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.component.kafka;
  
  import org.apache.camel.CamelContext;
  import org.apache.camel.Exchange;
  import org.apache.camel.Processor;
  import org.apache.camel.spi.SendDynamicAware;
  import org.apache.camel.spi.annotations.SendDynamic;
  import org.apache.camel.support.service.ServiceSupport;
  import org.apache.camel.util.StringHelper;
  
  /**
   * Kafka based {@link org.apache.camel.spi.SendDynamicAware} which allows to optimise Kafka components with the toD
   * (dynamic to) DSL in Camel. This implementation optimises by allowing to provide dynamic parameters via
   * {@link KafkaConstants#OVERRIDE_TOPIC} header instead of the endpoint uri. That allows to use a static endpoint and
   * its producer to service dynamic requests.
   */
  @SendDynamic("kafka")
  public class KafkaSendDynamicAware extends ServiceSupport implements SendDynamicAware {
  
      private CamelContext camelContext;
      private String scheme;
  
      @Override
      public String getScheme() {
          return scheme;
      }
  
      @Override
      public void setScheme(String scheme) {
          this.scheme = scheme;
      }
  
      @Override
      public CamelContext getCamelContext() {
          return camelContext;
      }
  
      @Override
      public void setCamelContext(CamelContext camelContext) {
          this.camelContext = camelContext;
      }
  
      @Override
      public boolean isLenientProperties() {
          return false;
      }
  
      @Override
      public DynamicAwareEntry prepare(Exchange exchange, String uri, String originalUri) throws Exception {
          return new DynamicAwareEntry(uri, originalUri, null, null);
      }
  
      @Override
      public String resolveStaticUri(Exchange exchange, DynamicAwareEntry entry) throws Exception {
          String destination = parseTopicName(entry.getUri());
          if (destination != null) {
              String originalDestination = parseTopicName(entry.getOriginalUri());
              if (!destination.equals(originalDestination)) {
                  // okay the topic was dynamic, so use the original as endpoint name
                  String answer = entry.getUri();
                  answer = StringHelper.replaceFirst(answer, destination, originalDestination);
                  return answer;
              }
          }
          return null;
      }
  
      @Override
      public Processor createPreProcessor(Exchange exchange, DynamicAwareEntry entry) throws Exception {
          if (exchange.getMessage().getHeader(KafkaConstants.OVERRIDE_TOPIC) != null) {
              return null;
          }
  
          final String topicName = parseTopicName(entry.getUri());
          return new Processor() {
              @Override
              public void process(Exchange exchange) throws Exception {
                  exchange.getMessage().setHeader(KafkaConstants.OVERRIDE_TOPIC, topicName);
              }
          };
      }
  
      @Override
      public Processor createPostProcessor(Exchange exchange, DynamicAwareEntry entry) throws Exception {
          // no post processor is needed
          return null;
      }
  
      private String parseTopicName(String uri) {
          // strip query
          uri = StringHelper.before(uri, "?", uri);
  
          // topic name is after first colon
          int pos = uri.indexOf(':');
          if (pos != -1) {
              uri = uri.substring(pos + 1);
          } else {
              return null;
          }
          if (uri.startsWith("//")) {
              // strip leading slashes
              uri = uri.substring(2);
          }
          return uri;
      }
  
  }
  