/*
 * 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.tuscany.sca.contribution.processor.xml;

import static javax.xml.stream.XMLStreamConstants.CDATA;
import static javax.xml.stream.XMLStreamConstants.CHARACTERS;
import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.events.XMLEvent;

import org.apache.tuscany.sca.contribution.Constants;
import org.apache.tuscany.sca.contribution.processor.ContributionReadException;
import org.apache.tuscany.sca.contribution.processor.ContributionResolveException;
import org.apache.tuscany.sca.contribution.processor.StAXArtifactProcessor;
import org.apache.tuscany.sca.contribution.resolver.ModelResolver;
import org.apache.tuscany.sca.core.FactoryExtensionPoint;
import org.apache.tuscany.sca.monitor.Monitor;

public class AnyElementProcessor implements StAXArtifactProcessor<Object> {
    private static final QName ANY_ELEMENT = new QName(Constants.XMLSCHEMA_NS, "anyElement");

    private XMLInputFactory xmlInputFactory;
    @SuppressWarnings("unused")
    private Monitor monitor;


    public AnyElementProcessor(FactoryExtensionPoint modelFactories, Monitor monitor) {
        xmlInputFactory = modelFactories.getFactory(XMLInputFactory.class);
        this.monitor = monitor;
    }

    public QName getArtifactType() {
        return ANY_ELEMENT;
    }

    public Class<Object> getModelType() {
        return Object.class;
    }

    /**
     * Reads the contetns of the unknown elements and generates a custom
     * implementation of XMLStreamReader i.e. XMLEventsStreamReader
     * 
     * @param reader
     * @return
     * @throws XMLStreamException
     */
    @SuppressWarnings("unchecked")
    public Object read(XMLStreamReader reader) throws ContributionReadException, XMLStreamException {

        // Custom variables
        String currentElement = null;
        List eventsList = new ArrayList();

        Map<String, NamespaceContext> eventContext = new HashMap<String, NamespaceContext>();

        try {
            // Cast the block of unknown elements into document
            XMLDocumentStreamReader docReader = new XMLDocumentStreamReader(reader);

            XMLEventReader xmlEventReader = xmlInputFactory.createXMLEventReader(docReader);

            while (xmlEventReader.hasNext()) {
                XMLEvent event = xmlEventReader.nextEvent();

                // Populate the eventContext map with the current element's name
                // and corresponding NamesapceContext
                if (currentElement != null && !(eventContext.containsKey(currentElement))) {
                    eventContext.put(currentElement, reader.getNamespaceContext());
                }

                // Populate the list with the XMLEvents
                eventsList.add(event);
                if (event.isStartElement()) {
                    currentElement = reader.getName().getLocalPart();
                }
                if (event.isEndDocument()) {
                    return new XMLEventsStreamReader(eventsList, eventContext);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * Writes unknown portions back to the writer
     * 
     * @param model
     * @param writer
     */
    public void write(Object model, XMLStreamWriter writer) throws XMLStreamException {
        if (!(model instanceof XMLStreamReader)) {
            return;
        }
        XMLStreamReader reader = (XMLStreamReader)model;

        int event = reader.getEventType();
        while (reader.hasNext()) {
            switch (event) {
                case START_ELEMENT:

                    writer.writeStartElement(reader.getPrefix(), reader.getLocalName(), reader.getNamespaceURI());
                    for (int i = 1; i <= reader.getAttributeCount(); i++) {
                        writer.writeAttribute(reader.getAttributePrefix(i), reader.getAttributeNamespace(i), reader
                            .getAttributeLocalName(i), reader.getAttributeValue(i));
                    }
                    break;

                case CHARACTERS:
                    writer.writeCharacters(reader.getText());
                    break;

                case CDATA:
                    writer.writeCData(reader.getText());
                    break;

                case END_ELEMENT:
                    writer.writeEndElement();
                    break;
            }
            if (reader.hasNext()) {
                event = reader.next();
            }
        }
    }

    public void resolve(Object model, ModelResolver resolver) throws ContributionResolveException {

    }
}