configureGtagConsent.ts

import { CookiePolicyAcceptance } from './CookiePolicyAcceptance';
import getStoredPolicyAcceptance from './getStoredPolicyAcceptance';

export type DataLayerName = 'dataLayer' | 'ga4DataLayer' | 'adwordsDataLayer';
export type GtagName = 'gtag' | 'adwordsGtag' | 'gtmGtag';

export const gtagFn = (
  dataLayerName: DataLayerName,
  gtagName: GtagName,
): ((..._args: any[]) => any) =>
  window[gtagName] ||
  (window[gtagName] = function () {
    // eslint-disable-next-line prefer-rest-params
    (window[dataLayerName] || (window[dataLayerName] = [])).push(arguments);
  });

/**
 * Send consent configuration to a google container using gtag.  This is used for
 * Google Tag Manager, Google Analytics, and Google AdWords to indicate whether they
 * can store cookies.
 *
 * @param dataLayerName Name of the dataLayer global
 * @param gtagName Name of the gtag global function
 * @param cookiePolicyAcceptance Which cookies the user has accepted.  Will be loaded from localStorage if
 *    not provided as an argument
 */
export default function configureGtagConsent(
  dataLayerName: DataLayerName,
  gtagName: GtagName,
  cookiePolicyAcceptance: CookiePolicyAcceptance = getStoredPolicyAcceptance(),
): void {
  const initialCall: boolean = !window[dataLayerName]?.some(
    args => args[0] === 'consent',
  );

  const gtag = gtagFn(dataLayerName, gtagName);

  const {
    isFunctionalCookiesAccepted,
    isPerformanceCookiesAccepted,
    isTargetingCookiesAccepted,
  } = cookiePolicyAcceptance;

  const consent = {
    ad_storage: isTargetingCookiesAccepted ? 'granted' : 'denied',
    analytics_storage: isPerformanceCookiesAccepted ? 'granted' : 'denied',
    functionality_storage: isFunctionalCookiesAccepted ? 'granted' : 'denied',
    // We don't have a special category for functionality related cookies, can lump into functional
    personalization_storage: isFunctionalCookiesAccepted ? 'granted' : 'denied',
    security_storage: 'granted',
  };

  if (initialCall) {
    gtag('consent', 'default', consent);
  } else {
    gtag('consent', 'update', consent);
  }
}