/*
    * 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;
     }
     
 }