/*
    * 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.log4j.chainsaw.prefs;
  
  import com.thoughtworks.xstream.XStream;
  import com.thoughtworks.xstream.io.xml.DomDriver;
  
  import javax.swing.event.ChangeEvent;
  import javax.swing.event.ChangeListener;
  import javax.swing.event.EventListenerList;
  import java.io.Reader;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.EventListener;
  import java.util.List;
  
  public class MRUFileList {
  
      private static MRUFileList log4jList = new MRUFileList();
      private static final int DEFAULT_MRU_SIZE = 5;
  
      private List<URL> fileList = new ArrayList<>();
      private int size = DEFAULT_MRU_SIZE;
  
      private static transient EventListenerList listeners = new EventListenerList();
  
      private MRUFileList() {
  
      }
  
      public static void addChangeListener(ChangeListener listener) {
          listeners.add(ChangeListener.class, listener);
      }
  
      public static void removeChangeListener(ChangeListener listener) {
          listeners.remove(ChangeListener.class, listener);
      }
  
      /**
       * Call this method when something opens a log file, this method
       * adds the URL to the list of known URL's, automatically
       * rolling the list to ensure the list maintains the
       * size property
       *
       * @param url
       */
      public void opened(URL url) {
          // first remove any existence of the URL already, make sure we don't have dupes
          fileList.remove(url);
          // now make sure we obey the size property,  leaving room for 1 more to be added at the front
          while (fileList.size() >= size) {
              fileList.remove(fileList.size() - 1);
          }
          fileList.add(0, url);
          fireChangeEvent();
      }
  
      private static void fireChangeEvent() {
  
          ChangeEvent event = null;
          EventListener[] eventListeners = listeners.getListeners(ChangeListener.class);
          for (EventListener eventListener : eventListeners) {
              ChangeListener listener = (ChangeListener) eventListener;
              if (event == null) {
                  event = new ChangeEvent(MRUFileList.class);
              }
              listener.stateChanged(event);
          }
      }
  
      /**
       * Returns an <b>unmodifiable</b> List of the MRU opened file list within Chainsaw
       *
       * @return
       */
      public List getMRUList() {
          return Collections.unmodifiableList(fileList);
      }
  
      public static MRUFileList log4jMRU() {
          return log4jList;
      }
  
      public static void loadLog4jMRUListFromXML(String xml) {
         XStream xstream = new XStream(new DomDriver());
         log4jList = (MRUFileList) xstream.fromXML(xml);
         fireChangeEvent();
     }
 
     public static void loadLog4jMRUListFromReader(Reader reader) {
         XStream xstream = new XStream(new DomDriver());
         log4jList = (MRUFileList) xstream.fromXML(reader);
         fireChangeEvent();
 
     }
     // TODO Auto-generated method stub
 }