/*
    * 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 static de.smartics.properties.api.core.domain.ConfigMessageBean.systemId;
  
  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.ConfigCode;
  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.classpath.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(systemId(
               ConfigCode.CONFIG_FILE_CANNOT_BE_READ, e,
               PropertiesContext.DECLARATION_FILE));
         }
         return parse(systemId, locales, in);
       }
       finally
       {
         IOUtils.closeQuietly(in);
       }
     }
     throw new ConfigException(systemId(ConfigCode.CONFIG_FILE_NOT_FOUND,
         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(ConfigCode.CONFIG_FILE_CANNOT_BE_READ,
           e, systemId));
     }
     catch (final IOException e)
     {
       throw new ConfigException(systemId(ConfigCode.CONFIG_FILE_CANNOT_BE_READ,
           e, systemId));
     }
   }
 
   @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);
       }
     }
   }
 }