/*

  * 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.myfaces.cdi.util;

 import javax.enterprise.context.spi.Contextual;

 import javax.enterprise.context.spi.CreationalContext;

 import javax.enterprise.inject.spi.BeanManager;

 import javax.enterprise.inject.spi.PassivationCapable;

 import java.io.Serializable;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 /**

  * This Storage holds all information needed for storing

  * Contextual Instances in a Context.

  *

  * It also addresses Serialisation in case of passivating scopes.

  * 

  * NOTE: Taken from Apache DeltaSpike

  */

 public class ContextualStorage implements Serializable

 {

     private static final long serialVersionUID = 1L;

     private final Map<Object, ContextualInstanceInfo<?>> contextualInstances;

     private final BeanManager beanManager;

     private final boolean concurrent;

     private final boolean passivationCapable;

     /**

      * @param beanManager is needed for serialisation

      * @param concurrent whether the ContextualStorage might get accessed concurrently by different threads

      * @param passivationCapable whether the storage is for passivation capable Scopes

      */

     public ContextualStorage(BeanManager beanManager, boolean concurrent, boolean passivationCapable)

     {

         this.beanManager = beanManager;

         this.concurrent = concurrent;

         this.passivationCapable = passivationCapable;

         if (concurrent)

         {

             contextualInstances = new ConcurrentHashMap<Object, ContextualInstanceInfo<?>>();

         }

         else

         {

             contextualInstances = new HashMap<Object, ContextualInstanceInfo<?>>();

         }

     }

     /**

      * @return the underlying storage map.

      */

     public Map<Object, ContextualInstanceInfo<?>> getStorage()

     {

         return contextualInstances;

     }

     /**

      * @return whether the ContextualStorage might get accessed concurrently by different threads.

      */

     public boolean isConcurrent()

     {

         return concurrent;

     }

     /**

      *

      * @param bean

      * @param creationalContext

      * @param <T>

      * @return

      */

     public <T> T createContextualInstance(Contextual<T> bean, CreationalContext<T> creationalContext)

     {

         Object beanKey = getBeanKey(bean);

         if (isConcurrent())

         {

             // locked approach

             ContextualInstanceInfo<T> instanceInfo = new ContextualInstanceInfo<T>();

             ConcurrentMap<Object, ContextualInstanceInfo<?>> concurrentMap

                 = (ConcurrentHashMap<Object, ContextualInstanceInfo<?>>) contextualInstances;

             ContextualInstanceInfo<T> oldInstanceInfo

                 = (ContextualInstanceInfo<T>) concurrentMap.putIfAbsent(beanKey, instanceInfo);

             if (oldInstanceInfo != null)

             {

                 instanceInfo = oldInstanceInfo;

             }

             synchronized (instanceInfo)

             {

                 T instance = instanceInfo.getContextualInstance();

                 if (instance == null)

                 {

                     instance = bean.create(creationalContext);

                     instanceInfo.setContextualInstance(instance);

                     instanceInfo.setCreationalContext(creationalContext);

                 }

                 return instance;

             }

         }

         else

         {

             // simply create the contextual instance

             ContextualInstanceInfo<T> instanceInfo = new ContextualInstanceInfo<T>();

             instanceInfo.setCreationalContext(creationalContext);

             instanceInfo.setContextualInstance(bean.create(creationalContext));

             contextualInstances.put(beanKey, instanceInfo);

             return instanceInfo.getContextualInstance();

         }

     }

     /**

      * If the context is a passivating scope then we return

      * the passivationId of the Bean. Otherwise we use

      * the Bean directly.

      * @return the key to use in the context map

      */

     public <T> Object getBeanKey(Contextual<T> bean)

     {

         if (passivationCapable)

         {

             // if the

             return ((PassivationCapable) bean).getId();

         }

         return bean;

     }

     /**

      * Restores the Bean from its beanKey.

      * @see #getBeanKey(javax.enterprise.context.spi.Contextual)

      */

     public Contextual<?> getBean(Object beanKey)

     {

         if (passivationCapable)

         {

             return beanManager.getPassivationCapableBean((String) beanKey);

         }

         else

         {

             return (Contextual<?>) beanKey;

         }

     }

 }