/*
    * 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.maven.bugzilla;
  
  import java.io.BufferedInputStream;
  import java.io.InputStream;
  import java.util.List;
  
  import org.apache.commons.io.FilenameUtils;
  import org.apache.commons.io.IOUtils;
  import org.apache.maven.plugin.MojoExecutionException;
  
  import de.smartics.maven.issue.config.Component;
  import de.smartics.maven.issue.config.Configuration;
  import de.smartics.maven.issue.config.ConfigurationLoader;
  
  /**
   * Loads default descriptions for components.
   */
  public final class ComponentDescriptionLoader
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    /**
     * If no configuration is specified or the specified configuration does not
     * exist, the system configuration is used as default. Without the
     * <code>.xml</code> file name extension.
     * <p>
     * The value of this constant is {@value}.
     * </p>
     */
    private static final String SYSTEM_CONFIG_PREFIX =
        "bugzilla-configuration-system";
  
    // --- members --------------------------------------------------------------
  
    /**
     * The name of the configuration file to load from the class path.
     */
    private final String configurationName;
  
    /**
     * The name of the locale to use if standard component descriptions are used.
     */
    private final String locale;
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Default constructor.
     *
     * @param configurationName the name of the configuration file to load from
     *          the class path.
     * @param locale the name of the locale to use if standard component
     *          descriptions are used.
     */
    public ComponentDescriptionLoader(final String configurationName,
        final String locale)
    {
      this.configurationName = configurationName;
      this.locale = locale;
    }
  
    // ****************************** Inner Classes *****************************
  
    // ********************************* Methods ********************************
  
    // --- init -----------------------------------------------------------------
  
    // --- get&set --------------------------------------------------------------
  
    // --- business -------------------------------------------------------------
  
    List<Component> loadDefaultComponents() throws MojoExecutionException
    {
      final InputStream input = openDefaultComponentsStream();
  
      try
      {
        final ConfigurationLoader loader = new ConfigurationLoader();
        final Configuration configuration = loader.load(input);
        return configuration.getDefaultComponents();
     }
     finally
     {
       IOUtils.closeQuietly(input);
     }
   }
 
   private InputStream openDefaultComponentsStream()
     throws MojoExecutionException
   {
     final ClassLoader classLoader =
         Thread.currentThread().getContextClassLoader();
     InputStream in = openStream(classLoader);
 
     if (in == null)
     {
       in = openStream(classLoader, SYSTEM_CONFIG_PREFIX);
     }
 
     if (in != null)
     {
       return new BufferedInputStream(in);
     }
 
     throw new MojoExecutionException(
         "Cannot find configuration for default components. Neither resource '"
             + configurationName + "' nor the system default resource '"
             + SYSTEM_CONFIG_PREFIX + ".xml' has been found on the class path.");
   }
 
   private InputStream openStream(final ClassLoader classLoader)
   {
     final String stem = FilenameUtils.getBaseName(configurationName);
     return openStream(classLoader, stem);
   }
 
   private InputStream openStream(final ClassLoader classLoader,
       final String stem)
   {
     final String localizedName = stem + '-' + locale + ".xml";
     InputStream in = classLoader.getResourceAsStream(localizedName);
     if (in == null)
     {
       in = classLoader.getResourceAsStream(stem + "-en.xml");
     }
     return in;
   }
 
   // --- object basics --------------------------------------------------------
 
 }