create custome hook

// referrece link : http://codeigniter.com/user_guide/general/hooks.html
class customHook extends CI_Hooks{
public $CI;
function __construct()
{
parent::__construct();
$this->CI = get_instance();
}
/*
+++++++++++++++++++++++++++++++++++++++++++++
This function will detect admin url and
check for session, if session null then
check for cookie, if cookie exist then
take username from it work ahead.
+++++++++++++++++++++++++++++++++++++++++++++
*/
function adminAutoLogin()
{
//check for admin url access or not
if($this->CI->router->directory == 'admin/')
{
//checking for admin session.
if(!$this->CI->session->userdata('admin_id') && $this->CI->input->cookie('bsgp_admin') != ''):
$this->CI->encrypt->set_cipher(MCRYPT_GOST); // set encryption type
$admin = $this->CI->encrypt->decode($this->CI->input->cookie('bsgp_admin')); // decode cookie value
if(is_string($admin)):
$admin_info = $this->CI->db->select('admin_id,username as admin_user', FALSE)->where('username',$admin)->get('bsgp_admins')->row_array();
$this->CI->session->set_userdata($admin_info);
endif;
elseif(!$this->CI->session->userdata('admin_id')):
$this->_setReferrer();
if($this->CI->router->class == 'login' && $this->CI->router->method != 'index')
redirect('admin/login');
else if($this->CI->router->class != 'login')
redirect('admin/login');
endif;
}
}
/*
+++++++++++++++++++++++++++++++++++++++++++
setting referrring url. user will redirect
this url after successfull login
+++++++++++++++++++++++++++++++++++++++++++
*/
private function _setReferrer()
{
if(isset($_SERVER['REDIRECT_QUERY_STRING']))
{
if(($this->CI->uri->rsegment('1') == 'login' && $this->CI->uri->rsegment('2') != 'index') || $this->CI->uri->rsegment('1') != 'login')
setFlashMessage('referrer',$_SERVER['REDIRECT_QUERY_STRING']);

}
}
}