/*-
 * ============LICENSE_START=======================================================
 * Copyright (C) 2019-2022 AT&T Intellectual Property. All rights reserved.
 * Modifications Copyright (C) 2021 Nordix Foundation.
 * ================================================================================
 * 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.pdpx.main.rest;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.stream.Collectors;
import lombok.Getter;
import lombok.Setter;
import org.onap.policy.common.endpoints.http.client.HttpClient;
import org.onap.policy.models.decisions.concepts.DecisionRequest;
import org.onap.policy.models.tosca.authorative.concepts.ToscaConceptIdentifier;
import org.onap.policy.models.tosca.authorative.concepts.ToscaPolicy;
import org.onap.policy.pdp.xacml.application.common.XacmlApplicationException;
import org.onap.policy.pdp.xacml.application.common.XacmlApplicationServiceProvider;
import org.onap.policy.pdpx.main.parameters.XacmlApplicationParameters;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class XacmlPdpApplicationManager {
    private static final Logger LOGGER = LoggerFactory.getLogger(XacmlPdpApplicationManager.class);

    @Getter
    @Setter
    private static XacmlPdpApplicationManager current;

    private final ServiceLoader<XacmlApplicationServiceProvider> applicationLoader;
    private final Map<String, XacmlApplicationServiceProvider> providerActionMap = new HashMap<>();
    private final List<ToscaConceptIdentifier> toscaPolicyTypeIdents = new ArrayList<>();
    private final Map<ToscaPolicy, XacmlApplicationServiceProvider> mapLoadedPolicies = new HashMap<>();


    /**
     * One time to initialize the applications upon startup.
     */
    public XacmlPdpApplicationManager(XacmlApplicationParameters applicationParameters,
                    HttpClient policyApiClient) {
        if (LOGGER.isInfoEnabled()) {
            LOGGER.info("Initialization applications {} {}", applicationParameters, policyApiClient);
        }
        //
        // Load service
        //
        applicationLoader = ServiceLoader.load(XacmlApplicationServiceProvider.class);
        //
        // Iterate through the applications for actions and supported policy types
        //
        for (XacmlApplicationServiceProvider application : applicationLoader) {
            if (LOGGER.isInfoEnabled()) {
                LOGGER.info("Application {} supports {}", application.applicationName(),
                    application.supportedPolicyTypes());
            }
            //
            // Check for exclusions
            //
            if (applicationParameters.isExcluded(application.getClass().getName())) {
                LOGGER.info("excluded {}", application.getClass().getName());
                continue;
            }
            //
            // We are not going to make this available unless the application can
            // install correctly.
            //
            var applicationInitialized = false;
            //
            // Have it initialize at a path
            //
            try {
                initializeApplicationPath(Paths.get(applicationParameters.getApplicationPath()), application,
                                policyApiClient);
                //
                // We are initialized
                //
                applicationInitialized = true;
            } catch (XacmlApplicationException e) {
                LOGGER.error("Failed to initialize path for {}", application.applicationName(), e);
            }
            if (applicationInitialized) {
                //
                // Iterate through the actions and save in the providerActionMap
                //
                for (String action : application.actionDecisionsSupported()) {
                    //
                    // Save the actions that it supports
                    //
                    providerActionMap.put(action, application);
                }
                //
                // Add all the supported policy types
                //
                toscaPolicyTypeIdents.addAll(application.supportedPolicyTypes());
            }
        }
        //
        // we have initialized
        //
        LOGGER.info("Finished applications initialization {}", providerActionMap);

    }

    public XacmlApplicationServiceProvider findApplication(DecisionRequest request) {
        return providerActionMap.get(request.getAction());
    }

    public XacmlApplicationServiceProvider findNativeApplication() {
        return providerActionMap.get("native");
    }

    /**
     * getToscaPolicies.
     *
     * @return the map containing ToscaPolicies
     */
    public Map<ToscaPolicy, XacmlApplicationServiceProvider> getToscaPolicies() {
        return mapLoadedPolicies;
    }

