/*
 * Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source 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
 * (at your option) any later version.
 *
 * Resin Open Source 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, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.jms.connection;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.logging.Logger;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.Queue;
import javax.jms.QueueBrowser;

import com.caucho.jms.JmsRuntimeException;
import com.caucho.jms.message.MessageImpl;
import com.caucho.jms.message.MessageFactory;
import com.caucho.jms.queue.AbstractQueue;
import com.caucho.jms.queue.QueueEntry;
import com.caucho.jms.selector.Selector;
import com.caucho.jms.selector.SelectorParser;
import com.caucho.util.L10N;

/**
 * A basic message consumer.
 */
public class MessageBrowserImpl
  implements QueueBrowser
{
  static final Logger log
    = Logger.getLogger(MessageBrowserImpl.class.getName());
  static final L10N L = new L10N(MessageBrowserImpl.class);

  private MessageFactory _messageFactory = new MessageFactory();
  
  private JmsSession _session;
  private AbstractQueue _queue;
  private String _messageSelector;
  private Selector _selector;

  public MessageBrowserImpl(JmsSession session,
                            AbstractQueue queue,
                            String messageSelector)
    throws JMSException
  {
    _session = session;
    _queue = queue;
    _messageSelector = messageSelector;
    
    if (messageSelector != null)
      _selector = new SelectorParser().parse(messageSelector);
  }
  
  public Queue getQueue()
    throws JMSException
  {
    return _queue;
  }
  
  public String getMessageSelector()
    throws JMSException
  {
    return _messageSelector;
  }

  public Enumeration getEnumeration()
    throws JMSException
  {
    ArrayList<MessageImpl> list = new ArrayList<MessageImpl>(0);

    if (_session.isActive()) {
    
      ArrayList<QueueEntry> queueEntryList = _queue.getBrowserList();
      
      if (queueEntryList != null) { 
        Iterator<QueueEntry> iterator = queueEntryList.iterator();
        while (iterator.hasNext()) {
          
          // Copying the message. So that if client actor tampers the message
          // will not affect the message in the Queue.
          MessageImpl messageCopy 
               = _messageFactory.copy((MessageImpl)iterator.next().getPayload());
          list.add(messageCopy);
        }
      }
    }
    
    return new BrowserEnumeration(list, _selector);
  }

  public void close()
    throws JMSException
  {
  }

  public String toString()
  {
    return "MessageBrowserImpl[" + _queue + "]";
  }

  public static class BrowserEnumeration implements Enumeration {
    private ArrayList<MessageImpl> _messages;
    private Selector _selector;

    private int _index;
    
    BrowserEnumeration(ArrayList<MessageImpl> messages,
                       Selector selector)
    {
      _messages = messages;
      _selector = selector;

      nextValidMessage();
    }

    public boolean hasMoreElements()
    {
      return _index < _messages.size();
    }

    public Object nextElement()
    {
      if (_index < _messages.size()) {
        MessageImpl msg = _messages.get(_index);

        _index++;
        nextValidMessage();

        return msg;
      }
      else
        return null;
    }

    private void nextValidMessage()
    {
      try {
        for (; _index < _messages.size(); _index++) {
          MessageImpl msg = _messages.get(_index);

          if (_selector == null || _selector.isMatch(msg))
            return;
        }
      } catch (RuntimeException e) {
        throw e;
      } catch (Exception e) {
        throw new JmsRuntimeException(e);
      }
    }
  }
}