/**
    * Copyright 2005-2013 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;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.log4j.Logger;
  import org.kuali.rice.core.api.util.xml.XmlJotter;
  import org.kuali.rice.kim.api.identity.Person;
  import org.kuali.rice.krad.util.GlobalVariables;
  import org.w3c.dom.Document;
  
  import javax.servlet.http.HttpServletResponse;
  import javax.xml.transform.OutputKeys;
  import javax.xml.transform.Transformer;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;
  import javax.xml.xpath.XPathFactory;
  import java.util.Stack;
  
  
  /**
   * Contains a stack of EDLControllers.  Allows EDL components to add new controllers to the chain runtime.  The idea
   * being that this is how you would page between edls.  Uses the template associated with the last edl controller
   * to render the dom of the last edl controller.
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   *
   */
  public class EDLControllerChain {
  
  	private static final Logger LOG = Logger.getLogger(EDLControllerChain.class);
  
  	private Stack<EDLController> edlControllers = new Stack<EDLController>();
  
  	public void renderEDL(RequestParser requestParser, HttpServletResponse response) throws Exception {
  		EDLController edlController = edlControllers.pop();
  		edlController.setEdlContext(getInitialEDLContext(edlController, requestParser, edlController.getStyle().newTransformer()));
  
  		Document dom = edlController.notifyComponents();
  		if (edlControllers.isEmpty()) {
  			transform(edlController.getEdlContext(), dom, response);
  		} else {
  			renderEDL(requestParser, response);
  		}
  	}
  
  	public void addEdlController(EDLController edlController) {
  		edlControllers.add(edlController);
  	}
  
  	private void transform(EDLContext edlContext, Document dom, HttpServletResponse response) throws Exception {
  		if (StringUtils.isNotBlank(edlContext.getRedirectUrl())) {
  			response.sendRedirect(edlContext.getRedirectUrl());
  			return;
  		}
  	    response.setContentType("text/html; charset=UTF-8");
  		Transformer transformer = edlContext.getTransformer();
  
          transformer.setOutputProperty("indent", "yes");
          transformer.setOutputProperty(OutputKeys.INDENT, "yes");
          String user = null;
          String loggedInUser = null;
          if (edlContext.getUserSession() != null) {
              Person wu = edlContext.getUserSession().getPerson();
              if (wu != null) user = wu.getPrincipalId();
              wu = edlContext.getUserSession().getPerson();
              if (wu != null) loggedInUser = wu.getPrincipalId();
          }
          transformer.setParameter("user", user);
          transformer.setParameter("loggedInUser", loggedInUser);
          if (LOG.isDebugEnabled()) {
          	LOG.debug("Transforming dom " + XmlJotter.jotNode(dom, true));
          }
          transformer.transform(new DOMSource(dom), new StreamResult(response.getOutputStream()));
  	}
  
  	private EDLContext getInitialEDLContext(EDLController edlController, RequestParser requestParser, Transformer transformer) {
  		EDLContext edlContext = new EDLContext();
  		edlContext.setEdlControllerChain(this);
  		edlContext.setEdocLiteAssociation(edlController.getEdocLiteAssociation());
  		edlContext.setUserSession(GlobalVariables.getUserSession());
  		edlContext.setTransformer(transformer);
  		edlContext.setRequestParser(requestParser);
          edlContext.setXpath(XPathFactory.newInstance().newXPath());
          return edlContext;
  	}
 
 }