function convert_images_to_webp($image) {
    if (is_array($image)) {
        $image_path = $image['file'];
    } else {
        $image_path = $image;
    }

    $image_extension = pathinfo($image_path, PATHINFO_EXTENSION);
    $webp_path = preg_replace('/\.(jpe?g|png|gif)$/i', '.webp', $image_path);

    if (file_exists($webp_path)) {
        return $webp_path;
    }

    if (imagewebp(imagecreatefromstring(file_get_contents($image_path)), $webp_path, 80)) {
        return $webp_path;
    }

    return $image;
}

function display_webp_images($content) {
    $pattern = '/<img(.*?)src=[\'"](.*?).(bmp|gif|ico|jpe?g|png)[\'"](.*?)>/i';
    $replacement = '<img$1src="$2.$3" data-src-webp="$2.webp"$4>';
    $content = preg_replace($pattern, $replacement, $content);

    return $content;
}

function generate_webp_images() {
    if (!function_exists('imagewebp')) {
        return;
    }

    add_filter('wp_generate_attachment_metadata', function ($metadata, $attachment_id) {
        $attachment = get_post($attachment_id);
        $mime_type = get_post_mime_type($attachment_id);

        if (strpos($mime_type, 'image') !== false) {
            $file = get_attached_file($attachment_id);
            $webp_file = convert_images_to_webp($file);

            if (is_array($metadata) && isset($metadata['sizes'])) {
                foreach ($metadata['sizes'] as $size => $size_info) {
                    $file = path_join(dirname($webp_file), $size_info['file']);
                    $metadata['sizes'][$size]['file'] = $file;
                    convert_images_to_webp($file);
                }
            }
        }

        return $metadata;
    }, 10, 2);

    add_filter('the_content', 'display_webp_images', 99);
    add_filter('post_thumbnail_html', 'display_webp_images', 99);
    add_filter('widget_text_content', 'display_webp_images', 99);
    add_filter('wp_get_attachment_image_attributes', function ($attr) {
        if (isset($attr['data-src-webp'])) {
            $attr['src'] = $attr['data-src-webp'];
            unset($attr['data-src-webp']);
        }

        return $attr;
    });
}

generate_webp_images();