/* Copyright 2012-2015 SAP SE
 *
 * 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 eu.aniketos.securebpmn.xacml.combine;

import java.util.Iterator;
import java.util.List;

import eu.aniketos.securebpmn.xacml.AnalysisCtx;

import com.sun.xacml.AbstractPolicy;
import com.sun.xacml.ConfigurationStore;
import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.MatchResult;
import com.sun.xacml.combine.CombinerElement;
import com.sun.xacml.combine.CombinerParameter;
import com.sun.xacml.combine.FirstApplicablePolicyAlg;
import com.sun.xacml.combine.PolicyCombinerElement;
import com.sun.xacml.ctx.Result;

public class AnalysisFirstApplicablePolicyAlg extends FirstApplicablePolicyAlg {

    public AnalysisFirstApplicablePolicyAlg() {
        super();
    }

    @Override
    public Result combine(EvaluationCtx context, List<CombinerParameter> parameters,
                          List<CombinerElement> policyElements) {

        Result finalResult = null;

        Iterator<CombinerElement> it = policyElements.iterator();

        while (it.hasNext()) {
            AbstractPolicy policy =
                ((PolicyCombinerElement)(it.next())).getPolicy();

            // make sure that the policy matches the context
            context.newEvent(policy);
            MatchResult match = policy.match(context);

            if (match.getResult() == MatchResult.INDETERMINATE) {
                Result result =  new Result(Result.DECISION_INDETERMINATE,
                                            match.getStatus(),
                                            context);
                context.closeCurrentEvent(result);

                if ( ((AnalysisCtx)context).getEvalInfo().isMissingAttribute() ) {
                    if ( finalResult == null) {
                        finalResult = result;
                    }
                } else {
                    return result;
                }
            }

            if (match.getResult() == MatchResult.NO_MATCH) {
                context.closeCurrentEvent(
                    new Result(Result.DECISION_NOT_APPLICABLE));
            }

            if (match.getResult() == MatchResult.MATCH) {
                // evaluate the policy
                Result result = policy.evaluate(context);
                context.closeCurrentEvent(result);


                // do not treat the discarded values
                if (result != null) {
                    int effect = result.getDecision();

                    // in the case of PERMIT, DENY, or INDETERMINATE, we always
                    // just return that result, so only on a rule that doesn't
                    // apply do we keep going...
                    if (effect != Result.DECISION_NOT_APPLICABLE) {
                        if (((AnalysisCtx)context).getEvalInfo().isMissingAttribute()) {
                            if ( ( finalResult == null) ) {
                                finalResult = result;
                            }

                        } else {
                            return result;
                        }
                    }
                }
            }
        }
        if ( finalResult != null ) {
            return finalResult;
        }

        // if we got here, then none of the rules applied
        return new Result(Result.DECISION_NOT_APPLICABLE,
                          context);
    }


    public void setConfigurationStore(ConfigurationStore conf) {
        //this.conf = conf;
    }



}