content: /*
   * Symphony - A modern community (forum/BBS/SNS/blog) platform written in Java.
   * Copyright (C) 2012-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.symphony.repository;
  
  import org.apache.commons.codec.digest.DigestUtils;
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  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.annotation.Repository;
  import org.b3log.symphony.model.Link;
  import org.json.JSONObject;
  
  /**
   * Link repository.
   *
   * @author <a href="http://88250.b3log.org">Liang Ding</a>
   * @version 1.0.0.1, Oct 1, 2018
   * @since 1.6.0
   */
  @Repository
  public class LinkRepository extends AbstractRepository {
  
      /**
       * Logger.
       */
      private static final Logger LOGGER = LogManager.getLogger(LinkRepository.class);
  
      /**
       * Gets a link with the specified address.
       *
       * @param addr the specified address
       * @return a link, returns {@code null} if not found
       */
      public JSONObject getLink(final String addr) {
          final String hash = DigestUtils.sha1Hex(addr);
          final Query query = new Query().setFilter(new PropertyFilter(Link.LINK_ADDR_HASH, FilterOperator.EQUAL, hash)).
                  setPageCount(1).setPage(1, 1);
          try {
              return getFirst(query);
          } catch (final Exception e) {
              LOGGER.log(Level.ERROR, "Gets link by address [addr=" + addr + ", hash=" + hash + "] failed", e);
              return null;
          }
      }
  
      /**
       * Public constructor.
       */
      public LinkRepository() {
          super(Link.LINK);
      }
  }
  