PenaltyController

  package bookrental.controller.penalty;

import bookrental.service.penalty.PenaltyPaymentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class PenaltyController {

    private final PenaltyPaymentService penaltyPaymentService;

    @Autowired
    public PenaltyController(PenaltyPaymentService penaltyPaymentService) {
        this.penaltyPaymentService = penaltyPaymentService;
    }

    @PutMapping("paypenalty/{userID}")
    public String payPenalty(@PathVariable int userID) {
        return penaltyPaymentService.payPenalty(userID);
    }
}

PenaltyPaymentService

package bookrental.service.penalty;

import bookrental.model.account.User;
import bookrental.repository.account.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class PenaltyPaymentService {

    private final UserRepository userRepository;

    @Autowired
    public PenaltyPaymentService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public String payPenalty(int userID) {
        User user = userRepository.findById(userID).orElse(null);
        if (userRepository.doesAccountExistsWithGivenID(userID)) {
            assert user != null;
            long amountOfCashToPay = user.getAmountOfCashToPay();
            if (amountOfCashToPay == 0) {
                return "You have nothing to pay!";
            } else {
                user.setAmountOfCashToPay(0);
                System.out.println(user.getAmountOfCashToPay());
                return "Thanks for paying! To next!";
            }
        } else
            return "Account does not exist";
    }
}

PenaltyService

package bookrental.service.penalty;

import bookrental.model.account.User;
import bookrental.model.book.BookRentals;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import java.time.temporal.ChronoUnit;

@Slf4j
@Service
public class PenaltyService {

    private long hours;
    private long minutes;

    private boolean checkIfPenaltyIsNeeded(BookRentals bookToReturn) {
        hours = ChronoUnit.HOURS.between(bookToReturn.getDateOfRental(), bookToReturn.getDateOfReturn());
        minutes = ChronoUnit.MINUTES.between(bookToReturn.getDateOfRental(), bookToReturn.getDateOfReturn());
        log.info("hours: " + hours + " minutes: " + minutes);
        return minutes > 1 || hours > 0;
    }

    private long calculatePenalty() {
        long amountOfCashToPay;
        amountOfCashToPay = hours * 60 + minutes - 1; // I took away 1, because one minute is free. Next minutes are paid.
        return amountOfCashToPay;
    }

    public void executePenaltyProcess(BookRentals bookToReturn, User user) {
        if (checkIfPenaltyIsNeeded(bookToReturn)) {
            long amountOfCashToPay = calculatePenalty();
            System.out.println("You need to pay: " + amountOfCashToPay + " $. Please go to paypenalty/userID to settle " +
                    "the arrears, otherwise you can not rent more books!");
            user.setAmountOfCashToPay(amountOfCashToPay);
        } else {
            System.out.println("You have nothing to pay! To next!");
        }
    }
}

Po zwróceniu książki:

[
    {
        "id": 1,
        "name": "admin",
        "password": "123",
        "amountOfCashToPay": 0
    },
    {
        "id": 2,
        "name": "piotri",
        "password": "123,",
        "amountOfCashToPay": 2 <<<<<<<<<<
    }
]

ReturnService

package bookrental.service.book.rentals;

import bookrental.model.account.User;
import bookrental.model.book.Book;
import bookrental.model.book.BookRentals;
import bookrental.repository.account.UserRepository;
import bookrental.repository.book.BookRentalsRepository;
import bookrental.repository.book.BookRepository;
import bookrental.service.penalty.PenaltyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;

@Service
public class ReturnBookService {
    private final BookRentalsRepository bookRentalsRepository;
    private final BookRepository bookRepository;
    private final UserRepository userRepository;
    private final PenaltyService penaltyCheckerService;

    @Autowired
    public ReturnBookService(BookRentalsRepository bookRentalsRepository, BookRepository bookRepository, UserRepository userRepository, PenaltyService penaltyCheckerService) {
        this.bookRentalsRepository = bookRentalsRepository;
        this.bookRepository = bookRepository;
        this.userRepository = userRepository;
        this.penaltyCheckerService = penaltyCheckerService;
    }

    public String returnBook(int userID, int bookID) {
        if (bookRentalsRepository.isBookRentedWithGivenIDByUserWithGivenID(bookID, userID)) {
            BookRentals bookToReturn = bookRentalsRepository.getBookBybBookID(bookID);
            User user = userRepository.findById(userID).orElse(null);
            assert bookToReturn != null;
            BookRentals preparedBookToReturn = prepareBookToReturn(bookToReturn);
            penaltyCheckerService.executePenaltyProcess(bookToReturn,user);
            updateBookAvailabilityAndSaveToDb(bookID);
            bookRentalsRepository.delete(preparedBookToReturn);
        } else {
            throw new IllegalArgumentException("Book was not rented!");
        }
        return "Book was returned";
    }

    private BookRentals prepareBookToReturn(BookRentals preparedBookToReturn) {
        assert preparedBookToReturn != null;
        preparedBookToReturn.setDateOfReturn(LocalDateTime.now());
        return preparedBookToReturn;
    }

    private void updateBookAvailabilityAndSaveToDb(int bookID) {
        Book bookToReturn = bookRepository.findById(bookID).orElse(null);
        assert bookToReturn != null;
        bookToReturn.setAvailable(true);
        bookRepository.save(bookToReturn);
    }
}