/*

  * 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.classpath;

 import java.net.URL;

 import java.net.URLClassLoader;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.Iterator;

 import java.util.Set;

 import java.util.regex.Pattern;

 import org.reflections.Reflections;

 import org.reflections.scanners.ResourcesScanner;

 import org.reflections.util.ConfigurationBuilder;

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

 /**

  * Loads properties files found on the class path.

  */

 public final class PropertiesFilesLoader

 {

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

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

   /**

    * Pattern to filter properties files.

    * <p>

    * Every properties file (with file extension <code>properties</code> is

    * allowed as long as the name does not contain any underscores. Underscores

    * are used to distinguish localized information (like

    * <code>my-properties_en.properties</code>) and therefore must not

    * considered.

    * </p>

    *

    * @impl Note that the pattern here is only the file name pattern without a

    *       path.

    */

   private static final Pattern PROPERTIES_PATTERN = Pattern

       .compile("[^_]+\\.properties");

   /**

    * Pattern to detect boot properties files.

    *

    * @impl Note that the pattern here is only the file name pattern without a

    *       path.

    */

   private static final Pattern BOOT_PROPERTIES_PATTERN = Pattern

       .compile("boot\\.properties");

   /**

    * Default scanner to use.

    */

   private static final ResourcesScanner SCANNER = new ResourcesScanner();

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

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

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

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

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

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

   private static Reflections buildReflections(final Collection<URL> urls)

   {

     final ClassLoader classLoader =

         new URLClassLoader(urls.toArray(new URL[urls.size()]), Thread

             .currentThread().getContextClassLoader());

     final ConfigurationBuilder builder = new ConfigurationBuilder();

     builder.addScanners(SCANNER).addClassLoader(classLoader).addUrls(urls);

     final Reflections reflections = new Reflections(builder);

     return reflections;

   }

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

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

   /**

    * Returns all files with the extension <code>.properties</code>.

    *

    * @param urls the class roots to search for files that have the

    *          <code>.properties</code> file name extension.

    * @return the names of properties files relative to the class path root.

    */

   public Set<String> getPropertiesFiles(final Collection<URL> urls)

   {

     if (urls == null || urls.isEmpty())

     {

       return Collections.emptySet();

     }

     final Reflections reflections = buildReflections(urls);

     final Set<String> pathes = reflections.getResources(PROPERTIES_PATTERN);

     return pathes;

   }

   /**

    * Returns all boot properties that are defined to control the configuration

    * parsing process. Properties are stored in files matching

    * <code>/{@value de.smartics.properties.api.core.domain.PropertiesContext#META_INF_HOME}/boot.properties</code>

    * .

    *

    * @param urls the URLs to search in.

    * @return the names of properties files relative to the class path root.

    */

   public Set<String> getBootPropertiesFiles(final Collection<URL> urls)

   {

     if (urls == null || urls.isEmpty())

     {

       return Collections.emptySet();

     }

     final Reflections reflections = buildReflections(urls);

     final Set<String> pathes =

         reflections.getResources(BOOT_PROPERTIES_PATTERN);

     for (final Iterator<String> i = pathes.iterator(); i.hasNext();)

     {

       final String path = i.next();

       if (!path.endsWith(PropertiesContext.META_INF_HOME + "/boot.properties"))

       {

         i.remove();

       }

     }

     return pathes;

   }

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

 }