e-book

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 { take, tap, filter, switchMap, catchError } from 'rxjs/operators';
import * as fromRoot from '../store';

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

  canActivate(): Observable<boolean> {
    return this.checkStore().pipe(
        switchMap(() => of(true)),
        catchError(() => of(false))
    );
  }

  checkStore(): Observable<boolean> {
      return this.store.pipe(
        select(fromRoot.getMetaMaskEnable),
         tap(connected => {
          if (!connected) {
            this.store.dispatch(fromRoot.Web3ProviderActions.init());
          }
        }),
         filter(connected => connected),
         take(1)
      );
  }
}