/* 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.acegisecurity.vote;

import org.acegisecurity.AccessDeniedException;
import org.acegisecurity.Authentication;
import org.acegisecurity.ConfigAttributeDefinition;

import java.util.Iterator;


/**
 * Simple concrete implementation of  {@link org.acegisecurity.AccessDecisionManager} that uses a  consensus-based
 * approach.
 */
public class ConsensusBased extends AbstractAccessDecisionManager {
    //~ Instance fields ================================================================================================

    private boolean allowIfEqualGrantedDeniedDecisions = true;

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

    /**
     * This concrete implementation simply polls all configured  {@link AccessDecisionVoter}s and upon
     * completion determines the consensus of granted vs denied responses.<p>If there were an equal number of
     * grant and deny votes, the decision will be based on the {@link #isAllowIfEqualGrantedDeniedDecisions()}
     * property (defaults to true).</p>
     *  <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 config the configuration attributes associated with the method being invoked
     *
     * @throws AccessDeniedException if access is denied
     */
    public void decide(Authentication authentication, Object object, ConfigAttributeDefinition config)
        throws AccessDeniedException {
        Iterator iter = this.getDecisionVoters().iterator();
        int grant = 0;
        int deny = 0;
        int abstain = 0;

        while (iter.hasNext()) {
            AccessDecisionVoter voter = (AccessDecisionVoter) iter.next();
            int result = voter.vote(authentication, object, config);

            switch (result) {
            case AccessDecisionVoter.ACCESS_GRANTED:
                grant++;

                break;

            case AccessDecisionVoter.ACCESS_DENIED:
                deny++;

                break;

            default:
                abstain++;

                break;
            }
        }

        if (grant > deny) {
            return;
        }

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

        if ((grant == deny) && (grant != 0)) {
            if (this.allowIfEqualGrantedDeniedDecisions) {
                return;
            } else {
                throw new AccessDeniedException(messages.getMessage("AbstractAccessDecisionManager.accessDenied",
                        "Access is denied"));
            }
        }

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

    public boolean isAllowIfEqualGrantedDeniedDecisions() {
        return allowIfEqualGrantedDeniedDecisions;
    }

    public void setAllowIfEqualGrantedDeniedDecisions(boolean allowIfEqualGrantedDeniedDecisions) {
        this.allowIfEqualGrantedDeniedDecisions = allowIfEqualGrantedDeniedDecisions;
    }
}
