/*
    * 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.syncope.ext.scimv2.cxf;
  
  import java.io.IOException;
  import java.time.OffsetDateTime;
  import javax.ws.rs.container.ContainerRequestContext;
  import javax.ws.rs.container.ContainerResponseContext;
  import javax.ws.rs.container.ContainerResponseFilter;
  import javax.ws.rs.core.EntityTag;
  import javax.ws.rs.core.HttpHeaders;
  import javax.ws.rs.ext.Provider;
  import org.apache.commons.lang3.StringUtils;
  import org.apache.syncope.ext.scimv2.api.data.SCIMGroup;
  import org.apache.syncope.ext.scimv2.api.data.SCIMUser;
  
  @Provider
  public class AddETagFilter implements ContainerResponseFilter {
  
      @Override
      public void filter(final ContainerRequestContext reqCtx, final ContainerResponseContext resCtx) throws IOException {
          if (resCtx.getEntityTag() == null) {
              OffsetDateTime lastModified;
              if (resCtx.getEntity() instanceof SCIMUser) {
                  lastModified = ((SCIMUser) resCtx.getEntity()).getMeta().getLastModified();
                  if (resCtx.getEntity() instanceof SCIMGroup) {
                      lastModified = ((SCIMGroup) resCtx.getEntity()).getMeta().getLastModified();
                  }
  
                  if (lastModified != null) {
                      String etagValue = String.valueOf(lastModified.toInstant().toEpochMilli());
                      if (StringUtils.isNotBlank(etagValue)) {
                          resCtx.getHeaders().add(HttpHeaders.ETAG, new EntityTag(etagValue, true).toString());
                      }
                  }
              }
          }
      }
  }