New user login redirect, Cookie-based solution

new-user-login-cookie-based-redirect.php

<?php
// Send new users to a special page
function redirectOnFirstLogin( $redirect_to, $requested_redirect_to, $user )
{
    // URL to redirect to
    $redirect_url = 'http://yoursite.com/firstloginpage';
    // How many times to redirect the user
    $num_redirects = 1;
    // Cookie-based solution: captures users who registered within the last n hours
    // The reason to set it as "last n hours" is so that if a user clears their cookies or logs in with a different browser,
    // they don't get this same redirect treatment long after they're already a registered user
    // 172800 seconds = 48 hours
    $message_period = 172800;

    // If they're on the login page, don't do anything
    if( !isset( $user->user_login ) )
    {
        return $redirect_to;
    }

    $key_name = 'redirect_on_first_login_' . $user->ID;

    if( strtotime( $user->user_registered ) > ( time() - $message_period )
        && ( !isset( $_COOKIE[$key_name] ) || intval( $_COOKIE[$key_name] ) < $num_redirects )
      )
    {
        if( isset( $_COOKIE[$key_name] ) )
        {
            $num_redirects = intval( $_COOKIE[$key_name] ) + 1;
        }
        setcookie( $key_name, $num_redirects, time() + $message_period, COOKIEPATH, COOKIE_DOMAIN );
        return $redirect_url;
    }
    else
    {
        return $redirect_to;
    }
}

add_filter( 'login_redirect', 'redirectOnFirstLogin', 10, 3 );
?>