/*!
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* 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 Lesser General Public License for more details.
*
* Copyright (c) 2002-2013 Pentaho Corporation.. All rights reserved.
*/
package org.pentaho.reporting.designer.core.util.undo;
import java.io.Serializable;
import java.util.ArrayList;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.reporting.designer.core.editor.ReportDocumentContext;
public class UndoManager implements Serializable
{
private static class UndoRecord implements Serializable
{
private static final int UNDO_THREASHOLD = 250; // after 250 msecs we assume we see a new event ..
private long timestamp;
private UndoEntry entry;
private UndoRecord(final UndoEntry entry)
{
if (entry == null)
{
throw new NullPointerException();
}
this.timestamp = System.currentTimeMillis();
this.entry = entry;
}
public long getTimestamp()
{
return timestamp;
}
public UndoEntry getEntry()
{
return entry;
}
public boolean isNear(final long time)
{
if (Math.abs(timestamp - time) < UNDO_THREASHOLD)
{
return true;
}
return false;
}
}
private static final Log LOG = LogFactory.getLog(UndoManager.class);
private static final int MAXIMUM_UNDO_SIZE = 5000;//to ensure not to be completely unbound, prevents OOME
private transient EventListenerList undoListeners;
private ArrayList<UndoRecord> undos;
private ArrayList<String> undoNames;
/**
* The next position where to insert the undo-record. Offset -1 is the position of the next redo.
*/
private int offset;
public UndoManager()
{
undoListeners = new EventListenerList();
undos = new ArrayList<UndoRecord>(MAXIMUM_UNDO_SIZE);
undoNames = new ArrayList<String>(MAXIMUM_UNDO_SIZE);
}
public void addChange(final String undoName, final UndoEntry entry)
{
while (offset < undos.size())
{
undos.remove(undos.size() - 1);
undoNames.remove(undoNames.size() - 1);
}
if (offset > 0)
{
final UndoRecord lastRecord = undos.get(offset - 1);
if (lastRecord.isNear(System.currentTimeMillis()))
{
final UndoEntry merged = lastRecord.getEntry().merge(entry);
if (merged != null)
{
undos.set(offset - 1, new UndoRecord(merged));
undoNames.set(offset - 1, undoName);
fireChangeEvent();
return;
}
}
}
undos.add(new UndoRecord(entry));
undoNames.add(undoName);
offset = undos.size();
while (undos.size() > MAXIMUM_UNDO_SIZE)
{
removeLastRecord();
}
fireChangeEvent();
}
private void fireChangeEvent()
{
final ChangeListener[] changeListeners = undoListeners.getListeners(ChangeListener.class);
final ChangeEvent event = new ChangeEvent(this);
for (int i = 0; i < changeListeners.length; i++)
{
final ChangeListener listener = changeListeners[i];
listener.stateChanged(event);
}
}
private void removeLastRecord()
{
// this should remove all entries that are within the threshold
undos.remove(0);
undoNames.remove(0);
}
public String getUndoName() {
if (offset == 0)
{
return null;
}
final String name = undoNames.get(offset - 1);
return name;
}
public String getRedoName() {
if (undos.isEmpty())
{
return null;
}
if (offset == (undos.size()))
{
return null;
}
final String name = undoNames.get(offset);
return name;
}
public void undo(final ReportDocumentContext context)
{
if (offset == 0)
{
return;
}
final UndoRecord record = undos.get(offset - 1);
offset -= 1;
record.getEntry().undo(context);
fireChangeEvent();
}
public void redo(final ReportDocumentContext context)
{
if (undos.isEmpty())
{
return;
}
if (offset == (undos.size()))
{
return;
}
final UndoRecord record = undos.get(offset);
offset += 1;
record.getEntry().redo(context);
fireChangeEvent();
}
public boolean isUndoPossible()
{
return offset > 0;
}
public void removeUndoListener(final ChangeListener undoAction)
{
undoListeners.remove(ChangeListener.class, undoAction);
}
public void addUndoListener(final ChangeListener undoAction)
{
undoListeners.add(ChangeListener.class, undoAction);
}
public boolean isRedoPossible()
{
return offset < undos.size();
}
}