/*
 * Copyright (c) 2010 Lockheed Martin Corporation
 *
 * 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.eurekastreams.server.persistence.mappers.cache;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.Query;

import org.eurekastreams.server.domain.stream.StreamScope.ScopeType;
import org.eurekastreams.server.persistence.mappers.BaseDomainMapper;

/**
 * Implementation of {@link FollowedActivityIdsLoader}.
 * 
 */
public class FollowedActivityIdsLoaderImpl extends BaseDomainMapper implements FollowedActivityIdsLoader
{

    /**
     * {@inheritDoc}
     */
    public List<Long> getFollowedActivityIds(final long inPersonId, final int inMaxResults)
    {
        List<Long> results = new ArrayList<Long>();

        results.addAll(getPersonActivityIdsFollowed(inPersonId, inMaxResults));

        // trim list if needed.
        if (results.size() > inMaxResults)
        {
            results = results.subList(0, inMaxResults);
        }

        return results;
    }

    /**
     * Returns list of activity ids for people the user is following.
     * 
     * @param inPersonId
     *            The user's id.
     * @param inMaxResults
     *            Max. number of ids to return
     * @return List of activity ids for people the user is following.
     */
    @SuppressWarnings("unchecked")
    private List< ? extends Long> getPersonActivityIdsFollowed(final long inPersonId, final int inMaxResults)
    {
        String queryString = "SELECT a.id FROM " + "Activity a, " + "Follower f, " + "Person followedPerson "
                + "WHERE f.pk.followerId = :userId " + "AND followedPerson.id = f.pk.followingId "
                + "AND (a.recipientStreamScope = followedPerson.streamScope "
                + "OR (a.recipientStreamScope.scopeType = :resourceScopeType AND "
                + "a.actorType = :personScopeType AND a.actorId = followedPerson.streamScope.uniqueKey "
                + "AND a.showInStream = :showInStreamFlag)) ORDER BY a.id DESC";

        Query query = getEntityManager().createQuery(queryString).setParameter("userId", inPersonId).setParameter(
                "resourceScopeType", ScopeType.RESOURCE).setParameter("personScopeType", ScopeType.PERSON)
                .setParameter("showInStreamFlag", true).setMaxResults(inMaxResults);

        return query.getResultList();
    }
}