/*-
 * ============LICENSE_START=======================================================
 *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
 *  Modifications Copyright (C) 2019-2021 Nordix Foundation.
 *  Modifications Copyright (C) 2020-2021 Bell Canada. All rights reserved.
 *  Modifications Copyright (C) 2021 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.apex.service.engine.main;

import java.util.Arrays;
import java.util.Base64;
import java.util.List;
import java.util.Map.Entry;
import java.util.stream.Collectors;
import lombok.Getter;
import lombok.Setter;
import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
import org.onap.policy.apex.model.enginemodel.concepts.AxEngineModel;
import org.onap.policy.apex.service.parameters.ApexParameterConstants;
import org.onap.policy.apex.service.parameters.ApexParameterHandler;
import org.onap.policy.apex.service.parameters.ApexParameters;
import org.onap.policy.apex.service.parameters.engineservice.EngineServiceParameters;
import org.onap.policy.apex.service.parameters.eventhandler.EventHandlerParameters;
import org.onap.policy.common.parameters.ParameterService;
import org.onap.policy.common.utils.cmd.CommandLineException;
import org.slf4j.ext.XLogger;
import org.slf4j.ext.XLoggerFactory;

/**
 * This class initiates Apex as a complete service from the command line.
 *
 * @author Liam Fallon (liam.fallon@ericsson.com)
 */
public class ApexMain {
    private static final String APEX_SERVICE_FAILED_MSG = "start of Apex service failed";

    private static final XLogger LOGGER = XLoggerFactory.getXLogger(ApexMain.class);

    // The Apex Activator that activates the Apex engine
    @Getter
    private ApexActivator activator;

    // The parameters read in from JSON for each policy
    @Getter
    private ApexParameters apexParameters;

    private ApexParameterHandler apexParameterHandler = new ApexParameterHandler();

    @Getter
    @Setter(lombok.AccessLevel.PRIVATE)
    private volatile boolean alive = false;

    /**
     * Instantiates the Apex service.
     *
     * @param args the command line arguments
     * @throws ApexException the apex exception.
     */
    public ApexMain(final String[] args) {
        LOGGER.entry("Starting Apex service with parameters " + Arrays.toString(args) + " . . .");
        try {
            apexParameters = populateApexParameters(args);
        } catch (ApexException e) {
            LOGGER.error(APEX_SERVICE_FAILED_MSG, e);
            return;
        }
        try {
            aggregateParametersAndRegister();

            // Now, create the activator for the Apex service
            activator = new ApexActivator(apexParameters);

            // Start the activator
            activator.initialize();
            setAlive(true);
        } catch (final ApexException e) {
            LOGGER.error("start of Apex service failed, used parameters are {}", Arrays.toString(args), e);
            return;
        }

        // Add a shutdown hook to shut everything down in an orderly manner
        Runtime.getRuntime().addShutdownHook(new ApexMainShutdownHookClass());
        LOGGER.exit("Started Apex");
    }

    private ApexParameters populateApexParameters(String[] args) throws ApexException {
        // Check the arguments
        final var arguments = new ApexCommandLineArguments();
        try {
            // The arguments return a string if there is a message to print and we should exit
            final String argumentMessage = arguments.parse(args);
            if (argumentMessage != null) {
                throw new ApexException(argumentMessage);
            }

            // Validate that the arguments are sane
            arguments.validateInputFiles();
        } catch (final ApexException | CommandLineException e) {
            throw new ApexException("Arguments validation failed.", e);
        }

        ApexParameters axParameters;
        // Read the parameters
        try {
            axParameters = apexParameterHandler.getParameters(arguments);
        } catch (final Exception e) {
            throw new ApexException("Cannot create APEX Parameters from the arguments provided.", e);
        }

        // Set incoming Java properties
        setJavaProperties(axParameters);

