/*
    * Copyright 2012-2021 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.util;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.function.Function;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.codelibs.fesen.common.xcontent.ToXContent;
  import org.codelibs.fesen.common.xcontent.XContentBuilder;
  import org.codelibs.fesen.common.xcontent.XContentFactory;
  import org.codelibs.fesen.common.xcontent.XContentType;
  import org.codelibs.fesen.search.SearchHit;
  import org.codelibs.fess.es.client.SearchEngineClient;
  
  public final class SearchEngineUtil {
  
      private static final Logger logger = LogManager.getLogger(SearchEngineUtil.class);
  
      private SearchEngineUtil() {
      }
  
      public static OutputStream getXContentBuilderOutputStream(final XContentBuilderCallback func, final XContentType xContentType) {
          try (final XContentBuilder builder = func.apply(XContentFactory.contentBuilder(xContentType), ToXContent.EMPTY_PARAMS)) {
              builder.flush();
              return builder.getOutputStream();
          } catch (final IOException e) {
              if (logger.isDebugEnabled()) {
                  logger.debug("Failed to print the output.", e);
              }
              return new ByteArrayOutputStream();
          }
      }
  
      public static OutputStream getXContentOutputStream(final ToXContent xContent, final XContentType xContentType) {
          return getXContentBuilderOutputStream((builder, params) -> xContent.toXContent(builder, params), xContentType);
      }
  
      public static long scroll(final String index, final Function<SearchHit, Boolean> callback) {
          final SearchEngineClient client = ComponentUtil.getSearchEngineClient();
          return client.<SearchHit> scrollSearch(index, searchRequestBuilder -> true, (searchResponse, hit) -> hit,
                  hit -> callback.apply(hit));
      }
  
      public interface XContentBuilderCallback {
          XContentBuilder apply(XContentBuilder builder, ToXContent.Params params) throws IOException;
      }
  
  }