/*
    * ====================================================================
    * 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.security.Principal;
  
  import javax.net.ssl.SSLSession;
  
  import org.apache.hc.client5.http.HttpRoute;
  import org.apache.hc.client5.http.UserTokenHandler;
  import org.apache.hc.client5.http.auth.AuthExchange;
  import org.apache.hc.client5.http.auth.AuthScheme;
  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.HttpHost;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.protocol.HttpContext;
  
  /**
   * Default implementation of {@link UserTokenHandler}. This class will use
   * an instance of {@link Principal} as a state object for HTTP connections,
   * if it can be obtained from the given execution context. This helps ensure
   * persistent connections created with a particular user identity within
   * a particular security context can be reused by the same user only.
   * <p>
   * DefaultUserTokenHandler will use the user principal of connection
   * based authentication schemes such as NTLM or that of the SSL session
   * with the client authentication turned on. If both are unavailable,
   * {@code null} token will be returned.
   * </p>
   *
   * @since 4.0
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  public class DefaultUserTokenHandler implements UserTokenHandler {
  
      public static final DefaultUserTokenHandler INSTANCE = new DefaultUserTokenHandler();
  
      @Override
      public Object getUserToken(final HttpRoute route, final HttpContext context) {
          return getUserToken(route, null, context);
      }
  
      @Override
      public Object getUserToken(final HttpRoute route, final HttpRequest request, final HttpContext context) {
  
          final HttpClientContext clientContext = HttpClientContext.adapt(context);
  
          final HttpHost target = request != null ? new HttpHost(request.getScheme(), request.getAuthority()) : route.getTargetHost();
  
          final AuthExchange targetAuthExchange = clientContext.getAuthExchange(target);
          if (targetAuthExchange != null) {
              final Principal authPrincipal = getAuthPrincipal(targetAuthExchange);
              if (authPrincipal != null) {
                  return authPrincipal;
              }
          }
          final HttpHost proxy = route.getProxyHost();
          if (proxy != null) {
              final AuthExchange proxyAuthExchange = clientContext.getAuthExchange(proxy);
              if (proxyAuthExchange != null) {
                  final Principal authPrincipal = getAuthPrincipal(proxyAuthExchange);
                  if (authPrincipal != null) {
                      return authPrincipal;
                  }
              }
          }
          final SSLSession sslSession = clientContext.getSSLSession();
          if (sslSession != null) {
              return sslSession.getLocalPrincipal();
          }
          return null;
      }
  
     private static Principal getAuthPrincipal(final AuthExchange authExchange) {
         final AuthScheme scheme = authExchange.getAuthScheme();
         if (scheme != null && scheme.isConnectionBased()) {
             return scheme.getPrincipal();
         }
         return null;
     }
 
 }