/**
    * 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;
  
  /**
   * If the passed in authorization is null, then this ScanLabelGenerator
   * feeds the set of predefined authorization labels for the given user. That is
   * the set defined by the admin using the VisibilityClient admin interface
   * or the set_auths shell command.
   * Otherwise the passed in authorization labels are returned with no change.
   *
   * Note: This SLG should not be used alone because it does not check
   * the passed in authorization labels against what the user is authorized for.
   */
  @InterfaceAudience.Private
  public class FeedUserAuthScanLabelGenerator implements ScanLabelGenerator {
  
    private static final Log LOG = LogFactory.getLog(FeedUserAuthScanLabelGenerator.class);
  
    private Configuration conf;
    private VisibilityLabelsCache labelsCache;
  
    public FeedUserAuthScanLabelGenerator() {
      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) {
      if (authorizations == null || authorizations.getLabels() == null
          || authorizations.getLabels().isEmpty()) {
        String userName = user.getShortName();
        Set<String> auths = new HashSet<String>();
        auths.addAll(this.labelsCache.getUserAuths(userName));
        auths.addAll(this.labelsCache.getGroupAuths(user.getGroupNames()));
        return new ArrayList<String>(auths);
      }
      return authorizations.getLabels();
    }
  
  }