/**
 * Copyright 2005-2013 Restlet S.A.S.
 * 
 * The contents of this file are subject to the terms of one of the following
 * open source licenses: Apache 2.0 or LGPL 3.0 or LGPL 2.1 or CDDL 1.0 or EPL
 * 1.0 (the "Licenses"). You can select the license that you prefer but you may
 * not use this file except in compliance with one of these Licenses.
 * 
 * You can obtain a copy of the Apache 2.0 license at
 * http://www.opensource.org/licenses/apache-2.0
 * 
 * You can obtain a copy of the LGPL 3.0 license at
 * http://www.opensource.org/licenses/lgpl-3.0
 * 
 * You can obtain a copy of the LGPL 2.1 license at
 * http://www.opensource.org/licenses/lgpl-2.1
 * 
 * You can obtain a copy of the CDDL 1.0 license at
 * http://www.opensource.org/licenses/cddl1
 * 
 * You can obtain a copy of the EPL 1.0 license at
 * http://www.opensource.org/licenses/eclipse-1.0
 * 
 * See the Licenses for the specific language governing permissions and
 * limitations under the Licenses.
 * 
 * Alternatively, you can obtain a royalty free commercial license with less
 * limitations, transferable or non-transferable, directly at
 * http://www.restlet.com/products/restlet-framework
 * 
 * Restlet is a registered trademark of Restlet S.A.S.
 */

package org.restlet.ext.jaas;

import java.security.AccessControlContext;
import java.security.Principal;
import java.security.PrivilegedAction;

import javax.security.auth.Subject;

import org.restlet.data.ClientInfo;
import org.restlet.security.Role;

/**
 * Utility class to facilitate integration between the Restlet and JAAS APIs.
 * 
 * @author Jerome Louvel
 */
public final class JaasUtils {

    /**
     * Creates a JAAS subject based on a given {@link ClientInfo}. It adds a
     * {@link ClientInfo#getUser()}, all the entries in
     * {@link ClientInfo#getRoles()} and all other principals in
     * {@link ClientInfo#getPrincipals()}.
     * 
     * @param clientInfo
     *            The client info to expose as a subject.
     * @return The populated JAAS subject.
     */
    public static Subject createSubject(ClientInfo clientInfo) {
        Subject result = new Subject();

        if (clientInfo != null) {
            if (clientInfo.getUser() != null) {
                result.getPrincipals().add(clientInfo.getUser());
            }

            for (Role role : clientInfo.getRoles()) {
                result.getPrincipals().add(role);
            }

            for (Principal principal : clientInfo.getPrincipals()) {
                result.getPrincipals().add(principal);
            }
        }

        return result;
    }

    /**
     * Creates a JAAS subject on the {@link ClientInfo} and uses it to run the
     * action, using
     * {@link Subject#doAsPrivileged(Subject, PrivilegedAction, AccessControlContext)}
     * .
     * 
     * @param <T>
     *            the return type of the action.
     * @param clientInfo
     *            the client info from which to build a subject.
     * @param action
     *            the code to be run as the specified Subject.
     * @param acc
     *            the AccessControlContext to be tied to the specified subject
     *            and action.
     * @return the value returned by the action.
     */
    @SuppressWarnings("unchecked")
    public static <T> T doAsPriviledged(ClientInfo clientInfo,
            PrivilegedAction<T> action, AccessControlContext acc) {
        Subject subject = JaasUtils.createSubject(clientInfo);
        T result = (T) Subject.doAsPrivileged(subject, action, acc);
        return result;
    }

    /**
     * Creates a JAAS subject on the {@link ClientInfo} and uses it to run the
     * action, using
     * {@link Subject#doAsPrivileged(Subject, PrivilegedAction, AccessControlContext)}
     * . This uses a null {@link AccessControlContext}.
     * 
     * @param <T>
     *            the return type of the action.
     * @param clientInfo
     *            the client info from which to build as a subject.
     * @param action
     *            the code to be run as the specified Subject.
     * @return the value returned by the action.
     */
    public static <T> T doAsPriviledged(ClientInfo clientInfo,
            PrivilegedAction<T> action) {
        return doAsPriviledged(clientInfo, action, null);
    }
}