content: /*
   *  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.
   */
  package org.apache.causeway.security.keycloak.handler;
  
  import org.springframework.security.core.context.SecurityContextHolder;
  import org.springframework.security.oauth2.core.oidc.user.OidcUser;
  import org.springframework.stereotype.Service;
  import org.springframework.web.client.RestTemplate;
  import org.springframework.web.util.UriComponentsBuilder;
  
  import org.apache.causeway.core.security.authentication.logout.LogoutHandler;
  
  import lombok.RequiredArgsConstructor;
  
  import lombok.extern.slf4j.Slf4j;
  
  /**
   * Propagates logouts to Keycloak.
   *
   * <p>
   * Necessary because Spring Security 5 (currently) doesn't support
   * end-session-endpoints.
   * </p>
   */
  @Service
  @Slf4j
  @RequiredArgsConstructor
  public class LogoutHandlerForKeycloak implements LogoutHandler {
  
      private final RestTemplate restTemplate;
  
      public LogoutHandlerForKeycloak() {
          this(new RestTemplate());
      }
  
      @Override public void logout() {
          var authentication = SecurityContextHolder.getContext().getAuthentication();
          if (authentication != null) {
              propagateLogoutToKeycloak((OidcUser) authentication.getPrincipal());
          }
  
      }
      private void propagateLogoutToKeycloak(final OidcUser user) {
  
          var endSessionEndpoint = String.format("%s/protocol/openid-connect/logout", user.getIssuer());
  
          var builder = UriComponentsBuilder
                  .fromUriString(endSessionEndpoint)
                  .queryParam("id_token_hint", user.getIdToken().getTokenValue());
  
          var logoutResponse = restTemplate.getForEntity(builder.toUriString(), String.class);
          if (logoutResponse.getStatusCode().is2xxSuccessful()) {
              log.info("Successfully logged out in Keycloak");
          } else {
              log.info("Could not propagate logout to Keycloak");
          }
      }
  
  }
  