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JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF2.1 features. A JSF2.1 implementation is required to use this version of the Tomahawk library.
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/*
 * 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.custom.transform;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Writer;
import java.net.URI;
import java.net.URL;

import javax.faces.component.UIComponentBase;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

/**
 * Transforms XML using and XSL stylesheet.
 * 
 * Used to transform XML (from either a String or URL) using either XSLT or
 * Velocity.
 *
 * @JSFComponent
 *   name = "t:xmlTransform"
 *   class = "org.apache.myfaces.custom.transform.XmlTransform"
 *   tagClass = "org.apache.myfaces.custom.transform.XmlTransformTag"
 * @since 1.1.7
 * @author Sean Schofield
 */
public abstract class AbstractXmlTransform extends UIComponentBase
{
    public static final String COMPONENT_TYPE = "org.apache.myfaces.tomahawk.XmlTransform";
    public static final String COMPONENT_FAMILY = "org.apache.myfaces.tomahawk.Transform";

    private Object contentStream;
    private Object styleStream;
    
    // see superclass for documentation
    public String getFamily()
    {
        return COMPONENT_FAMILY;
    }

    public void encodeBegin(FacesContext context)
            throws IOException
    {
        InputStream xmlStream = (InputStream)getContentStream();
        String xml = getContent();
        String xmlLocation = getContentLocation();

        InputStream xslStream = (InputStream)getStyleStream();
        String xsl = getStylesheet();
        String xslLocation = getStylesheetLocation();

        if (context == null) throw new NullPointerException("context");
        if (!isRendered()) return;

        if (getContent() == null && getContentLocation() == null && getContentStream() == null)
            throw new NullPointerException("content/contentLocation/contentStream cannot all be null");

        //TODO - handle all cases
        if (xmlLocation != null)
        {
            ClassLoader loader = Thread.currentThread().getContextClassLoader();
            if (loader == null)
            {
                loader = AbstractXmlTransform.class.getClassLoader();
            }

            URL url = loader.getResource(xmlLocation);
            xmlStream = new FileInputStream(new File(URI.create(url.toString())));
        }

        if (xslLocation != null)
        {
            ClassLoader loader = Thread.currentThread().getContextClassLoader();
            if (loader == null)
            {
                loader = AbstractXmlTransform.class.getClassLoader();
            }

            URL url = loader.getResource(xslLocation);
            xslStream = new FileInputStream(new File(URI.create(url.toString())));
        }

        if (xml != null)
        {
            xmlStream = new ByteArrayInputStream(xml.getBytes());
        }

        if (xsl != null)
        {
            xslStream = new ByteArrayInputStream(xsl.getBytes());
        }

        if (xmlStream != null && xslStream != null)
        {
            transformContent(xmlStream, xslStream);
        }
    }

    /**
     * Transforms an XML string using the stylesheet string provided.
     *
     * @param content The XML to transform
     * @param stylesheet The stylesheet to use in the transformation
     * @throws IOException
     */
    private void transformContent(InputStream content, InputStream stylesheet)
        throws IOException
    {
        try
        {
            TransformerFactory tFactory = TransformerFactory.newInstance();
            Transformer transformer = tFactory.newTransformer(new StreamSource(stylesheet));

            Writer responseWriter = FacesContext.getCurrentInstance().getResponseWriter();
            transformer.transform(new StreamSource(content), new StreamResult(responseWriter));
        }
        catch (TransformerException te)
        {
            throw new IOException("Error while transforming XML: " + te.getMessage());
        }
    }

    // component does not need to manage its own children (its not allowed to have any)
    public void encodeChildren(FacesContext context)
            throws IOException
    {}

    // nothing special to do here
    public void encodeEnd(FacesContext context)
            throws IOException
    {}

    /**
     * String containing the XML content to be transformed.
     * 
     * @JSFProperty
     */
    public abstract String getContent();

    /**
     * String containing the location of the XML content to be transformed.
     * 
     * @JSFProperty
     */
    public abstract String getContentLocation();

    /**
     * String containing the XSL information to use in the transformation.
     * 
     * @JSFProperty
     */
    public abstract String getStylesheet();
    
    public void setContentStream(Object contentStream)
    {
        this.contentStream = contentStream;
    }

    /**
     * Value binding expression referencing an InputStream from which the XML content is to be read.
     * 
     * @JSFProperty
     */
    public Object getContentStream()
    {
        if (contentStream != null) return contentStream;

        ValueBinding vb = getValueBinding("contentStream");
        return (vb != null) ? vb.getValue(getFacesContext()) : null;
    }
    

    /**
     * String containing the location of the XSL stylesheet to use in the transformation.
     * 
     * @JSFProperty
     */
    public abstract String getStylesheetLocation();
  
    public void setStyleStream(Object styleStream)
    {
        this.styleStream = styleStream;
    }

    /**
     * Value binding expression referencing an InputStream from which the XSL stylesheet is to be read.
     * 
     * @JSFProperty
     */
    public Object getStyleStream()
    {
        if (styleStream != null) return styleStream;

        ValueBinding vb = getValueBinding("styleStream");
        return (vb != null) ? vb.getValue(getFacesContext()) : null;
    }
    
}