EmailService.php

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<?php

namespace Elgg;

use Elgg\Assets\CssCompiler;
use Elgg\Assets\ImageFetcherService;
use Elgg\Email\Attachment;
use Elgg\Email\HtmlPart;
use Elgg\Email\PlainTextPart;
use Elgg\Exceptions\RuntimeException;
use Elgg\Traits\Loggable;
use Elgg\Views\HtmlFormatter;
use Laminas\Mail\Header\ContentType;
use Laminas\Mail\Message as MailMessage;
use Laminas\Mail\Transport\TransportInterface;
use Laminas\Mime\Message as MimeMessage;
use Laminas\Mime\Exception\InvalidArgumentException;
use Laminas\Mime\Part;
use Laminas\Mime\Mime;

class EmailService {

    use Loggable;

    public function __construct(
        protected Config $config,
        protected EventsService $events,
        protected TransportInterface $mailer,
        protected HtmlFormatter $html_formatter,
        protected ViewsService $views,
        protected ImageFetcherService $image_fetcher,
        protected CssCompiler $css_compiler
    ) {
    }

    public function send(Email $email): bool {
        $email = $this->events->triggerResults('prepare', 'system:email', [], $email);
        if (!$email instanceof Email) {
            $msg = "'prepare','system:email' event handlers should return an instance of " . Email::class;
            throw new RuntimeException($msg);
        }

        $is_valid = $email->getFrom() && !empty($email->getTo());
        if (!$this->events->triggerResults('validate', 'system:email', ['email' => $email], $is_valid)) {
            return false;
        }

        return $this->transport($email);
    }

    public function transport(Email $email): bool {
        if ($this->events->triggerResults('transport', 'system:email', ['email' => $email], false)) {
            return true;
        }

        // create the e-mail message
        $message = new MailMessage();
        $message->setEncoding('UTF-8');
        $message->setSender($email->getFrom());
        $message->addFrom($email->getFrom());
        $message->addTo($email->getTo());
        $message->addCc($email->getCc());
        $message->addBcc($email->getBcc());
        
        // set headers
        $headers = [
            'MIME-Version' => '1.0',
            'Content-Transfer-Encoding' => '8bit',
        ];
        $headers = array_merge($headers, $email->getHeaders());

        foreach ($headers as $name => $value) {
            // See #11018
            // Create a headerline as a concatenated string "name: value"
            // This is done to force correct class detection for each header type,
            // which influences the output of the header in the message
            $message->getHeaders()->addHeaderLine("{$name}: {$value}");
        }
        
        // add the body to the message
        try {
            $message = $this->setMessageBody($message, $email);
        } catch (InvalidArgumentException $e) {
            $this->getLogger()->error($e->getMessage());
            
            return false;
        }
        
        $message->setSubject($this->prepareSubject($email->getSubject()));
        
        // allow others to modify the $message content
        // eg. add html body, add attachments
        $message = $this->events->triggerResults('zend:message', 'system:email', ['email' => $email], $message);

        // fix content type header
        // @see https://github.com/Elgg/Elgg/issues/12555
        $ct = $message->getHeaders()->get('Content-Type');
        if ($ct instanceof ContentType) {
            $ct->addParameter('format', 'flowed');
        }
        
        try {
            $this->mailer->send($message);
        } catch (RuntimeException $e) {
            $this->getLogger()->error($e->getMessage());

            return false;
        }

        return true;
    }
    
    protected function prepareSubject(string $subject): string {
        $subject = elgg_strip_tags($subject);
        $subject = html_entity_decode($subject, ENT_QUOTES, 'UTF-8');
        // Sanitise subject by stripping line endings
        $subject = preg_replace("/(\r\n|\r|\n)/", ' ', $subject);
        return trim($subject);
    }
    
    protected function setMessageBody(MailMessage $message, Email $email): MailMessage {
        // create body
        $multipart = new MimeMessage();
        $raw_body = $email->getBody();
        $message_content_type = '';
        
        // add plain text part
        $plain_text_part = new PlainTextPart($raw_body);
        $multipart->addPart($plain_text_part);
        
        $make_html = (bool) elgg_get_config('email_html_part');
        
        if ($make_html) {
            $multipart->addPart($this->makeHtmlPart($email));
            $message_content_type = Mime::MULTIPART_ALTERNATIVE;
        }
        
        $body = $multipart;
        
        // process attachments
        $attachments = $email->getAttachments();
        if (!empty($attachments)) {
            if ($make_html) {
                $multipart_content = new Part($multipart->generateMessage());
                $multipart_content->setType(Mime::MULTIPART_ALTERNATIVE);
                $multipart_content->setBoundary($multipart->getMime()->boundary());
            
                $body = new MimeMessage();
                $body->addPart($multipart_content);
            }
            
            foreach ($attachments as $attachement) {
                $body->addPart($attachement);
            }
            
            $message_content_type = Mime::MULTIPART_MIXED;
        }
        
        $message->setBody($body);
        
        if (!empty($message_content_type)) {
            // set correct message content type
            
