web3-provider.effects.ts

import { Injectable, Inject } from '@angular/core';

import { Actions, ofType, createEffect } from '@ngrx/effects';
import { of, from, EMPTY as empty } from 'rxjs';
import { exhaustMap, switchMap, map, tap, catchError } from 'rxjs/operators';

import { MetamaskWeb3Provider } from '../../services/tokens';
import { ProviderService } from '../../services/provider.services';
import { Web3ProviderActions, SpinnerActions, ErrorActions } from '../actions';

@Injectable()
export class Web3ProviderEffects {
  constructor(
    @Inject(MetamaskWeb3Provider) private web3Provider,
    private providerSrv: ProviderService,
    private readonly actions$: Actions
  ) {}

  getAccount$ = createEffect(() =>
    this.actions$.pipe(
      ofType(Web3ProviderActions.initSuccess),
      switchMap(() =>
        this.providerSrv.getAccount().pipe(
          map((address: string) => Web3ProviderActions.account({ address })),
          catchError((err: Error) =>
            of(ErrorActions.errorMessage({ errorMsg: err.message }))
          )
        )
      )
    )
  );

  getBalance$ = createEffect(() =>
    this.actions$.pipe(
      ofType(Web3ProviderActions.initSuccess),
      switchMap(() =>
        this.providerSrv.getBalance().pipe(
          map((balance: string) =>
            Web3ProviderActions.balanceSuccess({ balance })
          ),
          catchError((err: Error) =>
            of(ErrorActions.errorMessage({ errorMsg: err.message }))
          )
        )
      )
    )
  );
}