Cofem/lib/inliner.php

<?php
function inlineLocalStylesFromHref($inputString) {
    // Define the regular expression pattern to match <link> tags with href attribute for CSS files
    $pattern = '/<link.*?(?:(?:rel=["\']stylesheet["\'].*?href=["\']\/(.*?)["\'])|(?: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
        $href = isset($match[1]) ? $match[1] : $match[2];

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

        // Replace url() declarations in the CSS content with inline data
        $cssContent = preg_replace_callback('/url\(["\']?(\/.*?)["\']?\)/i', function($urlMatch) {
            // Extract the URL value
            $url = $urlMatch[1];

            // Get the content of the external file specified in the url()
            $fileContent = file_get_contents($_SERVER['DOCUMENT_ROOT'] . $url);

            // Base64 encode the content for inline use
            $base64Content = base64_encode($fileContent);

            // Create the inline data URI
            $dataUri = 'url("data:image/' . pathinfo($url, PATHINFO_EXTENSION) . ';base64,' . $base64Content . '")';

            return $dataUri;
        }, $cssContent);

        // Create an inline style tag with the modified 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;
}