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package org.ufcspa.simdecs.bn.jpa;

import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Query;
import javax.persistence.EntityNotFoundException;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import javax.transaction.UserTransaction;
import org.ufcspa.simdecs.bn.entity.Answer;
import org.ufcspa.simdecs.bn.entity.Question;
import org.ufcspa.simdecs.bn.jpa.exceptions.NonexistentEntityException;
import org.ufcspa.simdecs.bn.jpa.exceptions.RollbackFailureException;

/**
 *
 * @author mchelem
 */
public class AnswerJpaController implements Serializable {

    public AnswerJpaController(UserTransaction utx, EntityManagerFactory emf) {
        this.utx = utx;
        this.emf = emf;
    }
    private UserTransaction utx = null;
    private EntityManagerFactory emf = null;

    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }

    public void create(Answer answer) throws RollbackFailureException, Exception {
        EntityManager em = null;
        try {
            utx.begin();
            em = getEntityManager();
            Question question = answer.getQuestion();
            if (question != null) {
                question = em.getReference(question.getClass(), question.getId());
                answer.setQuestion(question);
            }
            em.persist(answer);
            if (question != null) {
                question.getAnswers().add(answer);
                question = em.merge(question);
            }
            utx.commit();
        } catch (Exception ex) {
            try {
                utx.rollback();
            } catch (Exception re) {
                throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public void edit(Answer answer) throws NonexistentEntityException, RollbackFailureException, Exception {
        EntityManager em = null;
        try {
            utx.begin();
            em = getEntityManager();
            Answer persistentAnswer = em.find(Answer.class, answer.getId());
            Question questionOld = persistentAnswer.getQuestion();
            Question questionNew = answer.getQuestion();
            if (questionNew != null) {
                questionNew = em.getReference(questionNew.getClass(), questionNew.getId());
                answer.setQuestion(questionNew);
            }
            answer = em.merge(answer);
            if (questionOld != null && !questionOld.equals(questionNew)) {
                questionOld.getAnswers().remove(answer);
                questionOld = em.merge(questionOld);
            }
            if (questionNew != null && !questionNew.equals(questionOld)) {
                questionNew.getAnswers().add(answer);
                questionNew = em.merge(questionNew);
            }
            utx.commit();
        } catch (Exception ex) {
            try {
                utx.rollback();
            } catch (Exception re) {
                throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
            }
            String msg = ex.getLocalizedMessage();
            if (msg == null || msg.length() == 0) {
                Long id = answer.getId();
                if (findAnswer(id) == null) {
                    throw new NonexistentEntityException("The answer with id " + id + " no longer exists.");
                }
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public void destroy(Long id) throws NonexistentEntityException, RollbackFailureException, Exception {
        EntityManager em = null;
        try {
            utx.begin();
            em = getEntityManager();
            Answer answer;
            try {
                answer = em.getReference(Answer.class, id);
                answer.getId();
            } catch (EntityNotFoundException enfe) {
                throw new NonexistentEntityException("The answer with id " + id + " no longer exists.", enfe);
            }
            Question question = answer.getQuestion();
            if (question != null) {
                question.getAnswers().remove(answer);
                question = em.merge(question);
            }
            em.remove(answer);
            utx.commit();
        } catch (Exception ex) {
            try {
                utx.rollback();
            } catch (Exception re) {
                throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public List<Answer> findAnswerEntities() {
        return findAnswerEntities(true, -1, -1);
    }

    public List<Answer> findAnswerEntities(int maxResults, int firstResult) {
        return findAnswerEntities(false, maxResults, firstResult);
    }

    private List<Answer> findAnswerEntities(boolean all, int maxResults, int firstResult) {
        EntityManager em = getEntityManager();
        try {
            CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
            cq.select(cq.from(Answer.class));
            Query q = em.createQuery(cq);
            if (!all) {
                q.setMaxResults(maxResults);
                q.setFirstResult(firstResult);
            }
            return q.getResultList();
        } finally {
            em.close();
        }
    }

    public Answer findAnswer(Long id) {
        EntityManager em = getEntityManager();
        try {
            return em.find(Answer.class, id);
        } finally {
            em.close();
        }
    }

    public int getAnswerCount() {
        EntityManager em = getEntityManager();
        try {
            CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
            Root<Answer> rt = cq.from(Answer.class);
            cq.select(em.getCriteriaBuilder().count(rt));
            Query q = em.createQuery(cq);
            return ((Long) q.getSingleResult()).intValue();
        } finally {
            em.close();
        }
    }
    
}