/*
 * Copyright 2005-2010 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.wamblee.security.authentication.jpa;

import java.util.List;
import java.util.Set;
import java.util.TreeSet;

import javax.persistence.EntityManager;
import javax.persistence.TypedQuery;

import org.wamblee.persistence.JpaMergeSupport;
import org.wamblee.security.authentication.Group;
import org.wamblee.security.authentication.GroupSet;

/**
 * Group set backed by the database.
 * 
 * @author Erik Brakkee
 */
public class JpaGroupSet implements GroupSet {

    private EntityManager em;

    public JpaGroupSet(EntityManager aEm) {
        em = aEm;
    }

    @Override
    public boolean add(Group aGroup) {
        assert aGroup.getPrimaryKey() == null;
        if (contains(aGroup)) {
            return false;
        }
        em.persist(aGroup);
        em.flush(); // to make sure the version is updated. 
        return true;
    }

    @Override
    public boolean contains(Group aGroup) {
        return find(aGroup.getName()) != null;
    }

    @Override
    public Group find(String aName) {
        TypedQuery<Group> query = em.createNamedQuery(Group.QUERY_FIND_BY_NAME,
            Group.class);
        query.setParameter(Group.NAME_PARAM, aName);
        List<Group> groups = query.getResultList();
        if (groups.size() > 1) {
            throw new RuntimeException(
                "More than one group with the same name '" + aName + "'");
        }

        if (groups.size() == 0) {
            return null;
        }
        return groups.get(0);
    }

    @Override
    public void groupModified(Group aGroup) {
        assert aGroup.getPrimaryKey() != null;
        Group merged = em.merge(aGroup);
        // Need to flush so that version of the merged instance is updated so we
        // can use
        // the updated version in the original group passed in. That allows the
        // same
        // group object to continue to be used as a detached object.
        em.flush();
        JpaMergeSupport.merge(merged, aGroup);
    }

    @Override
    public Set<Group> list() {
        List<Group> groups = em.createNamedQuery(Group.QUERY_ALL_GROUPS,
            Group.class).getResultList();
        Set<Group> res = new TreeSet<Group>(groups);
        return res;
    }

    @Override
    public boolean remove(Group aGroup) {
        Group group = find(aGroup.getName());
        if (group == null) {
            return false;
        }
        em.remove(group);
        return true;
    }

    @Override
    public int size() {
        Long res = (Long) em.createNamedQuery(Group.QUERY_COUNT_GROUPS)
            .getSingleResult();
        return res.intValue();
    }
}