/*
    * Fsgrep is a simple Java application which allows a user to
    * search all files in a directory structure for lines matching
    * a given pattern.  Its functionality is a combination of the
    * Unix 'find' and 'grep' utilities.
    * Visit [http://fsgrep.sourceforge.net/] for more information.
    * 
    * Copyright (C) 2003-2006 Murali Krishnan [murali_ca_us@users.sourceforge.net]
    * 
   * Fsgrep is free software; you can redistribute it and/or modify
   * it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   * 
   * Fsgrep 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 Fsgrep (see the file named LICENSE.txt); if not, write
   * to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
   * Boston, MA  02111-1307  USA
   */
  
  package mk.fsgrep.util;
  
  
  import java.util.*;
  
  
  
  /***
   * Most recently used list.  A list ordered by recent use where the
   * first element is the most recently used entry.  It also trims itself
   * to a maximum size.
   * 
   * @author  Murali Krishnan
   *
   */
  public class MRUList extends LinkedList<String> {
  
      //------------------------------------------------------------
      //- Class Variables
  
      /***
       * The maximum number of recent items kept when saved.
       */
      public static final int MAX_SIZE = 10;
  
  
      /***
       * Constant representing an undefined persistent map prefix (the default).
       * 
       */
      protected static final String UNDEFINED_PREFIX = "undefined";
  
  
      /***
       * A reference to the persistent data object (singleton).
       */
      private static final PersistentData pdata = PersistentData.getInstance();
  
  
  
  
      //------------------------------------------------------------
      //- Class Functions
  
  
  
  
      //------------------------------------------------------------
      //- Instance Variables
  
      private int _maxSize = MAX_SIZE;
      private String _persistentTablePrefix = null;
  
  
      //------------------------------------------------------------
      //- Constructors
  
      public MRUList() {
          this (MAX_SIZE, UNDEFINED_PREFIX);
      }
  
  
      public MRUList(String pPrefix) {
          this (MAX_SIZE, pPrefix);
      }
  
  
      public MRUList(int pSize, String pPrefix) {
          _maxSize = pSize;
  
          readData(pPrefix);
      }
  
  
      //------------------------------------------------------------
     //- Accessors
 
     public int getMaxSize() {return _maxSize;}
     protected String getPrefix() {return _persistentTablePrefix;}
 
 
     //------------------------------------------------------------
     //- Settors
 
     public void setMaxSize(int val) {
         _maxSize=val;
 
         trim();
     }
 
 
     //------------------------------------------------------------
     //- Private/Protected Utility Functions
 
     /***
      * Trim the number of entries to the maximum size by removing
      * the older elements.
      */
     protected void trim() {
         while (size() > getMaxSize()) {
             removeLast();
         }
     }
 
 
 
     //------------------------------------------------------------
     //- Public Interface Functions
 
 
     /***
      * Saves the state of this object to the persistent store.
      * 
      */
     public void saveData() {
         pdata.removeKeysPrefixed(getPrefix());  // Clear stale entries.
 
         int i = 0;
         Iterator myIterator = iterator();
         while (myIterator.hasNext()) {
             String spec = (String) myIterator.next();
             pdata.put(getPrefix(), i++, spec);
         }
         pdata.store();
     }
 
 
     /***
      * Read the stored profiles from the persistent data using the given
      * persistent map prefix.
      * @param pPrefix  The string prefix of the desired entries.
      */
     public void readData(String pPrefix) {
         _persistentTablePrefix = pPrefix;
 
         readData();
     }
 
 
     /***
      * Read the stored profiles from the persistent data.  This will only
      * work if a persistent map prefix was defined.
      */
     public void readData() {
         if (!UNDEFINED_PREFIX.equals(getPrefix())) {
             List<String> list = new ArrayList<String>(pdata.getKeysPrefixed(getPrefix()));
             Collections.reverse(list);  // Add last to first.
 
             for (String key : list) {
                 String val = pdata.getProperty(key);
                 add(val);
             }
         }
     }
 
 
     /***
      * Remove all items except the first one.
      * 
      */
     public void keepFirst() {
         if (!isEmpty()) {
             String first = getFirst();
             clear();
             add(first);
         }
     }
 
 
     //------------------------------------------------------------
     //- Class Interface Functions
 
     public boolean add(String entry) {
         //noinspection UnusedDeclaration
         boolean alreadyExists = remove(entry);
         addFirst(entry);
         trim();
 
         return true;
     }
 
 
     //------------------------------------------------------------
     //- Inner Classes
 
 
 
     //------------------------------------------------------------
     //- Main
 
 
 
 }