solid-1-list-component.ts

enum ListLevel {
    AUTHORS = 'AUTHORS',
    ARTICLES = 'ARTICLES'
}

interface Pagination {
    first: number;
    last: number;
}

@Component({
    selector: 'list',
    templateUrl: 'list.component.html',
    providers: [ApiService, StoreService]
})
export class ListComponent implements OnInit {
    public showNbOfArticlesDropdown$: Observable<boolean>;
    public mainList$: Observable<Authors[] | Articles[]>;
    public listLevel$: Observable<ListLevel>;
    public pagination$: Observable<Pagination>;
    public topic$: Observable<string>;
    public nbArticles$: Observable<number>;

    constructor(
        private apiService: ApiService,
        private storeService: StoreService
    ) {
        this.listLevel$ = this.storeService.select('listLevel');
        this.pagination$ = this.storeService.select('pagination');
        this.topic$ = this.storeService.select('topic');
        this.nbArticles$ = this.storeService.select('nbOfArticles');
    }

    ngOnInit(): void {
        this.mainList$ = this.getMainList();
        this.showNbOfArticlesDropdown$ = this.showNbOfArticles();
    }

    private getMainList(): Observable<Authors[] | Articles[]> {
        return combineLatest(
            this.listLevel$,
            this.pagination$,
            this.topic$,
        ).pipe(
            switchMap(([listLevel, pagination, topic]) => {
                const { first, last } = pagination;
                switch (listLevel) {
                    case ListLevel.AUTHORS:
                        return this.nbArticles$.pipe(
                            switchMap(nbArticles => {
                                return this.apiService.fecthAuthors({first, last, topic, nbArticles})
                            })
                        );
                    case ListLevel.ARTICLES:
                        return this.apiService.fecthArticles({ first, last, topic });
                    default:
                        break;
                }
            })
        )
    }

    private getArticlesByAuthor(authorId: number): Observable<Articles[]> {
        return this.apiService.fetchArticlesByAuthor(authorId);
    }

    private showNbOfArticles(): Observable<boolean> {
        return this.listLevel$.pipe(
            map(listLevel => {
                switch (listLevel) {
                    case ListLevel.AUTHORS:
                        return true;
                    case ListLevel.ARTICLES:
                        return false;
                    default:
                        break;
                }
            })
        )
    }
}