/*
    * 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.timer;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.codelibs.core.timer.TimeoutTarget;
  import org.codelibs.fess.helper.LogNotificationHelper;
  import org.codelibs.fess.helper.LogNotificationHelper.LogNotificationEvent;
  import org.codelibs.fess.opensearch.client.SearchEngineClient;
  import org.codelibs.fess.util.ComponentUtil;
  import org.opensearch.action.bulk.BulkRequestBuilder;
  import org.opensearch.action.bulk.BulkResponse;
  
  /**
   * A timer target that periodically flushes buffered log notification events
   * to an OpenSearch index for downstream processing.
   */
  public class LogNotificationTarget implements TimeoutTarget {
  
      /**
       * Default constructor.
       */
      public LogNotificationTarget() {
          // Default constructor
      }
  
      private static final Logger logger = LogManager.getLogger(LogNotificationTarget.class);
      private static final String NOTIFICATION_QUEUE_INDEX = "fess_log.notification_queue";
      private static final int BATCH_SIZE = 100;
      private volatile boolean indexChecked = false;
  
      @Override
      public void expired() {
          try {
              if (!ComponentUtil.getFessConfig().isLogNotificationEnabled()) {
                  return;
              }
          } catch (final Exception e) {
              return;
          }
  
          final LogNotificationHelper helper;
          try {
              helper = ComponentUtil.getLogNotificationHelper();
          } catch (final Exception e) {
              return;
          }
  
          final List<LogNotificationEvent> events = helper.drainAll();
          if (events.isEmpty()) {
              return;
          }
  
          try {
              final SearchEngineClient client = ComponentUtil.getSearchEngineClient();
              final String hostname = ComponentUtil.getSystemHelper().getHostname();
              final String indexName = resolveIndexName();
  
              ensureIndexExists(client, indexName);
  
              for (int i = 0; i < events.size(); i += BATCH_SIZE) {
                  final List<LogNotificationEvent> batch = events.subList(i, Math.min(i + BATCH_SIZE, events.size()));
                  final BulkRequestBuilder bulkRequest = client.prepareBulk();
                  for (final LogNotificationEvent event : batch) {
                      final Map<String, Object> source = new HashMap<>();
                      source.put("hostname", hostname);
                      source.put("level", event.getLevel());
                      source.put("loggerName", event.getLoggerName());
                      source.put("message", event.getMessage());
                      source.put("throwable", event.getThrowable() != null ? event.getThrowable() : "");
                      source.put("timestamp", event.getTimestamp());
                      bulkRequest.add(client.prepareIndex().setIndex(indexName).setSource(source));
                  }
                  final BulkResponse response = bulkRequest.execute().actionGet(30_000L);
                  if (response.hasFailures()) {
                      logger.warn("Failed to write log notifications: {}", response.buildFailureMessage());
                  }
              }
          } catch (final Exception e) {
              logger.debug("Failed to flush log notifications to OpenSearch.", e);
          }
     }
 
     /**
      * Flushes all buffered log notification events immediately.
      */
     public void flush() {
         expired();
     }
 
     private String resolveIndexName() {
         return ComponentUtil.getFessConfig().getIndexLogIndex() + ".notification_queue";
     }
 
     private void ensureIndexExists(final SearchEngineClient client, final String indexName) {
         if (!indexChecked) {
             if (!client.existsIndex(indexName)) {
                 client.createIndex(NOTIFICATION_QUEUE_INDEX, indexName);
             }
             indexChecked = true;
         }
     }
 }