// @flow
import React from 'react';
import { SHOW_ADS } from 'config';

const NO_COUNTRY_CHECK = true;

const GOOGLE_AD_URL = 'https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js';
let ad_blocker_detected;

export default function useShouldShowAds(
  hasPremiumPlus: boolean,
  userCountry: string,
  doSetAdBlockerFound: (boolean) => void
) {
  const [shouldShowAds, setShouldShowAds] = React.useState(resolveAdVisibility());

  function resolveAdVisibility() {
    // 'ad_blocker_detected' will be undefined at startup. Wait until we are
    // sure it is not blocked (i.e. === false) before showing the component.
    return ad_blocker_detected === false && SHOW_ADS && !hasPremiumPlus && (NO_COUNTRY_CHECK || userCountry === 'US');
  }

  React.useEffect(() => {
    if (ad_blocker_detected === undefined) {
      let mounted = true;

      fetch(GOOGLE_AD_URL)
        .then((response) => {
          const detected = response.redirected === true;
          ad_blocker_detected = detected;
          doSetAdBlockerFound(detected); // Also stash in redux for components to listen to.
        })
        .catch(() => {
          ad_blocker_detected = true;
          doSetAdBlockerFound(true);
        })
        .finally(() => {
          if (mounted) {
            setShouldShowAds(resolveAdVisibility());
          }
        });

      return () => {
        mounted = false;
      };
    }
  }, []);

  return shouldShowAds;
}