/*
    * ====================================================================
    * 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.protocol;
  
  import java.io.IOException;
  import java.util.Collection;
  
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.EntityDetails;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpRequestInterceptor;
  import org.apache.hc.core5.http.Method;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  
  /**
   * Request interceptor that adds default request headers.
   *
   * @since 4.0
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  public class RequestDefaultHeaders implements HttpRequestInterceptor {
  
      private final Collection<? extends Header> defaultHeaders;
  
      /**
       * @since 4.3
       */
      public RequestDefaultHeaders(final Collection<? extends Header> defaultHeaders) {
          super();
          this.defaultHeaders = defaultHeaders;
      }
  
      public RequestDefaultHeaders() {
          this(null);
      }
  
      @Override
      public void process(final HttpRequest request, final EntityDetails entity, final HttpContext context)
              throws HttpException, IOException {
          Args.notNull(request, "HTTP request");
  
          final String method = request.getMethod();
          if (Method.CONNECT.isSame(method)) {
              return;
          }
  
          if (this.defaultHeaders != null) {
              for (final Header defHeader : this.defaultHeaders) {
                  if(!request.containsHeader(defHeader.getName())) {
                      request.addHeader(defHeader);
                  }
              }
          }
      }
  
  }