/*-
 * ============LICENSE_START=======================================================
 * so
 * ================================================================================
 * Copyright (C) 2017-2019 AT&T Intellectual Property. All rights reserved.
 * Modifications Copyright (C) 2019-2020 Nordix Foundation.
 * Modifications Copyright (C) 2019 Samsung Electronics Co., Ltd.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.so;

import com.google.gson.GsonBuilder;
import com.google.gson.JsonSyntaxException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import org.apache.commons.lang3.tuple.Pair;
import org.onap.policy.common.endpoints.event.comm.Topic.CommInfrastructure;
import org.onap.policy.common.endpoints.utils.NetLoggerUtil;
import org.onap.policy.common.endpoints.utils.NetLoggerUtil.EventType;
import org.onap.policy.rest.RestManager;
import org.onap.policy.so.util.Serialization;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class handles the interface towards SO (Service Orchestrator) for the ONAP Policy Framework. The SO API is
 * defined at this link:
 * http://onap.readthedocs.io/en/latest/submodules/so.git/docs/SO_R1_Interface.html#get-orchestration-request
 *
 */
public final class SoManager {

    // TODO remove this class

    private static final Logger logger = LoggerFactory.getLogger(SoManager.class);

    private static ExecutorService executors = Executors.newCachedThreadPool();

    private static final int SO_RESPONSE_ERROR = 999;
    private static final String MEDIA_TYPE = "application/json";
    private static final String LINE_SEPARATOR = System.lineSeparator();

    // REST get timeout value in milliseconds
    private static final int GET_REQUESTS_BEFORE_TIMEOUT = 20;
    private static final long GET_REQUEST_WAIT_INTERVAL = 20000;

    // The REST manager used for processing REST calls for this VFC manager
    private RestManager restManager;

    private long restGetTimeout = GET_REQUEST_WAIT_INTERVAL;

    private String url;
    private String user;
    private String password;

    @FunctionalInterface
    public interface SoCallback {
        public void onSoResponseWrapper(SoResponseWrapper wrapper);
    }

    /**
     * Default constructor.
     */
    public SoManager(String url, String user, String password) {
        this.url = url;
        this.user = user;
        this.password = password;
        restManager = new RestManager();
    }

    /**
     * Create a service instance in SO.
     *
     * @param url the SO URL
     * @param urlBase the base URL
     * @param username user name on SO
     * @param password password on SO
     * @param request the request to issue to SO
     * @return the SO Response object
     */
    public SoResponse createModuleInstance(final String url, final String urlBase, final String username,
            final String password, final SoRequest request) {
        // Issue the HTTP POST request to SO to create the service instance
        String requestJson = Serialization.gsonPretty.toJson(request);
        NetLoggerUtil.getNetworkLogger().info("[OUT|{}|{}|{}|{}|{}|{}|]{}{}", "SO", url, username, password,
                createSimpleHeaders(), MEDIA_TYPE, LINE_SEPARATOR, requestJson);
        Pair<Integer, String> httpResponse =
                restManager.post(url, username, password, createSimpleHeaders(), MEDIA_TYPE, requestJson);

        // Process the response from SO
        SoResponse response = waitForSoOperationCompletion(urlBase, username, password, url, httpResponse);
        if (SO_RESPONSE_ERROR != response.getHttpResponseCode()) {
            return response;
        } else {
            return null;
        }
    }

    /**
     * Works just like SOManager#asyncSORestCall(String, WorkingMemory, String, String, String, SORequest) except the
     * vfModuleInstanceId is always null.
     *
     */
    public Future<SoResponse> asyncSoRestCall(final String requestId, final SoCallback callback,
            final String serviceInstanceId, final String vnfInstanceId, final SoRequest request) {
        return asyncSoRestCall(requestId, callback, serviceInstanceId, vnfInstanceId, null, request);
    }

    /**
     * This method makes an asynchronous Rest call to MSO and inserts the response into Drools working memory.
     *
     * @param requestId the request id
     * @param callback callback method
     * @param serviceInstanceId service instance id to construct the request url
     * @param vnfInstanceId vnf instance id to construct the request url
     * @param vfModuleInstanceId vfModule instance id to construct the request url (required in case of delete vf
     *        module)
     * @param request the SO request
     * @return a concurrent Future for the thread that handles the request
     */
    public Future<SoResponse> asyncSoRestCall(final String requestId, final SoCallback callback,
            final String serviceInstanceId, final String vnfInstanceId, final String vfModuleInstanceId,
            final SoRequest request) {
        return executors.submit(new AsyncSoRestCallThread(requestId, callback, serviceInstanceId, vnfInstanceId,
                vfModuleInstanceId, request, this));
    }

