/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.http.impl.client.cache;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.http.Header;
  import org.apache.http.HttpException;
  import org.apache.http.HttpResponse;
  import org.apache.http.client.cache.HeaderConstants;
  import org.apache.http.client.cache.HttpCacheEntry;
  import org.apache.http.client.methods.HttpExecutionAware;
  import org.apache.http.client.methods.HttpRequestWrapper;
  import org.apache.http.client.methods.CloseableHttpResponse;
  import org.apache.http.client.protocol.HttpClientContext;
  import org.apache.http.conn.routing.HttpRoute;
  
  /**
   * Class used to represent an asynchronous revalidation event, such as with
   * "stale-while-revalidate"
   */
  public class AsynchronousValidationRequest implements Runnable {
      private final AsynchronousValidator parent;
      private final CachingExec cachingExec;
      private final HttpRoute route;
      private final HttpRequestWrapper request;
      private final HttpClientContext context;
      private final HttpExecutionAware execAware;
      private final HttpCacheEntry cacheEntry;
      private final String identifier;
      private final int consecutiveFailedAttempts;
  
      private final Log log = LogFactory.getLog(getClass());
  
      /**
       * Used internally by {@link AsynchronousValidator} to schedule a
       * revalidation.
       * @param request
       * @param context
       * @param cacheEntry
       * @param identifier
       * @param consecutiveFailedAttempts
       */
      AsynchronousValidationRequest(
              final AsynchronousValidator parent,
              final CachingExec cachingExec,
              final HttpRoute route,
              final HttpRequestWrapper request,
              final HttpClientContext context,
              final HttpExecutionAware execAware,
              final HttpCacheEntry cacheEntry,
              final String identifier,
              final int consecutiveFailedAttempts) {
          this.parent = parent;
          this.cachingExec = cachingExec;
          this.route = route;
          this.request = request;
          this.context = context;
          this.execAware = execAware;
          this.cacheEntry = cacheEntry;
          this.identifier = identifier;
          this.consecutiveFailedAttempts = consecutiveFailedAttempts;
      }
  
      @Override
      public void run() {
          try {
              if (revalidateCacheEntry()) {
                  parent.jobSuccessful(identifier);
              } else {
                  parent.jobFailed(identifier);
              }
          } finally {
             parent.markComplete(identifier);
         }
     }
 
     /**
      * Revalidate the cache entry and return if the operation was successful.
      * Success means a connection to the server was established and replay did
      * not indicate a server error.
      * @return {@code true} if the cache entry was successfully validated;
      * otherwise {@code false}
      */
     private boolean revalidateCacheEntry() {
         try {
             final CloseableHttpResponse httpResponse = cachingExec.revalidateCacheEntry(route, request, context, execAware, cacheEntry);
             try {
                 final int statusCode = httpResponse.getStatusLine().getStatusCode();
                 return isNotServerError(statusCode) && isNotStale(httpResponse);
             } finally {
                 httpResponse.close();
             }
         } catch (final IOException ioe) {
             log.debug("Asynchronous revalidation failed due to I/O error", ioe);
             return false;
         } catch (final HttpException pe) {
             log.error("HTTP protocol exception during asynchronous revalidation", pe);
             return false;
         } catch (final RuntimeException re) {
             log.error("RuntimeException thrown during asynchronous revalidation: " + re);
             return false;
         }
     }
 
     /**
      * Return whether the status code indicates a server error or not.
      * @param statusCode the status code to be checked
      * @return if the status code indicates a server error or not
      */
     private boolean isNotServerError(final int statusCode) {
         return statusCode < 500;
     }
 
     /**
      * Try to detect if the returned response is generated from a stale cache entry.
      * @param httpResponse the response to be checked
      * @return whether the response is stale or not
      */
     private boolean isNotStale(final HttpResponse httpResponse) {
         final Header[] warnings = httpResponse.getHeaders(HeaderConstants.WARNING);
         if (warnings != null)
         {
             for (final Header warning : warnings)
             {
                 /**
                  * warn-codes
                  * 110 = Response is stale
                  * 111 = Revalidation failed
                  */
                 final String warningValue = warning.getValue();
                 if (warningValue.startsWith("110") || warningValue.startsWith("111"))
                 {
                     return false;
                 }
             }
         }
         return true;
     }
 
     public String getIdentifier() {
         return identifier;
     }
 
     /**
      * The number of consecutively failed revalidation attempts.
      * @return the number of consecutively failed revalidation attempts.
      */
     public int getConsecutiveFailedAttempts() {
         return consecutiveFailedAttempts;
     }
 
 }