/**
    * 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.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);
  				     }
  				}
  			}
  		   
  		 });
  	 }
  	 
  	 
  		 
  	 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);
  }