/*
    * ====================================================================
    * 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;
  
  import java.util.Iterator;
  
  import org.apache.hc.client5.http.ConnectionKeepAliveStrategy;
  import org.apache.hc.client5.http.config.RequestConfig;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.HeaderElement;
  import org.apache.hc.core5.http.HeaderElements;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.message.MessageSupport;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.TimeValue;
  
  /**
   * Default implementation of a strategy deciding duration
   * that a connection can remain idle.
   * <p>
   * The default implementation looks solely at the 'Keep-Alive'
   * header's timeout token.
   * </p>
   *
   * @since 4.0
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  public class DefaultConnectionKeepAliveStrategy implements ConnectionKeepAliveStrategy {
  
      public static final DefaultConnectionKeepAliveStrategy INSTANCE = new DefaultConnectionKeepAliveStrategy();
  
      @Override
      public TimeValue getKeepAliveDuration(final HttpResponse response, final HttpContext context) {
          Args.notNull(response, "HTTP response");
          final Iterator<HeaderElement> it = MessageSupport.iterate(response, HeaderElements.KEEP_ALIVE);
          while (it.hasNext()) {
              final HeaderElement he = it.next();
              final String param = he.getName();
              final String value = he.getValue();
              if (value != null && param.equalsIgnoreCase("timeout")) {
                  try {
                      return TimeValue.ofSeconds(Long.parseLong(value));
                  } catch(final NumberFormatException ignore) {
                  }
              }
          }
          final HttpClientContext clientContext = HttpClientContext.adapt(context);
          final RequestConfig requestConfig = clientContext.getRequestConfig();
          return requestConfig.getConnectionKeepAlive();
      }
  
  }