extscript-core-root/extscript-myfaces12-extensions/src/main/java/org/apache/myfaces/extensions/scripting/jsf/dynamicdecorators/implemetations/RenderkitProxy.java

/*
 * 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.extensions.scripting.jsf.dynamicdecorators.implemetations;

import org.apache.myfaces.extensions.scripting.api.Decorated;
import org.apache.myfaces.extensions.scripting.api.ScriptingConst;
import org.apache.myfaces.extensions.scripting.core.util.WeavingContext;

import javax.faces.context.FacesContext;
import javax.faces.context.ResponseStream;
import javax.faces.context.ResponseWriter;
import javax.faces.render.RenderKit;
import javax.faces.render.Renderer;
import javax.faces.render.ResponseStateManager;
import javax.servlet.ServletRequest;
import java.io.OutputStream;
import java.io.Writer;

/**
 * Weaving renderkit which
 * acts as a proxy factory for
 * our internal reloading referers
 *
 * @author Werner Punz
 */
public class RenderkitProxy extends RenderKit implements Decorated {

    RenderKit _delegate = null;

    public RenderkitProxy(RenderKit delegate) {
        _delegate = delegate;
    }

    public void addRenderer(String componentFamily, String rendererType, Renderer renderer) {
        weaveDelegate();
        //wo do it brute force here because we have sometimes casts and hence cannot rely on proxies
        //renderers itself are flyweight patterns which means they are shared over objects
        renderer = (Renderer) reloadInstance(renderer, ScriptingConst.ARTIFACT_TYPE_RENDERER);
        _delegate.addRenderer(componentFamily, rendererType, renderer);
    }

    public Renderer getRenderer(String componentFamily, String rendererType) {
        weaveDelegate();
        return (Renderer) reloadInstance(_delegate.getRenderer(componentFamily, rendererType), ScriptingConst.ARTIFACT_TYPE_RENDERER);
    }

    public ResponseStateManager getResponseStateManager() {
        weaveDelegate();
        return _delegate.getResponseStateManager();
    }

    public ResponseWriter createResponseWriter(Writer writer, String s, String s1) {
        weaveDelegate();
        return (ResponseWriter) reloadInstance(_delegate.createResponseWriter(writer, s, s1), ScriptingConst.ARTIFACT_TYPE_RESPONSEWRITER);
    }

    public ResponseStream createResponseStream(OutputStream outputStream) {
        weaveDelegate();
        return (ResponseStream) reloadInstance(_delegate.createResponseStream(outputStream), ScriptingConst.ARTIFACT_TYPE_RESPONSESTREAM);
    }

    public Object getDelegate() {
        return _delegate;
    }

    private final void weaveDelegate() {
        _delegate = (RenderKit) WeavingContext.getWeaver().reloadScriptingInstance(_delegate, ScriptingConst.ARTIFACT_TYPE_RENDERKIT);
    }

    private final Object reloadInstance(Object instance, int artefactType) {
        if (instance == null) {
            return null;
        }
        if (WeavingContext.isDynamic(instance.getClass()) && !alreadyWovenInRequest(instance.getClass().getName())) {
            instance = WeavingContext.getWeaver().reloadScriptingInstance(instance, artefactType);
            alreadyWovenInRequest(instance.getClass().getName());
        }
        return instance;
    }

    private final boolean alreadyWovenInRequest(String clazz) {
        //portlets now can be enabled thanks to the jsf2 indirections regarding the external context
        ServletRequest req = (ServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
        if (req.getAttribute(ScriptingConst.SCRIPTING_REQUSINGLETON + clazz) == null) {
            req.setAttribute(ScriptingConst.SCRIPTING_REQUSINGLETON + clazz, "");
            return false;
        }
        return true;
    }

}