PHP - Populate select options with 15 min time intervals - php

Question

Hi I am creating a website for a restaurant delivery service. Basically when the customer is checking out, he/she can choose when they want the food to be delivered. I want the select box to contain time intervals of 15 mins ranging from the current time until the close time. The restaurant is open for deliveries between 11:00 to 23:00. The first option I want is to be "As soon as possible", and then the next option is an hour later (rounded to nearest 15mins), and then 15 mins each time. So basically something like this:
(Suppose current time is 13:55)
As soon as possible
15:00
15:15
15:30
15:45
...and so on until close time (23:00)
If the restaurant is closed (after 23:00) then I just want the select box to have an option that says "CLOSED".
Here is what I have tried so far but it is not working:
<select>
<?php
$timenow = date("H:i");
if($timenow >"23:00" || $timenow < "11:00"){
echo '<option value="Closed">CLOSED</option>';
echo "</select>";
}
else{
$deliverytime = date("H:i", strtotime('+15 minutes', $timenow));
echo '<option value="asap">As soon as possible</option>';
while($deliverytime < "23:00" && $deliverytime > "11:00"){
echo '<option value="'. $deliverytime.'">' . $deliverytime . '</option>';
$deliverytime = date("H:i", strtotime('+15 minutes', $deliverytime));
}
echo "</select>";
}
?>

Answer 1

strtotime('+15 minutes', $timenow) is not correct. The second argument should be a timestamp, not a string. You want something like strtotime('+15 minutes', time()) or just leave off the second argument (current time is the default).
A better approach is to always work with the timestamps until you output. That makes rounding and comparisons much easier.
<select>
<?php
$timenow = time();
$opentime = strtotime('11:00');
$closetime = strtotime('23:00');
if($timenow > $closetime || $timenow <= $opentime){
echo '<option value="Closed">CLOSED</option>';
echo "</select>";
}
else{
// you said you wanted the time to start in 1 hour, but had +15 minutes...
$deliverytime = strtotime('+1 hour', $timenow);
// round to next 15 minutes (15 * 60 seconds)
$deliverytime = ceil($deliverytime / (15*60)) * (15*60);
echo '<option value="asap">As soon as possible</option>';
while($deliverytime <= $closetime && $deliverytime >= $opentime) {
echo '<option value="'. date('H:i', $deliverytime) .'">' . date('H:i', $deliverytime) . '</option>'."\n";
$deliverytime = strtotime('+15 minutes', $deliverytime);
}
echo "</select>";
}

Answer 2

I can't provide a complete solution but can point you in the right direction.
This code will handle the 15 minute interval parts for you:
$start = new DateTime();
$end = new DateTime('11PM');
$interval = new DateInterval('PT15M');
$period = new DatePeriod($start, $interval, $end);
foreach ($period as $dt)
{
echo $dt->format("l Y-m-d") . PHP_EOL;
}
The accepted answer in this Stack Overflow question shows how to get to the nearest 15 minute interval: PHP DateTime round up to nearest 10 minutes
Combine the two and you should have a complete solution to your problem.