    /**
     * getToscaPolicyIdentifiers.
     *
     * @return list of ToscaPolicyIdentifier
     */
    public List<ToscaConceptIdentifier> getToscaPolicyIdentifiers() {
        //
        // converting map to return List of ToscaPolicyIdentiers
        //
        return mapLoadedPolicies.keySet().stream().map(ToscaPolicy::getIdentifier).collect(Collectors.toList());
    }

    public List<ToscaConceptIdentifier> getToscaPolicyTypeIdents() {
        return toscaPolicyTypeIdents;
    }

    /**
     * Finds the appropriate application and removes the policy.
     *
     * @param policy Incoming policy
     */
    public void removeUndeployedPolicy(ToscaPolicy policy) {

        for (XacmlApplicationServiceProvider application : applicationLoader) {
            try {
                if (application.unloadPolicy(policy)) {
                    if (LOGGER.isInfoEnabled()) {
                        LOGGER.info("Unloaded ToscaPolicy {} from application {}", policy.getMetadata(),
                            application.applicationName());
                    }
                    if (mapLoadedPolicies.remove(policy) == null) {
                        LOGGER.error("Failed to remove unloaded policy {} from map size {}", policy.getMetadata(),
                                mapLoadedPolicies.size());
                    }
                }
            } catch (XacmlApplicationException e) {
                LOGGER.error("Failed to undeploy the Tosca Policy", e);
            }
        }
    }

    /**
     * Finds the appropriate application and loads the policy, throws an exception if it fails.
     *
     * @param policy Incoming policy
     * @throws XacmlApplicationException if loadPolicy fails
     */
    public void loadDeployedPolicy(ToscaPolicy policy) throws XacmlApplicationException {
        for (XacmlApplicationServiceProvider application : applicationLoader) {
            //
            // There should be only one application per policytype. We can
            // put more logic surrounding enforcement of that later. For now,
            // just use the first one found.
            //
            if (application.canSupportPolicyType(policy.getTypeIdentifier())) {
                //
                // Try to load the policy
                //
                application.loadPolicy(policy);
                mapLoadedPolicies.put(policy, application);
                if (LOGGER.isInfoEnabled()) {
                    LOGGER.info("Loaded ToscaPolicy {} into application {}", policy.getMetadata(),
                            application.applicationName());
                }
                return;
            }
        }
        //
        // Ideally we shouldn't ever get here if we
        // are ensuring we are reporting a set of Policy Types and the
        // pap honors that. The loadPolicy for each application should be
        // the one throwing exceptions if there are any errors in the policy type.
        //
        throw new XacmlApplicationException("Application not found for policy type" + policy.getTypeIdentifier());
    }

    /**
     * Returns the current count of policy types supported. This could be misleading a bit
     * as some applications can support wildcard of policy types. Eg. onap.Monitoring.* as
     * well as individual types/versions. Nevertheless useful for debugging and testing.
     *
     * @return Total count added from all applications
     */
    public long getPolicyTypeCount() {
        return toscaPolicyTypeIdents.size();
    }

    /**
     * Gets the number of policies currently deployed.
     *
     * @return the number of policies currently deployed
     */
    public int getPolicyCount() {
        return mapLoadedPolicies.size();
    }

    private void initializeApplicationPath(Path basePath, XacmlApplicationServiceProvider application,
                    HttpClient policyApiClient) throws XacmlApplicationException {
        //
        // Making an assumption that all application names are unique, and
        // they can result in a valid directory being created.
        //
        var path = Paths.get(basePath.toAbsolutePath().toString(), application.applicationName());
        if (LOGGER.isInfoEnabled()) {
            LOGGER.info("initializeApplicationPath {} at this path {}", application.applicationName(), path);
        }
        //
        // Create that the directory if it does not exist. Ideally
        // this is only for testing, but could be used for production
        // Probably better to have the docker container and/or helm
        // scripts setup the local directory.
        //
        if (! path.toFile().exists()) {
            try {
                //
                // Try to create the directory
                //
                Files.createDirectory(path);
            } catch (IOException e) {
                throw new XacmlApplicationException("Failed to create application directory " + path.toAbsolutePath(),
                        e);
            }
        }
        //
        // Have the application initialize
        //
        application.initialize(path, policyApiClient);
    }
}