            $headers = $message->getHeaders();
            foreach ($headers as $header) {
                if (!$header instanceof ContentType) {
                    continue;
                }
                
                $header->setType($message_content_type);
                $header->addParameter('boundary', $body->getMime()->boundary());
                break;
            }
        }
        
        return $message;
    }
    
    protected function makeHtmlPart(\Elgg\Email $email): Part {
        $mail_params = $email->getParams();
        $html_text = elgg_extract('html_message', $mail_params);
        if ($html_text instanceof Part) {
            return $html_text;
        }
    
        if (is_string($html_text)) {
            // html text already provided
            if (elgg_extract('convert_css', $mail_params, true)) {
                // still needs to be converted to inline CSS
                $css = (string) elgg_extract('css', $mail_params);
                $html_text = $this->html_formatter->inlineCss($html_text, $css);
            }
        } else {
            $html_text = $this->makeHtmlBody([
                'subject' => $email->getSubject(),
                'body' => elgg_extract('html_body', $mail_params, $email->getBody()),
                'email' => $email,
            ]);
        }
        
        // normalize urls in text
        $html_text = $this->html_formatter->normalizeUrls($html_text);
        if (empty($html_text)) {
            return new HtmlPart($html_text);
        }
        
        $email_html_part_images = elgg_get_config('email_html_part_images');
        if ($email_html_part_images !== 'base64' && $email_html_part_images !== 'attach') {
            return new HtmlPart($html_text);
        }
        
        $images = $this->findImages($html_text);
        if (empty($images)) {
            return new HtmlPart($html_text);
        }
        
        if ($email_html_part_images === 'base64') {
            foreach ($images as $url) {
                // remove wrapping quotes from the url
                $image_url = substr($url, 1, -1);
                
                // get the image contents
                $image = $this->image_fetcher->getImage($image_url);
                if (empty($image)) {
                    continue;
                }
                
                // build a valid uri
                // https://en.wikipedia.org/wiki/Data_URI_scheme
                $base64image = $image['content-type'] . ';charset=UTF-8;base64,' . base64_encode($image['data']);
                
                // build inline image
                $replacement = str_replace($image_url, "data:{$base64image}", $url);
                
                // replace in text
                $html_text = str_replace($url, $replacement, $html_text);
            }
            
            return new HtmlPart($html_text);
        }
        
        // attach images
        $attachments = [];
        foreach ($images as $url) {
            // remove wrapping quotes from the url
            $image_url = substr($url, 1, -1);
            
            // get the image contents
            $image = $this->image_fetcher->getImage($image_url);
            if (empty($image)) {
                continue;
            }
            
            // Unique ID
            $uid = uniqid();
            
            $attachments[$uid] = $image;
            
            // replace url in the text with uid
            $replacement = str_replace($image_url, "cid:{$uid}", $url);
            
            $html_text = str_replace($url, $replacement, $html_text);
        }
        
        // split html body and related images
        $message = new MimeMessage();
        $message->addPart(new HtmlPart($html_text));
        
        foreach ($attachments as $uid => $image_data) {
            $attachment = Attachment::factory([
                'id' => $uid,
                'content' => $image_data['data'],
                'type' => $image_data['content-type'],
                'filename' => $image_data['name'],
                'encoding' => Mime::ENCODING_BASE64,
                'disposition' => Mime::DISPOSITION_INLINE,
                'charset' => 'UTF-8',
            ]);
            
            $message->addPart($attachment);
        }
        
        $part = new Part($message->generateMessage());
        $part->setType(Mime::MULTIPART_RELATED);
        $part->setBoundary($message->getMime()->boundary());
        
        return $part;
    }
    
    protected function makeHtmlBody(array $options = []): string {
        $defaults = [
            'subject' => '',
            'body' => '',
            'language' => elgg_get_current_language(),
        ];
        
        $options = array_merge($defaults, $options);
        
        $options['body'] = $this->html_formatter->formatBlock($options['body']);
    
        // generate HTML mail body
        $options['body'] = $this->views->renderView('email/elements/body', $options);

        $css_views = $this->views->renderView('elements/variables.css', $options);
        $css_views .= $this->views->renderView('email/email.css', $options);

        $css_compiled = $this->css_compiler->compile($css_views);
        $minifier = new \MatthiasMullie\Minify\CSS($css_compiled);
        $css = $minifier->minify();
        
        $options['css'] = $css;
        
        $html = $this->views->renderView('email/elements/html', $options);
        
        return $this->html_formatter->inlineCss($html, $css);
    }
    
    protected function findImages(string $text): array {
        if (empty($text)) {
            return [];
        }
        
        // find all matches
        $matches = [];
        $pattern = '/\ssrc=([\'"]\S+[\'"])/i';
        
        preg_match_all($pattern, $text, $matches);
        
        if (empty($matches) || !isset($matches[1])) {
            return [];
        }
        
        // return all the found image urls
        return array_unique($matches[1]);
    }
}