/*

  * 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.Set;

 import org.reflections.Reflections;

 import org.reflections.scanners.TypeAnnotationsScanner;

 import org.reflections.util.ConfigurationBuilder;

 import de.smartics.properties.api.core.annotations.PropertySet;

 /**

  * Loads classes that have a {@link PropertySet} annotation.

  */

 public final class PropertySetClassesLoader

 {

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

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

   /**

    * Default scanner to use.

    */

   private static final TypeAnnotationsScanner SCANNER =

       new TypeAnnotationsScanner();

   // --- 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.setScanners(SCANNER).addClassLoader(classLoader).addUrls(urls);

     final Reflections reflections = new Reflections(builder);

     return reflections;

   }

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

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

   /**

    * Returns all types that are annotated as property set.

    *

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

    *          annotation.

    * @return the set of types that are annotated with {@link PropertySet}.

    */

   public Set<Class<?>> getPropertySetTypes(final Collection<URL> urls)

   {

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

     {

       return Collections.emptySet();

     }

     final Reflections reflections = buildReflections(urls);

     final Set<Class<?>> propertySetTypes =

         reflections.getTypesAnnotatedWith(PropertySet.class);

     return propertySetTypes;

   }

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

 }