/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.
 *
 */

/*
 *                        AT&T - PROPRIETARY
 *          THIS FILE CONTAINS PROPRIETARY INFORMATION OF
 *        AT&T AND IS NOT TO BE DISCLOSED OR USED EXCEPT IN
 *             ACCORDANCE WITH APPLICABLE AGREEMENTS.
 *
 *          Copyright (c) 2013 AT&T Knowledge Ventures
 *              Unpublished and Not for Publication
 *                     All Rights Reserved
 */
package org.apache.openaz.xacml.pdp.std;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;

import org.apache.openaz.xacml.api.Identifier;
import org.apache.openaz.xacml.pdp.policy.CombiningAlgorithm;
import org.apache.openaz.xacml.pdp.policy.CombiningAlgorithmFactory;
import org.apache.openaz.xacml.pdp.policy.PolicySetChild;
import org.apache.openaz.xacml.pdp.policy.Rule;

/**
 * StdCombiningAlgorithmFactory extends {@link org.apache.openaz.xacml.pdp.policy.CombiningAlgorithmFactory}
 * to implement a mapping from {@link org.apache.openaz.xacml.api.Identifier}s to the standard
 * {@link org.apache.openaz.xacml.pdp.policy.CombiningAlgorithm} implementations.
 */
public class StdCombiningAlgorithmFactory extends CombiningAlgorithmFactory {
    private static Map<Identifier, CombiningAlgorithm<Rule>> mapRuleCombiningAlgorithms = new HashMap<Identifier, CombiningAlgorithm<Rule>>();
    private static Map<Identifier, CombiningAlgorithm<PolicySetChild>> mapPolicyCombiningAlgorithms = new HashMap<Identifier, CombiningAlgorithm<PolicySetChild>>();
    private static boolean needInit = true;

    protected static void registerRuleCombiningAlgorithm(CombiningAlgorithm<Rule> ruleCombiningAlgorithm) {
        mapRuleCombiningAlgorithms.put(ruleCombiningAlgorithm.getId(), ruleCombiningAlgorithm);
    }

    protected static void registerPolicyCombiningAlgorithm(CombiningAlgorithm<PolicySetChild> policyCombiningAlgorithm) {
        mapPolicyCombiningAlgorithms.put(policyCombiningAlgorithm.getId(), policyCombiningAlgorithm);
    }

    @SuppressWarnings("unchecked")
    private static void initMap() {
        if (needInit) {
            synchronized (mapRuleCombiningAlgorithms) {
                if (needInit) {
                    needInit = false;
                    Field[] declaredFields = StdCombiningAlgorithms.class.getFields();
                    for (Field field : declaredFields) {
                        if (Modifier.isStatic(field.getModifiers())
                            && Modifier.isPublic(field.getModifiers())
                            && field.getName().startsWith(StdCombiningAlgorithms.PREFIX_CA)
                            && CombiningAlgorithm.class.isAssignableFrom(field.getType())) {
                            try {
                                if (field.getName().startsWith(StdCombiningAlgorithms.PREFIX_RULE)) {
                                    registerRuleCombiningAlgorithm((CombiningAlgorithm<Rule>)field.get(null));
                                } else if (field.getName().startsWith(StdCombiningAlgorithms.PREFIX_POLICY)) {
                                    registerPolicyCombiningAlgorithm((CombiningAlgorithm<PolicySetChild>)field
                                        .get(null));
                                }
                            } catch (IllegalAccessException ex) { // NOPMD
                                // TODO
                            }
                        }
                    }
                }
            }
        }
    }

    public StdCombiningAlgorithmFactory() {
        initMap();
    }

    @Override
    public CombiningAlgorithm<Rule> getRuleCombiningAlgorithm(Identifier combiningAlgorithmId) {
        return mapRuleCombiningAlgorithms.get(combiningAlgorithmId);
    }

    @Override
    public CombiningAlgorithm<PolicySetChild> getPolicyCombiningAlgorithm(Identifier combiningAlgorithmId) {
        return mapPolicyCombiningAlgorithms.get(combiningAlgorithmId);
    }
}