Snippet to filter AirBnB Not available events and fix the end date

ics-filter.php

<?php

$ch = curl_init("https://www.airbnb.de/calendar/ical/XYZ");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_FAILONERROR, true); 
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false); 
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

$data = curl_exec($ch);
curl_close($ch);

$state = 0;
$result = "";
$temp = "";
foreach(preg_split("/((\r?\n)|(\r\n?))/", $data) as $line){
  if (strcmp("BEGIN:VEVENT", $line) == 0) {
    $state = 1;
  }
  
  if (strcmp("SUMMARY:Not available", $line) == 0) {
    $state = 2;
  }
  
  if ($state == 0) {
    $result .= $line . "\n";
  } else {
    $DTENSTR = "DTEND;VALUE=DATE:";
    $datepos = strpos($line, $DTENSTR);
    
    if ($datepos !== false) {
      $temp = $temp . "\n" . $DTENSTR . date("Ymd", strtotime("+1 day", strtotime(substr($line, strlen($DTENSTR)))));
    } else {
      $temp = $temp . "\n" . $line;
    }
  }
  
  if (strcmp("END:VEVENT", $line) == 0) {
    if ($state == 1) {
      $result .= trim($temp) . "\n";
      $temp = "";
    }
    
    $state = 0;
  }
}

echo trim($result);

?>