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/***********************************************************************************************************************
 *
 * forceTen - open source geography
 * Copyright (C) 2007-2012 by Tidalwave s.a.s. (http://www.tidalwave.it)
 *
 ***********************************************************************************************************************
 *
 * Licensed 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.
 *
 ***********************************************************************************************************************
 *
 * WWW: http://forceten.tidalwave.it
 * SCM: https://bitbucket.org/tidalwave/forceten-src
 *
 **********************************************************************************************************************/
package it.tidalwave.geo.viewer.impl.spi;

/***********************************************************************************************************************
 *
 * A mangler for storing files in the tile cache.
 *
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 **********************************************************************************************************************/
public final class NameMangler
  {
    /***************************************************************************
     *
     * Mangles the given URL returning the local path to be used on the 
     * filesystem. The returned path is the original parameter prefixed with
     * two directories such as ab/cd/ where abcd is the CRC16 of
     * the original URL.
     * 
     * @param   url  the url to mangle
     * @return       the mangled path
     *
     **************************************************************************/
    public static String mangle (final String url)
      {
        String s = url.substring("http://".length());
        int i = s.indexOf('/');
        
        if (i > 0)
          {
            s = s.substring(i + 1);
          }
        
        i = s.lastIndexOf('?');
        
        if (i >= 0)
          {
            s = s.substring(0, i);
          }
        
        String crc16 = "0000" + Integer.toHexString(CRC16.crc16(s));
        crc16 = crc16.substring(crc16.length() - 4);
        
        return crc16.substring(0, 2) + "/" + crc16.substring(2, 4) + "/" + s;
      }
  }