content: /*
   * 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.camel.language.xpath;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import javax.xml.namespace.QName;
  import javax.xml.xpath.XPathVariableResolver;
  
  import org.apache.camel.Exchange;
  import org.apache.camel.Message;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.apache.camel.support.builder.Namespaces.ENVIRONMENT_VARIABLES;
  import static org.apache.camel.support.builder.Namespaces.EXCHANGE_PROPERTY;
  import static org.apache.camel.support.builder.Namespaces.IN_NAMESPACE;
  import static org.apache.camel.support.builder.Namespaces.OUT_NAMESPACE;
  import static org.apache.camel.support.builder.Namespaces.SYSTEM_PROPERTIES_NAMESPACE;
  
  /**
   * A variable resolver for XPath expressions which support properties on the message, exchange as well as making system
   * properties and environment properties available.
   * <p/>
   * Implementations of this resolver must be thread safe
   */
  public class MessageVariableResolver implements XPathVariableResolver {
      private static final Logger LOG = LoggerFactory.getLogger(MessageVariableResolver.class);
  
      private Map<String, Object> variables = new HashMap<>();
      private final ThreadLocal<Exchange> exchange;
  
      public MessageVariableResolver(ThreadLocal<Exchange> exchange) {
          this.exchange = exchange;
      }
  
      @Override
      public Object resolveVariable(QName name) {
          String uri = name.getNamespaceURI();
          String localPart = name.getLocalPart();
          Object answer = null;
  
          Message in = exchange.get().getIn();
          if (uri == null || uri.isEmpty()) {
              answer = variables.get(localPart);
              if (answer == null) {
                  if (in != null) {
                      answer = in.getHeader(localPart);
                  }
                  if (answer == null) {
                      answer = exchange.get().getProperty(localPart);
                  }
              }
          } else if (uri.equals(SYSTEM_PROPERTIES_NAMESPACE)) {
              try {
                  answer = System.getProperty(localPart);
              } catch (Exception e) {
                  LOG.debug("Security exception evaluating system property: {}. Reason: {}", localPart, e.getMessage(), e);
              }
          } else if (uri.equals(ENVIRONMENT_VARIABLES)) {
              answer = System.getenv().get(localPart);
          } else if (uri.equals(EXCHANGE_PROPERTY)) {
              answer = exchange.get().getProperty(localPart);
          } else if (uri.equals(IN_NAMESPACE)) {
              answer = in.getHeader(localPart);
              if (answer == null && localPart.equals("body")) {
                  answer = in.getBody();
              }
          } else if (uri.equals(OUT_NAMESPACE)) {
              if (exchange.get().hasOut()) {
                  Message out = exchange.get().getOut();
                  answer = out.getHeader(localPart);
                  if (answer == null && localPart.equals("body")) {
                      answer = out.getBody();
                  }
              }
          }
  
          // if we can't find an answer we must return an empty String.
          // if we return null, then the JDK default XPathEngine will throw an exception
          if (answer == null) {
              return "";
          } else {
              return answer;
          }
      }
  
      public void addVariable(String localPart, Object value) {
          variables.put(localPart, value);
      }
  }
  