/*
* 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.wicket.markup.html.internal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.wicket.Component;
import org.apache.wicket.RequestContext;
import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.IMarkupFragment;
import org.apache.wicket.markup.MarkupException;
import org.apache.wicket.markup.MarkupStream;
import org.apache.wicket.markup.WicketTag;
import org.apache.wicket.markup.html.IHeaderResponse;
import org.apache.wicket.markup.html.TransparentWebMarkupContainer;
import org.apache.wicket.markup.renderStrategy.AbstractHeaderRenderStrategy;
import org.apache.wicket.request.Response;
import org.apache.wicket.response.StringResponse;
/**
* The HtmlHeaderContainer is automatically created and added to the component hierarchy by a
* HtmlHeaderResolver instance. HtmlHeaderContainer tries to handle/render the >head> tag and
* its body. However depending on the parent component, the behavior must be different. E.g. if
* parent component is a Page all components of the page's hierarchy must be asked if they have
* something to contribute to the <head> section of the html response. If yes, it must
* <b>immediately</b> be rendered.
* <p>
* <head> regions may contain additional wicket components, which can be added by means of
* add(Component) as usual.
* <p>
* <wicket:head> tags are handled by simple WebMarkupContainers also created by a
* HtmlHeaderResolver.
* <p>
* <ul>
* <li><head> will be inserted in output automatically if required</li>
* <li><head> is <b>not</b> a wicket specific tag and you must use add() to add components
* referenced in body of the head tag</li>
* <li><head> is supported by panels, borders and inherited markup, but is <b>not</b> copied
* to the output. They are for previewability only (except on Pages)</li>
* <li><wicket:head> does not make sense in page markup (but does in inherited page markup)</li>
* <li><wicket:head> makes sense in Panels, Borders and inherited markup (of Panels, Borders
* and Pages)</li>
* <li>components within <wicket:head> must be added by means of add(), like always with
* Wicket. No difference.</li>
* <li><wicket:head> and it's content is copied to the output. Components contained in
* <org.apache.wicket.head> are rendered as usual</li>
* </ul>
*
* @author Juergen Donnerstag
*/
public class HtmlHeaderContainer extends TransparentWebMarkupContainer
{
private static final long serialVersionUID = 1L;
/**
* wicket:head tags (components) must only be added once. To allow for a little bit more
* control, each wicket:head has an associated scope which by default is equal to the java class
* name directly associated with the markup which contains the wicket:head. It can be modified
* by means of the scope attribute.
*/
private transient Map<String, List<String>> renderedComponentsPerScope;
/**
* Header response that is responsible for filtering duplicate contributions.
*/
private transient IHeaderResponse headerResponse = null;
/**
* Construct
*
* @see Component#Component(String)
*/
public HtmlHeaderContainer(final String id)
{
super(id);
// We will render the tags manually, because if no component asked to
// contribute to the header, the tags will not be printed either.
// No contribution usually only happens if none of the components
// including the page does have a <head> or <wicket:head> tag.
setRenderBodyOnly(true);
setAuto(true);
}
/**
* First render the body of the component. And if it is the header component of a Page (compared
* to a Panel or Border), than get the header sections from all component in the hierarchy and
* render them as well.
*
* @see org.apache.wicket.MarkupContainer#onComponentTagBody(org.apache.wicket.markup.MarkupStream,
* org.apache.wicket.markup.ComponentTag)
*/
@Override
protected final void onComponentTagBody(MarkupStream markupStream, ComponentTag openTag)
{
// We are able to automatically add <head> to the page if it is
// missing. But we only want to add it, if we have content to be
// written to its body. Thus we first write the output into a
// StringResponse and if not empty, we copy it to the original
// web response.
