/* 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.vote;

import java.util.Iterator;

import org.springframework.security.Authentication;
import org.springframework.security.ConfigAttribute;
import org.springframework.security.ConfigAttributeDefinition;
import org.springframework.security.GrantedAuthority;

/**
 * Votes if any {@link ConfigAttribute#getAttribute()} starts with a prefix
 * indicating that it is a role. The default prefix string is <Code>ROLE_</code>,
 * but this may be overridden to any value. It may also be set to empty, which
 * means that essentially any attribute will be voted on. As described further
 * below, the effect of an empty prefix may not be quite desirable.
 * <p>
 * Abstains from voting if no configuration attribute commences with the role
 * prefix. Votes to grant access if there is an exact matching
 * {@link org.springframework.security.GrantedAuthority} to a <code>ConfigAttribute</code>
 * starting with the role prefix. Votes to deny access if there is no exact
 * matching <code>GrantedAuthority</code> to a <code>ConfigAttribute</code>
 * starting with the role prefix.
 * <p>
 * An empty role prefix means that the voter will vote for every
 * ConfigAttribute. When there are different categories of ConfigAttributes
 * used, this will not be optimal since the voter will be voting for attributes
 * which do not represent roles. However, this option may be of some use when
 * using pre-existing role names without a prefix, and no ability exists to
 * prefix them with a role prefix on reading them in, such as provided for
 * example in {@link org.springframework.security.userdetails.jdbc.JdbcDaoImpl}.
 * <p>
 * All comparisons and prefixes are case sensitive.
 *
 * @author Ben Alex
 * @author colin sampaleanu
 * @version $Id$
 */
public class RoleVoter implements AccessDecisionVoter {
    //~ Instance fields ================================================================================================

    private String rolePrefix = "ROLE_";

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

    public String getRolePrefix() {
        return rolePrefix;
    }

    /**
     * Allows the default role prefix of <code>ROLE_</code> to be overridden.
     * May be set to an empty value, although this is usually not desirable.
     *
     * @param rolePrefix the new prefix
     */
    public void setRolePrefix(String rolePrefix) {
        this.rolePrefix = rolePrefix;
    }

    public boolean supports(ConfigAttribute attribute) {
        if ((attribute.getAttribute() != null) && attribute.getAttribute().startsWith(getRolePrefix())) {
            return true;
        }
        else {
            return false;
        }
    }

    /**
     * This implementation supports any type of class, because it does not query
     * the presented secure object.
     *
     * @param clazz the secure object
     *
     * @return always <code>true</code>
     */
    public boolean supports(Class clazz) {
        return true;
    }

    public int vote(Authentication authentication, Object object, ConfigAttributeDefinition config) {
        int result = ACCESS_ABSTAIN;
        Iterator iter = config.getConfigAttributes().iterator();
        GrantedAuthority[] authorities = extractAuthorities(authentication);        

        while (iter.hasNext()) {
            ConfigAttribute attribute = (ConfigAttribute) iter.next();

            if (this.supports(attribute)) {
                result = ACCESS_DENIED;

                // Attempt to find a matching granted authority
                for (int i = 0; i < authorities.length; i++) {
                    if (attribute.getAttribute().equals(authorities[i].getAuthority())) {
                        return ACCESS_GRANTED;
                    }
                }
            }
        }

        return result;
    }
    
    GrantedAuthority[] extractAuthorities(Authentication authentication) {
    	return authentication.getAuthorities();
    }
}
