/*

  * Copyright 2012-2013 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.properties.spi.core.context;

 import java.io.BufferedInputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import java.util.List;

 import java.util.Locale;

 import org.apache.commons.io.IOUtils;

 import org.apache.commons.lang.StringUtils;

 import org.jdom.Document;

 import org.jdom.Element;

 import org.jdom.JDOMException;

 import org.jdom.Namespace;

 import org.jdom.input.SAXBuilder;

 import de.smartics.properties.api.core.domain.ConfigException;

 import de.smartics.properties.api.core.domain.PropertiesContext;

 import de.smartics.properties.api.core.domain.PropertiesContext.Builder;

 import de.smartics.properties.spi.core.util.ClassLoaderUtils;

 import de.smartics.util.lang.ClassPathContext;

 /**

  * Parses the configuration file for properties.

  */

 public final class DeclarationConfigParser

 {

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

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

   /**

    * The namespace accepted by this parser.

    */

   private static final Namespace NS = Namespace

       .getNamespace("http://smartics.de/properties/declaration/1");

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

   /**

    * Helper to determine the supported locales by analyzing the property set

    * reports.

    */

   private final LocaleFinder localeFinder = new LocaleFinder();

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

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

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

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

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

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

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

   /**

    * Default constructor.

    */

   public DeclarationConfigParser()

   {

   }

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

   /**

    * Convenience method using a class' class loader to locate the configuration

    * file to parse the configuration file at

    * {@link PropertiesContext#DECLARATION_FILE}.

    *

    * @param type the type whose class loader to use to locate the configuration

    *          file.

    * @return the read configuration, never <code>null</code>.

    * @throws ConfigException on any problem loading the file.

    */

   public PropertiesContext parse(final Class<?> type) throws ConfigException

   {

     final String archivePath = ClassLoaderUtils.calcArchivePath(type);

     final ClassPathContext context =

         new ClassPathContext(type.getClassLoader(), archivePath);

     return parse(context);

   }

   /**

    * Parses the configuration file at {@link PropertiesContext#DECLARATION_FILE}

    * .

    *

    * @param context the context to use to locate the configuration file.

    * @return the read configuration, never <code>null</code>.

    * @throws ConfigException on any problem loading the file.

    */

   public PropertiesContext parse(final ClassPathContext context)

     throws ConfigException

   {

     final URL url = context.getResource(PropertiesContext.DECLARATION_FILE);

     if (url != null)

     {

       final String systemId = url.toExternalForm();

       final List<Locale> locales = localeFinder.find(systemId, context);

       InputStream in = null;

       try

       {

         try

         {

           in = new BufferedInputStream(url.openStream());

         }

         catch (final IOException e)

         {

           throw new ConfigException(PropertiesContext.DECLARATION_FILE, e);

         }

         return parse(systemId, locales, in);

       }

       finally

       {

         IOUtils.closeQuietly(in);

       }

     }

     throw new ConfigException(PropertiesContext.DECLARATION_FILE);

   }

   private PropertiesContext parse(final String systemId,

       final List<Locale> locales, final InputStream input)

     throws ConfigException

   {

     try

     {

       final SAXBuilder parser = new SAXBuilder();

       final Document document = parser.build(input, systemId);

       final PropertiesContext.Builder builder = new PropertiesContext.Builder();

       builder.withLocales(locales);

       final Element rootNode = document.getRootElement();

       final String homePageUrl = rootNode.getChildText("homepage-url", NS);

       final String propertiesReportUrl =

           rootNode.getChildText("properties-report-url", NS);

       if (StringUtils.isNotBlank(propertiesReportUrl))

       {

         builder.withHomePageUrl(homePageUrl).withPropertiesReportUrl(

             propertiesReportUrl);

       }

       handleAliases(rootNode, builder);

       return builder.build();

     }

     catch (final JDOMException e)

     {

       throw new ConfigException(systemId, e);

     }

     catch (final IOException e)

     {

       throw new ConfigException(systemId, e);

     }

   }

   @SuppressWarnings("unchecked")

   private void handleAliases(final Element rootNode, final Builder builder)

   {

     final Element aliases = rootNode.getChild("aliases", NS);

     if (aliases != null)

     {

       final List<Element> aliasElements = aliases.getChildren("alias", NS);

       for (final Element aliasElement : aliasElements)

       {

         final String alias = aliasElement.getTextNormalize();

         final String physical = aliasElement.getAttributeValue("for", NS);

         builder.withAlias(alias, physical);

       }

     }

   }

 }