Gazelle/sections/reports/ajax_claim_report.php

<?php
#declare(strict_types=1);

if (!check_perms('site_moderate_forums') || empty($_POST['id'])) {
  print
    json_encode(
      array(
        'status' => 'failure'
      )
    );
  die();
}

$ID = (int)$_POST['id'];
$DB->query("
  SELECT ClaimerID
  FROM reports
  WHERE ID = '$ID'");
list($ClaimerID) = $DB->next_record();
if ($ClaimerID) {
  print
    json_encode(
      array(
        'status' => 'dupe'
      )
    );
  die();
} else {
  $UserID = $LoggedUser['ID'];
  $DB->query("
    UPDATE reports
    SET ClaimerID = '$UserID'
    WHERE ID = '$ID'");
  print
    json_encode(
      array(
        'status' => 'success',
        'username' => $LoggedUser['Username']
      )
    );
  die();
}