<?php
/**
 * SuiteCRM is a customer relationship management program developed by SalesAgility Ltd.
 * Copyright (C) 2021 SalesAgility Ltd.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License version 3 as published by the
 * Free Software Foundation with the addition of the following permission added
 * to Section 15 as permitted in Section 7(a): FOR ANY PART OF THE COVERED WORK
 * IN WHICH THE COPYRIGHT IS OWNED BY SALESAGILITY, SALESAGILITY DISCLAIMS THE
 * WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License
 * version 3, these Appropriate Legal Notices must retain the display of the
 * "Supercharged by SuiteCRM" logo. If the display of the logos is not reasonably
 * feasible for technical reasons, the Appropriate Legal Notices must display
 * the words "Supercharged by SuiteCRM".
 */

class DateTimeService
{

    /**
     * @param string $start
     * @param string|null $end
     * @return int|null
     * @throws Exception
     */
    public function diffDateStrings(string $start, string $end = null): ?int
    {
        /* @noinspection PhpIncludeInspection */
        require_once 'include/portability/Services/DateTime/DateFormatService.php';
        $dateFormatService = new DateFormatService();

        $startDateTime = $dateFormatService->toDateTime($start);

        if ($startDateTime === null) {
            return null;
        }

        $endDateTime = new DateTime();
        if (!empty($end)) {
            $parsed = $dateFormatService->toDateTime($end);
            if ($parsed !== null) {
                $endDateTime = $parsed;
            }
        }

        return $this->diffDateTimes($startDateTime, $endDateTime);
    }

    /**
     * @param DateTime $start
     * @param DateTime $end
     * @return int
     */
    public function diffDateTimes(DateTime $start, DateTime $end): int
    {
        $diff = $start->diff($end);

        if ($diff->days === false) {
            throw new UnexpectedValueException('Unexpected date diff value');
        }

        return $diff->days;
    }

}