Use dedicated API for app FQDN resolving

[andrejtokarcik]

Fixes gravitational/teleport#6551, based on gravitational/teleport#6449.

I tried to incorporate the recommendations from #235, feel free to adapt further according to your coding conventions.

[kimlisa]

@andrejtokarcik thank you for remembering about the recommendations and applying it here! :)

[kimlisa]

i don't really like how we interchange between aap and app. Can we keep it app @alex-kovoy ?

[alex-kovoy]

I agree with @kimlisa, lets keep it consistent.

[andrejtokarcik]

Did a general aap => app rename, hope that's alright!

[alex-kovoy]

@andrejtokarcik Could you update this function with below code and add some comments // comment here ?

export default function useAppLauncher() {
  const params = useParams<UrlLauncherParams>();
  const { attempt, setAttempt } = useAttempt('processing');

  React.useEffect(() => {
    resolveRedirectUrl(params)
      .then(url => {
        window.location.replace(url);
      })
      .catch((err: Error) => {
        setAttempt({
          status: 'failed',
          statusText: err.message,
        });
      });
  }, []);

  return {
    ...attempt,
  };
}

function resolveRedirectUrl(params: UrlLauncherParams) {
  const location = window.location;
  const port = location.port ? ':' + location.port : '';
  const state = getUrlParameter('state', location.search);

  // comment here
  if (!state) {
    return service.getAppFqdn(params).then(result => {
      const url = new URL(`https://${result.fqdn}${port}/x-teleport-auth`);
      if (params.clusterId) {
        url.searchParams.set('cluster', params.clusterId);
      }
      if (params.publicAddr) {
        url.searchParams.set('addr', params.publicAddr);
      }

      return url.toString();
    });
  }

  // comment here
  return service.createAppSession(params).then(result => {
    const url = new URL(`https://${result.fqdn}${port}/x-teleport-auth`);
    url.searchParams.set('state', state);
    url.hash = `#value=${result.value}`;
    return url.toString();
  });
}

[andrejtokarcik]

Done.