/**

  * 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.List;

 import org.apache.commons.lang.StringUtils;

 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;

 /**

  * Handles setting the current page in the EDL XML.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  *

  */

 public class PageHandler implements EDLModelComponent {

         public static final String CURRENT_PAGE = "currentPage";

         public static final String PREVIOUS_PAGE = "previousPage";

         public static final String GOTO_PAGE = "edl.gotoPage";

         public void updateDOM(Document dom, Element configElement, EDLContext edlContext) {

             String currentPage = edlContext.getRequestParser().getParameterValue("edl." + CURRENT_PAGE);

             String previousPage = edlContext.getRequestParser().getParameterValue("edl." + PREVIOUS_PAGE);

             String gotoPage = findGotoPage(edlContext.getRequestParser(), currentPage);

             if (!StringUtils.isBlank(gotoPage)) {

                 previousPage = currentPage;

                 currentPage = gotoPage;

             }

             establishCurrentPage(dom, currentPage);

             establishPreviousPage(dom, previousPage);

         }

         /**

          * Find parameter that looks like gotoPage:<pageName>

          */

         private String findGotoPage(RequestParser requestParser, String currentPage) {

             List<String> parameterNames = requestParser.getParameterNames();

             for (String parameterName : parameterNames) {

                 if (parameterName.startsWith(GOTO_PAGE + ":")) {

                     return parameterName.split(":")[1];

                 }

             }

             return null;

         }

         private void establishCurrentPage(Document dom, String currentPage) {

             if (!StringUtils.isBlank(currentPage)) {

                 Element currentPageElement = EDLXmlUtils.getOrCreateChildElement(dom.getDocumentElement(), CURRENT_PAGE, true);

                 currentPageElement.appendChild(dom.createTextNode(currentPage));

             }

         }

         private void establishPreviousPage(Document dom, String previousPage) {

             if (!StringUtils.isBlank(previousPage)) {

                 Element previousPageElement = EDLXmlUtils.getOrCreateChildElement(dom.getDocumentElement(), PREVIOUS_PAGE, true);

                 previousPageElement.appendChild(dom.createTextNode(previousPage));

             }

         }

 }