/**

  * Copyright 2010 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.osedu.org/licenses/ECL-2.0

  *

  * 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.student.common.ui.client.widgets;

 import org.kuali.student.common.ui.client.event.NavigationActionEvent;

 import org.kuali.student.common.ui.client.mvc.Callback;

 import org.kuali.student.common.ui.client.mvc.Controller;

 import com.google.gwt.event.dom.client.ClickEvent;

 import com.google.gwt.event.dom.client.ClickHandler;

 import com.google.gwt.event.dom.client.KeyDownEvent;

 import com.google.gwt.event.dom.client.KeyDownHandler;

 import com.google.gwt.user.client.Window;

 public abstract class NavigationHandler implements ClickHandler, KeyDownHandler {

         private final String url;

          private final Controller controller;

          private final String navigationKey;

          private final Enum<?> navEnum;

          public NavigationHandler(String url) {

           this.url = url;

           this.controller = null;

           this.navigationKey = null;

           this.navEnum = null;

          }

          public NavigationHandler(Controller controller, String navigationKey) {

           this.url = null;

           this.controller = controller;

           this.navigationKey = navigationKey;

           this.navEnum = null;

          }

          public NavigationHandler(Controller controller, Enum<?> navigationEnum) {

                   this.url = null;

                   this.controller = controller;

                   this.navigationKey = null;

                   this.navEnum = navigationEnum;

          }

          public void onClick(ClickEvent event) {

                  doNavigate();

          }

          public void onKeyDown(KeyDownEvent event) {

                  doNavigate();

          }

          protected void doNavigate() {

                  beforeNavigate(new Callback<Boolean>() {

                    @Override

                            public void exec(Boolean result) {

                             if (result) {

                                      if (url != null) {

                                              Window.Location.assign(url);

                                      } else if(navEnum != null){

                                              controller.fireApplicationEvent(new NavigationActionEvent(navEnum));

                                      }

                                      else{

                                              controller.fireApplicationEvent(new NavigationActionEvent(navigationKey));

                                      }

                                 }

                         }

                  });

          }

          public String getUrl() {

                 return url;

         }

         public Controller getController() {

                 return controller;

         }

         public String getNavigationKey() {

                 return navigationKey;

         }

         public Enum<?> getNavEnum() {

                 return navEnum;

         }

         public abstract void beforeNavigate(Callback<Boolean> callback);

 }