remote-be/src/main/java/it/bgates/remotebe/service/DistributorService.java

package it.bgates.remotebe.service;

import it.bgates.remotebe.entities.Distributor;
import it.bgates.remotebe.entities.User;
import it.bgates.remotebe.exception.PermissionDeniedException;
import it.bgates.remotebe.exception.UserNotFoundException;
import it.bgates.remotebe.repository.DistributorRepository;
import it.bgates.remotebe.repository.UserRepository;
import jakarta.persistence.EntityManager;
import jakarta.persistence.TypedQuery;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

import java.security.Principal;
import java.util.List;
import java.util.Optional;

@Service
@RequiredArgsConstructor
public class DistributorService extends BaseService {

    private final DistributorRepository distributorRepository;
    private final UserRepository userRepository;
    private final EntityManager entityManager;

    /***
     * returns the list of distributors accessible the currently logged user
     * If the user is an admin, returns all the distributors
     * If the user is a distributor, returns only itself
     * @param principal
     * @return
     */
    public List<Distributor> getDistributors(Principal principal) throws UserNotFoundException {
        getUserDetails(principal);

        Optional<User> user = userRepository.findByUsername(userDetails.getUsername());
        if (user.isEmpty()) {
            return List.of();
        }

        if (isSuperUser()) {
            return distributorRepository.findAllByOrderByName();
        }
        if (isDistributor()) {
            return List.of(user.get().getDistributor());
        }

        return List.of();
    }

    public Distributor save(Distributor distributor, Principal principal) throws UserNotFoundException, PermissionDeniedException {
        getUserDetails(principal);

        if (!isSuperUser() && distributor.getId() == null) {
            throw new PermissionDeniedException("Accesso negato");
        }

        return distributorRepository.save(distributor);
    }

    public Distributor getDistributorById(Integer id) {
        return distributorRepository.findById(id).orElse(null);
    }

    public List<Distributor> filter(String filter, Principal principal) throws UserNotFoundException {
        getUserDetails(principal);

        Optional<User> user = userRepository.findByUsername(userDetails.getUsername());
        if (user.isEmpty()) {
            return List.of();
        }

        StringBuilder filterBuilder = new StringBuilder();

        if (isDistributor()) {
            filterBuilder.append("WHERE d = :distributor");
        } else if (isSuperUser()) {
            filterBuilder.append("WHERE true");
        } else if (isUser()) {
            filterBuilder.append("WHERE false");
        }

        List<String> params = buildFilter(filterBuilder, filter,  new String[] {
                "name",
                "vatNumber",
                "city"
        });


        String sql = "SELECT d FROM Distributor d " + filterBuilder.toString();
        TypedQuery<Distributor> query = entityManager.createQuery(sql, Distributor.class);
        for (int i = 0; i < params.size(); i++) {
            query.setParameter("param_" + i, params.get(i));
        }

        for (int i = 0; i < params.size(); i++) {
            query.setParameter("param_" + i, params.get(i));
        }

        if (isDistributor()) {
            query.setParameter("distributor", user.get().getDistributor());
        }

        List<Distributor> distributors = query.getResultList();
        return distributors;
    }
}