/*
* Copyright 2009 Federal Chancellery Austria and
* Graz University of Technology
*
* 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 at.gv.egiz.bku.slcommands;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import at.gv.egiz.bku.slexceptions.SLRuntimeException;
import at.gv.egiz.marshal.MarshallerFactory;

public class SLMarshallerFactory {
  
  static Log log = LogFactory.getLog(SLMarshallerFactory.class);

  /**
   * The JAXBContext used for result marshaling.
   * <p>
   * Note: Different contexts are used for marshaling and unmarshaling of
   * security layer requests and responses to avoid propagation of namespace
   * declarations of legacy namespaces into marshaled results.
   * </p>
   * @see #jaxbContextLegacy
   */
  protected static JAXBContext context;

  /**
   * The JAXBContext used for marshaling of of results in the legacy namespace.
   */
  protected static JAXBContext legacyContext;

  // ------------------- initialization on demand idiom -------------------
  // see http://en.wikipedia.org/wiki/Initialization_on_demand_holder_idiom
  // ----------------------------------------------------------------------
  
  /**
   * Private constructor called by {@link SLMarshallerFactoryInstanceHolder}.
   */
  private SLMarshallerFactory() {
    // context is initialized immediately while the legacy context is initialized only on demand
    try {
      String slPkg = at.buergerkarte.namespaces.securitylayer._1.ObjectFactory.class.getPackage().getName();
      String xmldsigPkg = org.w3._2000._09.xmldsig_.ObjectFactory.class.getPackage().getName();
      String cardChannelPkg = at.buergerkarte.namespaces.cardchannel.ObjectFactory.class.getPackage().getName();
      context = JAXBContext.newInstance(slPkg + ":" + xmldsigPkg + ":" + cardChannelPkg);
    } catch (JAXBException e) {
      log.error("Failed to setup JAXBContext security layer request.", e);
      throw new SLRuntimeException(e);
    }
  }
 
  /**
   * The lazy instance holder for this SLMarshallerFactory.
   */
  private static class SLMarshallerFactoryInstanceHolder {
    /**
     * The instance returned by {@link SLMarshallerFactory#getInstance()}
     */
    private static final SLMarshallerFactory instance = new SLMarshallerFactory();
  }

  /**
   * Get an instance of the <code>SLMarshallerFactory</code>. 
   */
  public static SLMarshallerFactory getInstance() {
    return SLMarshallerFactoryInstanceHolder.instance;
  }

  // ----------------------------------------------------------------------
  
  /**
   * Initialize the JAXBContext for the legacy namespace.
   */
  private static synchronized void ensureLegacyContext() {
    // legacy marshaller is initialized only on demand
    if (legacyContext == null) {
      try {
        String slPkgLegacy1_0 = at.buergerkarte.namespaces.securitylayer._20020225_.ObjectFactory.class.getPackage().getName();
        String slPkgLegacy1_1 = at.buergerkarte.namespaces.securitylayer._20020831_.ObjectFactory.class.getPackage().getName();
        String xmldsigPkg = org.w3._2000._09.xmldsig_.ObjectFactory.class.getPackage().getName();
        String cardChannelPkg = at.buergerkarte.namespaces.cardchannel.ObjectFactory.class.getPackage().getName();
        legacyContext = JAXBContext.newInstance(slPkgLegacy1_0 + ":" + slPkgLegacy1_1 + ":" + xmldsigPkg + ":" + cardChannelPkg);
      } catch (JAXBException e) {
        log.error("Failed to setup JAXBContext security layer request.", e);
        throw new SLRuntimeException(e);
      }
    }
  }

  /**
   * Creates an SL marshaller.
   * 
   * @param formattedOutput
   *          <code>true</code> if the marshaller should produce formated
   *          output, <code>false</code> otherwise
   * @return an SL marshaller
   */
  public Marshaller createMarshaller(boolean formattedOutput) {
    return createMarshaller(formattedOutput, false);
  }

  /**
   * Creates an SL marshaller.
   * 
   * @param formattedOutput
   *          <code>true</code> if the marshaller should produce formated
   *          output, <code>false</code> otherwise
   * @param fragment
   *          <code>true</code> if the marshaller should produce a XML fragment
   *          (omit XML declaration), <code>false</code> otherwise
   * @return an SL marshaller
   */
  public Marshaller createMarshaller(boolean formattedOutput, boolean fragment) {
    try {
      return MarshallerFactory.createMarshaller(context, formattedOutput, fragment);
    } catch (JAXBException e) {
      log.fatal("Failed to marshall error response.", e);
      throw new SLRuntimeException("Failed to marshall error response.", e);
    }
  }

  /**
   * Creates a legacy SL marshaller.
   * 
   * @param formattedOutput
   *          <code>true</code> if the marshaller should produce formated
   *          output, <code>false</code> otherwise
   * @return a legacy SL marshaller
   */
  public Marshaller createLegacyMarshaller(boolean formattedOutput) {
    return createLegacyMarshaller(formattedOutput, false);
  }
  
  /**
   * Creates a legacy SL marshaller.
   * 
   * @param formattedOutput
   *          <code>true</code> if the marshaller should produce formated
   *          output, <code>false</code> otherwise
   * @param fragment
   *          <code>true</code> if the marshaller should produce a XML fragment
   *          (omit XML declaration), <code>false</code> otherwise
   * @return a legacy SL marshaller
   */
  public Marshaller createLegacyMarshaller(boolean formattedOutput, boolean fragment) {
    try {
      ensureLegacyContext();
      return MarshallerFactory.createMarshaller(legacyContext, formattedOutput, fragment);
    } catch (JAXBException e) {
      log.fatal("Failed to marshall error response.", e);
      throw new SLRuntimeException("Failed to marshall error response.", e);
    }
  }
  
}