ngOnInit() {
    this.filteredRoutes$ = from(this.routes).pipe(
        concatMap((route) => {
            // handle if nothing is in canActivate
            if (!route.canActivate || !route.canActivate.length) {
                // create an object that has the route and result for filtering
                return of({ route, result: true });
            }

            return from(route.canActivate).pipe(
                // execute the guard
                switchMap(guard => {
                    const instance = this.injector.get(guard);
                    const result = instance.canActivate();
                    if (result instanceof Observable) {
                        return result;
                    } else {
                        return of(result);
                    }
                }
            ),
            // aggregate the guard results for the route
            toArray(),
            // ensure all results are true
            map(results => results.every(r => r)),
            // create an object that has the route and result for filtering
            map(result => ({ route, result })));
        }),
        // filter out the invalid guards
        filter(routeCanActivateResult => routeCanActivateResult.result),
        // return just the route
        map(routeCanActivateResult => routeCanActivateResult.route),
        // turn it back into an array
        toArray()
    );
}