trait BrowserHtmlDebugTrait

trait BrowserHtmlDebugTrait {
    
    /**
     * Class name for HTML output logging.
     *
     * @var string
     */
    protected $htmlOutputClassName;
    
    /**
     * Directory name for HTML output logging.
     *
     * @var string
     */
    protected $htmlOutputDirectory;
    
    /**
     * Counter storage for HTML output logging.
     *
     * @var string
     */
    protected $htmlOutputCounterStorage;
    
    /**
     * Counter for HTML output logging.
     *
     * @var int
     */
    protected $htmlOutputCounter = 1;
    
    /**
     * HTML output enabled.
     *
     * @var bool
     */
    protected $htmlOutputEnabled = FALSE;
    
    /**
     * The file name to write the list of URLs to.
     *
     * This file is read by the PHPUnit result printer.
     *
     * @var string
     *
     * @see \Drupal\Tests\Listeners\HtmlOutputPrinter
     */
    protected $htmlOutputFile;
    
    /**
     * HTML output test ID.
     *
     * @var int
     */
    protected $htmlOutputTestId;
    
    /**
     * The Base URI to use for links to the output files.
     *
     * @var string
     */
    protected $htmlOutputBaseUrl;
    
    /**
     * Formats HTTP headers as string for HTML output logging.
     *
     * @param array[] $headers
     *   Headers that should be formatted.
     *
     * @return string
     *   The formatted HTML string.
     */
    protected function formatHtmlOutputHeaders(array $headers) {
        $flattened_headers = array_map(function ($header) {
            if (is_array($header)) {
                return implode(';', array_map('trim', $header));
            }
            else {
                return $header;
            }
        }, $headers);
        return '<hr />Headers: <pre>' . Html::escape(var_export($flattened_headers, TRUE)) . '</pre>';
    }
    
    /**
     * Returns headers in HTML output format.
     *
     * @return string
     *   HTML output headers.
     */
    protected function getHtmlOutputHeaders() {
        return $this->formatHtmlOutputHeaders($this->getSession()
            ->getResponseHeaders());
    }
    
    /**
     * Logs a HTML output message in a text file.
     *
     * The link to the HTML output message will be printed by the results printer.
     *
     * @param string|null $message
     *   (optional) The HTML output message to be stored. If not supplied the
     *   current page content is used.
     *
     * @see \Drupal\Tests\Listeners\VerbosePrinter::printResult()
     */
    protected function htmlOutput($message = NULL) {
        if (!$this->htmlOutputEnabled) {
            return;
        }
        $message = $message ?: $this->getSession()
            ->getPage()
            ->getContent();
        $message = '<hr />ID #' . $this->htmlOutputCounter . ' (<a href="' . $this->htmlOutputClassName . '-' . ($this->htmlOutputCounter - 1) . '-' . $this->htmlOutputTestId . '.html">Previous</a> | <a href="' . $this->htmlOutputClassName . '-' . ($this->htmlOutputCounter + 1) . '-' . $this->htmlOutputTestId . '.html">Next</a>)<hr />' . $message;
        $html_output_filename = $this->htmlOutputClassName . '-' . $this->htmlOutputCounter . '-' . $this->htmlOutputTestId . '.html';
        file_put_contents($this->htmlOutputDirectory . '/' . $html_output_filename, $message);
        file_put_contents($this->htmlOutputCounterStorage, $this->htmlOutputCounter++);
        // Do not use the file_url_generator service as the module_handler service
        // might not be available.
        $uri = $this->htmlOutputBaseUrl . '/sites/simpletest/browser_output/' . $html_output_filename;
        file_put_contents($this->htmlOutputFile, $uri . "\n", FILE_APPEND);
    }
    
