/*
    *
    * 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.client;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.ClassSize;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public abstract class OperationWithAttributes extends Operation implements Attributes {
    // An opaque blob of attributes
    private Map<String, byte[]> attributes;
  
    // used for uniquely identifying an operation
    public static final String ID_ATRIBUTE = "_operation.attributes.id";
  
    @Override
    public void setAttribute(String name, byte[] value) {
      if (attributes == null && value == null) {
        return;
      }
  
      if (attributes == null) {
        attributes = new HashMap<String, byte[]>();
      }
  
      if (value == null) {
        attributes.remove(name);
        if (attributes.isEmpty()) {
          this.attributes = null;
        }
      } else {
        attributes.put(name, value);
      }
    }
  
    @Override
    public byte[] getAttribute(String name) {
      if (attributes == null) {
        return null;
      }
  
      return attributes.get(name);
    }
  
    @Override
    public Map<String, byte[]> getAttributesMap() {
      if (attributes == null) {
        return Collections.emptyMap();
      }
      return Collections.unmodifiableMap(attributes);
    }
  
    protected long getAttributeSize() {
      long size = 0;
      if (attributes != null) {
        size += ClassSize.align(this.attributes.size() * ClassSize.MAP_ENTRY);
        for(Map.Entry<String, byte[]> entry : this.attributes.entrySet()) {
          size += ClassSize.align(ClassSize.STRING + entry.getKey().length());
          size += ClassSize.align(ClassSize.ARRAY + entry.getValue().length);
        }
      }
      return size;
    }
  
    /**
     * This method allows you to set an identifier on an operation. The original
     * motivation for this was to allow the identifier to be used in slow query
     * logging, but this could obviously be useful in other places. One use of
     * this could be to put a class.method identifier in here to see where the
     * slow query is coming from.
     * @param id
     *          id to set for the scan
     */
    public void setId(String id) {
      setAttribute(ID_ATRIBUTE, Bytes.toBytes(id));
   }
 
   /**
    * This method allows you to retrieve the identifier for the operation if one
    * was set.
    * @return the id or null if not set
    */
   public String getId() {
     byte[] attr = getAttribute(ID_ATRIBUTE);
     return attr == null? null: Bytes.toString(attr);
   }
 }