<?php


if (! $_SERVER['REQUEST_METHOD'] === 'POST') {
    exit("not permitted bad request");
}


//initialising the user session if not already started
if (session_status() !== PHP_SESSION_ACTIVE) {
    session_start();
}

if (!isset($_SESSION["cart"])) {
    $_SESSION["cart"] = [];
}

function additemtocart($item){
    //checking if the item is already in the cart, adding it if not, setting the counter up if yes
    if (array_key_exists($item,$_SESSION["cart"])) {
        $_SESSION["cart"][$item]++;
    }else{
        $_SESSION["cart"][$item] = 1;
    }
    echo(json_encode(true));
}

function subtractitemsfromcart($item){
    //checking if the item is already in the cart, subtracting one if not, calling the removefromcart function if count is 0
    if (array_key_exists($item,$_SESSION["cart"])) {
        $_SESSION["cart"][$item]--;
        if ($_SESSION["cart"][$item] <= 0) {
            removefromcart($item);
        }else{
            echo(json_encode(true));
        }
        
    }else{
        echo(json_encode(false));
    }
}

//completely removing an ite mfrom the cart
function removefromcart($item){
    if (array_key_exists($item,$_SESSION["cart"])) {
        unset($_SESSION["cart"][$item]);
        echo(json_encode(true));
    }else{
        echo(json_encode(false));
    }
}

//getting the request data
$requestData = json_decode(file_get_contents('php://input'), true);

if (isset($requestData["add"])) {
    additemtocart($requestData["add"]);
}

if (isset($requestData["subtract"])) {
    subtractitemsfromcart($requestData["subtract"]);
}

if (isset($requestData["remove"])) {
    removefromcart($requestData["remove"]);
}

if (isset($requestData["print"])) {
    $cart = $_SESSION["cart"];
    echo(json_encode($cart));
}

?>