/**

  * Copyright (c) 2011-2014, jcabi.com

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met: 1) Redistributions of source code must retain the above

  * copyright notice, this list of conditions and the following

  * disclaimer. 2) Redistributions in binary form must reproduce the above

  * copyright notice, this list of conditions and the following

  * disclaimer in the documentation and/or other materials provided

  * with the distribution. 3) Neither the name of the jcabi.com nor

  * the names of its contributors may be used to endorse or promote

  * products derived from this software without specific prior written

  * permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT

  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL

  * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

  * OF THE POSSIBILITY OF SUCH DAMAGE.

  */

 package com.jcabi.matchers;

 import java.io.StringWriter;

 import javax.xml.bind.JAXBContext;

 import javax.xml.bind.JAXBElement;

 import javax.xml.bind.JAXBException;

 import javax.xml.bind.JAXBIntrospector;

 import javax.xml.bind.Marshaller;

 import javax.xml.bind.annotation.XmlType;

 import javax.xml.namespace.QName;

 import javax.xml.transform.Source;

 import lombok.EqualsAndHashCode;

 import lombok.ToString;

 /**

  * JAXB-empowered object to XML converting utility.

  *

  * <p>The object has to be annotated with JAXB annotations

  * in order to be convertable. Let's consider an example JAXB-annotated class:

  *

  * <pre> import javax.xml.bind.annotation.XmlAccessType;

  * import javax.xml.bind.annotation.XmlAccessorType;

  * import javax.xml.bind.annotation.XmlElement;

  * import javax.xml.bind.annotation.XmlRootElement;

  * @XmlRootElement(name = "employee")

  * @XmlAccessorType(XmlAccessType.NONE)

  * public class Employee {

  *   @XmlElement(name = "name")

  *   public String getName() {

  *     return "John Doe";

  *   }

  * }</pre>

  *

  * <p>Now you want to test how it works with real data after convertion

  * to XML (in a unit test):

  *

  * <pre> import com.jcabi.matchers.JaxbConverter;

  * import com.jcabi.matchers.XhtmlMatchers;

  * import org.junit.Assert;

  * import org.junit.Test;

  * public final class EmployeeTest {

  *   @Test

  *   public void testObjectToXmlConversion() throws Exception {

  *     final Object object = new Employee();

  *     Assert.assertThat(

  *       JaxbConverter.the(object),

  *       XhtmlMatchers.hasXPath("/employee/name[.='John Doe']")

  *     );

  *   }

  * }</pre>

  *

  * @author Yegor Bugayenko (yegor@tpc2.com)

  * @version $Id$

  */

 @ToString

 @EqualsAndHashCode

 public final class JaxbConverter {

     /**

      * Private ctor, to avoid direct instantiation of the class.

      */

     private JaxbConverter() {

         // intentionally empty

     }

     /**

      * Convert an object to XML.

      *

      * <p>The method will throw {@link AssertionError} if marshalling of

      * provided object fails for some reason.

      *

      * <p>The name of the method is motivated by

      * <a href="http://code.google.com/p/xml-matchers/">xmlatchers</a> project

      * and their {@code XmlMatchers.the(String)} method. Looks like this name

      * is short enough and convenient for unit tests.

      *

      * @param object The object to convert

      * @param deps Dependencies that we should take into account

      * @return DOM source/document

      * @throws JAXBException If an exception occurs inside

      */

     public static Source the(final Object object, final Class<?>... deps)

         throws JAXBException {

         final Class<?>[] classes = new Class<?>[deps.length + 1];

         classes[0] = object.getClass();

         System.arraycopy(deps, 0, classes, 1, deps.length);

         final JAXBContext ctx;

         try {

             ctx = JAXBContext.newInstance(classes);

         } catch (final JAXBException ex) {

             throw new IllegalArgumentException(ex);

         }

         final JAXBIntrospector intro = ctx.createJAXBIntrospector();

         Object subject = object;

         if (intro.getElementName(object) == null) {

             @SuppressWarnings("unchecked")

             final Class<Object> type = (Class<Object>) object.getClass();

             subject = new JAXBElement<Object>(

                 JaxbConverter.qname(object),

                 type,

                 object

             );

         }

         final Marshaller mrsh = JaxbConverter.marshaller(ctx);

         final StringWriter writer = new StringWriter();

         try {

             mrsh.marshal(subject, writer);

         } catch (final JAXBException ex) {

             throw new AssertionError(ex);

         }

         final String xml = writer.toString();

         return new StringSource(xml);

     }

     /**

      * Create marshaller.

      * @param ctx The context

      * @return Marshaller

      * @throws JAXBException If an exception occurs inside

      */

     private static Marshaller marshaller(final JAXBContext ctx)

         throws JAXBException {

         final Marshaller mrsh = ctx.createMarshaller();

         mrsh.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

         return mrsh;

     }

     /**

      * Get type name, if XmlType annotation is present (exception otherwise).

      * @param obj The object

      * @return Qualified name

      * @see XmlElement#namespace()

      */

     private static QName qname(final Object obj) {

         final XmlType type = XmlType.class.cast(

             obj.getClass().getAnnotation(XmlType.class)

         );

         if (type == null) {

             throw new AssertionError(

                 String.format(

                     // @checkstyle LineLength (1 line)

                     "@XmlType or @XmlRootElement annotation required at %s",

                     obj.getClass().getName()

                 )

             );

         }

         final QName qname;

         if ("##default".equals(type.namespace())) {

             qname = new QName(type.name());

         } else {

             qname = new QName(type.namespace(), type.name());

         }

         return qname;

     }

 }