resource.service.ts

import {
  BehaviorSubject,
  Observable,
  catchError,
  combineLatest,
  filter,
  map,
  mergeMap,
  of,
  startWith,
  tap,
  throwError,
} from 'rxjs';
import { ResourceServiceConfig } from './resource.model';
import {
  StateResource,
  createEmptyStateResource,
  createErrorStateResource,
  createStateResource,
  isLoadingRequired,
  throwErrorOn,
} from './resource.util';
import { Resource, getUrl, hasLink } from '@ngxp/rest';
import { ResourceRepository } from './resource.repository';
import { isEqual, isNull } from 'lodash-es';
import { isNotNull } from '../tech.util';
import { HttpErrorResponse } from '@angular/common/http';
import { isUnprocessableEntity } from '../http.util';
import { HttpError, ProblemDetail } from '../tech.model';
import { isDevMode } from '@angular/core';

/**
 * B = Type of baseresource
 * T = Type of the resource which is working on
 */
export class ResourceService<B extends Resource, T extends Resource> {
  readonly stateResource: BehaviorSubject<StateResource<T>> = new BehaviorSubject(
    createEmptyStateResource(),
  );

  configResource: B;

  constructor(
    private config: ResourceServiceConfig<B>,
    private repository: ResourceRepository,
  ) {}

  public get(): Observable<StateResource<T>> {
    return combineLatest([this.stateResource.asObservable(), this.getConfigResource()]).pipe(
      tap(([, configResource]) => this.handleConfigResourceChanged(configResource)),
      tap(([, configResource]) => this.handleNullConfigResource(configResource)),
      tap(([stateResource, configResource]) =>
        this.handleConfigResource(stateResource, configResource),
      ),
      filter(([stateResource]) => !this.shouldFilter(stateResource)),
      map(([stateResource]) => stateResource),
      startWith(createEmptyStateResource<T>(true)),
    );
  }

  private getConfigResource(): Observable<B> {
    return this.config.resource.pipe(
      filter((stateResource) => stateResource.loaded && !stateResource.loading),
      map((stateResource) => stateResource.resource),
    );
  }

  handleConfigResourceChanged(configResource: B): void {
    if (!isEqual(this.configResource, configResource)) {
      this.configResource = configResource;