// Copyright 2007, 2008, 2009 The Apache Software Foundation

 //

 // Licensed 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.tapestry5.corelib.base;

 import org.apache.tapestry5.*;

 import org.apache.tapestry5.annotations.Parameter;

 import org.apache.tapestry5.annotations.SetupRender;

 import org.apache.tapestry5.annotations.SupportsInformalParameters;

 import org.apache.tapestry5.dom.Element;

 import org.apache.tapestry5.ioc.annotations.Inject;

 /**

  * Provides base utilities for classes that generate clickable links.

  */

 @SupportsInformalParameters

 public abstract class AbstractLink implements ClientElement

 {

     /**

      * An anchor value to append to the generated URL (the hash separator will be added automatically).

      */

     @Parameter(defaultPrefix = BindingConstants.LITERAL)

     private String anchor;

     /**

      * If true, then then no link element is rendered (and no informal parameters as well). The body is, however, still

      * rendered.

      */

     @Parameter("false")

     private boolean disabled;

     @Inject

     private ComponentResources resources;

     @Inject

     private RenderSupport renderSupport;

     private Link link;

     private Element element;

     private String clientId;

     private String buildHref(Link link)

     {

         String href = link.toURI();

         if (anchor == null) return href;

         return href + "#" + anchor;

     }

     @SetupRender

     void resetElementAndClientId()

     {

         element = null;

         clientId = null;

     }

     /**

      * Writes an <a> element with the provided link as the href attribute.  A call to {@link

      * org.apache.tapestry5.MarkupWriter#end()} is <em>not</em> provided.            Automatically appends an anchor if

      * the component's anchor parameter is non-null.  Informal parameters are rendered as well.

      *

      * @param writer         to write markup to

      * @param link           the link that will form the href

      * @param namesAndValues additional attributes to write

      */

     protected final void writeLink(MarkupWriter writer, Link link, Object... namesAndValues)

     {

         element = writer.element("a", "href", buildHref(link));

         writer.attributes(namesAndValues);

         resources.renderInformalParameters(writer);

         this.link = link;

     }

     /**

      * Returns the most recently rendered {@link org.apache.tapestry5.Link} for this component.  Subclasses calculate

      * their link value as they render, and the value is valid until the end of the request, or the next time the same

      * component renders itself (if inside a loop).

      *

      * @return the most recent link, or null

      */

     public Link getLink()

     {

         return link;

     }

     /**

      * Returns the unique client id for this element. This is valid only after the component has rendered (its start

      * tag).  A client id is generated the first time this method is invoked, after the link renders its start tag.

      */

     public final String getClientId()

     {

         if (clientId == null)

         {

             if (element == null)

                 throw new IllegalStateException(

                         String.format("Client id for %s is not available as it did not render yet (or was disabled).",

                                       resources.getCompleteId()));

             clientId = renderSupport.allocateClientId(resources);

             element.forceAttributes("id", clientId);

         }

         return clientId;

     }

     /**

      * Returns true if the component is disabled (as per its disabled parameter). Disabled link components should not

      * render a tag, but should still render their body.

      */

     public boolean isDisabled()

     {

         return disabled;

     }

     /**

      * Used for testing.

      */

     final void inject(String anchor, ComponentResources resources)

     {

         this.anchor = anchor;

         this.resources = resources;

     }

 }