/*!
* 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 org.pentaho.reporting.designer.core.editor.ReportDocumentContext;
import org.pentaho.reporting.designer.core.model.ModelUtility;
import org.pentaho.reporting.engine.classic.core.ReportElement;
import org.pentaho.reporting.engine.classic.core.style.ElementStyleSheet;
import org.pentaho.reporting.engine.classic.core.style.StyleKey;
import org.pentaho.reporting.engine.classic.core.util.InstanceID;
import org.pentaho.reporting.libraries.base.util.ObjectUtilities;

public class StyleEditUndoEntry implements UndoEntry {
  private InstanceID target;
  private StyleKey styleKey;
  private Object oldValue;
  private Object newValue;

  public StyleEditUndoEntry( final InstanceID target, final StyleKey styleKey,
                             final Object oldValue, final Object newValue ) {
    this.target = target;
    this.styleKey = styleKey;
    this.oldValue = oldValue;
    this.newValue = newValue;
  }

  public void undo( final ReportDocumentContext renderContext ) {
    final ReportElement elementById = ModelUtility.findElementById( renderContext.getReportDefinition(), target );
    elementById.getStyle().setStyleProperty( styleKey, oldValue );
  }

  public void redo( final ReportDocumentContext renderContext ) {
    final ReportElement elementById = ModelUtility.findElementById( renderContext.getReportDefinition(), target );
    elementById.getStyle().setStyleProperty( styleKey, newValue );
  }

  public UndoEntry merge( final UndoEntry newEntry ) {
    if ( newEntry instanceof StyleEditUndoEntry == false ) {
      return null;
    }

    final StyleEditUndoEntry entry = (StyleEditUndoEntry) newEntry;
    if ( entry.target == target &&
      ObjectUtilities.equal( entry.styleKey, styleKey ) ) {
      return newEntry;
    }
    return null;
  }

  public static StyleEditUndoEntry createConditional( final ReportElement element,
                                                      final StyleKey key,
                                                      final Object newValue ) {
    final ElementStyleSheet styleSheet = element.getStyle();
    final Object oldValue;
    if ( styleSheet.isLocalKey( key ) ) {
      oldValue = styleSheet.getStyleProperty( key );
    } else {
      oldValue = null;
    }
    return new StyleEditUndoEntry( element.getObjectID(), key, oldValue, newValue );
  }

}