/*
    * ====================================================================
    * 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.core5.http.protocol;
  
  import java.io.IOException;
  import java.net.URISyntaxException;
  
  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.HttpHeaders;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpRequestInterceptor;
  import org.apache.hc.core5.http.HttpVersion;
  import org.apache.hc.core5.http.ProtocolException;
  import org.apache.hc.core5.http.ProtocolVersion;
  import org.apache.hc.core5.net.URIAuthority;
  import org.apache.hc.core5.util.Args;
  
  /**
   * This request interceptor is responsible for copying {@code Host} header value to
   * {@link HttpRequest#setAuthority(URIAuthority)} of incoming request messages.
   * <p>
   * This interceptor is essential for the HTTP protocol conformance and
   * the correct operation of the server-side message processing pipeline.
   * </p>
   *
   * @since 5.0
   */
  @Contract(threading = ThreadingBehavior.IMMUTABLE)
  public class RequestValidateHost implements HttpRequestInterceptor {
  
      public static final RequestValidateHost INSTANCE = new RequestValidateHost();
  
      public RequestValidateHost() {
          super();
      }
  
      @Override
      public void process(final HttpRequest request, final EntityDetails entity, final HttpContext context)
              throws HttpException, IOException {
          Args.notNull(request, "HTTP request");
  
          // Request authority already specified (likely in an absolute request URI)
          if (request.getAuthority() != null) {
              return;
          }
  
          final Header header = request.getHeader(HttpHeaders.HOST);
          if (header != null) {
              final URIAuthority authority;
              try {
                  authority = URIAuthority.create(header.getValue());
              } catch (final URISyntaxException ex) {
                  throw new ProtocolException(ex.getMessage(), ex);
              }
              request.setAuthority(authority);
          } else {
              final ProtocolVersion version = request.getVersion() != null ? request.getVersion() : HttpVersion.HTTP_1_1;
              if (version.greaterEquals(HttpVersion.HTTP_1_1)) {
                  throw new ProtocolException("Host header is absent");
              }
          }
      }
  
  }