/*
    * ====================================================================
    * 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.hc.client5.http.impl.async;
  
  import java.io.IOException;
  
  import org.apache.hc.client5.http.HttpRequestRetryStrategy;
  import org.apache.hc.client5.http.HttpRoute;
  import org.apache.hc.client5.http.async.AsyncExecCallback;
  import org.apache.hc.client5.http.async.AsyncExecChain;
  import org.apache.hc.client5.http.async.AsyncExecChainHandler;
  import org.apache.hc.client5.http.impl.RequestCopier;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.Internal;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.EntityDetails;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.nio.AsyncDataConsumer;
  import org.apache.hc.core5.http.nio.AsyncEntityProducer;
  import org.apache.hc.core5.http.nio.entity.NoopEntityConsumer;
  import org.apache.hc.core5.util.Args;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Request executor in the asynchronous request execution chain that is
   * responsible for making a decision whether a request that failed due to
   * an I/O exception or received a specific response from the target server should
   * be re-executed. Note that this exec chain handler <em>will not</em> respect
   * {@link HttpRequestRetryStrategy#getRetryInterval(HttpResponse, int, org.apache.hc.core5.http.protocol.HttpContext)}.
   * <p>
   * Further responsibilities such as communication with the opposite
   * endpoint is delegated to the next executor in the request execution
   * chain.
   * </p>
   *
   * @since 5.0
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  @Internal
  public final class AsyncHttpRequestRetryExec implements AsyncExecChainHandler {
  
      private static final Logger LOG = LoggerFactory.getLogger(AsyncHttpRequestRetryExec.class);
  
      private final HttpRequestRetryStrategy retryStrategy;
  
      public AsyncHttpRequestRetryExec(final HttpRequestRetryStrategy retryStrategy) {
          Args.notNull(retryStrategy, "retryStrategy");
          this.retryStrategy = retryStrategy;
      }
  
      private static class State {
  
          volatile int execCount;
          volatile boolean retrying;
  
      }
  
      private void internalExecute(
              final State state,
              final HttpRequest request,
              final AsyncEntityProducer entityProducer,
              final AsyncExecChain.Scope scope,
              final AsyncExecChain chain,
              final AsyncExecCallback asyncExecCallback) throws HttpException, IOException {
  
          final String exchangeId = scope.exchangeId;
  
          chain.proceed(RequestCopier.INSTANCE.copy(request), entityProducer, scope, new AsyncExecCallback() {
  
              @Override
              public AsyncDataConsumer handleResponse(
                     final HttpResponse response,
                     final EntityDetails entityDetails) throws HttpException, IOException {
                 final HttpClientContext clientContext = scope.clientContext;
                 if (entityProducer != null && !entityProducer.isRepeatable()) {
                     if (LOG.isDebugEnabled()) {
                         LOG.debug("{}: cannot retry non-repeatable request", exchangeId);
                     }
                     return asyncExecCallback.handleResponse(response, entityDetails);
                 }
                 state.retrying = retryStrategy.retryRequest(response, state.execCount, clientContext);
                 if (state.retrying) {
                     return new NoopEntityConsumer();
                 } else {
                     return asyncExecCallback.handleResponse(response, entityDetails);
                 }
             }
 
             @Override
             public void handleInformationResponse(final HttpResponse response) throws HttpException, IOException {
                 asyncExecCallback.handleInformationResponse(response);
             }
 
             @Override
             public void completed() {
                 if (state.retrying) {
                     state.execCount++;
                     try {
                         internalExecute(state, request, entityProducer, scope, chain, asyncExecCallback);
                     } catch (final IOException | HttpException ex) {
                         asyncExecCallback.failed(ex);
                     }
                 } else {
                     asyncExecCallback.completed();
                 }
             }
 
             @Override
             public void failed(final Exception cause) {
                 if (cause instanceof IOException) {
                     final HttpRoute route = scope.route;
                     final HttpClientContext clientContext = scope.clientContext;
                     if (entityProducer != null && !entityProducer.isRepeatable()) {
                         if (LOG.isDebugEnabled()) {
                             LOG.debug("{}: cannot retry non-repeatable request", exchangeId);
                         }
                     } else if (retryStrategy.retryRequest(request, (IOException) cause, state.execCount, clientContext)) {
                         if (LOG.isDebugEnabled()) {
                             LOG.debug("{}: {}", exchangeId, cause.getMessage(), cause);
                         }
                         if (LOG.isInfoEnabled()) {
                             LOG.info("Recoverable I/O exception ({}) caught when processing request to {}",
                                     cause.getClass().getName(), route);
                         }
                         try {
                             scope.execRuntime.discardEndpoint();
                             if (entityProducer != null) {
                                 entityProducer.releaseResources();
                             }
                             state.retrying = true;
                             state.execCount++;
                             internalExecute(state, request, entityProducer, scope, chain, asyncExecCallback);
                         } catch (final Exception ex) {
                             asyncExecCallback.failed(ex);
                         }
                         return;
                     }
                 }
                 asyncExecCallback.failed(cause);
             }
 
         });
 
     }
 
     @Override
     public void execute(
             final HttpRequest request,
             final AsyncEntityProducer entityProducer,
             final AsyncExecChain.Scope scope,
             final AsyncExecChain chain,
             final AsyncExecCallback asyncExecCallback) throws HttpException, IOException {
         final State state = new State();
         state.execCount = 1;
         state.retrying = false;
         internalExecute(state, request, entityProducer, scope, chain, asyncExecCallback);
     }
 
 }