('/') +
    removeAmpJsParamsFromSearch(url.search) +
    (url.hash || '')
  );
}

/**
 * Returns the source origin of an AMP document for documents served