package net.bpfurtado.sessionlocktest;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.LockMode;
import org.hibernate.Session;

public class Main
{
    private static SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss");

    public static void main(String[] args)
    {
        lockFirstDetachedThenPersistent();
        lockFirstPersistentThenDetached(); //Here I get the 'NonUniqueObjectException' exception
    }

    private static void lockFirstDetachedThenPersistent()
    {
        Book detached = createDetached();

        HibernateUtil.beginTransaction();
        Book persistent = (Book) HibernateUtil.getSession().load(Book.class, detached.getId());

        HibernateUtil.getSession().lock(detached, LockMode.NONE);
        HibernateUtil.getSession().lock(persistent, LockMode.NONE); //Here I don´t get the error and I can do anything I want with the detached or transient instance.

        detached.setTitle("Detached updated " + sdf.format(new Date()));

        HibernateUtil.commitTransaction();
        HibernateUtil.closeSession();
    }

    private static void lockFirstPersistentThenDetached()
    {
        Book detached = createDetached();

        HibernateUtil.beginTransaction();
        Book persistent = (Book) HibernateUtil.getSession().load(Book.class, detached.getId());

        HibernateUtil.getSession().lock(persistent, LockMode.NONE);
        HibernateUtil.getSession().lock(detached, LockMode.NONE); //Here I get the 'NonUniqueObjectException' exception

        detached.setTitle("Detached updated " + sdf.format(new Date()));

        HibernateUtil.commitTransaction();
        HibernateUtil.closeSession();
    }

    private static Book createDetached()
    {
        Book detached = new Book();
        detached.setTitle("Detached " + sdf.format(new Date()));

        HibernateUtil.beginTransaction();

        Session session = HibernateUtil.getSession();
        session.save(detached);

        HibernateUtil.commitTransaction();
        HibernateUtil.closeSession();
        return detached;
    }
}

    private Serializable getObjectId(Object obj) {
        ClassMetadata md = factory.getClassMetadata(obj.getClass());
        Serializable id = md.getIdentifier(obj, EntityMode.POJO);
        return id;
    }

    public void attach(Object obj) {
        Session session = factory.getCurrentSession();
        Serializable id = getObjectId(obj);
        if(id != null) {
            if(!session.contains(obj)) {
                // We need a cache to sustain the performance hit.
                Object oldObj = session.get(obj.getClass(), id);
                if(oldObj != null) {
                    session.evict(oldObj);
                }
            }

            // Reattach and version-check.
            session.lock(obj, LockMode.READ);
        }
    }