/**
    * 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.hadoop.hbase.security.visibility;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.security.User;
  
  /**
   * This ScanLabelGenerator enforces a set of predefined authorizations for a
   * given user, the set defined by the admin using the VisibilityClient admin
   * interface or the set_auths shell command. Any authorizations requested with
   * Scan#authorizations will be ignored.
   */
  @InterfaceAudience.Private
  public class EnforcingScanLabelGenerator implements ScanLabelGenerator {
  
    private static final Log LOG = LogFactory.getLog(EnforcingScanLabelGenerator.class);
  
    private Configuration conf;
    private VisibilityLabelsCache labelsCache;
  
    public EnforcingScanLabelGenerator() {
      this.labelsCache = VisibilityLabelsCache.get();
    }
  
    @Override
    public void setConf(Configuration conf) {
      this.conf = conf;
    }
  
    @Override
    public Configuration getConf() {
      return this.conf;
    }
  
    @Override
    public List<String> getLabels(User user, Authorizations authorizations) {
      String userName = user.getShortName();
      if (authorizations != null) {
        LOG.warn("Dropping authorizations requested by user " + userName + ": " + authorizations);
      }
      Set<String> auths = new HashSet<String>();
      auths.addAll(this.labelsCache.getUserAuths(userName));
      auths.addAll(this.labelsCache.getGroupAuths(user.getGroupNames()));
      return new ArrayList<String>(auths);
    }
  
  }