/*
 * Copyright 2002,2004 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.struts.faces.renderer;


import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

import javax.faces.application.FacesMessage;
import javax.faces.component.EditableValueHolder;
import javax.faces.component.UIComponent;
import javax.faces.component.ValueHolder;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.faces.el.ValueBinding;
import javax.faces.render.Renderer;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


/**
 * <p>Abstract base class for concrete implementations of
 * <code>javax.faces.render.Renderer</code> for the
 * <em>Struts-Faces Integration Library</em>.</p>
 *
 * @version $Rev: 54934 $ $Date: 2004-10-16 18:07:50 +0100 (Sat, 16 Oct 2004) $
 */

public abstract class AbstractRenderer extends Renderer {


    // -------------------------------------------------------- Static Variables


    private static final Log log =
	LogFactory.getLog(AbstractRenderer.class);


    // -------------------------------------------------------- Renderer Methods


    /**
     * <p>Decode any new state of the specified <code>UIComponent</code>
     * from the request contained in the specified <code>FacesContext</code>,
     * and store that state on the <code>UIComponent</code>.</p>
     *
     * <p>The default implementation calls <code>setSubmittedValue()</code>
     * unless this component has a boolean <code>disabled</code> or
     * <code>readonly</code> attribute that is set to <code>true</code>.</p>
     *
     * @param context <code>FacesContext</code> for the current request
     * @param component <code>UIComponent</code> to be decoded
     *
     * @exception NullPointerException if <code>context</code> or
     *  <code>component</code> is <code>null</code>
     */
    public void decode(FacesContext context, UIComponent component) {

        // Enforce NPE requirements in the Javadocs
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }

        // Disabled or readonly components are not decoded
        if (isDisabled(component) || isReadOnly(component)) {
            return;
        }

        // Save submitted value on EditableValueHolder components
        if (component instanceof EditableValueHolder) {
            setSubmittedValue(context, component);
        }
        
    }


    /**
     * <p>Render the beginning of the specified <code>UIComponent</code>
     * to the output stream or writer associated with the response we are
     * creating.</p>
     *
     * <p>The default implementation calls <code>renderStart()</code> and
     * <code>renderAttributes()</code>.</p>
     *
     * @param context <code>FacesContext</code> for the current request
     * @param component <code>UIComponent</code> to be decoded
     *
     * @exception NullPointerException if <code>context</code> or
     *  <code>component</code> is <code>null</code>
     *
     * @exception IOException if an input/output error occurs
     */
    public void encodeBegin(FacesContext context, UIComponent component)
        throws IOException {

        // Enforce NPE requirements in the Javadocs
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }

	if (log.isTraceEnabled()) {
	    log.trace("encodeBegin(id=" + component.getId() +
		      ", family=" + component.getFamily() +
		      ", rendererType=" + component.getRendererType() + ")");
	}

        // Render the element and attributes for this component
        ResponseWriter writer = context.getResponseWriter();
        renderStart(context, component, writer);
        renderAttributes(context, component, writer);

    }


    /**
     * <p>Render the children of the specified <code>UIComponent</code>
     * to the output stream or writer associated with the response we are
     * creating.</p>
     *
     * <p>The default implementation iterates through the children of
     * this component and renders them.</p>
     *
     * @param context <code>FacesContext</code> for the current request
     * @param component <code>UIComponent</code> to be decoded
     *
     * @exception NullPointerException if <code>context</code> or
     *  <code>component</code> is <code>null</code>
     *
     * @exception IOException if an input/output error occurs
     */
    public void encodeChildren(FacesContext context, UIComponent component)
        throws IOException {

        if (context == null || component == null) {
            throw new NullPointerException();
        }

	if (log.isTraceEnabled()) {
	    log.trace("encodeChildren(id=" + component.getId() +
		      ", family=" + component.getFamily() +
		      ", rendererType=" + component.getRendererType() + ")");
	}
	Iterator kids = component.getChildren().iterator();
	while (kids.hasNext()) {
	    UIComponent kid = (UIComponent) kids.next();
	    kid.encodeBegin(context);
	    if (kid.getRendersChildren()) {
		kid.encodeChildren(context);
	    }
	    kid.encodeEnd(context);
	}
	if (log.isTraceEnabled()) {
	    log.trace("encodeChildren(id=" + component.getId() + ") end");
	}

