/*
    * ====================================================================
    * 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;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.net.URI;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.http.HttpHost;
  import org.apache.http.HttpRequest;
  import org.apache.http.HttpResponse;
  import org.apache.http.annotation.ThreadSafe;
  import org.apache.http.client.HttpClient;
  import org.apache.http.client.ResponseHandler;
  import org.apache.http.client.ServiceUnavailableRetryStrategy;
  import org.apache.http.client.methods.HttpUriRequest;
  import org.apache.http.conn.ClientConnectionManager;
  import org.apache.http.params.HttpParams;
  import org.apache.http.protocol.HttpContext;
  import org.apache.http.util.EntityUtils;
  
  /**
   * {@link HttpClient} implementation that can automatically retry the request in case of
   * a non-2xx response using the {@link ServiceUnavailableRetryStrategy} interface.
   *
   * @since 4.2
   */
  @ThreadSafe
  public class AutoRetryHttpClient implements HttpClient {
  
      private final HttpClient backend;
  
      private final ServiceUnavailableRetryStrategy retryStrategy;
  
      private final Log log = LogFactory.getLog(getClass());
  
      public AutoRetryHttpClient(
              final HttpClient client, final ServiceUnavailableRetryStrategy retryStrategy) {
          super();
          if (client == null) {
              throw new IllegalArgumentException("HttpClient may not be null");
          }
          if (retryStrategy == null) {
              throw new IllegalArgumentException(
                      "ServiceUnavailableRetryStrategy may not be null");
          }
          this.backend = client;
          this.retryStrategy = retryStrategy;
      }
  
      /**
       * Constructs a {@code AutoRetryHttpClient} with default caching settings that
       * stores cache entries in memory and uses a vanilla
       * {@link DefaultHttpClient} for backend requests.
       */
      public AutoRetryHttpClient() {
          this(new DefaultHttpClient(), new DefaultServiceUnavailableRetryStrategy());
      }
  
      /**
       * Constructs a {@code AutoRetryHttpClient} with the given caching options that
       * stores cache entries in memory and uses a vanilla
       * {@link DefaultHttpClient} for backend requests.
       *
       * @param config
       *            retry configuration module options
       */
      public AutoRetryHttpClient(ServiceUnavailableRetryStrategy config) {
          this(new DefaultHttpClient(), config);
      }
  
      /**
      * Constructs a {@code AutoRetryHttpClient} with default caching settings that
      * stores cache entries in memory and uses the given {@link HttpClient} for
      * backend requests.
      *
      * @param client
      *            used to make origin requests
      */
     public AutoRetryHttpClient(HttpClient client) {
         this(client, new DefaultServiceUnavailableRetryStrategy());
     }
 
     public HttpResponse execute(HttpHost target, HttpRequest request)
             throws IOException {
         HttpContext defaultContext = null;
         return execute(target, request, defaultContext);
     }
 
     public <T> T execute(HttpHost target, HttpRequest request,
             ResponseHandler<? extends T> responseHandler) throws IOException {
         return execute(target, request, responseHandler, null);
     }
 
     public <T> T execute(HttpHost target, HttpRequest request,
             ResponseHandler<? extends T> responseHandler, HttpContext context)
             throws IOException {
         HttpResponse resp = execute(target, request, context);
         return responseHandler.handleResponse(resp);
     }
 
     public HttpResponse execute(HttpUriRequest request) throws IOException {
         HttpContext context = null;
         return execute(request, context);
     }
 
     public HttpResponse execute(HttpUriRequest request, HttpContext context)
             throws IOException {
         URI uri = request.getURI();
         HttpHost httpHost = new HttpHost(uri.getHost(), uri.getPort(),
                 uri.getScheme());
         return execute(httpHost, request, context);
     }
 
     public <T> T execute(HttpUriRequest request,
             ResponseHandler<? extends T> responseHandler) throws IOException {
         return execute(request, responseHandler, null);
     }
 
     public <T> T execute(HttpUriRequest request,
             ResponseHandler<? extends T> responseHandler, HttpContext context)
             throws IOException {
         HttpResponse resp = execute(request, context);
         return responseHandler.handleResponse(resp);
     }
 
     public HttpResponse execute(HttpHost target, HttpRequest request,
             HttpContext context) throws IOException {
         for (int c = 1;; c++) {
             HttpResponse response = backend.execute(target, request, context);
             try {
                 if (retryStrategy.retryRequest(response, c, context)) {
                     EntityUtils.consume(response.getEntity());
                     long nextInterval = retryStrategy.getRetryInterval();
                     try {
                         log.trace("Wait for " + nextInterval);
                         Thread.sleep(nextInterval);
                     } catch (InterruptedException e) {
                         Thread.currentThread().interrupt();
                         throw new InterruptedIOException();
                     }
                 } else {
                     return response;
                 }
             } catch (RuntimeException ex) {
                 try {
                     EntityUtils.consume(response.getEntity());
                 } catch (IOException ioex) {
                     log.warn("I/O error consuming response content", ioex);
                 }
                 throw ex;
             }
         }
     }
 
     public ClientConnectionManager getConnectionManager() {
         return backend.getConnectionManager();
     }
 
     public HttpParams getParams() {
         return backend.getParams();
     }
 
 }