/*
 * 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.cdi.maven;

import org.apache.maven.plugins.shade.resource.ResourceTransformer;
import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.Iterator;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;

/**
 * A resource transformer for the maven shade-plugin which
 * processes beans.xml files correctly.
 * <p/>
 * Most of the code is taken from the XmlAppendingTransformer from the shade-plugin.
 */
public class BeansXmlTransformer implements ResourceTransformer
{
    public static final String XSI_NS = "http://www.w3.org/2001/XMLSchema-instance";

    private boolean ignoreDtd = true;

    private String resource;

    private Document doc;

    public boolean canTransformResource(String r)
    {
        return resource != null && resource.equalsIgnoreCase(r);
    }

    public void processResource(String resource, InputStream is, List relocators) throws IOException
    {
        Document r;
        try
        {
            SAXBuilder builder = new SAXBuilder(false);
            builder.setExpandEntities(false);
            if (ignoreDtd)
            {
                builder.setEntityResolver(new EntityResolver()
                {
                    public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException
                    {
                        return new InputSource(new StringReader(""));
                    }
                });
            }
            r = builder.build(is);
        }
        catch (JDOMException e)
        {
            throw new RuntimeException(e);
        }

        if (doc == null)
        {
            doc = r;
        }
        else
        {
            Element root = r.getRootElement();

            for (Iterator itr = root.getAttributes().iterator(); itr.hasNext();)
            {
                Attribute a = (Attribute) itr.next();
                itr.remove();

                Element mergedEl = doc.getRootElement();
                Attribute mergedAtt = mergedEl.getAttribute(a.getName(), a.getNamespace());
                if (mergedAtt == null)
                {
                    mergedEl.setAttribute(a);
                }
            }

            Element docRoot = doc.getRootElement();

            for (Iterator itr = root.getChildren().iterator(); itr.hasNext();)
            {
                Element child = (Element) itr.next();
                itr.remove();

                // check if the given element already exists as a child of the
                // root element and if so, only add the grandchildren to the
                // already existing child and not the whole child again
                Element docChild = docRoot.getChild(child.getName(), child.getNamespace());
                if (docChild != null)
                {
                    // the docRoot already has this child
                    // --> add the grandchildren to the existing element
                    for (Iterator childrenItr = child.getChildren().iterator(); childrenItr.hasNext();)
                    {
                        Element grandchild = (Element) childrenItr.next();
                        childrenItr.remove();

                        docChild.addContent(grandchild);
                    }
                }
                else
                {
                    // the docRoot does not have this child yet
                    docRoot.addContent(child);
                }
            }
        }
    }

    public boolean hasTransformedResource()
    {
        return doc != null;
    }

    public void modifyOutputStream(JarOutputStream jos)
            throws IOException
    {
        jos.putNextEntry(new JarEntry(resource));

        new XMLOutputter(Format.getPrettyFormat()).output(doc, jos);

        doc = null;
    }
}