/* Copyright 2004, 2005, 2006 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.aopalliance;

import org.acegisecurity.intercept.method.MethodDefinitionSource;

import org.aopalliance.intercept.MethodInvocation;

import org.springframework.aop.framework.AopConfigException;
import org.springframework.aop.support.StaticMethodMatcherPointcutAdvisor;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Method;


/**
 * Advisor driven by a {@link MethodDefinitionSource}, used to exclude a {@link MethodSecurityInterceptor} from
 * public (ie non-secure) methods.<p>Because the AOP framework caches advice calculations, this is normally faster
 * than just letting the <code>MethodSecurityInterceptor</code> run and find out itself that it has no work to do.</p>
 *  <p>This class also allows the use of Spring's <code>DefaultAdvisorAutoProxyCreator</code>, which makes
 * configuration easier than setup a <code>ProxyFactoryBean</code> for each object requiring security. Note that
 * autoproxying is not supported for BeanFactory implementations, as post-processing is automatic only for application
 * contexts.</p>
 *  <p>Based on Spring's TransactionAttributeSourceAdvisor.</p>
 *
 * @author Ben Alex
 * @version $Id$
 */
public class MethodDefinitionSourceAdvisor extends StaticMethodMatcherPointcutAdvisor {
    //~ Instance fields ================================================================================================

    private MethodDefinitionSource transactionAttributeSource;

    //~ Constructors ===================================================================================================

    public MethodDefinitionSourceAdvisor(MethodSecurityInterceptor advice) {
        super(advice);

        if (advice.getObjectDefinitionSource() == null) {
            throw new AopConfigException("Cannot construct a MethodDefinitionSourceAdvisor using a "
                + "MethodSecurityInterceptor that has no ObjectDefinitionSource configured");
        }

        this.transactionAttributeSource = advice.getObjectDefinitionSource();
    }

    //~ Methods ========================================================================================================

    public boolean matches(Method m, Class targetClass) {
        MethodInvocation methodInvocation = new InternalMethodInvocation(m);

        return (this.transactionAttributeSource.getAttributes(methodInvocation) != null);
    }

    //~ Inner Classes ==================================================================================================

    /**
     * Represents a <code>MethodInvocation</code>.<p>Required as <code>MethodDefinitionSource</code> only
     * supports lookup of configuration attributes for <code>MethodInvocation</code>s.</p>
     */
    class InternalMethodInvocation implements MethodInvocation {
        Method method;

        public InternalMethodInvocation(Method method) {
            this.method = method;
        }

        protected InternalMethodInvocation() {
            throw new UnsupportedOperationException();
        }

        public Object[] getArguments() {
            throw new UnsupportedOperationException();
        }

        public Method getMethod() {
            return this.method;
        }

        public AccessibleObject getStaticPart() {
            throw new UnsupportedOperationException();
        }

        public Object getThis() {
            throw new UnsupportedOperationException();
        }

        public Object proceed() throws Throwable {
            throw new UnsupportedOperationException();
        }
    }
}
