/**
 * Copyright (C) 2009 eXo Platform SAS.
 * 
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 * 
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.services.common;

import org.exoplatform.services.common.ServiceConfig.ServiceType;

import java.lang.ref.SoftReference;
import java.lang.reflect.Constructor;
import java.util.Arrays;
import java.util.Comparator;
import java.util.concurrent.ConcurrentHashMap;

/**
 *  Author : Nhu Dinh Thuan
 *          Email:nhudinhthuan@yahoo.com
 * Jun 3, 2007
 */
public class ServicesContainer
{

   private static ConcurrentHashMap<String, Object> map = new ConcurrentHashMap<String, Object>();

   /*public static <T> void put(Class<T> clazz) { put(clazz.getName(), clazz); }

   public static <T> void put(String id, Class<T> clazz) {
     try {
       map.put(id, create(clazz));
     }catch (Exception e) {
       throw new RuntimeException(e);
     }
   }*/

   public static <T> T get(Class<T> clazz)
   {
      return get(clazz.getName(), clazz);
   }

   public static <T> T get(String id, Class<T> clazz)
   {
      ServiceType type = ServiceType.INSTANCE;
      ServiceConfig config = clazz.getAnnotation(ServiceConfig.class);
      if (config != null)
         type = config.type();
      return get(type, id, clazz);
   }

   @SuppressWarnings("unchecked")
   public static <T> T get(ServiceType type, String id, Class<T> clazz)
   {
      if (type == ServiceType.INSTANCE)
      {
         try
         {
            return create(clazz);
         }
         catch (Exception e)
         {
            throw new RuntimeException(e);
         }
      }

      if (type == ServiceType.SINGLE_FINAL)
      {
         Object service = map.get(id);
         if (service != null)
            return clazz.cast(service);
         try
         {
            service = create(clazz);
            map.put(id, service);
            return clazz.cast(service);
         }
         catch (Exception e)
         {
            throw new RuntimeException(e);
         }
      }

      //  if(type == ServiceType.SOFT_REFERENCE) { 
      ThreadSoftReference<T> thread = (ThreadSoftReference<T>)map.get(clazz);
      if (thread == null)
      {
         thread = new ThreadSoftReference<T>(clazz);
         map.put(id, thread);
      }
      try
      {
         return clazz.cast(thread.getRef());
      }
      catch (Exception e)
      {
         throw new RuntimeException(e);
      }
      /*}

      if(type == ServiceType.LAZY_FINAL) return clazz.cast(map.get(id));

      return null;*/
   }

   @SuppressWarnings("unchecked")
   private static <T> T create(Class<T> clazz) throws Exception
   {
      Constructor<T>[] constructors = (Constructor<T>[])clazz.getDeclaredConstructors();
      Arrays.sort(constructors, new Comparator<Constructor<T>>()
      {
         public int compare(Constructor<T> cons1, Constructor<T> cons2)
         {
            return cons1.getParameterTypes().length - cons2.getParameterTypes().length;
         }
      });
      if (constructors.length < 1)
         throw new Exception("Not constructor in class " + clazz);
      Constructor<T> constructor = constructors[0];
      Class<?>[] classes = constructors[0].getParameterTypes();
      if (classes.length < 1)
         return clazz.newInstance();
      Object[] objs = new Object[classes.length];
      for (int i = 0; i < classes.length; i++)
      {
         objs[i] = get(classes[i]);
      }
      constructor.setAccessible(true);
      return clazz.cast(constructor.newInstance(objs));
   }

   private static class ThreadSoftReference<T> extends ThreadLocal<SoftReference<T>>
   {

      private Class<T> clazz;

      @SuppressWarnings("unchecked")
      private ThreadSoftReference(Class<?> clazz)
      {
         this.clazz = (Class<T>)clazz;
      }

      private T getRef() throws Exception
      {
         SoftReference<T> sr = get();
         if (sr == null || sr.get() == null)
         {
            sr = new SoftReference<T>(create(clazz));
            set(sr);
         }
         return sr.get();
      }

   }

}
