Metaweather.com API proxy to implement cache and CORS headers

metaweather.php

<?php

define ('API_URI_BASE', 'https://www.metaweather.com/api/');
define ('CACHE_DIR', 'metaweather-cache');
define ('CACHE_TIME', 3600);

// Create Cache Directory
$cache_name = sha1($_SERVER['REQUEST_URI']);

if (!is_dir(CACHE_DIR)) {
  if (file_exists(CACHE_DIR)) {
    die ('Cache dir is a file');
  }
  mkdir(CACHE_DIR);
}

if (file_exists(CACHE_DIR.'/'.$cache_name) && filemtime(CACHE_DIR.'/'.$cache_name) >= (time() - CACHE_TIME)) {
  // If cached, return the cached file
  $json = file_get_contents(CACHE_DIR.'/'.$cache_name);
} else {

  // Else make api request and cache
  $method = (isset($_GET['method']) ? $_GET['method'] : null);
  $apiCall = API_URI_BASE.$method.'/';
  
  switch ($method) {
    case null:
      $json = null;
      break;
    case 'location/search':
      $query = (isset($_GET['query']) ? urlencode($_GET['query']) : null);
      $lattlong = (isset($_GET['lattlong']) ? urlencode($_GET['lattlong']) : null);
      if (!empty($query)) {
        $json = file_get_contents($apiCall.'?query='.$query);
      } elseif (!empty($lattlong)) {
        $json = file_get_contents($apiCall.'?lattlong='.$lattlong);
      } else {
        $json = json_encode([]);
      }
      break;
    default:
      $json = file_get_contents($apiCall);
      break;
  }
  
  // Write json to cach
  file_put_contents(CACHE_DIR.'/'.$cache_name, $json);
}

// Output with CORS Header
header('Content-Type: application/json');
header("Access-Control-Allow-Origin: *");
echo $json;
exit;
?>