Return browser headers in JSON

json_http_headers.php

<?php

class JsonHttpHeaders {
  function headers() {
    $headers = '';
    foreach ($_SERVER as $name => $value) {
      if (substr($name, 0, 5) == 'HTTP_') {
        $header_name =
          str_replace(' ', '-',
            ucwords(strtolower(str_replace('_', ' ', substr($name, 5)))));
        $headers[$header_name] = $value;
      }
    }
    return $headers;
  }

  function get_json_headers() {
    return json_encode($this->headers());
  }

  function json_headers() {
    header('Content-Type: application/json');
    echo $this->get_json_headers();
  }

  function json_headers_callback($callback) {
    header('Content-Type: application/javascript');
    echo "{$callback}({$this->get_json_headers()});";
  }

  function run($callback = null) {
    if($callback) { $this->json_headers_callback($callback); }
    else { $this->json_headers(); }
  }
}

$json_http_headers = new JsonHttpHeaders();
$json_http_headers->run($_GET['callback']);