/*
 * Symphony - A modern community (forum/SNS/blog) platform written in Java.
 * Copyright (C) 2012-2017,  b3log.org & hacpai.com
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.b3log.symphony.repository;

import java.util.List;
import org.b3log.latke.Keys;
import org.b3log.latke.repository.AbstractRepository;
import org.b3log.latke.repository.FilterOperator;
import org.b3log.latke.repository.PropertyFilter;
import org.b3log.latke.repository.Query;
import org.b3log.latke.repository.RepositoryException;
import org.b3log.latke.repository.SortDirection;
import org.b3log.latke.repository.annotation.Repository;
import org.b3log.latke.util.CollectionUtils;
import org.b3log.symphony.model.Article;
import org.b3log.symphony.model.Tag;
import org.json.JSONArray;
import org.json.JSONObject;

/**
 * Tag-Article relation repository.
 *
 * @author <a href="http://88250.b3log.org">Liang Ding</a>
 * @version 1.1.0.0, Mar 19, 2016
 * @since 0.2.0
 */
@Repository
public class TagArticleRepository extends AbstractRepository {

    /**
     * Public constructor.
     */
    public TagArticleRepository() {
        super(Tag.TAG + "_" + Article.ARTICLE);
    }
    
    /**
     * Removes tag-articles relations by the specified article id.
     * 
     * @param articleId the specified article id
     * @throws RepositoryException repository exception
     */
    public void removeByArticleId(final String articleId) throws RepositoryException {
        final List<JSONObject> relations = getByArticleId(articleId);
        for (final JSONObject relation : relations) {
            remove(relation.optString(Keys.OBJECT_ID));
        }
    }

    /**
     * Gets tag-article relations by the specified article id.
     *
     * @param articleId the specified article id
     * @return for example      <pre>
     * [{
     *         "oId": "",
     *         "tag_oId": "",
     *         "article_oId": articleId
     * }, ....], returns an empty list if not found
     * </pre>
     *
     * @throws RepositoryException repository exception
     */
    public List<JSONObject> getByArticleId(final String articleId) throws RepositoryException {
        final Query query = new Query().setFilter(
                new PropertyFilter(Article.ARTICLE + "_" + Keys.OBJECT_ID, FilterOperator.EQUAL, articleId)).
                setPageCount(1);

        final JSONObject result = get(query);
        final JSONArray array = result.optJSONArray(Keys.RESULTS);

        return CollectionUtils.jsonArrayToList(array);
    }

    /**
     * Gets tag-article relations by the specified tag id.
     *
     * @param tagId the specified tag id
     * @param currentPageNum the specified current page number, MUST greater then {@code 0}
     * @param pageSize the specified page size(count of a page contains objects), MUST greater then {@code 0}
     * @return for example      <pre>
     * {
     *     "pagination": {
     *       "paginationPageCount": 88250
     *     },
     *     "rslts": [{
     *         "oId": "",
     *         "tag_oId": tagId,
     *         "article_oId": ""
     *     }, ....]
     * }
     * </pre>
     *
     * @throws RepositoryException repository exception
     */
    public JSONObject getByTagId(final String tagId, final int currentPageNum, final int pageSize)
            throws RepositoryException {
        final Query query = new Query().setFilter(
                new PropertyFilter(Tag.TAG + "_" + Keys.OBJECT_ID, FilterOperator.EQUAL, tagId)).
                addSort(Article.ARTICLE + "_" + Keys.OBJECT_ID, SortDirection.DESCENDING).
                setCurrentPageNum(currentPageNum).
                setPageSize(pageSize).
                setPageCount(1);

        return get(query);
    }
}
