/*-
 * ============LICENSE_START=======================================================
 * ONAP
 * ================================================================================
 * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.pdp.xacml.application.common.std;

import com.att.research.xacml.api.AttributeAssignment;
import com.att.research.xacml.api.Decision;
import com.att.research.xacml.api.Obligation;
import com.att.research.xacml.api.Request;
import com.att.research.xacml.api.Response;
import com.att.research.xacml.api.Result;
import com.google.gson.Gson;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.AttributeAssignmentExpressionType;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.AttributeValueType;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.EffectType;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.ObjectFactory;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.ObligationExpressionType;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.ObligationExpressionsType;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.PolicyType;
import oasis.names.tc.xacml._3_0.core.schema.wd_17.RuleType;
import org.onap.policy.models.decisions.concepts.DecisionRequest;
import org.onap.policy.models.decisions.concepts.DecisionResponse;
import org.onap.policy.models.tosca.authorative.concepts.ToscaPolicy;
import org.onap.policy.pdp.xacml.application.common.ToscaDictionary;
import org.onap.policy.pdp.xacml.application.common.ToscaPolicyConversionException;
import org.onap.policy.pdp.xacml.application.common.ToscaPolicyTranslator;
import org.onap.policy.pdp.xacml.application.common.XacmlPolicyUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class StdBaseTranslator implements ToscaPolicyTranslator {
    private static final Logger LOGGER = LoggerFactory.getLogger(StdBaseTranslator.class);
    private static Gson gson = new Gson();

    public static final String POLICY_ID = "policy-id";

    @Override
    public PolicyType convertPolicy(ToscaPolicy toscaPolicy) throws ToscaPolicyConversionException {
        throw new ToscaPolicyConversionException("Please override converPolicy");
    }

    @Override
    public Request convertRequest(DecisionRequest request) {
        return null;
    }

    @Override
    public DecisionResponse convertResponse(Response xacmlResponse) {
        LOGGER.info("Converting Response {}", xacmlResponse);
        DecisionResponse decisionResponse = new DecisionResponse();
        //
        // Setup policies
        //
        decisionResponse.setPolicies(new HashMap<>());
        //
        // Iterate through all the results
        //
        for (Result xacmlResult : xacmlResponse.getResults()) {
            //
            // Check the result
            //
            if (xacmlResult.getDecision() == Decision.PERMIT) {
                //
                // Go through obligations
                //
                scanObligations(xacmlResult.getObligations(), decisionResponse);
            } else if (xacmlResult.getDecision() == Decision.DENY
                    || xacmlResult.getDecision() == Decision.INDETERMINATE) {
                //
                // TODO we have to return an ErrorResponse object instead
                //
                decisionResponse.setStatus("A better error message");
            }
        }

        return decisionResponse;
    }

    @SuppressWarnings("unchecked")
    protected void scanObligations(Collection<Obligation> obligations, DecisionResponse decisionResponse) {
        for (Obligation obligation : obligations) {
            LOGGER.info("Obligation: {}", obligation);
            for (AttributeAssignment assignment : obligation.getAttributeAssignments()) {
                LOGGER.info("Attribute Assignment: {}", assignment);
                //
                // We care about the content attribute
                //
                if (ToscaDictionary.ID_OBLIGATION_POLICY_MONITORING_CONTENTS
                        .equals(assignment.getAttributeId())) {
                    //
                    // The contents are in Json form
                    //
                    Object stringContents = assignment.getAttributeValue().getValue();
                    LOGGER.info("DCAE contents: {}{}", XacmlPolicyUtils.LINE_SEPARATOR, stringContents);
                    //
                    // Let's parse it into a map using Gson
                    //
                    Map<String, Object> result;
                    result = gson.fromJson(stringContents.toString(), Map.class);
                    //
                    // Find the metadata section
                    //
                    Map<String, Object> metadata = (Map<String, Object>) result.get("metadata");
                    if (metadata != null) {
                        decisionResponse.getPolicies().put(metadata.get(POLICY_ID).toString(), result);
                    } else {
                        LOGGER.error("Missing metadata section in policy contained in obligation.");
                    }
                }
            }
        }
    }

    /**
     * From the TOSCA metadata section, pull in values that are needed into the XACML policy.
     *
     * @param policy Policy Object to store the metadata
     * @param map The Metadata TOSCA Map
     * @return Same Policy Object
     * @throws ToscaPolicyConversionException If there is something missing from the metadata
     */
    protected PolicyType fillMetadataSection(PolicyType policy,
            Map<String, String> map) throws ToscaPolicyConversionException {
        //
        // Ensure the policy-id exists - we don't use it here. It
        // is saved in the TOSCA Policy Name field.
        //
        if (! map.containsKey(POLICY_ID)) {
            throw new ToscaPolicyConversionException(policy.getPolicyId() + " missing metadata policy-id");
        }
        //
        // Ensure the policy-version exists
        //
        if (! map.containsKey("policy-version")) {
            throw new ToscaPolicyConversionException(policy.getPolicyId() + " missing metadata policy-version");
        }
        //
        // Add in the Policy Version
        //
        policy.setVersion(map.get("policy-version"));
        return policy;
    }

    protected RuleType addObligation(RuleType rule, String jsonPolicy) {
        //
        // Convert the YAML Policy to JSON Object
        //
        LOGGER.info("JSON Optimization Policy {}{}", XacmlPolicyUtils.LINE_SEPARATOR, jsonPolicy);
        //
        // Create an AttributeValue for it
        //
        AttributeValueType value = new AttributeValueType();
        value.setDataType(ToscaDictionary.ID_OBLIGATION_POLICY_MONITORING_DATATYPE.stringValue());
        value.getContent().add(jsonPolicy);
        //
        // Create our AttributeAssignmentExpression where we will
        // store the contents of the policy in JSON format.
        //
        AttributeAssignmentExpressionType expressionType = new AttributeAssignmentExpressionType();
        expressionType.setAttributeId(ToscaDictionary.ID_OBLIGATION_POLICY_MONITORING_CONTENTS.stringValue());
        ObjectFactory factory = new ObjectFactory();
        expressionType.setExpression(factory.createAttributeValue(value));
        //
        // Create an ObligationExpression for it
        //
        ObligationExpressionType obligation = new ObligationExpressionType();
        obligation.setFulfillOn(EffectType.PERMIT);
        obligation.setObligationId(ToscaDictionary.ID_OBLIGATION_REST_BODY.stringValue());
        obligation.getAttributeAssignmentExpression().add(expressionType);
        //
        // Now we can add it into the rule
        //
        ObligationExpressionsType obligations = new ObligationExpressionsType();
        obligations.getObligationExpression().add(obligation);
        rule.setObligationExpressions(obligations);
        return rule;
    }

}