FutureDates

<?php
date_default_timezone_set("UTC");
$numbersString=$_GET['numbersString'];
$dateString=$_GET['dateString'];

//sum nums
$regexNumbers='/([^a-zA-Z])(\d+)([^a-zA-Z])/';
preg_match_all($regexNumbers, $numbersString, $numbersArr);
$sum=0;
for($i=0; $i<count($numbersArr[2]); $i++){
    $number=intval($numbersArr[2][$i]);
    $sum+=$number;
}
//REVERSE
$reverseSum=0;
while($sum>0){
    $reverseSum = $reverseSum * 10;
    $reverseSum = $reverseSum + $sum%10;
    $sum = (int)($sum/10);
}
$sum =  $reverseSum;

//!Take dates
$regexDates= '/([0-9]{4})-([0-9]){2}-([0-9]){2}/';
preg_match_all($regexDates, $dateString, $datesArr);
$dates=[];

for($i=0; $i<count($datesArr[0]); $i++){
    $date = $datesArr[0][$i];
    $dateNew= date('Y-m-d', strtotime("+$sum day", strtotime($date)));
    $dates[] = $dateNew;
    //var_dump($dates);
}
if(!count($dates)){
    echo "<p>No dates</p>";
}else{
    echo "<ul>";
    foreach($dates as $date){
        echo "<li>".$date."</li>";
    }
    echo "</ul>";
}