class DevelMailLog

class DevelMailLog extends DefaultMailSystem {
    
    /**
     * Converts a message array to a string.
     *
     * @param $message
     *   The message array containing the body and headers.
     *
     * @return
     *   The message as it will be printed in the file.
     */
    public function composeMessage($message) {
        $mimeheaders = array();
        $message['headers']['To'] = $message['to'];
        foreach ($message['headers'] as $name => $value) {
            $mimeheaders[] = $name . ': ' . mime_header_encode($value);
        }
        $line_endings = variable_get('mail_line_endings', MAIL_LINE_ENDINGS);
        $output = join($line_endings, $mimeheaders) . $line_endings;
        // 'Subject:' is a mail header and should not be translated.
        $output .= 'Subject: ' . $message['subject'] . $line_endings;
        // Blank line to separate headers from body.
        $output .= $line_endings;
        $output .= preg_replace('@\\r?\\n@', $line_endings, $message['body']);
        return $output;
    }
    
    /**
     * Gets a filename for a message using tokens.
     *
     * @param $message
     *   The message that will supply values for token replacement.
     *
     * @return
     *   The full path and filename after token replacement.
     */
    public function getFileName($message) {
        $output_directory = $this->getOutputDirectory();
        $this->makeOutputDirectory($output_directory);
        $output_file_format = variable_get('devel_debug_mail_file_format', '%to-%subject-%datetime.mail.txt');
        $tokens = array(
            '%to' => $message['to'],
            '%subject' => $message['subject'],
            '%datetime' => date('y-m-d_his'),
        );
        return $output_directory . '/' . $this->dirify(str_replace(array_keys($tokens), array_values($tokens), $output_file_format));
    }
    
    /**
     * Convert a string to a valid directory name.
     *
     * @return
     *   The sanitized string, replacing any characters not whitelisted with "_".
     */
    private function dirify($string) {
        return preg_replace('/[^a-zA-Z0-9_\\-\\.@]/', '_', $string);
    }
    
    /**
     * Save a mail message to a file using Drupal variables and default settings.
     *
     * @param $message
     *   A message array, as described in hook_mail_alter().
     * @return
     *   TRUE if the mail was successfully accepted, otherwise FALSE.
     *
     * @see http://php.net/manual/en/function.mail.php
     * @see drupal_mail()
     */
    public function mail(array $message) {
        $output = $this->composeMessage($message);
        $output_file = $this->getFileName($message);
        return file_put_contents($output_file, $output);
    }
    
    /**
     * Creates the directory to contain the message file if necessary.
     *
     * @throws Exception
     *   Exception thrown when unable to create the destination directory.
     */
    protected function makeOutputDirectory($output_directory) {
        if (!file_prepare_directory($output_directory, FILE_CREATE_DIRECTORY)) {
            throw new Exception("Unable to continue sending mail, {$output_directory} is not writable");
        }
    }
    
    /**
     * Retrieves the directory that contains message files.
     *
     * @return
     *   The path to mail messages, possibly using a file URI scheme.
     */
    public function getOutputDirectory() {
        return variable_get('devel_debug_mail_directory', 'temporary://devel-mails');
    }

}