ad');\"" : "") . ">";

                if($line['as'] == 'image') {
                    array_unshift(self::$preloads_ready, $preload);
                }
                else {
                    self::$preloads_ready[] = $preload;
                }
            }
        }

        if(!empty(self::$preloads_ready)) {
            $preloads_string = "";
            foreach(apply_filters('perfmatters_preloads_ready', self::$preloads_ready) as $preload) {
                $preloads_string.= $preload;
            }
            $pos = strpos($html, '</title>');
            if($pos !== false) {
                $html = substr_replace($html, '</title>' . $preloads_string, $pos, 8);
            }
        }
        
        return $html;
    }

    //add critical image preloads
    public static function add_critical_image_preloads(&$html, $clean_html) {

        //exclude images from preloading by parent selector
        $parent_exclusions = apply_filters('perfmatters_critical_image_parent_exclusions', array());
        if(!empty($parent_exclusions)) {

            //match all selectors
            preg_match_all('#<(div|section|figure)(\s[^>]*?(' . implode('|', $parent_exclusions) . ').*?)>.*?<\/\g1>#is', $clean_html, $selectors, PREG_SET_ORDER);

            if(!empty($selectors)) {

                foreach($selectors as $selector) {

                    //match all img tags
                    preg_match_all('#<img([^>]+?)\/?>#is', $selector[0], $images, PREG_SET_ORDER);

                    if(!empty($images)) {

                        //loop through images
                        foreach($images as $image) {

                            //remove image from current working clean html
                            $clean_html = str_replace($image[0], '', $clean_html);
                        }
                    }
                }
            }
        }

        //match all image formats
        preg_match_all('#(<picture.*?)?<img([^>]+?)\/?>(?><\/picture>)?#is', $clean_html, $matches, PREG_SET_ORDER);

        if(!empty($matches)) {

            $exclusions = apply_filters('perfmatters_critical_image_exclusions', array(
                ';base64',
                'w3.org',
                'data-perfmatters-skip-preload'
            ));

            $count = 0;
            
            foreach($matches as $match) {

                if($count >= self::$critical_images) {
                    break;
                }

                if(strpos($match[0], 'secure.gravatar.com') !== false) {
                    continue;
                }

                if(!empty($exclusions) && is_array($exclusions)) {
                    foreach($exclusions as $exclusion) {
                        if(strpos($match[0], $exclusion) !== false) {
                            continue 2;
                        }
                    }
                }

                //picture tag
                if(!empty($match[1])) {
                    preg_match('#<source([^>]+?image\/(webp|avif)[^>]+?)\/?>#is', $match[0], $source);

                    if(!empty($source)) {
                        if(self::generate_critical_image_preload($source[1])) {
                            $new_picture = str_replace('<picture', '<picture data-perfmatters-preload', $match[0]);
                            $new_picture = str_replace('<img', '<img data-perfmatters-preload', $new_picture);
                            $html = str_replace($match[0], $new_picture, $html);
                            $count++;
                        }
                        continue;
                    }
                }

                //img tag
                if(!empty($match[2])) {
                    if(self::generate_critical_image_preload($match[2])) {
                        $new_image = str_replace('<img', '<img data-perfmatters-preload', $match[0]);
                        $html = str_replace($match[0], $new_image, $html);
                        $count++;
                    }
                }
            }
        }

        if(!empty(self::$preloads_ready)) {
            ksort(self::$preloads_ready);
        }
    }

    //generate preload link from att string
    private static function generate_critical_image_preload($att_string) {
        if(!empty($att_string)) {
            $atts = Utilities::get_atts_array($att_string);
            $src = $atts['data-src'] ?? $atts['src'] ?? '';

            //dont add if src was already used
            if(in_array($src, self::$used_srcs)) {
                return false;
            }

            //generate preload
            self::$preloads_ready[] = '<link rel="preload" href="' . $src . '" as="image"' . (!empty($atts['srcset']) ? ' imagesrcset="' . $atts['srcset'] . '"' : '') . (!empty($atts['sizes']) ? ' imagesizes="' . $atts['sizes'] . '"' : '') . ' />';

            //mark src used and return
            if(!empty($src)) {
                self::$used_srcs[] = $src;
            }
            return true;
        }
    }

    private static function location_check($locations) {

        $location_match = false;

        $exploded_locations = explode(',', $locations);
        $trimmed_locations = array_map('trim', $exploded_locations);

        //single post exclusion
        if(is_singular()) {
            global $post;
            if(in_array($post->ID, $trimmed_locations)) {
                $location_match = true;
            }
        }
        //posts page exclusion
        elseif(is_home() && in_array('blog', $trimmed_locations)) {
            $location_match = true;
        }
        elseif(is_archive()) {
            //woocommerce shop check
            if(function_exists('is_shop') && is_shop()) {
                if(in_array(wc_get_page_id('shop'), $trimmed_locations)) {
                    $location_match = true;
                }
            }
        }

        return $location_match;
    }

    public static function disable_core_fetch($loading_attrs) {
        unset($loading_attrs['fetchpriority']);
        return $loading_attrs;
    }
}