/**
    * This file Copyright (c) 2003-2014 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.commands;
  
  import info.magnolia.cms.util.AlertUtil;
  
  import java.util.Collections;
  import java.util.Map;
  
  import org.apache.commons.beanutils.BeanUtils;
  import org.apache.commons.beanutils.PropertyUtils;
  import org.apache.commons.chain.Command;
  import org.apache.commons.chain.Context;
  import org.apache.commons.lang.exception.NestableException;
  import org.apache.commons.pool.BasePoolableObjectFactory;
  import org.apache.commons.pool.impl.StackObjectPool;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * To make the coding of commands as easy as possible the default values set in the config are set and the values of the
   * context are set as properties too if the naming matches. To get a better performance we use an inner object pool. The
   * execution of the command gets a clone from the pool and executes the clone
   * @author Philipp Bracher
   * @version $Revision$ ($Author$)
   */
  public abstract class MgnlCommand implements Command {
  
      public static Logger log = LoggerFactory.getLogger(MgnlCommand.class);
  
      /**
       * The default properties. Lazy bound.
       */
      private Map defaultProperties;
  
      private boolean isClone = false;
  
      private boolean isEnabled = true;
  
      /**
       * Command factory creating clones of the master/prototype command and pooling the cloned instances.
       * @author Philipp Bracher
       * @version $Id$
       */
      class MgnlCommandFactory extends BasePoolableObjectFactory {
  
          /**
           * The prototype we clone for faster execution.
           */
          private MgnlCommand prototype;
  
          /**
           * @param prototype
           */
          public MgnlCommandFactory(MgnlCommand prototype) {
              this.prototype = prototype;
          }
  
          @Override
          public Object makeObject() throws Exception {
              MgnlCommand cmd = (MgnlCommand) BeanUtils.cloneBean(this.prototype);
              cmd.setClone(true);
              return cmd;
          }
  
          @Override
          public void activateObject(Object arg0) throws Exception {
             super.activateObject(arg0);
             // set default properties
             BeanUtils.populate(arg0, defaultProperties);
         }
 
         @Override
         public void passivateObject(Object cmd) throws Exception {
             ((MgnlCommand) cmd).release();
             super.passivateObject(cmd);
         }
 
     }
 
     /**
      * Pool of inner commands.
      */
     private StackObjectPool pool;
 
     /**
      * True if we can use object pooling. Else we synchronize the execution.
      */
     private boolean pooling = true;
 
     /**
      * Make sure that the context is castable to a magnolia context.
      * @return true on success, false otherwise
      */
     @Override
     public boolean execute(Context ctx) throws Exception {
         if (!(ctx instanceof info.magnolia.context.Context)) {
             throw new IllegalArgumentException("context must be of type " + info.magnolia.context.Context.class);
         }
 
         if (this.defaultProperties == null) {
             initDefaultProperties();
         }
 
         MgnlCommand cmd;
 
         if (pooling) {
             // do not instantiate until the pool is really needed
             // means: do not create a pool for command objects created in the pool itself
             if (pool == null) {
                 pool = new StackObjectPool(new MgnlCommandFactory(this));
             }
 
             try {
                 // try to use the pool
                 cmd = (MgnlCommand) pool.borrowObject();
             }
             // this happens if the commons constructor is not public: anonymous classes for example
             catch (Throwable t) {
                 pooling = false;
                 // start again
                 return execute(ctx);
             }
         }
         else {
             cmd = this;
         }
 
         boolean success = executePooledOrSynchronized(ctx, cmd);
         // convert the confusing true false behavior to fit commons chain
         return !success;
     }
 
     private boolean executePooledOrSynchronized(Context ctx, MgnlCommand cmd) throws Exception {
         boolean success = false; // break execution
 
         // populate the command if we are using a pool
         if (pooling) {
             BeanUtils.populate(cmd, ctx);
             // cast to mgnl context class
             try {
                 success = cmd.execute((info.magnolia.context.Context) ctx);
             }
             catch (Exception e) {
                 AlertUtil.setException(e, (info.magnolia.context.Context) ctx);
                 throw new NestableException("exception during executing command", e);
             }
             finally {
                 pool.returnObject(cmd);
             }
         }
         else {
             synchronized (cmd) {
                 BeanUtils.populate(cmd, ctx);
                 try {
                     success = cmd.execute((info.magnolia.context.Context) ctx);
                 }
                 catch (Exception e) {
                     AlertUtil.setException(e, (info.magnolia.context.Context) ctx);
                     throw new NestableException("exception during executing command", e);
                 }
                 finally {
                     if (pooling) {
                         pool.returnObject(cmd);
                     }
                     else {
                         cmd.release();
                         BeanUtils.populate(cmd, defaultProperties);
                     }
                 }
             }
         }
         return success;
     }
 
     private void initDefaultProperties() {
         try {
             this.defaultProperties = PropertyUtils.describe(this);
         } catch (Exception e) {
             if (log.isDebugEnabled()) {
                 log.warn("Failed to persist "+ this.getClass().getName()+" command properties due to "+ e.getMessage()+". Please review your configuration.", e);
             } else {
                 log.warn("Failed to persist {} command properties due to {}. Please review your configuration.", this.getClass().getName(), e.getMessage());
             }
             this.defaultProperties = Collections.EMPTY_MAP;
         }
     }
 
     public abstract boolean execute(info.magnolia.context.Context context) throws Exception;
 
     /**
      * If a clone is passivated we call this method. Please clean up private properties.
      */
     public void release() {
     }
 
     /**
      * @return the isClone
      */
     protected boolean isClone() {
         return isClone;
     }
 
     /**
      * @param isClone the isClone to set
      */
     protected void setClone(boolean isClone) {
         this.isClone = isClone;
     }
 
 
     public boolean isEnabled() {
         return this.isEnabled;
     }
 
 
     public void setEnabled(boolean isEnabled) {
         this.isEnabled = isEnabled;
     }
 
 }