/*

  * Copyright 2012 smartics, Kronseder & Reiner GmbH

  *

  * 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 de.smartics.ci.config.load;

 import java.io.FileNotFoundException;

 import java.io.IOException;

 import org.jdom.Document;

 import org.jdom.Element;

 import org.jdom.JDOMException;

 import org.jdom.input.SAXBuilder;

 import org.jdom.xpath.XPath;

 import org.xml.sax.InputSource;

 import de.smartics.ci.config.hudson.AbstractHudsonConfigHelper;

 import de.smartics.ci.config.utils.JDomUtils;

 import de.smartics.util.lang.Arguments;

 import de.smartics.util.lang.NullArgumentException;

 /**

  * Loader of XML job configurations.

  */

 public final class HudsonJobConfigLoader

 {

   // ********************************* Fields *********************************

   // --- constants ------------------------------------------------------------

   // --- members --------------------------------------------------------------

   /**

    * The location manager to load resources.

    */

   private final LocationManager locationManager;

   /**

    * The loader configuration to control the loading and creation of Hudson job

    * configuration files.

    */

   private final HudsonJobConfigurationLoaderConfig loaderConfig;

   /**

    * Helper to merge Hudson XML config files.

    */

   private final DocumentMerger merger = new DocumentMerger();

   // ****************************** Initializer *******************************

   // ****************************** Constructors ******************************

   /**

    * Default constructor.

    *

    * @param locationManager the location manager to load resources.

    * @param loaderConfig the loader configuration to control the loading and

    *          creation of Hudson job configuration files.

    * @throws NullArgumentException if {@code locationManager} or

    *           {@code loaderConfig} is <code>null</code>.

    */

   public HudsonJobConfigLoader(final LocationManager locationManager,

       final HudsonJobConfigurationLoaderConfig loaderConfig)

     throws NullArgumentException

   {

     Arguments.checkNotNull("locationManager", locationManager);

     Arguments.checkNotNull("loaderConfig", loaderConfig);

     this.locationManager = locationManager;

     this.loaderConfig = loaderConfig;

   }

   // ****************************** Inner Classes *****************************

   // ********************************* Methods ********************************

   // --- init -----------------------------------------------------------------

   // --- get&set --------------------------------------------------------------

   // --- business -------------------------------------------------------------

   /**

    * Loads the XML document from the given loader plan. The loader plan

    * instructs the job config loader to load a number of Hudson job

    * configuration files to merge their contents.

    *

    * @param plan the plan to load a number of job config files in a given order.

    *          Later config files override values previously loaded.

    * @return the document containing the merged information from the job config

    *         files specified by the plan as an XML string.

    * @throws NullArgumentException if {@code plan} is <code>null</code>.

    * @throws IllegalArgumentException if {@code plan} is empty.

    * @throws JDOMException on any XML parsing or generation problem.

    */

   public HudsonJobConfig loadHudsonConfig(final LoaderPlan plan)

     throws NullArgumentException, IllegalArgumentException, JDOMException

   {

     final Document document = load(plan);

     final String xmlString = JDomUtils.toString(document);

     final String id = fetchId(document);

     return new HudsonJobConfig(id, xmlString);

   }

   private String fetchId(final Document document) throws JDOMException

   {

     final Element projectIdElement =

         (Element) XPath.selectSingleNode(document,

             "/maven2-moduleset/authToken");

     final String projectId = projectIdElement.getTextNormalize();

     return projectId;

   }

   /**

    * Loads the XML document from the given loader plan. The loader plan

    * instructs the job config loader to load a number of Hudson job

    * configuration files to merge their contents.

    *

    * @param plan the plan to load a number of job config files in a given order.

    *          Later config files override values previously loaded.

    * @return the document containing the merged information from the job config

    *         files specified by the plan as an XML string.

    * @throws NullArgumentException if {@code plan} is <code>null</code>.

    * @throws IllegalArgumentException if {@code plan} is empty.

    * @throws JDOMException on any XML parsing or generation problem.

    */

   public Document load(final LoaderPlan plan) throws NullArgumentException,

     IllegalArgumentException, JDOMException

   {

     checkArguments(plan);

     Document document = createDocument(plan);

     String resource = null;

     try

     {

       for (final String configName : plan)

       {

         resource = configName + ".xml";

         final InputSource inputSource = locationManager.open(resource);

         document = mergeDocument(document, inputSource);

       }

       final HudsonJobDocumentFixer fixer =

           new HudsonJobDocumentFixer(loaderConfig, document);

       fixer.fix();

       return document;

     }

     catch (final FileNotFoundException e)

     {

       throw new IllegalArgumentException("Resource '" + resource // NOPMD

                                          + "' cannot be found.", e);

     }

     catch (final JDOMException e)

     {

       throw new IllegalArgumentException("Resource '" + resource

                                          + "' is not valid.", e);

     }

     catch (final IOException e)

     {

       throw new IllegalArgumentException("Resource '" + resource

                                          + "' cannot be read.", e);

     }

   }

   private static void checkArguments(final LoaderPlan plan)

     throws IllegalArgumentException, NullArgumentException

   {

     Arguments.checkNotNull("plan", plan);

     if (plan.isEmpty())

     {

       throw new IllegalArgumentException("The loader plan must not be empty.");

     }

   }

   private Document createDocument(final LoaderPlan plan) throws JDOMException

   {

     final Document hudsonConfigXml =

         AbstractHudsonConfigHelper.createDocument();

     final MavenInfoApplier maven = new MavenInfoApplier(loaderConfig, plan);

     maven.addAllInfo(hudsonConfigXml);

     return hudsonConfigXml;

   }

   private Document mergeDocument(final Document document,

       final InputSource inputSource) throws JDOMException, IOException

   {

     final SAXBuilder builder = new SAXBuilder();

     final Document newDocument = builder.build(inputSource);

     final Document mergedDocument = merger.merge(document, newDocument);

     return mergedDocument;

   }

   // --- object basics --------------------------------------------------------

 }