/**
    * This file Copyright (c) 2016 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.config.registry.decoration;
  
  import info.magnolia.config.registry.DefinitionProvider;
  
  import com.google.common.base.Objects;
  
  
  /**
   * Caches the decoration result - won't do decoration again if incoming argument is the same.
   *
   * @param <T> the decorated definition type
   */
  public class CachingDefinitionDecorator<T> implements DefinitionDecorator<T> {
  
      private DefinitionDecorator<T> delegate;
  
      private DefinitionProvider<T> decorationResult;
  
      private DefinitionProvider<T> decoratedDefinitionProvider;
  
      private long lastDecorationTimestamp = -1;
  
      public CachingDefinitionDecorator(DefinitionDecorator<T> delegate) {
          this.delegate = delegate;
      }
  
      @Override
      public DefinitionDecoratorMetadata metadata() {
          return delegate.metadata();
      }
  
      @Override
      public boolean appliesTo(DefinitionProvider<T> definitionProvider) {
          return delegate.appliesTo(definitionProvider);
      }
  
      @Override
      public DefinitionProvider<T> decorate(DefinitionProvider<T> definitionProvider) {
          if (!definitionProvider.equals(decoratedDefinitionProvider) || definitionProvider.getLastModified() > lastDecorationTimestamp) {
              this.decoratedDefinitionProvider = definitionProvider;
              this.decorationResult = delegate.decorate(definitionProvider);
              this.lastDecorationTimestamp = System.currentTimeMillis();
          }
  
          return decorationResult;
      }
  
      @Override
      public String toString() {
          return this.delegate.toString();
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
  
          if (!(o instanceof DefinitionDecorator)) {
              return false;
          }
  
          DefinitionDecorator other = (DefinitionDecorator) o;
          if (other instanceof CachingDefinitionDecorator) {
              other = ((CachingDefinitionDecorator)other).delegate;
          }
  
          return Objects.equal(this.delegate, other);
     }
 
     @Override
     public int hashCode() {
         return Objects.hashCode(delegate);
     }
 }