adlerka.space/lib/inliner.php

<?php
function inlineLocalStylesFromHref($inputString) {
    // Define the regular expression pattern to match <link> tags with href attribute for CSS files
    $pattern = '/<link.*?href=["\']\/(.*?)["\'].*?rel=["\']stylesheet["\'].*?>/i';

    // Use preg_replace_callback to replace matched link tags with inline styles
    $outputString = preg_replace_callback($pattern, function($match) {
        // Extract the href attribute value
        $href = $match[1];

        // Get the content of the local CSS file
        $cssContent = file_get_contents($_SERVER['DOCUMENT_ROOT'] . '/' . $href);

        // Create an inline style tag with the CSS content
        return "<style>\n{$cssContent}\n</style>";
    }, $inputString);

    return $outputString;
}

function inlineScriptFromSrc($inputString) {
    // Define the regular expression pattern to match <script> tags with src attribute
    $pattern = '/<script.*?src=["\']\/(.*?)["\'].*?>\s*<\/script>/i';

    // Use preg_replace_callback to replace matched script tags with inline script
    $outputString = preg_replace_callback($pattern, function($match) {
        // Extract the src attribute value
        $src = $match[1];

        // Get the content of the JavaScript file
        $jsContent = file_get_contents($_SERVER['DOCUMENT_ROOT'] . '/' . $src);

        // Escape the JavaScript content for inline use
        $escapedJsContent = htmlspecialchars($jsContent, ENT_QUOTES, 'UTF-8');

        // Create an inline script with the escaped content
        return "<script>\n{$escapedJsContent}\n</script>";
    }, $inputString);

    return $outputString;
}