Custom URL Parameters Add Field Settings>Permalinks Page

/**
 * Custom URL Parameters Add Field Settings>Permalinks Page
 * 
 */
if(!function_exists('http_build_url')) {
    /**
     * HTTP Build URL
     * Combines arrays in the form of parse_url() into a new string based on specific options
     * @name http_build_url
     * @param string|array $url     The existing URL as a string or result from parse_url
     * @param string|array $parts   Same as $url
     * @param int $flags            URLs are combined based on these
     * @param array &$new_url       If set, filled with array version of new url
     * @return string
     */
    function http_build_url( $url, $parts = array(), $flags = HTTP_URL_REPLACE, &$new_url = false)
    {
        // If the $url is a string
        if(is_string($url))
        {
            $url = parse_url($url);
        }

        // If the $parts is a string
        if(is_string($parts))
        {
            $parts  = parse_url($parts);
        }

        // Scheme and Host are always replaced
        if(isset($parts['scheme'])) $url['scheme']  = $parts['scheme'];
        if(isset($parts['host']))   $url['host']    = $parts['host'];

        // (If applicable) Replace the original URL with it's new parts
        if(HTTP_URL_REPLACE & $flags)
        {
            // Go through each possible key
            foreach(array('user','pass','port','path','query','fragment') as $key)
            {
                // If it's set in $parts, replace it in $url
                if(isset($parts[$key])) $url[$key]  = $parts[$key];
            }
        }
        else
        {
            // Join the original URL path with the new path
            if(isset($parts['path']) && (HTTP_URL_JOIN_PATH & $flags))
            {
                if(isset($url['path']) && $url['path'] != '')
                {
                    // If the URL doesn't start with a slash, we need to merge
                    if($url['path'][0] != '/')
                    {
                        // If the path ends with a slash, store as is
                        if('/' == $parts['path'][strlen($parts['path'])-1])
                        {
                            $sBasePath  = $parts['path'];
                        }
                        // Else trim off the file
                        else
                        {
                            // Get just the base directory
                            $sBasePath  = dirname($parts['path']);
                        }

                        // If it's empty
                        if('' == $sBasePath)    $sBasePath  = '/';

                        // Add the two together
                        $url['path']    = $sBasePath . $url['path'];

                        // Free memory
                        unset($sBasePath);
                    }

                    if(false !== strpos($url['path'], './'))
                    {
                        // Remove any '../' and their directories
                        while(preg_match('/\w+\/\.\.\//', $url['path'])){
                            $url['path']    = preg_replace('/\w+\/\.\.\//', '', $url['path']);
                        }

                        // Remove any './'
                        $url['path']    = str_replace('./', '', $url['path']);
                    }
                }
                else
                {
                    $url['path']    = $parts['path'];
                }
            }

            // Join the original query string with the new query string
            if(isset($parts['query']) && (HTTP_URL_JOIN_QUERY & $flags))
            {
                if (isset($url['query']))   $url['query']   .= '&' . $parts['query'];
                else                        $url['query']   = $parts['query'];
            }
        }

        // Strips all the applicable sections of the URL
        if(HTTP_URL_STRIP_USER & $flags)        unset($url['user']);
        if(HTTP_URL_STRIP_PASS & $flags)        unset($url['pass']);
        if(HTTP_URL_STRIP_PORT & $flags)        unset($url['port']);
        if(HTTP_URL_STRIP_PATH & $flags)        unset($url['path']);
        if(HTTP_URL_STRIP_QUERY & $flags)       unset($url['query']);
        if(HTTP_URL_STRIP_FRAGMENT & $flags)    unset($url['fragment']);

        // Store the new associative array in $new_url
        $new_url    = $url;

        // Combine the new elements into a string and return it
        return
             ((isset($url['scheme'])) ? $url['scheme'] . '://' : '')
            .((isset($url['user'])) ? $url['user'] . ((isset($url['pass'])) ? ':' . $url['pass'] : '') .'@' : '')
            .((isset($url['host'])) ? $url['host'] : '')
            .((isset($url['port'])) ? ':' . $url['port'] : '')
            .((isset($url['path'])) ? $url['path'] : '')
            .((isset($url['query'])) ? '?' . $url['query'] : '')
            .((isset($url['fragment'])) ? '#' . $url['fragment'] : '')
        ;
    }
} 

function custom_url_parameters() {
    if( isset( $_POST['custom_url_parameters'] ) ) {
        update_option( 'custom_url_parameters', esc_attr( $_POST['custom_url_parameters'] ) );
    }
    
    // Add a settings field to the permalink page
    add_settings_field( 'custom_url_parameters', __( 'URL Parameters' ), 'custom_url_parameters_field_callback', 'permalink', 'optional' );
}
add_action( 'load-options-permalink.php', 'custom_url_parameters' );

function custom_url_parameters_field_callback() {
    $value = get_option( 'custom_url_parameters' );  

    echo '<input type="text" value="' . esc_attr( $value ) . '" name="custom_url_parameters" id="custom_url_parameters" class="regular-text" placeholder="Enter your custom url parameters" />';
}

function custom_url_parameters_redirect() {
    $url_parameters = get_option( 'custom_url_parameters' );

    if ( isset( $url_parameters ) && !empty( $url_parameters ) ) {

        $parameters_array = array_column(array_map(function($v){
            return explode("=", $v);
        }, explode("&", html_entity_decode( $url_parameters ))), 1, 0);

        //Prevent infinite loop
        if ($_GET[array_keys($parameters_array)[0]] == array_values($parameters_array)[0]) return;

        $url_parts = parse_url($_SERVER['REQUEST_SCHEME']."://".$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI']);
        parse_str(html_entity_decode( $url_parameters ), $params);

        // $params["redirected"] = "1";
        foreach (array_keys($_GET) as $n) {
            $params[$n] = $_GET[$n];
        }

        // Note that this will url_encode all values
        $url_parts['query'] = http_build_query($params);
        wp_redirect(http_build_url($url_parts));
        exit;
    }
}
add_action('template_redirect', 'custom_url_parameters_redirect');

function custom_url_parameters_load_head() { 
    $url_parameters = get_option( 'custom_url_parameters' );

    if ( isset( $url_parameters ) && !empty( $url_parameters ) ): 
        $parameters_array = array_column(array_map(function($v){
            return explode("=", $v);
        }, explode("&", html_entity_decode( $url_parameters ))), 1, 0);
        ?>
        <script type="text/javascript">
            (function ($) {
                var currentUrl = window.location.href;
                var url = new URL(currentUrl);
                var urlParameters = url.searchParams.getAll("<?php echo array_keys($parameters_array)[0]; ?>");
                $(document).ready(function () {
                    if (urlParameters != null) {
                        $('a:not([href*="tel"]):not([href*="mailto"])').each(function (index, element) {
                            var url = $(element).prop('href');

                            if (url.indexOf('?') == -1) {
                                url += '?' + '<?php echo html_entity_decode( $url_parameters ); ?>';
                            }
                            $(element).prop('href', url);
                        });
                    }
                });
            })(jQuery);
        </script>
        <?php 
    endif;
}
add_action('wp_head', 'custom_url_parameters_load_head');