<?php

namespace PhpOffice\PhpSpreadsheet\Shared;

use DateTimeZone;
use PhpOffice\PhpSpreadsheet\Exception as PhpSpreadsheetException;

class TimeZone
{
    /**
     * Default Timezone used for date/time conversions.
     *
     * @var string
     */
    protected static $timezone = 'UTC';

    /**
     * Validate a Timezone name.
     *

<      * @param string $timezone Time zone (e.g. 'Europe/London')



>      * @param string $timezoneName Time zone (e.g. 'Europe/London')


     *
     * @return bool Success or failure
     */

<     private static function validateTimeZone($timezone)



>     private static function validateTimeZone(string $timezoneName): bool


    {

<         return in_array($timezone, DateTimeZone::listIdentifiers());



>         return in_array($timezoneName, DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC), true);


    }

    /**
     * Set the Default Timezone used for date/time conversions.
     *

<      * @param string $timezone Time zone (e.g. 'Europe/London')



>      * @param string $timezoneName Time zone (e.g. 'Europe/London')


     *
     * @return bool Success or failure
     */

<     public static function setTimeZone($timezone)



>     public static function setTimeZone(string $timezoneName): bool


    {

<         if (self::validateTimezone($timezone)) {
<             self::$timezone = $timezone;



>         if (self::validateTimeZone($timezoneName)) {
>             self::$timezone = $timezoneName;



            return true;
        }

        return false;
    }

    /**
     * Return the Default Timezone used for date/time conversions.
     *
     * @return string Timezone (e.g. 'Europe/London')
     */

<     public static function getTimeZone()



>     public static function getTimeZone(): string


    {
        return self::$timezone;
    }

    /**
     *    Return the Timezone offset used for date/time conversions to/from UST
     * This requires both the timezone and the calculated date/time to allow for local DST.
     *

<      * @param string $timezone The timezone for finding the adjustment to UST
<      * @param int $timestamp PHP date/time value
<      *
<      * @throws PhpSpreadsheetException



>      * @param ?string $timezoneName The timezone for finding the adjustment to UST
>      * @param float|int $timestamp PHP date/time value


     *
     * @return int Number of seconds for timezone adjustment
     */

<     public static function getTimeZoneAdjustment($timezone, $timestamp)



>     public static function getTimeZoneAdjustment(?string $timezoneName, $timestamp): int


    {

<         if ($timezone !== null) {
<             if (!self::validateTimezone($timezone)) {
<                 throw new PhpSpreadsheetException('Invalid timezone ' . $timezone);
<             }
<         } else {
<             $timezone = self::$timezone;



>         $timezoneName = $timezoneName ?? self::$timezone;
>         $dtobj = Date::dateTimeFromTimestamp("$timestamp");
>         if (!self::validateTimeZone($timezoneName)) {
>             throw new PhpSpreadsheetException("Invalid timezone $timezoneName");


        }

>         $dtobj->setTimeZone(new DateTimeZone($timezoneName));




<         if ($timezone == 'UST') {
<             return 0;
<         }
< 
<         $objTimezone = new DateTimeZone($timezone);
<         $transitions = $objTimezone->getTransitions($timestamp, $timestamp);
< 
<         return (count($transitions) > 0) ? $transitions[0]['offset'] : 0;



>         return $dtobj->getOffset();


    }
}