/* Copyright 2004, 2005 Acegi Technology Pty Limited
    *
    * 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.acegisecurity.intercept.method;
  
  import org.acegisecurity.ConfigAttribute;
  import org.acegisecurity.ConfigAttributeDefinition;
  
  import org.springframework.metadata.Attributes;
  
  import java.lang.reflect.Method;
  
  import java.util.Collection;
  import java.util.Iterator;
  
  
  /***
   * Stores a {@link ConfigAttributeDefinition} for each method signature defined
   * by Commons Attributes.
   * 
   * <P>
   * This class will only detect those attributes which are defined for:
   * 
   * <ul>
   * <li>
   * The class-wide attributes defined for the intercepted class.
   * </li>
   * <li>
   * The class-wide attributes defined for interfaces explicitly implemented by
   * the intercepted class.
   * </li>
   * <li>
   * The method-specific attributes defined for the intercepted method of the
   * intercepted class.
   * </li>
   * <li>
   * The method-specific attributes defined by any explicitly implemented
   * interface if that interface contains a method signature matching that of
   * the intercepted method.
   * </li>
   * </ul>
   * </p>
   * 
   * <P>
   * Note that attributes defined against parent classes (either for their
   * methods or interfaces) are not detected. The attributes must be defined
   * against an explicit method or interface on the intercepted class.
   * </p>
   * 
   * <p>
   * Attributes detected that do not implement {@link ConfigAttribute} will be
   * ignored.
   * </p>
   *
   * @author Cameron Braid
   * @author Ben Alex
   * @version $Id: MethodDefinitionAttributes.java,v 1.5 2005/11/17 00:56:09 benalex Exp $
   */
  public class MethodDefinitionAttributes extends AbstractMethodDefinitionSource {
      //~ Instance fields ========================================================
  
      private Attributes attributes;
  
      //~ Methods ================================================================
  
      public void setAttributes(Attributes attributes) {
          this.attributes = attributes;
      }
  
      public Iterator getConfigAttributeDefinitions() {
          return null;
      }
  
      protected ConfigAttributeDefinition lookupAttributes(Method method) {
          ConfigAttributeDefinition definition = new ConfigAttributeDefinition();
  
          Class interceptedClass = method.getDeclaringClass();
  
          // add the class level attributes for the implementing class
          addClassAttributes(definition, interceptedClass);
  
          // add the class level attributes for the implemented interfaces
          addClassAttributes(definition, interceptedClass.getInterfaces());
  
          // add the method level attributes for the implemented method
          addMethodAttributes(definition, method);
  
         // add the method level attributes for the implemented intreface methods
         addInterfaceMethodAttributes(definition, method);
 
         if (definition.size() == 0) {
             return null;
         } else {
             return definition;
         }
     }
 
     private void add(ConfigAttributeDefinition definition, Collection attribs) {
         for (Iterator iter = attribs.iterator(); iter.hasNext();) {
             Object o = (Object) iter.next();
 
             if (o instanceof ConfigAttribute) {
                 definition.addConfigAttribute((ConfigAttribute) o);
             }
         }
     }
 
     private void addClassAttributes(ConfigAttributeDefinition definition,
         Class clazz) {
         addClassAttributes(definition, new Class[] {clazz});
     }
 
     private void addClassAttributes(ConfigAttributeDefinition definition,
         Class[] clazz) {
         for (int i = 0; i < clazz.length; i++) {
             Collection classAttributes = attributes.getAttributes(clazz[i]);
 
             if (classAttributes != null) {
                 add(definition, classAttributes);
             }
         }
     }
 
     private void addInterfaceMethodAttributes(
         ConfigAttributeDefinition definition, Method method) {
         Class[] interfaces = method.getDeclaringClass().getInterfaces();
 
         for (int i = 0; i < interfaces.length; i++) {
             Class clazz = interfaces[i];
 
             try {
                 Method m = clazz.getDeclaredMethod(method.getName(),
                         (Class[]) method.getParameterTypes());
                 addMethodAttributes(definition, m);
             } catch (Exception e) {
                 // this won't happen since we are getting a method from an interface that 
                 // the declaring class implements
             }
         }
     }
 
     private void addMethodAttributes(ConfigAttributeDefinition definition,
         Method method) {
         // add the method level attributes
         Collection methodAttributes = attributes.getAttributes(method);
 
         if (methodAttributes != null) {
             add(definition, methodAttributes);
         }
     }
 }