    /**
     * This class handles an asynchronous request to SO as a thread.
     */
    private class AsyncSoRestCallThread implements Callable<SoResponse> {
        final String requestId;
        final SoCallback callback;
        final String serviceInstanceId;
        final String vnfInstanceId;
        final String vfModuleInstanceId;
        final SoRequest request;
        final String baseUrl;
        final String user;
        final String password;

        /**
         * Constructor, sets the context of the request.
         *
         * @param requestID The request ID
         * @param wm reference to the Drools working memory
         * @param serviceInstanceId the service instance in SO to use
         * @param vnfInstanceId the VNF instance that is the subject of the request
         * @param vfModuleInstanceId the vf module instance id (not null in case of delete vf module request)
         * @param request the request itself
         */
        private AsyncSoRestCallThread(final String requestId, final SoCallback callback, final String serviceInstanceId,
                final String vnfInstanceId, final String vfModuleInstanceId, final SoRequest request,
                final SoManager callingSoManager) {
            this.requestId = requestId;
            this.callback = callback;
            this.serviceInstanceId = serviceInstanceId;
            this.vnfInstanceId = vnfInstanceId;
            this.vfModuleInstanceId = vfModuleInstanceId;
            this.request = request;
            this.baseUrl = callingSoManager.url;
            this.user = callingSoManager.user;
            this.password = callingSoManager.password;
        }

        /**
         * Process the asynchronous SO request.
         */
        @Override
        public SoResponse call() {

            // Create a JSON representation of the request
            String soJson = new GsonBuilder().disableHtmlEscaping().setPrettyPrinting().create().toJson(request);
            String initialUrl = null;
            Pair<Integer, String> httpResponse = null;

            if (request.getOperationType() != null && request.getOperationType().equals(SoOperationType.SCALE_OUT)) {
                initialUrl = this.baseUrl + "/serviceInstantiation/v7/serviceInstances/" + serviceInstanceId + "/vnfs/"
                        + vnfInstanceId + "/vfModules/scaleOut";
                NetLoggerUtil.log(EventType.OUT, CommInfrastructure.REST, initialUrl, soJson);
                httpResponse = restManager.post(initialUrl, this.user, this.password, createSimpleHeaders(), MEDIA_TYPE,
                        soJson);
            } else if (request.getOperationType() != null
                    && request.getOperationType().equals(SoOperationType.DELETE_VF_MODULE)) {
                initialUrl = this.baseUrl + "/serviceInstances/v7/" + serviceInstanceId + "/vnfs/" + vnfInstanceId
                        + "/vfModules/" + vfModuleInstanceId;
                NetLoggerUtil.log(EventType.OUT, CommInfrastructure.REST, initialUrl, soJson);
                httpResponse = restManager.delete(initialUrl, this.user, this.password, createSimpleHeaders(),
                        MEDIA_TYPE, soJson);
            } else {
                return null;
            }

            // Process the response from SO
            SoResponse response =
                    waitForSoOperationCompletion(this.baseUrl, this.user, this.password, initialUrl, httpResponse);

            // Return the response to Drools in its working memory
            SoResponseWrapper soWrapper = new SoResponseWrapper(response, requestId);
            if (this.callback != null) {
                this.callback.onSoResponseWrapper(soWrapper);
            }

            return response;
        }
    }

    /**
     * Wait for the SO operation we have ordered to complete.
     *
     * @param urlBaseSo The base URL for SO
     * @param username user name on SO
     * @param password password on SO
     * @param initialRequestUrl The URL of the initial HTTP request
     * @param initialHttpResponse The initial HTTP message returned from SO
     * @return The parsed final response of SO to the request
     */
    private SoResponse waitForSoOperationCompletion(final String urlBaseSo, final String username,
            final String password, final String initialRequestUrl, final Pair<Integer, String> initialHttpResponse) {
        // Process the initial response from SO, the response to a post
        SoResponse response = processSoResponse(initialRequestUrl, initialHttpResponse);
        if (SO_RESPONSE_ERROR == response.getHttpResponseCode()) {
            return response;
        }

        // The SO URL to use to get the status of orchestration requests
        String urlGet = urlBaseSo + "/orchestrationRequests/v5/" + response.getRequestReferences().getRequestId();

        // The HTTP status code of the latest response
        Pair<Integer, String> latestHttpResponse = initialHttpResponse;

        // Wait for the response from SO
        for (int attemptsLeft = GET_REQUESTS_BEFORE_TIMEOUT; attemptsLeft >= 0; attemptsLeft--) {
            // The SO request may have completed even on the first request so we check the
            // response
            // here before
            // issuing any other requests
            if (isRequestStateFinished(latestHttpResponse, response)) {
                return response;
            }

