envoy/src/main/java/envoy/server/database/PersistenceManager.java

package envoy.server.database;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Persistence;

import org.hibernate.Session;

import envoy.server.data.Message;
import envoy.server.data.User;

/**
 * Project: <strong>envoy-server-standalone</strong><br>
 * File: <strong>PersistenceManager.java</strong><br>
 * Created: <strong>1 Jan 2020</strong><br>
 *
 * @author Leon Hofmeister
 * @since Envoy Server Standalone v0.1-alpha
 */
public class PersistenceManager {

	private EntityManager entityManager = Persistence.createEntityManagerFactory("envoy").createEntityManager();

	/**
	 *
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	public PersistenceManager() {
		/*
		 * // TODO TESTING
		 * User user = new User(3, "t");
		 * User user2 = new User(2, "w");
		 * Message msg = new MessageBuilder(user.getId(), user2.getId()).build();
		 * entityManager.getTransaction().begin();
		 * entityManager.persist(user);
		 * entityManager.persist(user2);
		 * entityManager.persist(msg);
		 * entityManager.getTransaction().commit();
		 */ // TODO delete until here
	}

	/**
	 * Adds a user to the database.
	 *
	 * @param User the {@link User} to add to the database
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	public void addUser(User User) { entityManager.persist(User); }

	/**
	 * Adds a message to the database.
	 *
	 * @param message the {@link Message} to add to the database
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	public void addMessage(Message message) { entityManager.persist(message); }// TODO these functions or the one below?

	/**
	 * This is a delegate function for {@link EntityManager#persist} in order to add
	 * an {@link User} / a {@link Message} into the database
	 *
	 * @param obj the object to add to the database
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	public void addObject(Object obj) { entityManager.persist(obj); }

	/**
	 * Updates a row of database objects, either a Message or a User with new data.
	 *
	 * @param obj the object to update (existing User/Message)
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	public void updateObject(Object obj) { entityManager.unwrap(Session.class).merge(obj); }

	/**
	 * Searches for a user with a specific id.
	 *
	 * @param id - the id to search for
	 * @return the user with the specified id
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	public User getUserById(long id) { return (User) entityManager.createNamedQuery("getUserById").setParameter("id", id).getSingleResult(); }

	/**
	 * Returns all messages received while being offline.
	 *
	 * @param user - the user who wants to receive his unread messages
	 * @return all messages that the client does not yet have (unread messages)
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	@SuppressWarnings("unchecked")
	public List<Message> getUnreadMessages(User user) {// TODO may need to be changed to clientId
		return entityManager.createNamedQuery("getUnreadMessages").setParameter("recipient", user).getResultList();
	}
}