PHP начала текущей, прошлой, следующей недели

<?php
if (isset($argv[1])) {
    $next_date = $argv[1];
} elseif (isset($_GET["next_date"]) || isset($_POST["next_date"])) {
    $next_date = isset($_GET["next_date"]) ? $_GET["next_date"] : $_POST["next_date"];
}
 
$LastWeek = new DateTime("Monday last week ".$next_date);
$ThisWeek = new DateTime("Monday this week ".$next_date);
$NextWeek = new DateTime("Monday next week ".$next_date);
 
echo "Last>>>>".$LastWeek->format("Y-m-d 05:00:00"). PHP_EOL;
echo "This>>>>".$ThisWeek->format("Y-m-d 05:00:00"). PHP_EOL;
echo "Next>>>>".$NextWeek->format("Y-m-d 05:00:00"). PHP_EOL;
?>