is_opening_hour.php

<?php

define('DEFAULT_TIMEZONE', 'America/Fortaleza');
define('WORKING_DAY_MONDAY', 1);
define('WORKING_DAY_TUESDAY', 2);
define('WORKING_DAY_WEDNESDAY', 3);
define('WORKING_DAY_THURSDAY', 4);
define('WORKING_DAY_FRIDAY', 5);
define('WORKING_DAY_SATURDAY', 6);
define('WORKING_DAY_SUNDAY', 7);


$opening_hours_config = [
    'monday_friday' => [
        'begin' => '8:00',
        'end' => '16:00',
    ],
    'saturday' => [
        'begin' => '8:00',
        'end' => '12:00',
    ],
];

/**
 * @return bool
 * @throws Exception
 */
function is_opening_hour()
{
    global $opening_hours_config; # bad!

    $timezone = new DateTimeZone(DEFAULT_TIMEZONE);
    $now = new DateTimeImmutable('now', $timezone);
    $weekday = $now->format('N');
    $opening_hours = null;

    if (in_array($weekday, [
        WORKING_DAY_MONDAY,
        WORKING_DAY_TUESDAY,
        WORKING_DAY_WEDNESDAY,
        WORKING_DAY_THURSDAY,
        WORKING_DAY_FRIDAY,
    ])) {
        $opening_hours = $opening_hours_config['monday_friday'];
    }

    if (WORKING_DAY_SATURDAY == $weekday) {
        $opening_hours = $opening_hours_config['saturday'];
    }

    # sunday
    if (is_null($opening_hours)) {
        return false;
    }

    # is opening? :)

    $begin = new DateTimeImmutable($opening_hours['begin'], $timezone);
    $end = new DateTimeImmutable($opening_hours['end'], $timezone);

    if ($now >= $begin && $now <= $end) {
        return true;
    }

    return false;
}

var_dump(is_opening_hour());