Help me write this shortcode

Hi all,

I want to write a shortcode to achieve the following:

For each user create a shortcode [email_”firstname”] where “firstname” is the user’s first name as defined in the backend.

This shortcode would display the following html:

<a href="mailto:"user's email address">"user's email address"</a>

Where “user’s email address” is the user’s email address as defined in the backend.

I am part the way there where I get the user info by user id, but I want this to be ‘dynamic’, this is to say I want this shortcode to work for each user without it being predefined in functions.php.

This is what I have so far, hope it makes sense.

My shortcode: [email_test]

<? php

add_shortcode('email_test', 'short_email_test');

function short_email_test {
$user_info = get_userdata(1);
$user_email = $user_info->user_email;
   echo "<a href=mailto:$user_email>$user_email</a>";
}
?>