/*
 * 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;
  }
}
