/*
 * Solo - A small and beautiful blogging system written in Java.
 * Copyright (c) 2010-present, b3log.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.b3log.solo.service;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.b3log.latke.Keys;
import org.b3log.latke.ioc.Inject;
import org.b3log.latke.model.Pagination;
import org.b3log.latke.repository.Query;
import org.b3log.latke.repository.SortDirection;
import org.b3log.latke.service.ServiceException;
import org.b3log.latke.service.annotation.Service;
import org.b3log.latke.util.Paginator;
import org.b3log.solo.model.Link;
import org.b3log.solo.repository.LinkRepository;
import org.json.JSONArray;
import org.json.JSONObject;

import java.util.List;

/**
 * Link query service.
 *
 * @author <a href="http://88250.b3log.org">Liang Ding</a>
 * @version 1.0.0.2, Oct 31, 2011
 * @since 0.4.0
 */
@Service
public class LinkQueryService {

    /**
     * Logger.
     */
    private static final Logger LOGGER = LogManager.getLogger(LinkQueryService.class);

    /**
     * Link repository.
     */
    @Inject
    private LinkRepository linkRepository;

    /**
     * Gets links by the specified request json object.
     *
     * @param requestJSONObject the specified request json object, for example,
     *                          "paginationCurrentPageNum": 1,
     *                          "paginationPageSize": 20,
     *                          "paginationWindowSize": 10
     *                          see {@link Pagination} for more details
     * @return for example,
     * <pre>
     * {
     *     "pagination": {
     *         "paginationPageCount": 100,
     *         "paginationPageNums": [1, 2, 3, 4, 5]
     *     },
     *     "links": [{
     *         "oId": "",
     *         "linkTitle": "",
     *         "linkAddress": "",
     *         ""linkDescription": ""
     *      }, ....]
     * }
     * </pre>
     * @throws ServiceException service exception
     * @see Pagination
     */
    public JSONObject getLinks(final JSONObject requestJSONObject) throws ServiceException {
        final JSONObject ret = new JSONObject();

        try {
            final int currentPageNum = requestJSONObject.getInt(Pagination.PAGINATION_CURRENT_PAGE_NUM);
            final int pageSize = requestJSONObject.getInt(Pagination.PAGINATION_PAGE_SIZE);
            final int windowSize = requestJSONObject.getInt(Pagination.PAGINATION_WINDOW_SIZE);

            final Query query = new Query().setPage(currentPageNum, pageSize).addSort(Link.LINK_ORDER, SortDirection.ASCENDING);
            final JSONObject result = linkRepository.get(query);
            final int pageCount = result.getJSONObject(Pagination.PAGINATION).getInt(Pagination.PAGINATION_PAGE_COUNT);

            final JSONObject pagination = new JSONObject();
            final List<Integer> pageNums = Paginator.paginate(currentPageNum, pageSize, pageCount, windowSize);

            pagination.put(Pagination.PAGINATION_PAGE_COUNT, pageCount);
            pagination.put(Pagination.PAGINATION_PAGE_NUMS, pageNums);

            final JSONArray links = result.getJSONArray(Keys.RESULTS);

            ret.put(Pagination.PAGINATION, pagination);
            ret.put(Link.LINKS, links);

            return ret;
        } catch (final Exception e) {
            LOGGER.log(Level.ERROR, "Gets links failed", e);
            throw new ServiceException(e);
        }
    }

    /**
     * Gets a link by the specified link id.
     *
     * @param linkId the specified link id
     * @return for example,
     * <pre>
     * {
     *     "link": {
     *         "oId": "",
     *         "linkTitle": "",
     *         "linkAddress": "",
     *         "linkDescription": ""
     *     }
     * }
     * </pre>, returns {@code null} if not found
     * @throws ServiceException service exception
     */
    public JSONObject getLink(final String linkId) throws ServiceException {
        final JSONObject ret = new JSONObject();

        try {
            final JSONObject link = linkRepository.get(linkId);

            if (null == link) {
                return null;
            }

            ret.put(Link.LINK, link);

            return ret;
        } catch (final Exception e) {
            LOGGER.log(Level.ERROR, "Gets a link failed", e);

            throw new ServiceException(e);
        }
    }
}