            // Wait for the defined interval before issuing a get
            try {
                Thread.sleep(restGetTimeout);
            } catch (InterruptedException e) {
                logger.error("Interrupted exception: ", e);
                Thread.currentThread().interrupt();
                response.setHttpResponseCode(SO_RESPONSE_ERROR);
                return response;
            }

            // Issue a GET to find the current status of our request
            NetLoggerUtil.getNetworkLogger().info("[OUT|{}|{}|{}|{}|{}|{}|]{}", "SO", urlGet, username, password,
                    createSimpleHeaders(), MEDIA_TYPE, LINE_SEPARATOR);
            Pair<Integer, String> httpResponse = restManager.get(urlGet, username, password, createSimpleHeaders());

            // Get our response
            response = processSoResponse(urlGet, httpResponse);
            if (SO_RESPONSE_ERROR == response.getHttpResponseCode()) {
                return response;
            }

            // Our latest HTTP response code
            latestHttpResponse = httpResponse;
        }

        // We have timed out on the SO request
        response.setHttpResponseCode(SO_RESPONSE_ERROR);
        return response;
    }

    /**
     * Parse the response message from SO into a SOResponse object.
     *
     * @param requestURL The URL of the HTTP request
     * @param httpResponse The HTTP message returned from SO
     * @return The parsed response
     */
    private SoResponse processSoResponse(final String requestUrl, final Pair<Integer, String> httpResponse) {
        SoResponse response = new SoResponse();

        // A null httpDetails indicates a HTTP problem, a valid response from SO must be
        // either 200
        // or 202
        if (!httpResultIsNullFree(httpResponse) || (httpResponse.getLeft() != 200 && httpResponse.getLeft() != 202)) {
            logger.error("Invalid HTTP response received from SO");
            response.setHttpResponseCode(SO_RESPONSE_ERROR);
            return response;
        }

        // Parse the JSON of the response into our POJO
        try {
            response = Serialization.gsonPretty.fromJson(httpResponse.getRight(), SoResponse.class);
        } catch (JsonSyntaxException e) {
            logger.error("Failed to deserialize HTTP response into SOResponse: ", e);
            response.setHttpResponseCode(SO_RESPONSE_ERROR);
            return response;
        }

        // Set the HTTP response code of the response if needed
        if (response.getHttpResponseCode() == 0) {
            response.setHttpResponseCode(httpResponse.getLeft());
        }

        NetLoggerUtil.log(EventType.IN, CommInfrastructure.REST, requestUrl, httpResponse.getRight());

        if (logger.isDebugEnabled()) {
            logger.debug("***** Response to SO Request to URL {}:", requestUrl);
            logger.debug(httpResponse.getRight());
        }

        return response;
    }

    /**
     * Method to allow tuning of REST get timeout.
     *
     * @param restGetTimeout the timeout value
     */
    protected void setRestGetTimeout(final long restGetTimeout) {
        this.restGetTimeout = restGetTimeout;
    }

    /**
     * Check that the request state of a response is defined.
     *
     * @param response The response to check
     * @return true if the request for the response is defined
     */
    private boolean isRequestStateDefined(final SoResponse response) {
        return response != null && response.getRequest() != null && response.getRequest().getRequestStatus() != null
                && response.getRequest().getRequestStatus().getRequestState() != null;
    }

    /**
     * Check that the request state of a response is finished.
     *
     * @param latestHttpDetails the HTTP details of the response
     * @param response The response to check
     * @return true if the request for the response is finished
     */
    private boolean isRequestStateFinished(final Pair<Integer, String> latestHttpDetails, final SoResponse response) {
        if (latestHttpDetails != null && 200 == latestHttpDetails.getLeft() && isRequestStateDefined(response)) {
            String requestState = response.getRequest().getRequestStatus().getRequestState();
            return "COMPLETE".equalsIgnoreCase(requestState) || "FAILED".equalsIgnoreCase(requestState);
        } else {
            return false;
        }
    }

    /**
     * Check that a HTTP operation result has no nulls.
     *
     * @param httpOperationResult the result to check
     * @return true if no nulls are found
     */
    private boolean httpResultIsNullFree(Pair<Integer, String> httpOperationResult) {
        return httpOperationResult != null && httpOperationResult.getLeft() != null
                && httpOperationResult.getRight() != null;
    }

    /**
     * Create simple HTTP headers for unauthenticated requests to SO.
     *
     * @return the HTTP headers
     */
    private Map<String, String> createSimpleHeaders() {
        Map<String, String> headers = new HashMap<>();
        headers.put("Accept", MEDIA_TYPE);
        return headers;
    }
}