<?php
// $clock implements Clock
// interface Clock
// {
//     public function now() : DateTimeImmutable;
// }

// setup
$startDate = Date::fromString('2019-01-04');

// variant 1A) Tell, Don't Ask
$isNotPast = $startDate->isNotInThePast($clock);

// variant 1B)
$isNotPast = (new IsNotInThePastValidator($clock))
  ->isNotInThePast($startDate);


// ==== Add Offset Support, Check if given Date is today in another Timezone
// Example: It's 2019-01-04 08:00 in UTC
// User Submitted 2019-01-03 as Checkindate
// Check if 2019-01-03 is still today for an earlier timezone.

// setup
$startDate = Date::fromString('2019-01-04');
$offset = '-0800';

// variant 2A) Tell, Don't Ask
$isNotPast = $startDate->isNotInThePast($clock, $offset);

// via @matthiasnoback
$isNotPast = $startDate->isNotInThePast($clock->now(), $offset);

// variant 2B)
$isNotPast = (new IsNotInThePastValidator($clock, $offset))
  ->isNotInThePast($startDate);

// variant 2C)
$isNotPast = (new IsNotInThePastValidator($clock))
  ->isNotInThePast($startDate, $offset);