    }


    /**
     * <p>Render the ending of the specified <code>UIComponent</code>
     * to the output stream or writer associated with the response we are
     * creating.</p>
     *
     * <p>The default implementation calls <code>renderEnd()</code>.</p>
     *
     * @param context <code>FacesContext</code> for the current request
     * @param component <code>UIComponent</code> to be decoded
     *
     * @exception NullPointerException if <code>context</code> or
     *  <code>component</code> is <code>null</code>
     *
     * @exception IOException if an input/output error occurs
     */
    public void encodeEnd(FacesContext context, UIComponent component)
        throws IOException {

        // Enforce NPE requirements in the Javadocs
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }

	if (log.isTraceEnabled()) {
	    log.trace("encodeEnd(id=" + component.getId() +
		      ", family=" + component.getFamily() +
		      ", rendererType=" + component.getRendererType() + ")");
	}

        // Render the element closing for this component
        ResponseWriter writer = context.getResponseWriter();
        renderEnd(context, component, writer);

    }


    // --------------------------------------------------------- Package Methods


    // ------------------------------------------------------- Protected Methods


    /**
     * <p>Render nested child components by invoking the encode methods
     * on those components, but only when the <code>rendered</code>
     * property is <code>true</code>.</p>
     */
    protected void encodeRecursive(FacesContext context, UIComponent component)
        throws IOException {

        // suppress rendering if "rendered" property on the component is
        // false.
        if (!component.isRendered()) {
            return;
        }

        // Render this component and its children recursively
	if (log.isTraceEnabled()) {
	    log.trace("encodeRecursive(id=" + component.getId() +
		      ", family=" + component.getFamily() +
		      ", rendererType=" + component.getRendererType() +
		      ") encodeBegin");
	}
        component.encodeBegin(context);
        if (component.getRendersChildren()) {
	    if (log.isTraceEnabled()) {
		log.trace("encodeRecursive(id=" + component.getId() +
			  ") delegating");
	    }
            component.encodeChildren(context);
        } else {
	    if (log.isTraceEnabled()) {
		log.trace("encodeRecursive(id=" + component.getId() +
			  ") recursing");
	    }
            Iterator kids = component.getChildren().iterator();
            while (kids.hasNext()) {
                UIComponent kid = (UIComponent) kids.next();
                encodeRecursive(context, kid);
            }
        }
	if (log.isTraceEnabled()) {
	    log.trace("encodeRecursive(id=" + component.getId() + ") encodeEnd");
	}
        component.encodeEnd(context);

    }


    /**
     * <p>Return <code>true</code> if the specified component is disabled.</p>
     *
     * @param component <code>UIComponent</code> to be checked
     */
    protected boolean isDisabled(UIComponent component) {

        Object disabled = component.getAttributes().get("disabled");
        if (disabled == null) {
            return (false);
        }
        if (disabled instanceof String) {
            return (Boolean.valueOf((String) disabled).booleanValue());
        } else {
            return (disabled.equals(Boolean.TRUE));
        }

    }


    /**
     * <p>Return <code>true</code> if the specified component is read only.</p>
     *
     * @param component <code>UIComponent</code> to be checked
     */
    protected boolean isReadOnly(UIComponent component) {

        Object readonly = component.getAttributes().get("readonly");
        if (readonly == null) {
            return (false);
        }
        if (readonly instanceof String) {
            return (Boolean.valueOf((String) readonly).booleanValue());
        } else {
            return (readonly.equals(Boolean.TRUE));
        }

    }


    /**
     * <p>Render the element attributes for the generated markup related to this
     * component.  Simple renderers that create a single markup element
     * for this component should override this method and include calls to
     * to <code>writeAttribute()</code> and <code>writeURIAttribute</code>
     * on the specified <code>ResponseWriter</code>.</p>
     *
     * <p>The default implementation does nothing.</p>
     *
     * @param context <code>FacesContext</code> for the current request
     * @param component <code>EditableValueHolder</code> component whose
     *  submitted value is to be stored
     * @param writer <code>ResponseWriter</code> to which the element
     *  start should be rendered
     *
     * @exception IOException if an input/output error occurs
     */
    protected void renderAttributes(FacesContext context, UIComponent component,
                                    ResponseWriter writer) throws IOException {

    }


    /**
     * <p>Render the element end for the generated markup related to this
     * component.  Simple renderers that create a single markup element
     * for this component should override this method and include a call
     * to <code>endElement()</code> on the specified
     * <code>ResponseWriter</code>.</p>
     *