<?php

namespace Drupal\Core\Test\HttpClientMiddleware;

use Drupal\Core\Utility\Error;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;

/**
 * Overrides the User-Agent HTTP header for outbound HTTP requests.
 */
class TestHttpClientMiddleware {

  /**
   * {@inheritdoc}
   *
   * HTTP middleware that replaces the user agent for simpletest requests.
   */
  public function __invoke() {
    // If the database prefix is being used by SimpleTest to run the tests in a copied
    // database then set the user-agent header to the database prefix so that any
    // calls to other Drupal pages will run the SimpleTest prefixed database. The
    // user-agent is used to ensure that multiple testing sessions running at the
    // same time won't interfere with each other as they would if the database
    // prefix were stored statically in a file or database variable.
    return function ($handler) {
      return function (RequestInterface $request, array $options) use ($handler) {
        if ($test_prefix = drupal_valid_test_ua()) {
          $request = $request->withHeader('User-Agent', drupal_generate_test_ua($test_prefix));
        }
        return $handler($request, $options)
          ->then(function (ResponseInterface $response) use ($request) {
            if (!drupal_valid_test_ua()) {
              return $response;
            }
            $headers = $response->getHeaders();
            foreach ($headers as $header_name => $header_values) {
              if (preg_match('/^X-Drupal-Assertion-[0-9]+$/', $header_name, $matches)) {
                foreach ($header_values as $header_value) {
                  // Call \Drupal\simpletest\WebTestBase::error() with the parameters from
                  // the header.
                  $parameters = unserialize(urldecode($header_value));
                  if (count($parameters) === 3) {
                    throw new \Exception($parameters[1] . ': ' . $parameters[0] . "\n" . Error::formatBacktrace([$parameters[2]]));
                  }
                  else {
                    throw new \Exception('Error thrown with the wrong amount of parameters.');
                  }
                }
              }
            }
            return $response;
          });
      };
    };
  }

}