/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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.apache.logging.log4j.core.lookup;
  
  import java.util.Objects;
  
  import javax.naming.NamingException;
  
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.Marker;
  import org.apache.logging.log4j.MarkerManager;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.net.JndiManager;
  import org.apache.logging.log4j.status.StatusLogger;
  
  /**
   * Looks up keys from JNDI resources.
   */
  @Plugin(name = "jndi", category = StrLookup.CATEGORY)
  public class JndiLookup extends AbstractLookup {
  
      private static final Logger LOGGER = StatusLogger.getLogger();
      private static final Marker LOOKUP = MarkerManager.getMarker("LOOKUP");
  
      /** JNDI resource path prefix used in a J2EE container */
      static final String CONTAINER_JNDI_RESOURCE_PATH_PREFIX = "java:comp/env/";
  
      /**
       * Constructs a new instance or throw IllegalStateException if this feature is disabled.
       */
      public JndiLookup() {
          if (!JndiManager.isJndiLookupEnabled()) {
              throw new IllegalStateException("JNDI must be enabled by setting log4j2.enableJndiLookup=true");
          }
      }
  
      /**
       * Looks up the value of the JNDI resource.
       * 
       * @param event The current LogEvent (is ignored by this StrLookup).
       * @param key the JNDI resource name to be looked up, may be null
       * @return The String value of the JNDI resource.
       */
      @Override
      public String lookup(final LogEvent event, final String key) {
          if (key == null) {
              return null;
          }
          final String jndiName = convertJndiName(key);
          try (final JndiManager jndiManager = JndiManager.getDefaultManager()) {
              return Objects.toString(jndiManager.lookup(jndiName), null);
          } catch (final NamingException e) {
              LOGGER.warn(LOOKUP, "Error looking up JNDI resource [{}].", jndiName, e);
              return null;
          }
      }
  
      /**
       * Convert the given JNDI name to the actual JNDI name to use. Default implementation applies the "java:comp/env/"
       * prefix unless other scheme like "java:" is given.
       * 
       * @param jndiName The name of the resource.
       * @return The fully qualified name to look up.
       */
      private String convertJndiName(final String jndiName) {
          if (!jndiName.startsWith(CONTAINER_JNDI_RESOURCE_PATH_PREFIX) && jndiName.indexOf(':') == -1) {
              return CONTAINER_JNDI_RESOURCE_PATH_PREFIX + jndiName;
          }
          return jndiName;
      }
  }