    /**
     * Creates the directory to store browser output.
     *
     * Creates the directory to store browser output in if a file to write
     * URLs to has been created by \Drupal\Tests\Listeners\HtmlOutputPrinter.
     */
    protected function initBrowserOutputFile() {
        $browser_output_file = getenv('BROWSERTEST_OUTPUT_FILE');
        $this->htmlOutputEnabled = is_string($browser_output_file) && is_file($browser_output_file);
        $this->htmlOutputBaseUrl = getenv('BROWSERTEST_OUTPUT_BASE_URL') ?: $GLOBALS['base_url'];
        if ($this->htmlOutputEnabled) {
            $this->htmlOutputFile = $browser_output_file;
            $this->htmlOutputClassName = str_replace("\\", "_", static::class);
            $this->htmlOutputDirectory = DRUPAL_ROOT . '/sites/simpletest/browser_output';
            // Do not use the file_system service so this method can be called before
            // it is available. Checks !is_dir() twice around mkdir() because a
            // concurrent test might have made the directory and caused mkdir() to
            // fail. In this case we can still use the directory even though we failed
            // to make it.
            if (!is_dir($this->htmlOutputDirectory) && !@mkdir($this->htmlOutputDirectory, 0775, TRUE) && !is_dir($this->htmlOutputDirectory)) {
                throw new \RuntimeException(sprintf('Unable to create directory: %s', $this->htmlOutputDirectory));
            }
            if (!file_exists($this->htmlOutputDirectory . '/.htaccess')) {
                file_put_contents($this->htmlOutputDirectory . '/.htaccess', "<IfModule mod_expires.c>\nExpiresActive Off\n</IfModule>\n");
            }
            $this->htmlOutputCounterStorage = $this->htmlOutputDirectory . '/' . $this->htmlOutputClassName . '.counter';
            $this->htmlOutputTestId = str_replace('sites/simpletest/', '', $this->siteDirectory);
            if (is_file($this->htmlOutputCounterStorage)) {
                $this->htmlOutputCounter = max(1, (int) file_get_contents($this->htmlOutputCounterStorage)) + 1;
            }
        }
    }
    
    /**
     * Provides a Guzzle middleware handler to log every response received.
     *
     * @return callable
     *   The callable handler that will do the logging.
     */
    protected function getResponseLogHandler() {
        return function (callable $handler) {
            return function (RequestInterface $request, array $options) use ($handler) {
                return $handler($request, $options)->then(function (ResponseInterface $response) use ($request) {
                    if ($this->htmlOutputEnabled) {
                        $caller = $this->getTestMethodCaller();
                        $html_output = 'Called from ' . $caller['function'] . ' line ' . $caller['line'];
                        $html_output .= '<hr />' . $request->getMethod() . ' request to: ' . $request->getUri();
                        
                        /** @var \Psr\Http\Message\StreamInterface $stream */
                        $stream = $response->getBody();
                        // Get the response body as a string. The response stream is set
                        // to the sink, which defaults to a readable temp stream but can
                        // be overridden by setting $options['sink'].
                        $body = $stream->isReadable() ? (string) $stream : 'Response is not readable.';
                        // On redirect responses (status code starting with '3') we need
                        // to remove the meta tag that would do a browser refresh. We
                        // don't want to redirect developers away when they look at the
                        // debug output file in their browser.
                        $status_code = (string) $response->getStatusCode();
                        if ($status_code[0] === '3') {
                            $body = preg_replace('#<meta http-equiv="refresh" content=.+/>#', '', $body, 1);
                        }
                        $html_output .= '<hr />' . $body;
                        $html_output .= $this->formatHtmlOutputHeaders($response->getHeaders());
                        $this->htmlOutput($html_output);
                    }
                    return $response;
                });
            };
        };
    }
    
    /**
     * Retrieves the current calling line in the class under test.
     *
     * @return array
     *   An associative array with keys 'file', 'line' and 'function'.
     */
    protected function getTestMethodCaller() {
        $backtrace = debug_backtrace();
        // Find the test class that has the test method.
        while ($caller = Error::getLastCaller($backtrace)) {
            if (isset($caller['class']) && $caller['class'] === static::class) {
                break;
            }
            // If the test method is implemented by a test class's parent then the
            // class name of $this will not be part of the backtrace.
            // In that case we process the backtrace until the caller is not a
            // subclass of $this and return the previous caller.
            if (isset($last_caller) && (!isset($caller['class']) || !is_subclass_of($this, $caller['class']))) {
                // Return the last caller since that has to be the test class.
                $caller = $last_caller;
                break;
            }
            // Otherwise we have not reached our test class yet: save the last caller
            // and remove an element from to backtrace to process the next call.
            $last_caller = $caller;
            array_shift($backtrace);
        }
        return $caller;
    }

}