/*
    * 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.ContextNotActiveException;
  import javax.enterprise.context.spi.Context;
  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.util.Map;
  
  /**
   * A skeleton containing the most important parts of a custom CDI Context.
   * An implementing Context needs to implement the missing methods from the
   * {@link Context} interface and {@link #getContextualStorage(boolean)}.
   * 
   * NOTE: Taken from Apache DeltaSpike
   */
  public abstract class AbstractContext implements Context
  {
      /**
       * Whether the Context is for a passivating scope.
       */
      private final boolean passivatingScope;
  
      protected AbstractContext(BeanManager beanManager)
      {
          passivatingScope = beanManager.isPassivatingScope(getScope());
      }
  
      /**
       * An implementation has to return the underlying storage which
       * contains the items held in the Context.
       * @param createIfNotExist whether a ContextualStorage shall get created if it doesn't yet exist.
       * @return the underlying storage
       */
      protected abstract ContextualStorage getContextualStorage(boolean createIfNotExist);
  
      /**
       * @return whether the served scope is a passivating scope
       */
      public boolean isPassivatingScope()
      {
          return passivatingScope;
      }
  
      @Override
      public <T> T get(Contextual<T> bean)
      {
          checkActive();
  
          ContextualStorage storage = getContextualStorage(false);
          if (storage == null)
          {
              return null;
          }
  
          Map<Object, ContextualInstanceInfo<?>> contextMap = storage.getStorage();
          ContextualInstanceInfo<?> contextualInstanceInfo = contextMap.get(storage.getBeanKey(bean));
          if (contextualInstanceInfo == null)
          {
              return null;
          }
  
          return (T) contextualInstanceInfo.getContextualInstance();
      }
  
      @Override
      public <T> T get(Contextual<T> bean, CreationalContext<T> creationalContext)
      {
          checkActive();
  
          if (passivatingScope)
          {
              if (!(bean instanceof PassivationCapable))
              {
                  throw new IllegalStateException(bean.toString() +
                          " doesn't implement " + PassivationCapable.class.getName());
              }
          }
  
         ContextualStorage storage = getContextualStorage(true);
 
         Map<Object, ContextualInstanceInfo<?>> contextMap = storage.getStorage();
         ContextualInstanceInfo<?> contextualInstanceInfo = contextMap.get(storage.getBeanKey(bean));
 
         if (contextualInstanceInfo != null)
         {
             @SuppressWarnings("unchecked")
             final T instance =  (T) contextualInstanceInfo.getContextualInstance();
 
             if (instance != null)
             {
                 return instance;
             }
         }
 
         return storage.createContextualInstance(bean, creationalContext);
     }
 
     /**
      * Destroy the Contextual Instance of the given Bean.
      * @param bean dictates which bean shall get cleaned up
      * @return <code>true</code> if the bean was destroyed, <code>false</code> if there was no such bean.
      */
     public boolean destroy(Contextual bean)
     {
         ContextualStorage storage = getContextualStorage(false);
         if (storage == null)
         {
             return false;
         }
         ContextualInstanceInfo<?> contextualInstanceInfo = storage.getStorage().get(storage.getBeanKey(bean));
 
         if (contextualInstanceInfo == null)
         {
             return false;
         }
 
         bean.destroy(contextualInstanceInfo.getContextualInstance(), contextualInstanceInfo.getCreationalContext());
 
         return true;
     }
 
     /**
      * destroys all the Contextual Instances in the Storage returned by
      * {@link #getContextualStorage(boolean)}.
      */
     public void destroyAllActive()
     {
         ContextualStorage storage = getContextualStorage(false);
         if (storage == null)
         {
             return;
         }
 
         destroyAllActive(storage);
     }
 
     /**
      * Destroys all the Contextual Instances in the specified ContextualStorage.
      * This is a static method to allow various holder objects to cleanup
      * properly in &#064;PreDestroy.
      */
     public static void destroyAllActive(ContextualStorage storage)
     {
         Map<Object, ContextualInstanceInfo<?>> contextMap = storage.getStorage();
         for (Map.Entry<Object, ContextualInstanceInfo<?>> entry : contextMap.entrySet())
         {
             Contextual bean = storage.getBean(entry.getKey());
 
             ContextualInstanceInfo<?> contextualInstanceInfo = entry.getValue();
             bean.destroy(contextualInstanceInfo.getContextualInstance(), contextualInstanceInfo.getCreationalContext());
         }
     }
 
     /**
      * Make sure that the Context is really active.
      * @throws ContextNotActiveException if there is no active
      *         Context for the current Thread.
      */
     protected void checkActive()
     {
         if (!isActive())
         {
             throw new ContextNotActiveException("CDI context with scope annotation @"
                 + getScope().getName() + " is not active with respect to the current thread");
         }
     }
 
 }