content: /*
   * Solo - A small and beautiful blogging system written in Java.
   * Copyright (c) 2010-present, b3log.org
   *
   * Solo is licensed under Mulan PSL v2.
   * You can use this software according to the terms and conditions of the Mulan PSL v2.
   * You may obtain a copy of Mulan PSL v2 at:
   *         http://license.coscl.org.cn/MulanPSL2
   * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
   * See the Mulan PSL v2 for more details.
   */
  package org.b3log.solo.repository;
  
  import org.b3log.latke.repository.*;
  import org.b3log.latke.repository.annotation.Repository;
  import org.b3log.solo.model.Link;
  import org.json.JSONObject;
  
  /**
   * Link repository.
   *
   * @author <a href="http://88250.b3log.org">Liang Ding</a>
   * @version 1.0.0.5, Jan 15, 2019
   * @since 0.3.1
   */
  @Repository
  public class LinkRepository extends AbstractRepository {
  
      /**
       * Public constructor.
       */
      public LinkRepository() {
          super(Link.LINK);
      }
  
      /**
       * Gets a link by the specified address.
       *
       * @param address the specified address
       * @return link, returns {@code null} if not found
       * @throws RepositoryException repository exception
       */
      public JSONObject getByAddress(final String address) throws RepositoryException {
          final Query query = new Query().setFilter(new PropertyFilter(Link.LINK_ADDRESS, FilterOperator.EQUAL, address)).setPageCount(1);
          return getFirst(query);
      }
  
      /**
       * Gets the maximum order.
       *
       * @return order number, returns {@code -1} if not found
       * @throws RepositoryException repository exception
       */
      public int getMaxOrder() throws RepositoryException {
          final Query query = new Query().addSort(Link.LINK_ORDER, SortDirection.DESCENDING);
          final JSONObject result = getFirst(query);
          if (null == result) {
              return -1;
          }
          return result.optInt(Link.LINK_ORDER);
      }
  
      /**
       * Gets the upper link of the link specified by the given id.
       *
       * @param id the given id
       * @return upper link, returns {@code null} if not found
       * @throws RepositoryException repository exception
       */
      public JSONObject getUpper(final String id) throws RepositoryException {
          final JSONObject link = get(id);
          if (null == link) {
              return null;
          }
  
          final Query query = new Query().setFilter(new PropertyFilter(Link.LINK_ORDER, FilterOperator.LESS_THAN, link.optInt(Link.LINK_ORDER))).
                  addSort(Link.LINK_ORDER, SortDirection.DESCENDING).setPage(1, 1);
          return getFirst(query);
      }
  
      /**
       * Gets the under link of the link specified by the given id.
       *
       * @param id the given id
       * @return under link, returns {@code null} if not found
       * @throws RepositoryException repository exception
       */
      public JSONObject getUnder(final String id) throws RepositoryException {
          final JSONObject link = get(id);
          if (null == link) {
              return null;
          }
  
          final Query query = new Query().setFilter(new PropertyFilter(Link.LINK_ORDER, FilterOperator.GREATER_THAN, link.optInt(Link.LINK_ORDER))).
                  addSort(Link.LINK_ORDER, SortDirection.ASCENDING).setPage(1, 1);
          return getFirst(query);
      }
  
      /**
       * Gets a link by the specified order.
       *
       * @param order the specified order
       * @return link, returns {@code null} if not found
       * @throws RepositoryException repository exception
       */
      public JSONObject getByOrder(final int order) throws RepositoryException {
          final Query query = new Query().setFilter(new PropertyFilter(Link.LINK_ORDER, FilterOperator.EQUAL, order));
          return getFirst(query);
      }
  }
  