Showing call-back times for the whole week: Mon - Fri: 9am - 6pm Sat: 9am -5:30pm Sun: 11am - 5pm ...and breathe!

available_times.php

<?php
$available_times = array(
    "09:00:00" => '<option value="%s 09:00:00">%s 9.00am - 10.00am</option>',
    "10:00:00" => '<option value="%s 10:00:00">%s 10.00am - 11.00am</option>',
    "11:00:00" => '<option value="%s 11:00:00">%s 11.00am - 12.00pm</option>',
    "12:00:00" => '<option value="%s 12:00:00">%s 12.00pm - 1.00pm</option>',
    "13:00:00" => '<option value="%s 13:00:00">%s 1.00pm - 2.00pm</option>',
    "14:00:00" => '<option value="%s 14:00:00">%s 2.00pm - 3.00pm</option>',
    "15:00:00" => '<option value="%s 15:00:00">%s 3.00pm - 4.00pm</option>',
    "16:00:00" => '<option value="%s 16:00:00">%s 4.00pm - 5.00pm</option>',
    "17:00:00" => '<option value="%s 17:00:00">%s 5.00pm - %s</option>',
);

$current_time = time();
$day_of_week  = date('N');
$end_time     = '6:00pm';

switch ($day_of_week) {
    case 6: //Saturday
        $end_time          = '5:30pm';
        $start_slice_index = 0;
        if ($current_time >= strtotime('09:00:00')) {
            $start_slice_index = ($current_time >= strtotime('10:00:00')) ? 2 : 1;
        }
        $end_slice_index   = ($current_time >= strtotime('17:00:00')) ? 6 : NULL;
        $available_times   = array_slice($available_times, $start_slice_index, $end_slice_index, TRUE);
        break;
    case 7: //Sunday
        $sunday_times   = &array_slice($available_times, 0, 2);
        $sunday_times[] = &$available_times['17:00:00'];
        foreach ($sunday_times as &$time) {
            $time = sprintf(
                $time,
                '%s',
                'Tomorrow',
                $end_time  
            );
        }
        unset($time);
        break;
    default:
    // do nothing
}

foreach ($available_times as $time => &$display) {
    if ($current_time > strtotime($time) || ($day_of_week == 7 && $time == "17:00:00") ) {
        $date = new DateTime(date('Y-m-d'));
        $date = $date->modify('+1 day')
                     ->format('Y-m-d');
        $day  = 'Tomorrow';
    } else {
        $date = date('Y-m-d');
        $day  = 'Today';
    }
    $display = sprintf(
        $display,
        $date,
        $day,
        $end_time
    );
}
unset($display);
asort($available_times);