/*
 * ============LICENSE_START========================================================================
 * ONAP : ccsdk feature sdnr wt
 * =================================================================================================
 * Copyright (C) 2019 highstreet technologies GmbH 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.
 * ============LICENSE_END==========================================================================
 */

package org.onap.ccsdk.features.sdnr.wt.devicemanager.maintenance.impl;

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import javax.annotation.Nonnull;

import org.onap.ccsdk.features.sdnr.wt.common.HtAssert;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.yang.types.rev130715.DateAndTime;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.data.provider.rev190801.MaintenanceEntity;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MaintenanceCalculator {

	private static final Logger LOG = LoggerFactory.getLogger(MaintenanceCalculator.class);

	private static ZoneId EsMaintenanceFilterTimeZone = ZoneId.of("UTC");
	//private static DateTimeFormatter FORMAT = DateTimeFormatter.ISO_DATE_TIME;       // "1986-04-08T12:30:00"
	private static DateTimeFormatter FORMAT = DateTimeFormatter.ISO_OFFSET_DATE_TIME; // 2011-12-03T10:15:30+01:00
	private static ZonedDateTime EMPTYDATETIME = ZonedDateTime.ofInstant(Instant.EPOCH, EsMaintenanceFilterTimeZone);

	/** Intended to be used static **/
	private MaintenanceCalculator() {
	}

	/**
	 * Verify maintenance status
	 * @param maintenance if null false, else according to settings
	 * @param objectIdRef NETCONF object id
	 * @param problem     name that was provided
	 * @param now         time to verify with
	 * @return true if in maintenance status
	 */
	public static boolean isONFObjectInMaintenance(MaintenanceEntity maintenance, String objectIdRef, String problem,
			ZonedDateTime now) {

		if (maintenance != null) {
			Boolean isActive = maintenance.isActive();
			if (isActive != null && isActive && isInMaintenance(maintenance, objectIdRef, problem, now)) {
				return true;
			}

		}
		return false;
	}

	/** Shortcut **/
	public static boolean isONFObjectInMaintenance(MaintenanceEntity maintenance, String objectIdRef, String problem) {
		return isONFObjectInMaintenance(maintenance, objectIdRef, problem, getNow());
	}

	/*---------------------------------------------
	 * private static helper functions to verify
	 */

	/**
	 * Get the actual time in the Filter time zone.
	 * @return actual Time
	 */
	private static ZonedDateTime getNow() {
		return ZonedDateTime.now(EsMaintenanceFilterTimeZone);
	}

	/**
	 * Verify if the filter is active for an object
	 *
	 * @param now point of time to verify
	 * @return if the object is covered by filter and now within point of time
	 */
	private static boolean isInMaintenance(MaintenanceEntity maintenance, String objectIdRef, String problem,
			ZonedDateTime now) {
		return appliesToObjectReference(maintenance, objectIdRef, problem)
				&& isInPeriod(maintenance.getStart(), maintenance.getEnd(), now);
	}

	/**
	 * Compare the if probe is within the range of start and end.
	 *
	 * @param start of range
	 * @param end   of range
	 * @param probe time to verify
	 * @return boolean result true if (start <= probe <= end)
	 */
	public static boolean isInPeriod(DateAndTime start, DateAndTime end, ZonedDateTime probe) {
		HtAssert.nonnull(start,end,probe);
		ZonedDateTime startZT = valueOf(start.getValue());
		ZonedDateTime endZT = valueOf(end.getValue());
		return startZT.compareTo(endZT) < 0 && startZT.compareTo(probe) <= 0 && endZT.compareTo(probe) >= 0;
	}

	/**
	 * Verify if the definied object is matching to the referenced object
	 * @param definition definition with parameters
	 * @param pObjectIdRef object-id-ref of fault notification
	 * @param pProblem problem of fault notification
	 * @return true if if referenced
	 */
	private static boolean appliesToObjectReference(@Nonnull MaintenanceEntity definition, @Nonnull String pObjectIdRef,
			@Nonnull String pProblem) {
		HtAssert.nonnull(definition,pObjectIdRef,pProblem);
		boolean res = (definition.getObjectIdRef()==null ||  pObjectIdRef.contains(definition.getObjectIdRef()))
				&& (definition.getProblem()==null || pProblem.contains(definition.getProblem()));
		LOG.debug("Check result applies {}: {} {} against: {}", res, pObjectIdRef, pProblem, definition);
		return res;
	}

	/**
	 * Convert String to time value
	 * @param zoneTimeString with time
	 * @return ZonedDateTime string
	 */
	public static ZonedDateTime valueOf(String zoneTimeString) {
		if (zoneTimeString == null || zoneTimeString.isEmpty()) {
			LOG.warn("Null or empty zoneTimeString");
			return EMPTYDATETIME;
		}
		try {
			return ZonedDateTime.parse(zoneTimeString, FORMAT);
		} catch (DateTimeParseException e) {
			LOG.warn("Can not parse zoneTimeString '{}'", zoneTimeString);
			return EMPTYDATETIME;
		}
	}

}