/*

  *  Licensed to the Apache Software Foundation (ASF) under one

  *  or more contributor license agreements.  See the NOTICE file

  *  distributed with this work for additional information

  *  regarding copyright ownership.  The ASF licenses this file

  *  to you under the Apache 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.apache.org/licenses/LICENSE-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.apache.myfaces.shared_impl.renderkit.html;

 import org.apache.myfaces.shared_impl.renderkit.JSFAttr;

 import javax.faces.application.ViewHandler;

 import javax.faces.component.UIComponent;

 import javax.faces.component.UIViewRoot;

 import javax.faces.context.FacesContext;

 import javax.faces.render.Renderer;

 import java.io.IOException;

 import java.util.List;

 /**

  * @author Manfred Geiler (latest modification by $Author: matzew $)

  * @version $Revision: 557350 $ $Date: 2007-07-18 13:19:50 -0500 (Wed, 18 Jul 2007) $

  */

 public abstract class HtmlRenderer

         extends Renderer

 {

     /**

      * Return the list of children of the specified component.

      * <p>

      * This default implementation simply returns component.getChildren().

      * However this method should always be used in order to allow

      * renderer subclasses to override it and provide filtered or

      * reordered views of the component children to rendering

      * methods defined in their ancestor classes.

      * <p>

      * Any method that overrides this to "hide" child components

      * should also override the getChildCount method.

      * 

      * @return a list of UIComponent objects.

      */

     public List getChildren(UIComponent component) 

     {

         return component.getChildren();

     }

     /**

      * Return the number of children of the specified component.

      * <p>

      * See {@link #getChildren(UIComponent)} for more information.

      */

     public int getChildCount(UIComponent component) 

     {

         return component.getChildCount();

     }

     /**

      * @param facesContext

      * @return String A String representing the action URL

      */

     protected String getActionUrl(FacesContext facesContext)

     {

         ViewHandler viewHandler = facesContext.getApplication().getViewHandler();

         String viewId = facesContext.getViewRoot().getViewId();

         return viewHandler.getActionURL(facesContext, viewId);

     }

     /**

      * Renders the client ID as an "id".

      */

     protected void renderId(

       FacesContext context,

       UIComponent  component) throws IOException

     {

       if (shouldRenderId(context, component))

       {

         String clientId = getClientId(context, component);

         context.getResponseWriter().writeAttribute(HTML.ID_ATTR, clientId, JSFAttr.ID_ATTR);

       }

     }

     /**

      * Returns the client ID that should be used for rendering (if

      * {@link #shouldRenderId} returns true).

      */

     protected String getClientId(

       FacesContext context,

       UIComponent  component)

     {

       return component.getClientId(context);

     }

     /**

      * Returns true if the component should render an ID.  Components

      * that deliver events should always return "true".

      * @todo Is this a bottleneck?  If so, optimize!

      */

     protected boolean shouldRenderId(

       FacesContext context,

       UIComponent  component)

     {

       String id = component.getId();

       // Otherwise, if ID isn't set, don't bother

       if (id == null)

         return false;

       // ... or if the ID was generated, don't bother

       if (id.startsWith(UIViewRoot.UNIQUE_ID_PREFIX))

         return false;

       return true;

     }

     /**

      * Coerces an object into a URI, accounting for JSF rules

      * with initial slashes.

      */

     static public String toUri(Object o)

     {

       if (o == null)

         return null;

       String uri = o.toString();

       if (uri.startsWith("/"))

       {

         // Treat two slashes as server-relative

         if (uri.startsWith("//"))

         {

           uri = uri.substring(1);

         }

         else

         {

           FacesContext fContext = FacesContext.getCurrentInstance();

           uri = fContext.getExternalContext().getRequestContextPath() + uri;

         }

       }

       return uri;

     }

 }