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<?php
/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/
declare(strict_types=1);
namespace Magento\Theme\Controller\Result;
use Magento\Framework\App\Config\ScopeConfigInterface;
use Magento\Store\Model\ScopeInterface;
use Magento\Framework\App\Response\Http;
use Magento\Framework\App\Response\HttpInterface as HttpResponseInterface;
use Magento\Framework\App\ResponseInterface;
use Magento\Framework\View\Result\Layout;
/**
* Plugin for asynchronous CSS loading.
*/
class AsyncCssPlugin
{
private const XML_PATH_USE_CSS_CRITICAL_PATH = 'dev/css/use_css_critical_path';
/**
* @var ScopeConfigInterface
*/
private $scopeConfig;
/**
* @param ScopeConfigInterface $scopeConfig
*/
public function __construct(ScopeConfigInterface $scopeConfig)
{
$this->scopeConfig = $scopeConfig;
}
/**
* Extracts styles to head after critical css if critical path feature is enabled.
*
* @param Layout $subject
* @param Layout $result
* @param HttpResponseInterface|ResponseInterface $httpResponse
* @return Layout (That should be void, actually)
* @SuppressWarnings(PHPMD.UnusedFormalParameter)
*/
public function afterRenderResult(Layout $subject, Layout $result, ResponseInterface $httpResponse)
{
if (!$this->isCssCriticalEnabled()) {
return $result;
}
$content = (string)$httpResponse->getContent();
$headCloseTag = '</head>';
$headEndTagFound = strpos($content, $headCloseTag) !== false;
if ($headEndTagFound) {
$styles = $this->extractLinkTags($content);
if ($styles) {
$newHeadEndTagPosition = strrpos($content, $headCloseTag);
$content = substr_replace($content, $styles . "\n", $newHeadEndTagPosition, 0);
$httpResponse->setContent($content);
}
}
return $result;
}
/**
* Extracts link tags found in given content.
*
* @param string $content
*/
private function extractLinkTags(string &$content): string
{
$styles = '';
$styleOpen = '<link';
$styleClose = '>';
$styleOpenPos = strpos($content, $styleOpen);
while ($styleOpenPos !== false) {
$styleClosePos = strpos($content, $styleClose, $styleOpenPos);
$style = substr($content, $styleOpenPos, $styleClosePos - $styleOpenPos + strlen($styleClose));
if (!preg_match('@rel=["\']stylesheet["\']@', $style)) {
// Link is not a stylesheet, search for another one after it.
$styleOpenPos = strpos($content, $styleOpen, $styleClosePos);
continue;
}
// Remove the link from HTML to add it before </head> tag later.
$content = str_replace($style, '', $content);
if (!preg_match('@href=("|\')(.*?)\1@', $style, $hrefAttribute)) {
throw new \RuntimeException("Invalid link {$style} syntax provided");
}
$href = $hrefAttribute[2];
if (preg_match('@media=("|\')(.*?)\1@', $style, $mediaAttribute)) {
$media = $mediaAttribute[2];
}
$media = $media ?? 'all';
$style = sprintf(
'<link rel="stylesheet" media="print" onload="this.onload=null;this.media=\'%s\'" href="%s">',
$media,
$href
);
$styles .= "\n" . $style;
// Link was cut out, search for the next one at its former position.
$styleOpenPos = strpos($content, $styleOpen, $styleOpenPos);
}
return $styles;
}
/**
* Returns information whether css critical path is enabled
*
* @return bool
*/
private function isCssCriticalEnabled(): bool
{
return $this->scopeConfig->isSetFlag(
self::XML_PATH_USE_CSS_CRITICAL_PATH,
ScopeInterface::SCOPE_STORE
);
}
}