package org.apache.onami.test.reflection;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.

  */

 import static com.google.common.base.Preconditions.checkArgument;

 import java.lang.annotation.Annotation;

 import java.lang.reflect.AnnotatedElement;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import com.google.common.collect.ArrayListMultimap;

 import com.google.common.collect.Multimap;

 /**

  * <p>

  * Class visitor engine.

  * </p>

  * <p>

  * Visit the input class and all super classes and invokes handler to register annotations.

  * </p>

  */

 public final class ClassVisitor

 {

     private static final String JAVA_PACKAGE = "java";

     private static final Logger LOGGER = Logger.getLogger( ClassVisitor.class.getName() );

     private final Multimap<Class<? extends Annotation>, AnnotationHandler<? extends Annotation, ? extends AnnotatedElement>> handlers =

         ArrayListMultimap.create();

     /**

      * Registers an annotation handler.

      *

      * @param <A> whatever annotation type

      * @param annotationType the annotation class to handle

      * @param handler the related annotation handler

      * @return the current {@code ClassVisitor} instance

      */

     public <A extends Annotation> ClassVisitor registerHandler( Class<A> annotationType,

                                                                 AnnotationHandler<A, ? extends AnnotatedElement> handler )

     {

         handlers.put( annotationType, handler );

         return this;

     }

     /**

      * Visits all fields, methods and super classes of the input class.

      *

      * @param <T> any type

      * @param type The type 

      * @throws HandleException when an error occurs.

      */

     public <T> void visit( final Class<? super T> type )

         throws HandleException

     {

         checkArgument( type != null, "Type to be visited cannot be null" );

         if ( LOGGER.isLoggable( Level.FINER ) )

         {

             LOGGER.finer( "  Visit class: " + type );

         }

         if ( type.getPackage() != null && type.getPackage().getName().startsWith( JAVA_PACKAGE ) )

         {

             return;

         }

         handle( type );

         handle( type.getDeclaredFields() );

         handle( type.getDeclaredMethods() );

         visit( type.getSuperclass() );

     }

     @SuppressWarnings( "unchecked" )

     private void handle( AnnotatedElement... elements )

         throws HandleException

     {

         for ( AnnotatedElement element : elements )

         {

             for ( Annotation annotation : element.getAnnotations() )

             {

                 for ( AnnotationHandler<? extends Annotation, ? extends AnnotatedElement> handler : handlers.get( annotation.annotationType() ) )

                 {

                     ( (AnnotationHandler<Annotation, AnnotatedElement>) handler ).handle( annotation, element );

                 }

             }

         }

     }

 }