        // Set the name of the event handler parameters for producers and consumers
        for (final Entry<String, EventHandlerParameters> ehParameterEntry : axParameters.getEventOutputParameters()
            .entrySet()) {
            if (!ehParameterEntry.getValue().checkSetName()) {
                ehParameterEntry.getValue().setName(ehParameterEntry.getKey());
            }
        }
        for (final Entry<String, EventHandlerParameters> ehParameterEntry : axParameters.getEventInputParameters()
            .entrySet()) {
            if (!ehParameterEntry.getValue().checkSetName()) {
                ehParameterEntry.getValue().setName(ehParameterEntry.getKey());
            }
        }
        return axParameters;
    }

    private void aggregateParametersAndRegister() throws ApexException {
        ApexParameters aggregatedParameters = null;
        if (ParameterService.contains(ApexParameterConstants.MAIN_GROUP_NAME)) {
            aggregatedParameters = ParameterService.get(ApexParameterConstants.MAIN_GROUP_NAME);
        } else {
            aggregatedParameters = new ApexParameters();
            aggregatedParameters.setEngineServiceParameters(new EngineServiceParameters());
            apexParameterHandler.registerParameters(aggregatedParameters);
        }
        List<String> duplicateInputParameters = aggregatedParameters.getEventInputParameters().keySet().stream()
            .filter(apexParameters.getEventInputParameters()::containsKey).collect(Collectors.toList());
        List<String> duplicateOutputParameters = aggregatedParameters.getEventOutputParameters().keySet().stream()
            .filter(apexParameters.getEventOutputParameters()::containsKey).collect(Collectors.toList());
        if (!(duplicateInputParameters.isEmpty() && duplicateOutputParameters.isEmpty())) {
            throw new ApexException(
                "start of Apex service failed because this policy has the following duplicate I/O parameters: "
                    + duplicateInputParameters + "/" + duplicateOutputParameters);
        }
        aggregatedParameters.getEventInputParameters().putAll(apexParameters.getEventInputParameters());
        aggregatedParameters.getEventOutputParameters().putAll(apexParameters.getEventOutputParameters());
        var aggregatedEngineParameters =
            aggregatedParameters.getEngineServiceParameters().getEngineParameters();
        var engineParameters = apexParameters.getEngineServiceParameters().getEngineParameters();
        aggregatedEngineParameters.getTaskParameters().addAll(engineParameters.getTaskParameters());
        aggregatedEngineParameters.getExecutorParameterMap().putAll(engineParameters.getExecutorParameterMap());
        aggregatedEngineParameters.getContextParameters().getSchemaParameters().getSchemaHelperParameterMap()
            .putAll(engineParameters.getContextParameters().getSchemaParameters().getSchemaHelperParameterMap());
    }

    /**
     * Shut down Execution.
     *
     * @throws ApexException on shutdown errors
     */
    public void shutdown() throws ApexException {
        if (activator != null) {
            activator.terminate();
        }
        setAlive(false);
    }

    /**
     * Get the Engine Stats.
     */
    public List<AxEngineModel> getEngineStats() {
        List<AxEngineModel> engineStats = null;
        if (activator != null) {
            engineStats = activator.getEngineStats();
        }
        return engineStats;
    }

    /**
     * The Class ApexMainShutdownHookClass terminates the Apex engine for the Apex service when its run
     * method is called.
     */
    private class ApexMainShutdownHookClass extends Thread {
        /**
         * {@inheritDoc}.
         */
        @Override
        public void run() {
            try {
                // Shutdown the Apex engine and wait for everything to stop
                activator.terminate();
                setAlive(false);
            } catch (final ApexException e) {
                LOGGER.warn("error occured during shut down of the Apex service", e);
            }
        }
    }

    /**
     * Set the Java properties specified in the parameters.
     *
     * @param parameters The incoming parameters
     */
    private void setJavaProperties(final ApexParameters parameters) {
        if (!parameters.checkJavaPropertiesSet()) {
            return;
        }

        // Set each Java property
        for (String[] javaProperty : parameters.getJavaProperties()) {
            String javaPropertyName = javaProperty[0];
            String javaPropertyValue = javaProperty[1];

            // Passwords are encoded using base64, better than sending passwords in the clear
            if (javaPropertyName.toLowerCase().contains("password")) {
                javaPropertyValue = new String(Base64.getDecoder().decode(javaPropertyValue.getBytes()));
            }

            // Set the Java property
            System.setProperty(javaPropertyName, javaPropertyValue);
        }
    }

    /**
     * The main method.
     *
     * @param args the arguments
     * @throws ApexException the apex exception.
     */
    public static void main(final String[] args) {
        new ApexMain(args);
    }
}