/**
    * Copyright 2005-2011 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.edl.impl.components;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.kuali.rice.edl.impl.EDLContext;
  import org.kuali.rice.edl.impl.EDLModelComponent;
  import org.kuali.rice.edl.impl.EDLXmlUtils;
  import org.kuali.rice.edl.impl.RequestParser;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  
  
  /**
   * Versions the data element if necessary by checking 'currentVersion' param on request.  If this request is
   * a doc handler request this will configure the dom so the next request will cause the data to be incremented.
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   *
   */
  public class VersioningPreprocessor implements EDLModelComponent {
  
      private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(VersioningPreprocessor.class);
  
  	public void updateDOM(Document dom, Element configElement, EDLContext edlContext) {
  
  		RequestParser requestParser = edlContext.getRequestParser();
  
  		boolean incrementVersion = edlContext.getUserAction().isIncrementVersionAction();
  		boolean replaceVersion = edlContext.getUserAction().isReplaceVersionAction();
  
  		Element edlContentElement = EDLXmlUtils.getEDLContent(dom, false);
  		Element dataElement = EDLXmlUtils.getDataFromEDLDocument(edlContentElement, false);
  		Element currentVersion = findCurrentVersion(dom);
  
  
  		if (currentVersion == null) {
  			Integer currentVersionCount = new Integer(0);
  			currentVersion = EDLXmlUtils.getVersionFromData(dataElement, currentVersionCount);
  		} else if (incrementVersion)  {
  			currentVersion.getAttributeNode("current").setNodeValue("false");
  			int currentVersionCount = new Integer(currentVersion.getAttribute("version")).intValue() + 1;
  			EDLXmlUtils.getVersionFromData(dataElement, new Integer(currentVersionCount));
  		} else if (replaceVersion) {
  		    NodeList children = currentVersion.getChildNodes();
  		    // important to store these in the last for removal later because we can't safely removeChild in the first for-loop below
  		    List<Node> childrenToRemove = new ArrayList<Node>();
  		    for (int index = 0; index < children.getLength(); index++) {
  			childrenToRemove.add(children.item(index));
  		    }
  		    for (Node childToRemove : childrenToRemove) {
  			currentVersion.removeChild(childToRemove);
  		    }
  		}
  		requestParser.setAttribute("currentVersion", currentVersion.getAttribute("currentVersion"));
  	}
  
  	public static Element findCurrentVersion(Document dom) {
  		Element edlContentElement = EDLXmlUtils.getEDLContent(dom, false);
  		Element dataElement = EDLXmlUtils.getDataFromEDLDocument(edlContentElement, false);
  		NodeList versionElements = dataElement.getElementsByTagName(EDLXmlUtils.VERSION_E);
  		for (int i = 0; i < versionElements.getLength(); i++) {
  			Element version = (Element) versionElements.item(i);
  			Boolean currentVersion = new Boolean(version.getAttribute("current"));
  			if (currentVersion.booleanValue()) {
  				return version;
  			}
  		}
  		return null;
  	}
  
  }