/*

  * 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.

  */

 package org.apache.onami.factoryannotation;

 import java.lang.annotation.Annotation;

 import com.google.inject.Injector;

 /**

  * The interface to describe a FactoryAnnotationProvider bound by {@link FactoryAnnotationModule} to the Guice

  * {@link Injector}. <h3>Implementing a FactoryAnnotationProvider</h3> An {@link FactoryAnnotationProvider} is a special

  * provider to return the actual instance of a injection type in combination with the actual factory annotation at the

  * injection point. At this point we omit the UserEntity class. It can be a simple POJO, a JPA entity or whatever class

  * you can image.

  * 

  * <pre>

  * public class UserEntityProvider implements FactoryAnnotationProvider<UserEntity, User> {

  * 

  *     {@literal @}Override

  *     public UserEntity buildValue(final User annotation) {

  *         return getRealEntityById(annotation.byId());

  *     }

  *     

  *     {@literal @}Override

  *     public Class<UserEntity> getInjectionType() {

  *         return UserEntity.class;

  *     }

  * 

  *     private UserEntity getRealEntityById(int id) {

  *         ...

  *     }

  *     

  * }

  * </pre>

  * 

  * @param <T> The type to be injected

  * @param <A> Annotation type where injection happens

  */

 public interface FactoryAnnotationProvider<T, A extends Annotation>

 {

     /**

      * Returns the type of injection points that should be captured for provision.

      */

     Class<T> getInjectionType();

     /**

      * <p>

      * The implementation of this method is responsible for building / requesting the instance that is referenced by the

      * actual injection points annotation to the annotation type bound at configuration time.

      * </p>

      * <p>

      * For more information see {@link FactoryAnnotationModule}.

      * </p>

      * 

      * @param annotation The actual annotation of the bound annotation type at the provision injection point.

      * @return The actual instance for a given annotation based value.

      */

     T buildValue( A annotation );

 }