Controller

@RestController
@RequestMapping("/cafe")
@RequiredArgsConstructor
public class CafeController {
    private final CafeService cafeService;

    @GetMapping("hello")
    public String welcomeMessage(){
        return "Welcome to The Wanted coding cafe!!";
    }

    @GetMapping("order")
    public String orderFromMenu(){
        HashMap<String, Integer> menu = new HashMap<String, Integer>();
        menu.put("AMERICANO", 3);
        return cafeService.orderFrom(menu);
    }
}

Service

@Service
@RequiredArgsConstructor
public class CafeService {
    private final Cafe wantedCafe;

    public String orderFrom(HashMap<String, Integer> menu){
        Cashier cashier = new Cashier(wantedCafe);
        Map<String, Integer> myOrders = new HashMap<>();
        myOrders.put("AMERICANO", 3);
        Customer c1 = new Customer("Card", myOrders);
        return c1.buyCoffee(cashier);
    }
}

Handler

@Component
public class Cafe {
    private final String name;
    private Long sales;

    public Cafe(){
        this.name = "wantedCodingCafe";
        this.sales = 10000L;
    }

    public String getCafeName(){
        return name;
    }

    public void plusSales(Long amount){
        this.sales += amount;
    }

    public void minusSales(Long amount){
        this.sales -= amount;
    }
}

public class Cashier {
    private final Cafe cafe;

    public Cashier(Cafe cafe) {
        this.cafe = cafe;
    }

    public long calculateTotalPrice(Map<String, Integer> orders) {
        long totalPrice = 0L;
        long americanoPrice = 100L;
        for (String key : orders.keySet()) {
            if (key.equalsIgnoreCase("AMERICANO"))
                totalPrice += americanoPrice * orders.get(key);
        }
        return totalPrice;
    }

    private String sendTo(Barista barista, Map<String, Integer> receivedOrders) {
        return barista.makeCoffeeTo(receivedOrders);
    }

    public String takeOrder(Map<String, Integer> receivedOrders, long totalPrice) {
        cafe.plusSales(totalPrice);
        return sendTo(new Barista(0,0), receivedOrders);
    }
}

public class Barista {
    private int rank; // 0: Beginner 1: Middle 2: Master
    private int status; // 0: Waiting 1: Making

    public Barista(int rank, int status){
        this.rank = rank;
        this.status = status;
    }

    private void setRank(int rank){
        this.rank = rank;
    }

    private void setStatus(int status){
        this.status = status;
    }

    public String makeCoffeeTo(Map<String, Integer> orders){
        StringBuilder makeOrders = new StringBuilder();
        for(String coffeeName : orders.keySet()){
            int quantity = orders.get(coffeeName);
            makeOrders.append(coffeeName)
                    .append(":")
                    .append(quantity);
        }
        return makeOrders.toString();
    }
}

public class Customer {
    private String paymentMethod;
    private final Map<String, Integer> myOrders;

    public Customer(String paymentMethod, Map<String, Integer> orders) {
        this.paymentMethod = paymentMethod;
        this.myOrders = orders;
    }

    private void setPaymentMethod(String paymentMethod) {
        this.paymentMethod = paymentMethod;
    }

    public String buyCoffee(Cashier cashier) {
        long totalPrice = cashier.calculateTotalPrice(myOrders);
        return cashier.takeOrder(myOrders, totalPrice);
    }
}