* CAuth
	Upon a successful authentication, `hd_login` handler will call
	`CSession::create(user_id)` to start a session.

* CSession
	`create` handler will save a new token by user_id.
	`getTimeout` will called by `CSessionCheck`, which in turn gets called by `hd_preprocessor`
	`getTimeout` get `sess_start` from DB using session token.
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SELECT `sess_start` FROM `tbl_user` WHERE (`sess_token` = 'mekliilatuvyhvtkszucrnguwdgklmpnnpuufjvakpzeymuowkbohzoekunjfoebujjyacfqgjsxbeezgtqanywkzngphcxjwotp')
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	Then updates `sess_start`
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UPDATE `tbl_user` SET `sess_start` = '2023-04-29 23:54:23' WHERE (`sess_token` = 'mekliilatuvyhvtkszucrnguwdgklmpnnpuufjvakpzeymuowkbohzoekunjfoebujjyacfqgjsxbeezgtqanywkzngphcxjwotp')
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	`getTimeout` will call CUserInfo::setup(token)

* CUserInfo
	`CUserInfo::setup` will load data from tbl_user.
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SELECT * FROM `tbl_user` WHERE (`sess_token` = 'mekliilatuvyhvtkszucrnguwdgklmpnnpuufjvakpzeymuowkbohzoekunjfoebujjyacfqgjsxbeezgtqanywkzngphcxjwotp')
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	Then store it in self::$info and save it in `CPhpSess` also.

* CUG
	CUG::isAdmin uses CUserInfo::get("b_admin")
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	public static function isAdmin(){
		return(intval(CUserInfo::get("b_admin"))===1);
	}
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* CPhpSess
	`CUserInfo::setup` will call `CPhpSess::setRect` to store userinfo.
	`CPhpSess::setRect` gets called every time a command is clicked on the side menu of the admin panel.

* CAdmin
	`CAdmin::isAdmin()` use CPhpSess::get` to obtain the value of `b_admin` 

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CUG::isAdmin() vs CAdmin::isAdmin()
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CUG::isAdmin() is used in the admin panel
CAdmin::isAdmin() is used outside of the admin panel
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