/*
    * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
    * the spring framework, http://el4j.sf.net
    * Copyright (C) 2005 by ELCA Informatique SA, Av. de la Harpe 22-24,
    * 1000 Lausanne, Switzerland, http://www.elca.ch
    *
    * EL4J is published under the GNU Lesser General Public License (LGPL)
    * Version 2.1. See http://www.gnu.org/licenses/
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   * GNU Lesser General Public License for more details.
   *
   * For alternative licensing, please contact info@elca.ch
   */
  package ch.elca.el4j.util.metadata;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Method;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.springframework.beans.factory.InitializingBean;
  
  import ch.elca.el4j.services.monitoring.notification.CoreNotificationHelper;
  
  /**
   * <p>
   * Depending to the used kind of metadata, it can be defined on a field, on a
   * method, on a class, and on a package. The used kinds of metadata are the
   * <b>Commons Attributes</b> and the <b>Java 5 Annotations</b>. Both can handle
   * metadata defined on a field, on a method, and on a class.
   * </p>
   *
   * <p>
   * This class collects metadata from different classes. The examples below
   * show you how the metadata is collected.
   * </p>
   *
   * <pre>
   * public interface X {
   *     public int getValue();
   * }
   *
   * public interface Y {
   *     public int getValue();
   * }
   *
   * public class A implements X {
   *     public int getValue() {...}
   * }
   *
   * public class B extends A implements Y {
   *     public int getValue() {...}
   * }
   *
   * public class C extends B {
   *     public int getValue() {...}
   * }
   * </pre>
   *
   * <p>
   * If metadata for method <code>getValue()</code> of Class <code>C</code> is
   * requested, the result will be a collection of metadata from class
   * <code>C</code> and interfaces <code>Y</code> and <code>X</code>. Metadata
   * defined in class <code>A</code> and <code>B</code> will be omitted.
   * </p>
   *
   * <p>
   * The same behavior can be found with metadata on class level. The collection
   * of metadata will also only contain metadata defined on class <code>C</code>
   * and interfaces <code>Y</code> and <code>X</code>.
   * </p>
   *
   * <p>
   * <b>Always the most specific implementation and all interfaces will be
   * inspected.</b>
   * </p>
   *
   * @svnLink $Revision: 4091 $;$Date: 2010-01-15 12:21:07 +0100 (Fr, 15. Jan 2010) $;$Author: jonasha $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/core/src/main/java/ch/elca/el4j/util/metadata/MetaDataCollector.java $
   *
   * @author Martin Zeltner (MZE)
   */
  public class MetaDataCollector implements Attributes, InitializingBean {
  	/**
  	 * Inner object to fetch metadata.
  	 */
  	private Attributes m_metaDataDelegator;
  
  	/**
  	 * @return Returns the metaDataDelegator.
  	 */
  	public Attributes getMetaDataDelegator() {
  		return m_metaDataDelegator;
  	}
 
 	/**
 	 * @param metaDataDelegator Is the metaDataDelegator to set.
 	 */
 	public void setMetaDataDelegator(Attributes metaDataDelegator) {
 		m_metaDataDelegator = metaDataDelegator;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@SuppressWarnings("unchecked")
 	public Collection getAttributes(Class targetClass) {
 		Set attributeSet = new LinkedHashSet();
 		List<Class> interfaceList
 			= getAllInterfaces(new ArrayList<Class>(), targetClass);
 		Attributes metaDataDelegator = getMetaDataDelegator();
 
 		attributeSet.addAll(metaDataDelegator.getAttributes(targetClass));
 		for (Class iface : interfaceList) {
 			attributeSet.addAll(metaDataDelegator.getAttributes(iface));
 		}
 		
 		return attributeSet;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@SuppressWarnings("unchecked")
 	public Collection getAttributes(Class targetClass, Class filter) {
 		Set attributeSet = new LinkedHashSet();
 		List<Class> interfaceList
 			= getAllInterfaces(new ArrayList<Class>(), targetClass);
 		Attributes metaDataDelegator = getMetaDataDelegator();
 
 		attributeSet.addAll(
 			metaDataDelegator.getAttributes(targetClass, filter));
 		for (Class iface : interfaceList) {
 			attributeSet.addAll(
 				metaDataDelegator.getAttributes(iface, filter));
 		}
 
 		return attributeSet;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@SuppressWarnings("unchecked")
 	public Collection getAttributes(Method targetMethod) {
 		Set attributeSet = new LinkedHashSet();
 		List<Class> interfaceList = getAllInterfaces(
 			new ArrayList<Class>(), targetMethod.getDeclaringClass());
 		Attributes metaDataDelegator = getMetaDataDelegator();
 
 		attributeSet.addAll(metaDataDelegator.getAttributes(targetMethod));
 		for (Class iface : interfaceList) {
 			try {
 				Method m = iface.getDeclaredMethod(targetMethod.getName(),
 						targetMethod.getParameterTypes());
 				attributeSet.addAll(metaDataDelegator.getAttributes(m));
 			// Checkstyle: EmptyBlock off
 			} catch (NoSuchMethodException e) {
 				// Do nothing. Method does not exist in current interface.
 			}
 			// Checkstyle: EmptyBlock off
 		}
 
 		return attributeSet;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@SuppressWarnings("unchecked")
 	public Collection getAttributes(Method targetMethod, Class filter) {
 		Set attributeSet = new LinkedHashSet();
 		List<Class> interfaceList = getAllInterfaces(
 			new ArrayList<Class>(), targetMethod.getDeclaringClass());
 		Attributes metaDataDelegator = getMetaDataDelegator();
 
 		attributeSet.addAll(
 			metaDataDelegator.getAttributes(targetMethod, filter));
 		for (Class iface : interfaceList) {
 			try {
 				Method m = iface.getDeclaredMethod(targetMethod.getName(),
 						targetMethod.getParameterTypes());
 				attributeSet.addAll(
 					metaDataDelegator.getAttributes(m, filter));
 			} catch (NoSuchMethodException e) {
 				// Do nothing. Method does not exist in current interface.
 			}
 		}
 
 		return attributeSet;
 	}
 
 	/**
 	 * Method to get all interfaces, that are implemented by the
 	 * given class and all its super classes.
 	 *
 	 * @param list
 	 *            Is the list with all interfaces.
 	 * @param clazz
 	 *            Is the class, that must be analyzed.
 	 * @return Returns the list with all interfaces.
 	 */
 	private List<Class> getAllInterfaces(List<Class> list, Class clazz) {
 		if (clazz != null && clazz != Object.class) {
 			Class[] classes = clazz.getInterfaces();
 			for (Class c : classes) {
 				list.add(c);
 			}
 			getAllInterfaces(list, clazz.getSuperclass());
 		}
 		return list;
 	}
 
 	/**
 	 * Directly calls the metadata delegator.
 	 *
 	 * {@inheritDoc}
 	 */
 	public Collection getAttributes(Field targetField) {
 		return getMetaDataDelegator().getAttributes(targetField);
 	}
 
 	/**
 	 * Directly calls the metadata delegator.
 	 *
 	 * {@inheritDoc}
 	 */
 	public Collection getAttributes(Field targetField, Class filter) {
 		return getMetaDataDelegator().getAttributes(targetField, filter);
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public void afterPropertiesSet() throws Exception {
 		if (getMetaDataDelegator() == null) {
 			CoreNotificationHelper.notifyLackingEssentialProperty(
 				"metaDataDelegator", this);
 		}
 	}
 }