http.basketRepository.ts

interface BasketBody {
    basket_items: string[]
}

interface BasketResponse {
    basket_items: string[]
}

export class HTTPBasketRepository implements BasketRepository {
    private endpoint = 'https://www.fakeapi.com/baskets'

    constructor(private httpClient: HTTPClient) {
    }

    getBasket(): Promise<Basket> {
        return this.httpClient.get<BasketResponse>(this.endpoint)
            .then(this.mapToBasket)
    }

    save(basket: Basket): Promise<void> {
        return this.httpClient.post<BasketBody>(this.endpoint, this.mapToBookBody(basket))
    }

    private mapToBasket(basketResponse: BasketResponse): Basket {
        const basket = new Basket()
        basketResponse.basket_items.forEach(item => basket.add(new Book(item)))
        return basket
    }

    private mapToBookBody(basket: Basket): BasketBody {
        return { basket_items: basket.items.map(item => item.title) }
    }
}