package org.apache.helix.healthcheck;
   
   /*
    * 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.
   */
  
  import org.apache.log4j.Logger;
  
  public class WindowAggregationType implements AggregationType
  {
  
    private static final Logger logger = Logger
        .getLogger(WindowAggregationType.class);
  
    public final String WINDOW_DELIM = "#";
  
    public final static String TYPE_NAME = "window";
  
    int _windowSize = 1;
  
    public WindowAggregationType(int ws)
    {
      super();
      _windowSize = ws;
    }
  
    @Override
    public String getName()
    {
      StringBuilder sb = new StringBuilder();
      sb.append(TYPE_NAME);
      sb.append(DELIM);
      sb.append(_windowSize);
      return sb.toString();
    }
  
    @Override
    public String merge(String incomingVal, String existingVal, long prevTimestamp)
    {
      String[] windowVals;
      if (existingVal == null)
      {
        return incomingVal;
      }
      else
      {
        windowVals = existingVal.split(WINDOW_DELIM);
        int currLength = windowVals.length;
        // window not full
        if (currLength < _windowSize)
        {
          return existingVal + WINDOW_DELIM + incomingVal;
        }
        // evict oldest
        else
        {
          int firstDelim = existingVal.indexOf(WINDOW_DELIM);
          return existingVal.substring(firstDelim + 1) + WINDOW_DELIM
              + incomingVal;
        }
      }
    }
  }