/*
    * Copyright 2012-2025 CodeLibs Project and the Others.
    *
    * 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.codelibs.fess.crawler.service;
  
  import java.util.List;
  import java.util.Map;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.codelibs.fess.crawler.entity.OpenSearchUrlQueue;
  import org.codelibs.fess.crawler.service.impl.OpenSearchUrlQueueService;
  import org.codelibs.fess.crawler.util.OpenSearchCrawlerConfig;
  import org.codelibs.fess.helper.CrawlingConfigHelper;
  import org.codelibs.fess.opensearch.config.exentity.CrawlingConfig;
  import org.codelibs.fess.opensearch.config.exentity.CrawlingConfig.ConfigName;
  import org.codelibs.fess.util.ComponentUtil;
  import org.opensearch.index.query.QueryBuilders;
  import org.opensearch.index.query.functionscore.FunctionScoreQueryBuilder;
  import org.opensearch.index.query.functionscore.RandomScoreFunctionBuilder;
  import org.opensearch.search.sort.SortBuilders;
  import org.opensearch.search.sort.SortOrder;
  
  /**
   * Fess-specific URL queue service that extends OpenSearch URL queue functionality.
   * This service provides customized URL fetching strategies including sequential and random ordering
   * based on crawling configuration parameters.
   */
  public class FessUrlQueueService extends OpenSearchUrlQueueService {
  
      private static final Logger logger = LogManager.getLogger(FessUrlQueueService.class);
  
      /** Configuration value for sequential URL processing order */
      protected static final String ORDER_SEQUENTIAL = "sequential";
  
      /** Configuration value for random URL processing order */
      protected static final String ORDER_RANDOM = "random";
  
      /**
       * Constructs a new FessUrlQueueService with the specified crawler configuration.
       *
       * @param crawlerConfig the OpenSearch crawler configuration
       */
      public FessUrlQueueService(final OpenSearchCrawlerConfig crawlerConfig) {
          super(crawlerConfig);
      }
  
      /**
       * Fetches URL queue list for the specified session with configurable ordering strategy.
       * Supports sequential (default) and random ordering based on crawling configuration.
       *
       * @param sessionId the crawling session identifier
       * @return list of URL queue entries for processing
       */
      @Override
      protected List<OpenSearchUrlQueue> fetchUrlQueueList(final String sessionId) {
          final CrawlingConfigHelper crawlingConfigHelper = ComponentUtil.getCrawlingConfigHelper();
          final CrawlingConfig crawlingConfig = crawlingConfigHelper.get(sessionId);
          final Map<String, String> configParams = crawlingConfig.getConfigParameterMap(ConfigName.CONFIG);
          final String crawlOrder = configParams.getOrDefault(CrawlingConfig.Param.Config.CRAWL_ORDER, ORDER_SEQUENTIAL);
          if (ORDER_RANDOM.equals(crawlOrder)) {
              return getList(OpenSearchUrlQueue.class, sessionId,
                      QueryBuilders.functionScoreQuery(QueryBuilders.matchAllQuery(),
                              new FunctionScoreQueryBuilder.FilterFunctionBuilder[] { new FunctionScoreQueryBuilder.FilterFunctionBuilder(
                                      new RandomScoreFunctionBuilder().seed(sessionId.hashCode())) }),
                      0, pollingFetchSize, SortBuilders.scoreSort().order(SortOrder.DESC));
          } else if (!ORDER_SEQUENTIAL.equals(crawlOrder)) {
              logger.warn("Invalid crawl order specified: {}. Falling back to sequential.", crawlOrder);
          }
          return super.fetchUrlQueueList(sessionId);
      }
  }