async function fetchOAuthRedirect(oAuthProvider) {
  return await fetch(
    `http://localhost:8080/api/auth/authorisationurl?thirdPartyId=${oAuthProvider}`,
    {
      method: 'GET',
      headers: {
        rid: 'thirdparty',
      },
    },
  ).then((response) => response.json());
}

function appendRedirectUri(url, oAuthProvider) {
  let urlObj = new URL(url);
  urlObj.searchParams.append(
    'redirect_uri',
    `http://localhost:8080/api/auth/callback/${oAuthProvider}`,
  );
  return urlObj.toString();
}

async function doSignInUp(code, thirdPartyId) {
  return await fetch('http://localhost:8080/api/auth/signinup', {
    method: 'POST',
    headers: {
      rid: 'thirdparty',
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      code,
      redirectURI: 'http://localhost:8080/auth/callback/github',
      thirdPartyId: thirdPartyId,
    }),
  });
}

async function signinup(oAuthProvider) {
  const redirect = await fetchOAuthRedirect(oAuthProvider);
  window.location.href = appendRedirectUri(redirect.url, oAuthProvider);

  //I don't understand where exactly I should place code down below, cause it's obvious that it's unreachable after the user is redirected to the third party auth page.
  let code = new URL(window.location.href).searchParams.get('code');
  const response = await doSignInUp(code, oAuthProvider);
}