<?php
// download.php?file=PlanningReport-24_Clifton_Drive_Sorell_TAS_7172.docx
$fn = basename($_GET['file'] ?? '');
if (!preg_match('/^PlanningReport-[\w\-]+\.docx$/', $fn)) {
    http_response_code(400); exit;
}
$path = sys_get_temp_dir() . '/' . $fn;
if (!is_file($path) || (time() - filemtime($path)) > 3600) {
    http_response_code(404); exit;  // expire after 1 hour
}

header('Content-Type: application/vnd.openxmlformats-officedocument.wordprocessingml.document');
header('Content-Disposition: attachment; filename="'.$fn.'"');
header('Content-Length: '.filesize($path));
readfile($path);