/*
    * Copyright 2007 Joachim Grueneis
    *
    * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
    * in compliance with the License. You may obtain a copy of the License at
    *
    * http://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software distributed under the License
   * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   * or implied. See the License for the specific language governing permissions and limitations under
   * the License.
   */
  package org.exolab.castor.xml.util.resolvers;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.exolab.castor.xml.Introspector;
  import org.exolab.castor.xml.MarshalException;
  import org.exolab.castor.xml.ResolverException;
  import org.exolab.castor.xml.XMLClassDescriptor;
  import org.exolab.castor.xml.util.ResolverStrategy;
  
  /**
   * Resolve a class by creating a generic descriptor based on the informations read from the class
   * with introspection.
   * 
   * @author <a href="mailto:jgrueneis AT gmail DOT com">Joachim Grueneis</a>
   * @author <a href="mailto:stevendolg AT gxm DOT at">Steven Dolg</a>
   * @version $Revision$ $Date$
   * @since 1.2
   */
  public class ByIntrospection extends AbstractResolverClassCommand {
    /**
     * Logger to be used.
     */
    private static final Log LOG = LogFactory.getLog(ByIntrospection.class);
  
    /**
     * No specific stuff needed.
     */
    public ByIntrospection() {
      super();
    }
  
    /**
     * Creates an XMLClassDescriptor for the given type by using introspection. This method will rely
     * on the <code>Introspector</code> set with <code>setIntrospector</code>. If a descriptor is
     * successfully created it will be added to the DescriptorCache. <br>
     * <b>NOTE</b>: If this XMLClassDescriptorResolver is NOT configured to use introspection this
     * method will NOT create an descriptor.<br>
     * <br>
     * {@inheritDoc}
     */
    protected Map internalResolve(final String className, final ClassLoader classLoader,
        final Map properties) throws ResolverException {
  
      Boolean useIntrospector = (Boolean) properties.get(ResolverStrategy.PROPERTY_USE_INTROSPECTION);
      HashMap results = new HashMap();
      if (classLoader == null) {
        LOG.debug("No class loader available.");
        return results;
      }
  
      if ((useIntrospector != null) && (!useIntrospector.booleanValue())) {
        // I know the logic is a bit weired... either introspection is explicitly
        // disabled or it is ok!
        LOG.debug("Introspection is disabled!");
        return results;
      }
  
      Introspector introspector =
          (Introspector) properties.get(ResolverStrategy.PROPERTY_INTROSPECTOR);
      if (introspector == null) {
        String message = "No Introspector defined in properties!";
        LOG.warn(message);
        throw new IllegalStateException(message);
      }
      Class clazz = ResolveHelpers.loadClass(classLoader, className);
      if (clazz != null) {
        try {
          XMLClassDescriptor descriptor = introspector.generateClassDescriptor(clazz);
          if (descriptor != null) {
            if (LOG.isDebugEnabled()) {
              LOG.debug("Found descriptor: " + descriptor);
            }
            results.put(clazz.getName(), descriptor);
          }
        } catch (MarshalException e) {
          String message =
              "Failed to generate class descriptor for: " + clazz + " with exception: " + e;
          LOG.warn(message);
          throw new ResolverException(message);
        }
      }
      return results;
   }
 }