// Temporarily replace the web response with a String response
final Response webResponse = getResponse();
try
{
final StringResponse response = new StringResponse();
getRequestCycle().setResponse(response);
IHeaderResponse headerResponse = getHeaderResponse();
if (!response.equals(headerResponse.getResponse()))
{
getRequestCycle().setResponse(headerResponse.getResponse());
}
// In any case, first render the header section directly associated
// with the markup
super.onComponentTagBody(markupStream, openTag);
// Render all header sections of all components on the page
AbstractHeaderRenderStrategy.get().renderHeader(this, getPage());
getHeaderResponse().close();
// Automatically add <head> if necessary
CharSequence output = response.getBuffer();
if (output.length() > 0)
{
if (output.charAt(0) == '\r')
{
for (int i = 2; i < output.length(); i += 2)
{
char ch = output.charAt(i);
if (ch != '\r')
{
output = output.subSequence(i - 2, output.length());
break;
}
}
}
else if (output.charAt(0) == '\n')
{
for (int i = 1; i < output.length(); i++)
{
char ch = output.charAt(i);
if (ch != '\n')
{
output = output.subSequence(i - 1, output.length());
break;
}
}
}
}
if (output.length() > 0)
{
if (renderOpenAndCloseTags())
{
webResponse.write("<head>");
}
webResponse.write(output);
if (renderOpenAndCloseTags())
{
webResponse.write("</head>");
}
}
}
finally
{
// Restore the original response
getRequestCycle().setResponse(webResponse);
}
}
/**
*
* @return True if open and close tag are to be rendered.
*/
protected boolean renderOpenAndCloseTags()
{
return true;
}
/**
* Check if the header component is ok to render within the scope given.
*
* @param scope
* The scope of the header component
* @param id
* The component's id
* @return true, if the component ok to render
*/
public boolean okToRenderComponent(final String scope, final String id)
{
if (renderedComponentsPerScope == null)
{
renderedComponentsPerScope = new HashMap<String, List<String>>();
}
List<String> componentScope = renderedComponentsPerScope.get(scope);
if (componentScope == null)
{
componentScope = new ArrayList<String>();
renderedComponentsPerScope.put(scope, componentScope);
}
if (componentScope.contains(id))
{
return false;
}
componentScope.add(id);
return true;
}
/**
*
* @see org.apache.wicket.Component#onDetach()
*/
@Override
protected void onDetach()
{
super.onDetach();
renderedComponentsPerScope = null;
headerResponse = null;
}
/**
* Factory method for creating header response
*
* @return new header response
*/
protected IHeaderResponse newHeaderResponse()
{
IHeaderResponse headerResponse = RequestContext.get().getHeaderResponse();
if (headerResponse == null)
{
// no (portlet) headerResponse override, create a default one
headerResponse = new HeaderResponse()
{
@Override
protected Response getRealResponse()
{
return HtmlHeaderContainer.this.getResponse();
}
};
}
return headerResponse;
}
/**
* Returns the header response.
*
* @return header response
*/
public IHeaderResponse getHeaderResponse()
{
if (headerResponse == null)
{
headerResponse = newHeaderResponse();
}
return headerResponse;
}
/**
* @see org.apache.wicket.Component#getMarkup()
*/
@Override
public IMarkupFragment getMarkup()
{
if (getParent() == null)
{
throw new WicketRuntimeException(
"Bug: The Wicket internal instance of HtmlHeaderContainer is not connected to a parent");
}
// Get the page markup
IMarkupFragment markup = getPage().getMarkup();
if (markup == null)
{
throw new MarkupException("Unable to get page markup: " + getPage().toString());
}
// Find the markup fragment
MarkupStream stream = new MarkupStream(markup);
IMarkupFragment headerMarkup = null;
while (stream.skipUntil(ComponentTag.class) && (headerMarkup == null))
{
ComponentTag tag = stream.getTag();
if (tag.isOpen() || tag.isOpenClose())
{
if (tag instanceof WicketTag)
{
WicketTag wtag = (WicketTag)tag;
if (wtag.isHeadTag())
{
if (tag.getMarkupClass() == null)
{
headerMarkup = stream.getMarkupFragment();
}
}
}
else if (tag.getName().equalsIgnoreCase("head"))
{
headerMarkup = stream.getMarkupFragment();
}
}
stream.next();
}
setMarkup(headerMarkup);
return headerMarkup;
}
}