/*
 * Copyright 2014 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed 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.jbpm.runtime.manager.impl.deploy;

import java.io.InputStream;
import java.io.StringWriter;
import java.net.URL;

import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

import org.kie.internal.runtime.conf.DeploymentDescriptor;
import org.xml.sax.SAXException;

/**
 * XML based deployment descriptor IO manager to read and write descriptors.
 * Underlying uses <code>XStream</code> for serialization with special class
 * and field mapping for more readability of the produced XML output.
 *
 */
public class DeploymentDescriptorIO {
		
	private static JAXBContext context = null;
	private static Schema schema = null;

	/**
	 * Reads XML data from given input stream and produces valid instance of 
	 * <code>DeploymentDescriptor</code>
	 * @param inputStream input stream that comes with xml data of the descriptor
	 * @return instance of the descriptor after deserialization
	 */
	public static DeploymentDescriptor fromXml(InputStream inputStream) {
		try {
			Unmarshaller unmarshaller = getContext().createUnmarshaller();
			unmarshaller.setSchema(schema);
			DeploymentDescriptor descriptor = (DeploymentDescriptor) unmarshaller.unmarshal(inputStream);
			
			return descriptor;
		} catch (Exception e) {
			throw new RuntimeException("Unable to read deployment descriptor from xml", e);
		}
	}
	
	/**
	 * Serializes descriptor instance to XML
	 * @param descriptor descriptor to be serialized
	 * @return xml representation of descriptor as string
	 */
	public static String toXml(DeploymentDescriptor descriptor) {
		try {
			
			Marshaller marshaller = getContext().createMarshaller();
	        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
	        marshaller.setProperty(Marshaller.JAXB_SCHEMA_LOCATION, "http://www.jboss.org/jbpm deployment-descriptor.xsd");
	        marshaller.setSchema(schema);
	        StringWriter stringWriter = new StringWriter();
	        
	        // clone the object and cleanup transients
	        DeploymentDescriptor clone = ((DeploymentDescriptorImpl)descriptor).clearClone();
	
	        marshaller.marshal(clone, stringWriter);
	        String output = stringWriter.toString();
	        
	        return output;
		} catch (Exception e) {
			throw new RuntimeException("Unable to generate xml from deployment descriptor", e);
		}
	}

	
	public static JAXBContext getContext() throws JAXBException, SAXException {
		if (context == null) {
			Class<?>[] jaxbClasses = { DeploymentDescriptorImpl.class};
			context = JAXBContext.newInstance(jaxbClasses);
			// load schema for validation
			URL schemaLocation = DeploymentDescriptorIO.class.getResource("/deployment-descriptor.xsd");
			schema = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(schemaLocation);
		} 
		
		return context;
	}
}