Custom auth token fields Nebular auth

core.module.ts

import { ModuleWithProviders, NgModule, Optional, SkipSelf } from '@angular/core';
import { CommonModule } from '@angular/common';
import { NbAuthModule, NbPasswordAuthStrategy } from '@nebular/auth';
import { throwIfAlreadyLoaded } from './module-import-guard';
import { DataModule } from './data/data.module';
import { environment as env } from '../../environments/environment';
import { HttpResponse } from '@angular/common/http';
import { getDeepFromObject } from '@nebular/auth/helpers';
import { AuthToken, AuthTokenFields } from './auth/token';
import { NbRoleProvider, NbSecurityModule } from '@nebular/security';

export function tokenGetter(module: string, res: HttpResponse<Object>) {
  const authToken: AuthTokenFields = {
    token: getDeepFromObject(res.body, 'access_token'),
    validUntil: getDeepFromObject(res.body, 'valid_until'),
  };
  return JSON.stringify(authToken); //Unfortunately, we need to return a string. We parse on the other side
}

export const NB_CORE_PROVIDERS = [
  ...DataModule.forRoot().providers,
  ...NbAuthModule.forRoot({
    strategies: [
      NbPasswordAuthStrategy.setup({
        name: 'email',
        baseEndpoint: `${env.api.url}`,
        login: {
          endpoint: 'login',
          method: 'post',
          defaultErrors: ['auth.login.incorrect-combination'],
        },
        token: {
          class: AuthToken,
          key: 'access_token',
          getter: tokenGetter,
        },
      }),
    ],
  }).providers,
  ...NbSecurityModule.forRoot({
    accessControl: {},
  }).providers,
  {
    provide: NbRoleProvider, useClass: AbilitiesService,
  },
];

@NgModule({
  imports: [
    CommonModule,
  ],
  exports: [
    NbAuthModule,
  ],
  declarations: [],
  entryComponents: [],
})
export class CoreModule {
  constructor(@Optional() @SkipSelf() parentModule: CoreModule) {
    throwIfAlreadyLoaded(parentModule, 'CoreModule');
  }

  static forRoot(): ModuleWithProviders {
    return <ModuleWithProviders>{
      ngModule: CoreModule,
      providers: [
        ...NB_CORE_PROVIDERS,
      ],
    };
  }
}

token.ts

import { NbAuthSimpleToken } from '@nebular/auth';
import * as moment from 'moment';

export interface AuthTokenFields {
  token: string;
  validUntil: string;
}

/**
 * Wrapper for auth token with additional methods.
 */
export class AuthToken extends NbAuthSimpleToken {

  static NAME = 'auth:token';

  private parsedToken: AuthTokenFields;

  getValue(): string {
    return this.parsePayload().token;
  }

  /**
   * Returns expiration date
   * @returns moment.Moment
   */
  getTokenExpiration(): moment.Moment {
    const payload = this.parsePayload();
    return moment(payload.validUntil);
  }

  /**
   * Is the token still valid
   * @returns {boolean}
   */
  isValid(): boolean {
    return super.isValid() && !this.getTokenExpiration().isBefore();
  }

  /**
   * Returns payload object
   * @returns AuthTokenFields
   */
  protected parsePayload(): AuthTokenFields {
    if (!this.token) {
      throw new Error('Cannot extract payload from an empty token.');
    }

    if (!this.parsedToken) {
      this.parsedToken = JSON.parse(this.token);
    }

    return this.parsedToken;
  }
}