CodeIgniter authenticate_user Accounts System

function authenticate_user( $username, $password )
{
    $CI = &get_instance();
    $accounts_table = $CI->config->item('accounts_table');

    $salt = $CI->db->select('salt')->from($accounts_table)->where('username', $username)->limit(1)->get()->result->row(0)->salt;

    if ( !$salt OR empty($salt) )
    {
        return false;
    }

    $password = apply_salt($password, $salt);

    $where = array(
            'username' => $username,
            'password' => $password
        );

    $results = $CI->db->get_where( $accounts_table, $where, 1 );

    if ( $results )
    {
        $user = $results->row(0);

        if ( $user->lockout_time != 0 )
        {
            $lockout_expire = $CI->config->item('login_lockout_expire');

            if ( time() - strtotime($user->lockout_time) >= $lockout_expire )
            {
                return array( 'user_id' => $user->user_id, 'activated' => $user->activated, 'locked' => !unlock_account($user->user_id) );
            }
            else
            {
                return array( 'user_id' => $user->user_id, 'locked', 'locked' => true );
            }
        }

        if ( $user->activated != 1 )
        {
            return array( 'user_id' => $user->user_id, 'activated' => $user->activated );
        }

        return $user->user_id;
    }

    return false;
}