/*
 * 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.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;

import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;

import org.apache.tuscany.sca.assembly.builder.impl.ProblemImpl;
import org.apache.tuscany.sca.contribution.Constants;
import org.apache.tuscany.sca.contribution.ModelFactoryExtensionPoint;
import org.apache.tuscany.sca.contribution.processor.StAXArtifactProcessor;
import org.apache.tuscany.sca.contribution.resolver.ModelResolver;
import org.apache.tuscany.sca.contribution.service.ContributionReadException;
import org.apache.tuscany.sca.contribution.service.ContributionResolveException;
import org.apache.tuscany.sca.monitor.Monitor;
import org.apache.tuscany.sca.monitor.Problem;
import org.apache.tuscany.sca.monitor.Problem.Severity;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.DocumentTraversal;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.NodeIterator;
import org.w3c.dom.traversal.TreeWalker;

public class AnyElementProcessor implements StAXArtifactProcessor<Object> {
	private static final QName ANY_ELEMENT = new QName(Constants.XMLSCHEMA_NS, "anyElement");
	
	private static final Logger logger = Logger.getLogger(AnyElementProcessor.class.getName());
	private DocumentBuilderFactory documentBuilderFactory;
	private Document document;
	private Monitor monitor;
	
	public AnyElementProcessor(ModelFactoryExtensionPoint modelFactories, Monitor monitor) {
		documentBuilderFactory = modelFactories.getFactory(DocumentBuilderFactory.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 the DOM	
	 * @param reader
	 * @param name
	 * @return
	 * @throws XMLStreamException
	 */
    public Object read(XMLStreamReader reader) throws ContributionReadException, XMLStreamException {
		
		int event = reader.getEventType();
		int level = 0;
		ArrayList<String> elementList = new ArrayList<String>();
		document = createDocument();
		
		QName name = reader.getName();
		
		while(reader.hasNext()){
	    	switch(event){
		    	case START_ELEMENT:
		    		elementList.add(reader.getName().getLocalPart());
		    		if(level == 0){
		    			generateDOM(reader,null);
		    			level++;
		    		}
		    		else{
		    			generateDOM(reader,elementList.get(elementList.size()-2).toString());
		    		}
		    		
		    		break;
		    	case END_ELEMENT:
		    		elementList.remove(reader.getName().getLocalPart());
	    	}
	    	if(reader.hasNext()){
	    		event = reader.next();
	    	}
	      	
	      	if(event == START_ELEMENT || event == END_ELEMENT){
	      		if(reader.getName().equals(name)){
	      			break;
	      		}
	      	}
	    }
		return document;
	}

	/**
	 * Writes unknown portions back to the writer
	 * @param model
	 * @param writer
	 */
	public void write(Object model, XMLStreamWriter writer) {
		
		if( ! (model instanceof Document)) {
			return;
		}
		
		Document doc = (Document)model;
		try{
			DocumentTraversal traversal = (DocumentTraversal)doc;
			TreeWalker walker = traversal.createTreeWalker(doc.getDocumentElement(),NodeFilter.SHOW_ALL, null, true);
			writeDOM(walker,writer);
		}
		catch(Exception e){
			if (logger.isLoggable(Level.SEVERE)) {
                logger.log(Level.SEVERE, "Document not created ");
            }
			error("Document not created",document,e);
		}
	}

    public void resolve(Object arg0, ModelResolver arg1) throws ContributionResolveException {
    	
    }
    
	/**
	 * Method to generate the DOM
	 * @param reader
	 * @param parent
	 * @throws Exception 
	 */
	//private void generateDOM(String elementText, String parent) {
	private void generateDOM(XMLStreamReader reader, String parent) {
		try{
			String elePrefix = reader.getPrefix();
			String eleQName = reader.getLocalName();
			if (elePrefix != null && elePrefix.length() != 0) {
                eleQName = elePrefix + ":" + eleQName;
            }
			
