/**
    * This file Copyright (c) 2013 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.i18nsystem.proxytoys;
  
  import com.thoughtworks.proxy.ProxyFactory;
  import com.thoughtworks.proxy.toys.decorate.Decorator;
  import info.magnolia.i18nsystem.I18nable;
  import info.magnolia.i18nsystem.I18nKeyGenerator;
  import info.magnolia.i18nsystem.I18nKeyGeneratorFactory;
  import info.magnolia.i18nsystem.I18nParentable;
  import info.magnolia.i18nsystem.I18nText;
  import info.magnolia.i18nsystem.I18nizer;
  import info.magnolia.i18nsystem.LocaleProvider;
  import info.magnolia.i18nsystem.TranslationService;
  
  import javax.inject.Inject;
  
  import net.sf.cglib.proxy.Enhancer;
  
  import com.thoughtworks.proxy.factory.CglibProxyFactory;
  import com.thoughtworks.proxy.toys.decorate.Decorating;
  import com.thoughtworks.proxy.toys.dispatch.Dispatching;
  
  /**
   * A implementation of {@link I18nizer} based on <a href="http://proxytoys.org">ProxyToys</a>, using proxies to decorate
   * the given objects.
   */
  public class ProxytoysI18nizer implements I18nizer {
      private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(ProxytoysI18nizer.class);
  
      private final TranslationService translationService;
      private final LocaleProvider localeProvider;
      private final ProxyFactory proxyFactory;
  
      @Inject
      public ProxytoysI18nizer(TranslationService translationService, LocaleProvider localeProvider) {
          this.translationService = translationService;
          this.localeProvider = localeProvider;
          this.proxyFactory = new CglibProxyFactory(false);
      }
  
      @Override
      public <C> C decorate(C child) {
          if (child == null) {
              return null;
          }
          // Check if this has already been decorated to avoid redundancy in client code
          // TODO however, it could be that the given object was already processed by CGLib, for other purposes ... need to implement better check.
          if (Enhancer.isEnhanced(child.getClass())) {
              throw new IllegalStateException(child + " has already been enhanced (presumably by ProxytoysI18nizer)");
          }
  
          return decorateChild(child, null);
      }
  
      protected <P, C> C decorateChild(C child, P parent) {
          log.debug("About to decorate {} (parent: {})", child, parent);
          if (child == null) {
              return null;
          }
          if (child instanceof I18nParentable) {
              log.debug(" - " + child + " is already an instance of I18nParentable - probably because we're in a list. Assuming it's also already decorated with i18n.");
              return child;
          }
  
          final Class<C> originalClass = (Class<C>) child.getClass();
          final C parentedChild = injectParentableInterface(originalClass, child, parent);
  
         final C i18nd = (C) decorateI18nTextMethods(parentedChild, (Class<Object>) originalClass, I18nParentable.class);
         return interceptGetters(i18nd, originalClass);
     }
 
     protected <T, P> T injectParentableInterface(Class<? extends T> ct, T object, P parent) {
         final I18nParentableImpl<P> parentable = new I18nParentableImpl<P>(parent);
         return Dispatching.proxy(ct, I18nParentable.class)
                 .with(object, parentable)
                 .build(proxyFactory);
     }
 
     protected <T> T decorateI18nTextMethods(T obj, Class<T> proxyPrimaryType, Class... proxyMoreTypes) {
         final I18nKeyGenerator<T> keyGen = I18nKeyGeneratorFactory.newKeyGeneratorFor(obj);
         final I18nTextMethodDecorator<T> decorator = newI18nTextMethodDecorator(keyGen);
 
         return decorateI18nTextMethods(obj, proxyPrimaryType, proxyMoreTypes, decorator);
     }
 
     protected <T> I18nTextMethodDecorator<T> newI18nTextMethodDecorator(I18nKeyGenerator<T> keyGen) {
         return new I18nTextMethodDecorator<T>(translationService, localeProvider, keyGen);
     }
 
     protected <T> T decorateI18nTextMethods(T obj, Class<T> proxyPrimaryType, Class[] proxyMoreTypes, Decorator<T> decorator) {
         return Decorating.proxy(proxyPrimaryType, proxyMoreTypes)
                 .with(obj)
                 .visiting(new FilteringMethodDecorator<T>(decorator, new MethodsAnnotatedWith(I18nText.class)))
                 .build(proxyFactory);
     }
 
     protected <T> T interceptGetters(T o, Class<T> originalClass) {
         final T proxy = Decorating.proxy(originalClass, new Class[] { I18nParentable.class })
                 .with(o)
                 .visiting(new FilteringMethodDecorator<T>(new ChildDecorator<T>(this), new ReturnsAnnotatedTypeArgument(I18nable.class)))
                 .build(proxyFactory);
         log.debug("Proxied {} (and returning {})", o, proxy);
         return proxy;
     }
 
 }