package de.intevation.lada.data;

import java.util.List;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.persistence.EntityManager;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import javax.inject.Named;

/**
 * This generic Container is an interface to request and select Data
 * obejcts from the connected database.
 * 
 * @author <a href="mailto:rrenkert@intevation.de">Raimund Renkert</a>
 */
@Named
@ApplicationScoped
public class Repository
{
    /**
     * The entitymanager managing the data.
     */
    @Inject
    private EntityManager em;

    /**
     * Get all objects of type <link>clazz</link>from database.
     *
     * @param clazz The class type.
     * @return List of objects.
     */
    public <T> List<T> findAll(Class<T> clazz) {
        CriteriaBuilder builder = em.getCriteriaBuilder();
        CriteriaQuery<T> criteria = builder.createQuery(clazz);
        Root<T> member = criteria.from(clazz);
        criteria.select(member);
        return em.createQuery(criteria).getResultList();
    }

    /**
     * Find a single object identified by its id.
     * 
     * @param clazz The class type.
     * @param id The object id.
     * @return The requested object of type clazz
     */
    public <T> T findById(Class<T> clazz, String id) {
        return em.find(clazz, id);
    }
}