/**
    * This file Copyright (c) 2010-2017 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.module.groovy.support.classes;
  
  import info.magnolia.context.Context;
  import info.magnolia.module.groovy.support.HierarchyManagerProvider;
  import info.magnolia.objectfactory.ClassFactory;
  import info.magnolia.objectfactory.DefaultClassFactory;
  import info.magnolia.objectfactory.ReloadableClassFactory;
  
  import org.codehaus.groovy.control.CompilationFailedException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import groovy.lang.GroovyClassLoader;
  import groovy.lang.GroovyObject;
  
  /**
   * A {@link info.magnolia.objectfactory.ClassFactory} which attempts to load classes using a
   * {@link groovy.lang.GroovyClassLoader} if they were not found using a delegate (which is a
   * {@link info.magnolia.objectfactory.DefaultClassFactory} by default).
   *
   * <p>A little bit of background:<br>
   * When loading classes via the GroovyClassLoader, we loose control on where classes
   * are loaded from. The GroovyClassLoader will always first attempt to load any given
   * class via its parent*. This is actually the expected behaviour from regular ClassLoader
   * implementations. As long as we first try loading our classes via the DefaultClassFactory,
   * we're fine, we keep control of the order in which ClassLoaders are poked for classes.
   * By default, the GroovyClassLoader uses the current thread's ContextClassLoader, while
   * we first use the caller's ClassLoader, *then* the thread's.<br>
   * Any class/script loaded via the GroovyClassLoader and using classes that haven't been
   * loaded yet will thus see those classes loaded via the current thread's ContextClassLoader.
   * If this were to become an issue, we'd probably need to create something along the lines of
   * a ClassFactoryAwareClassLoader, and give that as a parent to the GroovyClassLoader.</p>
   */
  public class GroovyClassFactory implements ReloadableClassFactory {
      private final static Logger log = LoggerFactory.getLogger(GroovyClassFactory.class);
  
      private final ClassFactory delegate;
      private final GroovyClassLoader gcl;
  
      public GroovyClassFactory() {
          // Using the SystemContext to load classes of the repository, by default.
          // Since the forName() method will attempt to load any class via the DefaultClassFactory *first*,
          // we should hopefully have a SystemContext implementation ready by the time we need to access the repository.
          // (and the repository should be ready by then too)
          this(new DefaultClassFactory());
      }
  
      public GroovyClassFactory(ClassFactory delegate) {
          this.delegate = delegate;
          this.gcl = new MgnlGroovyClassLoader();
      }
  
      /**
       * @deprecated since 2.4.3 please use {@link #GroovyClassFactory()} instead.
       */
      @Deprecated
      public GroovyClassFactory(ClassFactory delegate, HierarchyManagerProvider hmp) {
          this(delegate);
      }
  
      /**
       * @deprecated since 2.4.4 please use {@link #GroovyClassFactory()} instead.
       */
      @Deprecated
      public GroovyClassFactory(ClassFactory delegate, Context context) {
          this(delegate);
     }
 
     @Override
     public <C> Class<C> forName(String className) throws ClassNotFoundException {
         try {
             return delegate.forName(className);
         } catch (ClassNotFoundException e) {
             try {
                 return gcl.loadClass(className, true, false);
             } catch (CompilationFailedException compilationException) {
                 // TODO - would be nice to get the precise location of the source script ...
                 log.error("Could not compile {} with Groovy:\n{}", className, compilationException.getMessage());
                 throw new ClassNotFoundException("Could not compile " + className + " with Groovy", compilationException);
             }
         }
     }
 
     @Override
     public <T> T newInstance(Class<T> c, Object... objects) {
         final Class<T> klass = recompileClassIfNeeded(c);
         return delegate.newInstance(klass, objects);
     }
 
     @Override
     public <T> T newInstance(Class<T> c, Class<?>[] argTypes, Object... params) {
         final Class<T> klass = recompileClassIfNeeded(c);
         return delegate.newInstance(klass, argTypes, params);
     }
 
     // TODO - shouldn't this move to the ResourceLoader ?
     private <T> Class<T> recompileClassIfNeeded(Class<T> c) {
         Class<T> klass = c;
         if (GroovyObject.class.isAssignableFrom(c)) {
             log.debug("{} is a Groovy object, so check if a newer source is available", c.getName());
             try {
                 klass = gcl.loadClass(c.getName(), true, false);
             } catch (ClassNotFoundException e) {
                 log.warn(e.getMessage());
                 klass = c;
             }
         }
         return klass;
     }
 
     @Override
     public <T> Class<T> reload(Class<T> c) throws ClassNotFoundException {
         return recompileClassIfNeeded(c);
     }
 }