/*
 * Copyright 2017 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.kie.internal.runtime.manager.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;
    }
}
