eth-init.guard.ts

import { Injectable } from '@angular/core';
import { CanActivate } from '@angular/router';
import { Store, select } from '@ngrx/store';
import { Observable, of } from 'rxjs';
import { map, take, tap, filter, switchMap, catchError } from 'rxjs/operators';
import {EthAnchorModule} from '../eth.anchor.module';
import * as fromEth from '../../ethereum';


@Injectable({
  providedIn: EthAnchorModule,
})
export class EthInitGuard implements CanActivate {
  constructor(private store: Store<fromEth.AppState>) {}

  canActivate(): Observable<boolean> {
    return this.checkStore().pipe(

        switchMap(() => of(true)),
        catchError(() => of(false))
    );
  }

  checkStore(): Observable<boolean> {
      return this.store.pipe(
        select(fromEth.getConStatus),
        
        tap(connected => {
          if (!connected) {
            this.store.dispatch(new fromEth.InitEth());
          }
        }),
        
        filter(connected => connected),
        take(1)
      );
  }
}