			Element element = document.createElementNS(reader.getNamespaceURI(), eleQName);
				
			int attributeCount = reader.getAttributeCount();
			for(int i = 0;i < attributeCount;i++){
				String ns = reader.getAttributeNamespace(i);
                String prefix = reader.getAttributePrefix(i);
                String qname = reader.getAttributeLocalName(i);
                String value = reader.getAttributeValue(i);
                if (prefix != null && prefix.length() != 0) {
                    qname = prefix + ":" + qname;
                }
                element.setAttributeNS(ns,qname,value);
			}
			if(parent == null){
				if(document != null){
					document.appendChild(element);
				}
				else{
					if (logger.isLoggable(Level.SEVERE)) {
	                    logger.log(Level.SEVERE, "Document not created ");
	                }
					error("Document not created",document,element);
				}
			}
			else{
				Node parentNode = getParentNode(document,parent);
				if(parentNode != null){
					parentNode.appendChild(element);
				}
				else{
					if (logger.isLoggable(Level.SEVERE)) {
						logger.log(Level.SEVERE, "Parent node not found");
					}
					error("Parent node not found",document,parentNode.getNodeName());
				}
			}
		}
		catch(Exception e){
			e.printStackTrace();
			if (logger.isLoggable(Level.SEVERE)) {
                logger.log(Level.SEVERE, "Document not created ");
            }
			error("Document not created",document,e);
		}
	}

	/**
	 * Method to create an empty document
	 * @return
	 */
	private Document createDocument() {
		try {
	        document = documentBuilderFactory.newDocumentBuilder().newDocument();
	        return document;
	    } catch (ParserConfigurationException e) {
	    	e.printStackTrace();
	    }
	    return null;
	}

	/**
	 * Method to traverse the DOM structure and write the elements 
	 * @param walker
	 * @param writer
	 * @throws XMLStreamException
	 */
	private void writeDOM(TreeWalker walker,XMLStreamWriter writer) throws XMLStreamException {
	  
	    Node parent = walker.getCurrentNode();
	    
	    writer.writeStartElement(parent.getPrefix(), parent.getLocalName(), parent.getNamespaceURI());
	    
	    NamedNodeMap attributes = parent.getAttributes();
	   
	    for(int i = 0;i<attributes.getLength();i++){
		   writer.writeAttribute(attributes.item(i).getPrefix(), attributes.item(i).getNamespaceURI(), attributes.item(i).getLocalName(), attributes.item(i).getNodeValue());
	    }
	    	   
	    for (Node n = walker.firstChild();n != null;n = walker.nextSibling()) {
	      writeDOM(walker,writer);
	    }
	    writer.writeEndElement();
	    
	    walker.setCurrentNode(parent);
	}

	/**
	 * Method to get the Parent node out of the DOM structure
	 * @param doc
	 * @param parent
	 * @return
	 */
	private Node getParentNode(Node doc,String parent) {
		Node parentNode = null;
		try{
			DocumentTraversal traversal = (DocumentTraversal)doc;
			
			CharSequence prefixChar = ":";
			NodeIterator iterator = traversal.createNodeIterator(document.getDocumentElement(), NodeFilter.SHOW_ELEMENT, null, true);
			for (Node n = iterator.nextNode(); n != null; n = iterator.nextNode()) {
				String nodeName = n.getNodeName();
				String[] str = null;
				if(n.getNodeName().contains(prefixChar)){
					str = nodeName.split(":");
					nodeName = str[str.length-1];
				}
				if(parent.equalsIgnoreCase(nodeName)){
			    	  parentNode = n;
			    	}
			    }
			return parentNode;
		}
		catch(Exception e){
			e.printStackTrace();
		}
		return parentNode;
	}
	
	 /**
     * Marshals exceptions into the monitor
     * 
     * @param problems
     * @param message
     * @param model
     */
    private void error(String message, Object model, Exception ex) {
    	if (monitor != null) {
	        Problem problem = new ProblemImpl(this.getClass().getName(), "contribution-validation-messages", Severity.ERROR, model, message, ex);
	        monitor.problem(problem);
    	}
    }
    
    /**
     * Report a error.
     * 
     * @param problems
     * @param message
     * @param model
     */
    private void error(String message, Object model, Object... messageParameters) {
    	if (monitor != null) {
	        Problem problem = new ProblemImpl(this.getClass().getName(), "contribution-validation-messages", Severity.ERROR, model, message, (Object[])messageParameters);
	        monitor.problem(problem);
    	}
    }
	
}