How to redirect users to previous page using SESSION and/or COOKIES

Is there a solution recipe for the following:
User logins from main page -> user is redirected to user profile page
if user logins from shop.php page -> users is redirected to previous page

Below is a pieceof code that I found on this forum and works perfect for redirecting users based on their user level. Now I would like to make it redirect to previous page when users do not log in from main page.

<?php
if(!session_id()) session_start();
switch($_SESSION['userLevel']) {
case "1":
header("Location: admin_index.php");
break;
case "2":
header("Location: clients_index.php");
break;
}
?>


The problem that I have is
1) Can the above code have an else if statement to add the third scenario? If so, can you please tell what is wrong with the code below.

<?php
if(!session_id()) session_start();
switch($_SESSION['userLevel']) {
case "1":
header("Location: admin_index.php");
break;
case "2":
header("Location: clients_index.php");
break;
}
else if(!session_id()) session_start();
switch($_SESSION['userLevel']=9) {
case "3":
header("Location: admin_index.php");
}
?>

2) How do I add a SESSION to shop.php page so that Security Assist knows to redirect the user to the previous page and not the control page. I found and added the following code to the shop.php page but no luck. Does Security Assist has a function to add the SESSION to the page or I will have to hand code it allays?

<?php
if (!session_id()) session_start();
if(!isset($_SESSION["userLevel"])) {
$_SESSION["userLevel"] = "9";
}
?>

1) This code uses the switch case concept. You cannot add an else statement to the switch .. case.


think of it as a switchboard.


the switch statement sets a variable to be used for comparison. the case statement sets an action to be performed if the comparison variables matches the case value.

the code:

switch($_SESSION['userLevel']) { 

    case "1": 

        header("Location: admin_index.php"); 

        break; 

    case "2": 

        header("Location: clients_index.php"); 

        break; 

}

could also be written using if... else, but switch... case is more efficient:

<?php

if($_SESSION['userLevel'] == "1") {

    header("Location: admin_index.php"); 

} elseif($_SESSION['userLevel'] == "2") {

    header("Location: clients_index.php"); 

}

?>

to add a third scenario to the switch... case code, you just need to add another case statement:

switch($_SESSION['userLevel']) { 

    case "1": 

        header("Location: admin_index.php"); 

        break; 

    case "2": 

        header("Location: clients_index.php"); 

        break; 

    case "3": 

        header("Location: admin_index.php"); 

        break; 

}

2) Redirecting back to the previous page is not done using a session variable. when you access a proteced page, it redirects to the login page with a querystring varaible that contains the path to the protected page named "accesscheck":
users_login.php?accesscheck=%2Fsculptortocms%2Fadmin_cms%2Findex.php%3F

just make sure that the action of the login form on the login page is set to pass any existing querystreing variables by using this code for the action attribute:

 action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?><?php echo (isset($_SERVER["QUERY_STRING"]) && $_SERVER["QUERY_STRING"] != "")?"?".htmlspecialchars($_SERVER["QUERY_STRING"]):""; ?>"