Auto-link Site Name – Home Page

/**

 * Auto-link Site Name - Global Version

 * Pulls company name from Settings > General > Site Title

 * Pulls link title from Settings > General > Tagline

 */

function site_name_auto_links($content) {

    // Fire on all singular post types (posts, pages, and all custom post types)

    if (!is_singular()) {

        return $content;

    }

    if (empty($content) || strlen($content) < 50) {

        return $content;

    }

    // Get site name and tagline from WordPress settings

    $site_name = get_bloginfo('name');

    $site_tagline = get_bloginfo('description');

    $site_url = home_url('/');

    // Skip if no site name is set

    if (empty($site_name)) {

        return $content;

    }

    $links = array(

        $site_name => array(

            'url'   => $site_url,

            'title' => !empty($site_tagline) ? $site_tagline : $site_name

        ),

    );

    $dom = new DOMDocument();

    libxml_use_internal_errors(true);

    $dom->loadHTML('<?xml encoding="UTF-8"><div id="site-name-wrap">' . $content . '</div>', LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);

    libxml_clear_errors();

    foreach ($dom->childNodes as $item) {

        if ($item->nodeType == XML_PI_NODE) {

            $dom->removeChild($item);

        }

    }

    $dom->encoding = 'UTF-8';

    $xpath = new DOMXPath($dom);

    $text_nodes = $xpath->query('

        //text()[

            (ancestor::p or ancestor::li or ancestor::td)

            and not(ancestor::a)

            and not(ancestor::h1)

            and not(ancestor::h2)

            and not(ancestor::h3)

            and not(ancestor::h4)

            and not(ancestor::h5)

            and not(ancestor::h6)

            and not(ancestor::button)

            and not(ancestor::script)

            and not(ancestor::style)

            and not(ancestor::figcaption)

            and not(ancestor::figure)

            and not(ancestor::img)

            and not(ancestor::input)

            and not(ancestor::textarea)

            and not(ancestor::header)

            and not(ancestor::footer)

            and not(ancestor::nav)

            and not(ancestor::blockquote)

        ]

    ');

    foreach ($text_nodes as $text_node) {

        $text = $text_node->nodeValue;

        $replaced = false;

        foreach ($links as $keyword => $data) {

            if (stripos($text, $keyword) !== false) {

                $pattern = '/\b(' . preg_quote($keyword, '/') . ')\b/i';

                $replacement = '<a href="' . esc_url($data['url']) . '" title="' . esc_attr($data['title']) . '">$1</a>';

                $text = preg_replace($pattern, $replacement, $text, -1);

                $replaced = true;

            }

        }

        if ($replaced) {

            $fragment = $dom->createDocumentFragment();

            @$fragment->appendXML($text);

            if ($fragment->hasChildNodes()) {

                $text_node->parentNode->replaceChild($fragment, $text_node);

            }

        }

    }

    $wrapper = $dom->getElementById('site-name-wrap');

    if ($wrapper) {

        $result = '';

        foreach ($wrapper->childNodes as $child) {

            $result .= $dom->saveHTML($child);

        }

        return $result;

    }

    return $content;

}

add_filter('the_content', 'site_name_auto_links', 999);