<?php

class SessionManager{

    /*
    SETTINGS FOR OUR SESSION
    SESSION_NAME - Name of our session
    ACTIVE_DAYS  - Number of days you want the session to be active
    */
    public const SETTINGS=[
        "SESSION_NAME"=>"SHOPPING",
        "ACTIVE_DAYS"=>2
    ];


    public function __construct(){
        session_start();
        // setting name to our session
        session_name(self::SETTINGS["SESSION_NAME"]);
    }

    public function loginUser($userName){
        /*
        change paramter $userName as per your requirement
        $sessionData contains the information we are saving into the session.
        lastLogin - date and time when the user logged into his account
        */
        $sessionData=[
            "userName"=>$userName,
            "lastLogin"=>date('Y-m-d H:i:s')
        ];
        $_SESSION['account']=$sessionData;
        session_write_close();
    }

    public function logoutUser(){
        unset($_SESSION['account']);
    }

    public function isSessionValid(){
        /*
        Returns true
        if there is a session
        and
        the difference between the day user accessed the page and user logged into the page
        is less than ACTIVE_DAYS specified in SETTINGS
        */
        $currentLogin=new DateTime(date('Y-m-d H:i:s'));
        $lastLogin=new DateTime($_SESSION['account']['lastLogin']);
        $daysDifference=$currentLogin->diff($lastLogin)->format('%a');
        return ((isset($_SESSION['account']) && ($daysDifference) < self::SETTINGS["ACTIVE_DAYS"])) ? true : false ;
    }
}



/*

-------------     Usage    ------------------------
Assuming you have included above code in these files
for eg : include('sessionmanager.php');
*/

/* ------------ Login.php ------------------------- */

$s=new SessionManager();
$s->loginUser("John Doe");
echo "Login successfull";

/* ------------- Home.php ---------------------------*/

$s=new SessionManager();
if($s->isSessionValid()){
    echo "Hello {$_SESSION['account']['userName']}";
}
else{
    $s->logoutUser();
    echo "You need to login again";
}

/* -------------- Logout.php ------------------------ */

$s=new SessionManager();
$s->logoutUser();
echo "Logged out";


?>