/* 
    * 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.esigate.http;
  
  import java.io.IOException;
  import java.util.Properties;
  
  import org.apache.http.HttpException;
  import org.apache.http.HttpStatus;
  import org.apache.http.client.methods.CloseableHttpResponse;
  import org.apache.http.client.methods.HttpExecutionAware;
  import org.apache.http.client.methods.HttpRequestWrapper;
  import org.apache.http.client.protocol.HttpClientContext;
  import org.apache.http.conn.routing.HttpRoute;
  import org.apache.http.impl.client.cache.CachingHttpClientBuilder;
  import org.apache.http.impl.execchain.ClientExecChain;
  import org.esigate.HttpErrorPage;
  import org.esigate.cache.CacheAdapter;
  import org.esigate.events.EventManager;
  import org.esigate.events.impl.FetchEvent;
  
  public class ProxyingHttpClientBuilder extends CachingHttpClientBuilder {
      private Properties properties;
      private EventManager eventManager;
      private boolean useCache = true;
  
      @Override
      protected ClientExecChain decorateMainExec(ClientExecChain mainExec) {
          ClientExecChain result = mainExec;
          result = addFetchEvent(result);
          if (useCache) {
              CacheAdapter cacheAdapter = new CacheAdapter();
              cacheAdapter.init(properties);
              result = cacheAdapter.wrapBackendHttpClient(result);
              result = super.decorateMainExec(result);
              result = cacheAdapter.wrapCachingHttpClient(result);
          }
          return result;
      }
  
      public void setUseCache(boolean useCache) {
          this.useCache = useCache;
      }
  
      public void setEventManager(EventManager eventManager) {
          this.eventManager = eventManager;
      }
  
      public Properties getProperties() {
          return properties;
      }
  
      public void setProperties(Properties properties) {
          this.properties = properties;
      }
  
      public EventManager getEventManager() {
          return eventManager;
      }
  
      public boolean isUseCache() {
          return useCache;
      }
  
      /**
       * Decorate with fetch event managements
       * 
       * @param wrapped
       * @return the decorated ClientExecChain
       */
      private ClientExecChain addFetchEvent(final ClientExecChain wrapped) {
          return new ClientExecChain() {
  
              @Override
              public CloseableHttpResponse execute(HttpRoute route, HttpRequestWrapper request,
                      HttpClientContext httpClientContext, HttpExecutionAware execAware) {
                  OutgoingRequestContext context = OutgoingRequestContext.adapt(httpClientContext);
                  // Create request event
                  FetchEvent fetchEvent = new FetchEvent(context, request);
  
                  eventManager.fire(EventManager.EVENT_FETCH_PRE, fetchEvent);
  
                  if (fetchEvent.isExit()) {
                      if (fetchEvent.getHttpResponse() == null) {
                          // Provide an error page in order to avoid a NullPointerException
                          fetchEvent.setHttpResponse(HttpErrorPage.generateHttpResponse(
                                 HttpStatus.SC_INTERNAL_SERVER_ERROR,
                                 "An extension stopped the processing of the request without providing a response"));
                     }
                 } else {
                     try {
                         fetchEvent.setHttpResponse(wrapped.execute(route, request, context, execAware));
                     } catch (IOException | HttpException e) {
                         fetchEvent.setHttpResponse(HttpErrorPage.generateHttpResponse(e));
                     }
                 }
 
                 // Update the event and fire post event
                 eventManager.fire(EventManager.EVENT_FETCH_POST, fetchEvent);
 
                 return fetchEvent.getHttpResponse();
             }
         };
 
     }
 }