/*

  * Copyright 2007 Ivan Dubrov

  * Copyright 2007, 2008 Robin Helgelin

  *

  * 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 nu.localhost.tapestry.acegi.services.internal;

 import java.lang.reflect.Modifier;

 import org.acegisecurity.ConfigAttributeDefinition;

 import org.acegisecurity.SecurityConfig;

 import org.acegisecurity.annotation.Secured;

 import org.apache.tapestry.model.MutableComponentModel;

 import org.apache.tapestry.services.ClassTransformation;

 import org.apache.tapestry.services.ComponentClassTransformWorker;

 import org.apache.tapestry.services.TransformConstants;

 import org.apache.tapestry.services.TransformMethodSignature;

 /**

  * @author Ivan Dubrov

  */

 public class AcegiWorker implements ComponentClassTransformWorker {

     private SecurityChecker securityChecker;

     public AcegiWorker(final SecurityChecker securityChecker) {

         this.securityChecker = securityChecker;

     }

     public final void transform(final ClassTransformation transformation,

             final MutableComponentModel model) {

         // Secure methods

         for (TransformMethodSignature method : transformation

                 .findMethodsWithAnnotation(Secured.class)) {

             transformMethod(transformation, method);

         }

         // Secure pages

         Secured annotation = transformation.getAnnotation(Secured.class);

         if (annotation != null) {

             transformPage(transformation, annotation);

         }

     }

     private void transformPage(final ClassTransformation transformation,

             final Secured annotation) {

         // Security checker

         final String interField = transformation.addInjectedField(

                 SecurityChecker.class, "_$checker", securityChecker);

         // Attribute definition

         final String configField = createConfigAttributeDefinitionField(

                 transformation, annotation);

         // Interceptor token

         final String tokenField = transformation.addField(Modifier.PRIVATE,

                 "org.acegisecurity.intercept.InterceptorStatusToken",

                 "_$token");

         // Extend class

         transformation.extendMethod(

                 TransformConstants.BEGIN_RENDER_SIGNATURE,

                 tokenField + " = " + interField + ".checkBefore(" + configField

                 + ");");

         transformation.extendMethod(

                 TransformConstants.CLEANUP_RENDER_SIGNATURE,

                 interField + ".checkAfter(" + tokenField + ", null);");

     }

     private void transformMethod(final ClassTransformation transformation,

             final TransformMethodSignature method) {

         // Security checker

         final String interField = transformation.addInjectedField(SecurityChecker.class, "_$checker", securityChecker);

         // Interceptor status token

         final String statusToken = transformation.addField(Modifier.PRIVATE,

                 "org.acegisecurity.intercept.InterceptorStatusToken", "_$token");

         // Attribute definition

         final Secured annotation = transformation.getMethodAnnotation(method, Secured.class);

         final String configField = createConfigAttributeDefinitionField(transformation, annotation);

         // Prefix and extend method

         transformation.prefixMethod(method, statusToken + " = " + interField + ".checkBefore(" + configField + ");");

         transformation.extendExistingMethod(method, interField + ".checkAfter(" + statusToken + ", null);");

     }

     private String createConfigAttributeDefinitionField(

             final ClassTransformation transformation,

             final Secured annotation) {

         ConfigAttributeDefinition configAttributeDefinition =

             new ConfigAttributeDefinition();

         for (String auth : annotation.value()) {

             configAttributeDefinition.addConfigAttribute(

                     new SecurityConfig(auth));

         }

         return transformation.addInjectedField(ConfigAttributeDefinition.class,

                 "_$configAttributeDefinition", configAttributeDefinition);

     }

 }