/*
 * PropertyUtil.java - Utility methods for accessing properties
 *
 * Copyright (c) 2002 Greg Merrill
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

package xslt;

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

/**
 * Utility methods for accessing properties.
 */
public class PropertyUtil {

  /**
   * Returns a List of property values whose keys are identical excepct for
   * a trailing "." and index.
   *
   * @param key key of the enumerated property, excluding the trailing "." and
   *   index.  I.e., if you have properties "file.0=file0.txt" and 
   *   "file.1=file1.txt", calling getEnumeratedProperty("file", properties)
   *   would return a list containing "file0.txt" and "file1.txt".
   * @param properties Properties object from which the enumerated property
   *   should be retrieved
   */
  public static List getEnumeratedProperty (String key, Properties properties) {
    List values = new ArrayList();
    int i = 0;
    String value;
    while ((value = properties.getProperty(calculateKey(key, i++))) != null) {
      values.add(value);
    }
    return values;
  }

  /**
   * Sets a series of property values whose keys are identical excepct for
   * a trailing "." and index.
   *
   * @param key key of the enumerated property (see 
   *   {@link #getEnumeratedProperty})
   * @param values values to be assigned to the enumerated property, in order.
   *   All members of this List must be Strings.
   * @param properties Properties object from which the enumerated property
   *   should be retrieved
   */
  public static void setEnumeratedProperty (String key, List values, Properties properties) {
    List currentValues = getEnumeratedProperty(key, properties);
    for (int i=0; i < currentValues.size(); i++) {
      properties.remove(calculateKey(key, i));
    }
    for (int i=0; i < values.size(); i++) {
      properties.setProperty(calculateKey(key, i), (String)values.get(i));
    }
  }

  /**
   * @return indexed property key
   */
  private static String calculateKey (String key, int index) {
    return key+"."+index;
  }

}