/*
 * 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.vote;

import java.util.*;

import org.springframework.security.access.AccessDecisionVoter;
import org.springframework.security.access.AccessDeniedException;
import org.springframework.security.access.ConfigAttribute;
import org.springframework.security.core.Authentication;

/**
 * Simple concrete implementation of
 * {@link org.springframework.security.access.AccessDecisionManager} that grants access if
 * any <code>AccessDecisionVoter</code> returns an affirmative response.
 */
public class AffirmativeBased extends AbstractAccessDecisionManager {

	public AffirmativeBased(List<AccessDecisionVoter<? extends Object>> decisionVoters) {
		super(decisionVoters);
	}

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

	/**
	 * This concrete implementation simply polls all configured
	 * {@link AccessDecisionVoter}s and grants access if any
	 * <code>AccessDecisionVoter</code> voted affirmatively. Denies access only if there
	 * was a deny vote AND no affirmative votes.
	 * <p>
	 * If every <code>AccessDecisionVoter</code> abstained from voting, the decision will
	 * be based on the {@link #isAllowIfAllAbstainDecisions()} property (defaults to
	 * false).
	 * </p>
	 *
	 * @param authentication the caller invoking the method
	 * @param object the secured object
	 * @param configAttributes the configuration attributes associated with the method
	 * being invoked
	 *
	 * @throws AccessDeniedException if access is denied
	 */
	public void decide(Authentication authentication, Object object,
			Collection<ConfigAttribute> configAttributes) throws AccessDeniedException {
		int deny = 0;

		for (AccessDecisionVoter voter : getDecisionVoters()) {
			int result = voter.vote(authentication, object, configAttributes);

			if (logger.isDebugEnabled()) {
				logger.debug("Voter: " + voter + ", returned: " + result);
			}

			switch (result) {
			case AccessDecisionVoter.ACCESS_GRANTED:
				return;

			case AccessDecisionVoter.ACCESS_DENIED:
				deny++;

				break;

			default:
				break;
			}
		}

		if (deny > 0) {
			throw new AccessDeniedException(messages.getMessage(
					"AbstractAccessDecisionManager.accessDenied", "Access is denied"));
		}

		// To get this far, every AccessDecisionVoter abstained
		checkAllowIfAllAbstainDecisions();
	}
}
