/*
 * 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.NoResultException;
import javax.persistence.TypedQuery;

import org.wamblee.cache.Cache;
import org.wamblee.persistence.JpaMergeSupport;
import org.wamblee.security.authentication.AbstractUserSet;
import org.wamblee.security.authentication.Group;
import org.wamblee.security.authentication.MessageDigester;
import org.wamblee.security.authentication.NameValidator;
import org.wamblee.security.authentication.User;

/**
 * User set backed by the database.
 * 
 * @author Erik Brakkee
 */
public class JpaUserSet extends AbstractUserSet {

    /**
     * Cache of users. Every user in the cache has its password validator and
     * encoder set.
     */
    private Cache<String, User> cache;

    private EntityManager entityManager;

    /**
     * Constructs a user set backed by the database.
     * 
     * @param aCache
     *            User cache to use.
     */
    public JpaUserSet(Cache<String, User> aCache,
        NameValidator aPasswordValidator, MessageDigester aPasswordEncoder,
        EntityManager aEntityManager) {
        super(aPasswordValidator, aPasswordEncoder);
        cache = aCache;
        entityManager = aEntityManager;
    }

    @Override
    public void userModified(User aUser) {
        assert aUser.getPrimaryKey() != null;
        User merged = entityManager.merge(aUser);
        // Need to flush the entity manager to make sure the version is updated.
        entityManager.flush();
        JpaMergeSupport.merge(merged, aUser);
        cache.remove(aUser.getName());
        setPasswordInfo(aUser);
        cache.put(aUser.getName(), new User(aUser));
    }

    @Override
    public User find(String aName) {
        User user = cache.get(aName);

        if (user != null) {
            return user;
        }

        TypedQuery<User> query = entityManager.createNamedQuery(
            User.QUERY_FIND_BY_NAME, User.class);
        query.setParameter(User.NAME_PARAM, aName);
        try {
            user = query.getSingleResult();
            setPasswordInfo(user);
            cache.put(aName, user);
            return user;
        } catch (NoResultException e) {
            return null;
        }
    }

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

    @Override
    public boolean add(User aUser) {
        assert aUser.getPrimaryKey() == null;

        if (contains(aUser)) {
            return false;
        }

        entityManager.persist(aUser);
        entityManager.flush(); // to make sure the version is updated.
        setPasswordInfo(aUser);
        cache.put(aUser.getName(), aUser);

        return true;
    }

    @Override
    public boolean remove(User aUser) {
        if (!contains(aUser)) {
            return false;
        }

        User user = entityManager.merge(aUser);
        entityManager.remove(user);
        cache.remove(aUser.getName());

        return true;
    }

    @Override
    public Set<User> list() {
        Set<User> users = new TreeSet<User>();
        List<User> list = entityManager.createNamedQuery(User.QUERY_ALL_USERS,
            User.class).getResultList();

        for (User user : list) {
            setPasswordInfo(user);
            users.add(user);
        }

        return users;
    }

    @Override
    public Set<User> list(Group aGroup) {
        Set<User> users = new TreeSet<User>();
        TypedQuery<User> query = entityManager.createNamedQuery(
            User.QUERY_FIND_BY_GROUP_NAME, User.class);
        query.setParameter(User.NAME_PARAM, aGroup.getName());

        List<User> list = query.getResultList();
        users.addAll(list);
        for (User user : users) {
            setPasswordInfo(user);
        }

        return users;
    }

    @Override
    public int size() {
        Long result = entityManager.createNamedQuery(User.QUERY_COUNT_USERS,
            Long.class).getSingleResult();
        return result.intValue();
    }

    @Override
    public void clearCache() {
        cache.clear();
    }
}