使用php在html中定义BASE标记

I want to define the BASE tag in html using PHP

<!DOCTYPE html>
<html lang="<?php echo LANG; ?>">
<head>
    <meta charset="<?php echo CHARSET; ?>">
    <base href="<?php echo BASE; ?>">
</head>
....

Did some research here, and came up with this.

config.inc.php

define('LANG', 'es_ES');
define('CHARSET', 'utf-8');
define('SERVER_SERVER_NAME', 'http://' . $_SERVER['SERVER_NAME']);
define('SERVER_PHP_SELF', dirname($_SERVER['PHP_SELF']));

define('BASE', SERVER_SERVER_NAME . SERVER_PHP_SELF . '/');

2 questions:

  1. Is there a way to define the keyword http? Sometimes it can be https and hardcoding that keyword is a bad idea.

  2. Should i define the BASE value by ending it with a slash or not ?

Any improvements on this very simple code?

Thanks

  1. Just leave the protocol out, and start the URL with //. It will then default to the protocol of the document that contains it.

  2. The <base> URL should end with a / if you want it to specify a folder.