Psr7Middlewares\Utils\Helpers::getMimeType PHP Method

    public static function getMimeType(ResponseInterface $response)
    {
        $mime = strtolower($response->getHeaderLine('Content-Type'));
        $mime = explode(';', $mime, 2);
        return trim($mime[0]);
    }

 /**
  * Execute the middleware.
  *
  * @param ServerRequestInterface $request
  * @param ResponseInterface      $response
  * @param callable               $next
  *
  * @return ResponseInterface
  */
 public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
 {
     if (!self::hasAttribute($request, ClientIp::KEY)) {
         throw new RuntimeException('Csrf middleware needs ClientIp executed before');
     }
     if (Utils\Helpers::getMimeType($response) !== 'text/html') {
         return $next($request, $response);
     }
     $tokens =& self::getStorage($request, self::KEY);
     if (Utils\Helpers::isPost($request) && !$this->validateRequest($request, $tokens)) {
         return $response->withStatus(403);
     }
     $generator = function ($action = null) use($request, &$tokens) {
         if (empty($action)) {
             $action = $request->getUri()->getPath();
         }
         return $this->generateTokens($request, $action, $tokens);
     };
     if (!$this->autoInsert) {
         $request = self::setAttribute($request, self::KEY_GENERATOR, $generator);
         return $next($request, $response);
     }
     $response = $next($request, $response);
     return $this->insertIntoPostForms($response, function ($match) use($generator) {
         preg_match('/action=["\']?([^"\'\\s]+)["\']?/i', $match[0], $matches);
         return $match[0] . $generator(isset($matches[1]) ? $matches[1] : null);
     });
 }