/* 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.springframework.security.access.annotation;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.*;

import org.springframework.core.GenericTypeResolver;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.security.access.ConfigAttribute;
import org.springframework.security.access.SecurityConfig;
import org.springframework.security.access.method.AbstractFallbackMethodSecurityMetadataSource;
import org.springframework.util.Assert;


/**
 * Sources method security metadata from Spring Security's {@link Secured} annotation.
 * <p>
 * Can also be used with custom security annotations by injecting an {@link AnnotationMetadataExtractor}.
 * The annotation type will then be obtained from the generic parameter type supplied to this interface
 *
 * @author Ben Alex
 * @author Luke Taylor
 */
@SuppressWarnings({"unchecked"})
public class SecuredAnnotationSecurityMetadataSource extends AbstractFallbackMethodSecurityMetadataSource {
    private AnnotationMetadataExtractor annotationExtractor;
    private Class<? extends Annotation> annotationType;

    public SecuredAnnotationSecurityMetadataSource() {
        this(new SecuredAnnotationMetadataExtractor());
    }

    public SecuredAnnotationSecurityMetadataSource(AnnotationMetadataExtractor annotationMetadataExtractor) {
        Assert.notNull(annotationMetadataExtractor);
        annotationExtractor = annotationMetadataExtractor;
        annotationType = (Class<? extends Annotation>) GenericTypeResolver.resolveTypeArgument(
                annotationExtractor.getClass(), AnnotationMetadataExtractor.class);
        Assert.notNull(annotationType, annotationExtractor.getClass().getName()
                + " must supply a generic parameter for AnnotationMetadataExtractor");
    }

    protected Collection<ConfigAttribute> findAttributes(Class<?> clazz) {
        return processAnnotation(AnnotationUtils.findAnnotation(clazz, annotationType));
    }

    protected Collection<ConfigAttribute> findAttributes(Method method, Class<?> targetClass) {
        return processAnnotation(AnnotationUtils.findAnnotation(method, annotationType));
    }

    public Collection<ConfigAttribute> getAllConfigAttributes() {
        return null;
    }

    private Collection<ConfigAttribute> processAnnotation(Annotation a) {
        if (a == null) {
            return null;
        }

        return annotationExtractor.extractAttributes(a);
    }
}

class SecuredAnnotationMetadataExtractor implements AnnotationMetadataExtractor<Secured> {

    public Collection<ConfigAttribute> extractAttributes(Secured secured) {
        String[] attributeTokens = secured.value();
        List<ConfigAttribute> attributes = new ArrayList<ConfigAttribute>(attributeTokens.length);

        for(String token : attributeTokens) {
            attributes.add(new SecurityConfig(token));
        }

        return attributes;
    }
}
