/*
    * ====================================================================
    * 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.classic;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  
  import org.apache.hc.client5.http.ConnectionKeepAliveStrategy;
  import org.apache.hc.client5.http.HttpRoute;
  import org.apache.hc.client5.http.UserTokenHandler;
  import org.apache.hc.client5.http.classic.ExecChain;
  import org.apache.hc.client5.http.classic.ExecChainHandler;
  import org.apache.hc.client5.http.classic.ExecRuntime;
  import org.apache.hc.client5.http.impl.ConnectionShutdownException;
  import org.apache.hc.client5.http.io.HttpClientConnectionManager;
  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.ClassicHttpRequest;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.ConnectionReuseStrategy;
  import org.apache.hc.core5.http.HttpEntity;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.message.RequestLine;
  import org.apache.hc.core5.io.CloseMode;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.TimeValue;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Usually the last request execution handler in the classic request execution
   * chain that is responsible for execution of request / response exchanges with
   * the opposite endpoint.
   *
   * @since 4.3
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  @Internal
  public final class MainClientExec implements ExecChainHandler {
  
      private static final Logger LOG = LoggerFactory.getLogger(MainClientExec.class);
  
      private final HttpClientConnectionManager connectionManager;
      private final ConnectionReuseStrategy reuseStrategy;
      private final ConnectionKeepAliveStrategy keepAliveStrategy;
      private final UserTokenHandler userTokenHandler;
  
      /**
       * @since 4.4
       */
      public MainClientExec(
              final HttpClientConnectionManager connectionManager,
              final ConnectionReuseStrategy reuseStrategy,
              final ConnectionKeepAliveStrategy keepAliveStrategy,
              final UserTokenHandler userTokenHandler) {
          this.connectionManager = Args.notNull(connectionManager, "Connection manager");
          this.reuseStrategy = Args.notNull(reuseStrategy, "Connection reuse strategy");
          this.keepAliveStrategy = Args.notNull(keepAliveStrategy, "Connection keep alive strategy");
          this.userTokenHandler = Args.notNull(userTokenHandler, "User token handler");
      }
  
      @Override
      public ClassicHttpResponse execute(
              final ClassicHttpRequest request,
              final ExecChain.Scope scope,
              final ExecChain chain) throws IOException, HttpException {
          Args.notNull(request, "HTTP request");
          Args.notNull(scope, "Scope");
          final String exchangeId = scope.exchangeId;
          final HttpRoute route = scope.route;
          final HttpClientContext context = scope.clientContext;
          final ExecRuntime execRuntime = scope.execRuntime;
 
         if (LOG.isDebugEnabled()) {
             LOG.debug("{} executing {}", exchangeId, new RequestLine(request));
         }
         try {
             final ClassicHttpResponse response = execRuntime.execute(exchangeId, request, context);
 
             Object userToken = context.getUserToken();
             if (userToken == null) {
                 userToken = userTokenHandler.getUserToken(route, context);
                 context.setAttribute(HttpClientContext.USER_TOKEN, userToken);
             }
 
             // The connection is in or can be brought to a re-usable state.
             if (reuseStrategy.keepAlive(request, response, context)) {
                 // Set the idle duration of this connection
                 final TimeValue duration = keepAliveStrategy.getKeepAliveDuration(response, context);
                 if (LOG.isDebugEnabled()) {
                     final String s;
                     if (duration != null) {
                         s = "for " + duration;
                     } else {
                         s = "indefinitely";
                     }
                     LOG.debug("{} connection can be kept alive {}", exchangeId, s);
                 }
                 execRuntime.markConnectionReusable(userToken, duration);
             } else {
                 execRuntime.markConnectionNonReusable();
             }
             // check for entity, release connection if possible
             final HttpEntity entity = response.getEntity();
             if (entity == null || !entity.isStreaming()) {
                 // connection not needed and (assumed to be) in re-usable state
                 execRuntime.releaseEndpoint();
                 return new CloseableHttpResponse(response, null);
             }
             return new CloseableHttpResponse(response, execRuntime);
         } catch (final ConnectionShutdownException ex) {
             final InterruptedIOException ioex = new InterruptedIOException(
                     "Connection has been shut down");
             ioex.initCause(ex);
             execRuntime.discardEndpoint();
             throw ioex;
         } catch (final HttpException | RuntimeException | IOException ex) {
             execRuntime.discardEndpoint();
             throw ex;
         } catch (final Error error) {
             connectionManager.close(CloseMode.IMMEDIATE);
             throw error;
         }
 
     }
 
 }