realfan/public/signup/index.php

<?php require_once '/src/base.php' ?>
<?php

$signup_method = null;
if (isset($_SERVER['REDIRECT_URL'])) {

	# process URI
	$path = trim($_SERVER['REDIRECT_URL'], '/');
	$args = explode('/', $path);

	# no args is very unlikely, but still
	if (count($args) === 0) {
		die('Unexpected error');
	}

	# get the signup method from URL
	$signup_method = $args[1];
	if (!in_array($signup_method, ['mastodon'])) {
		die('The given arguments are not correct');
	}
}

?>
<?php require '/src/views/head.php' ?>
<?php require '/src/views/public/head.php' ?>
<main>
SIGNUP: <?php echo $signup_method ?>
</main>
<?php require '/src/views/public/foot.php' ?>
<?php require '/src/views/foot.php' ?>