import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

@Service
@RequiredArgsConstructor
public class PaymentService {
    private final PaymentRepository paymentRepository;
    private final FeeService feeService;
    private final UserService userService;
    private final CbrRestClient cbrRestClient;

    /**
     * detailed documentation
     * @param paymentDetails
     */
    @Transactional
    public void processPayment(PaymentDetails paymentDetails) {
        double someGoodName = cbrRestClient.doRequest().getRates().get(paymentDetails.getCurrency().getCode());
        double amountInUsd = paymentDetails.getAmount() * someGoodName;
        User user = userService.findCurrentUser();
        paymentRepository.save(new Payment(amountInUsd, user, paymentDetails.getRecipientId()));
        feeService.processFee(amountInUsd, user);
    }
}

import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

@Service
@RequiredArgsConstructor
public class FeeService {
    private final FeeRepository feeRepository;
    private final NotificationRestClient notificationRestClient;

    /**
     * detailed documentation
     * @param amountInUsd
     * @param user
     */
    public void processFee(double amountInUsd, User user) {
        double coefficient = 0.015;
        if (amountInUsd > 1000) {
            coefficient = 0.01;
        }
        if (amountInUsd > 5000) {
            coefficient = 0.005;
        }
        try {
            feeRepository.save(new Fee(amountInUsd * coefficient, user));
            notificationRestClient.notify(payment);
        } catch (DataAccessException e) {
            // log cause
            // throw new SomeCustomRuntimeException();
        } catch (Exception e) {
            // log cause
            // throw new SomeOtherCustomRuntimeException();
        }
    }
}

import lombok.Data;

@Data
public class PaymentDetails {
    private double amount;
    private Currency currency;
    private Long recipientId;
}