cart_functions.php

if (isset($_GET['action'])) {
  $action = $_GET['action'];
  $prod   = $_GET['prod_id'];
  $prodname = $_SESSION['product'][$prod];





  switch ($action) {
    case 'add':
        $result = add_prod($prod, $prodname);
    break;
    case 'plus':
        $result = plus_prod($prod, $prodname);

    break;
    case 'remove':
        $result = remove_prod($prod, $prodname);
    break;
    case 'delete':
        $result = delete_prod($prod, $prodname);
    break;
    default:
        $result = ['result'=>'error'];
    break;
  }

}

$total=0;
$all_products=0;
foreach ($_SESSION['product'] as $prod => $value){
$total_in_cart=count($_SESSION['product']);

}

$_SESSION['products']=$total_in_cart;

// Calculate subtotal here
$result['totals'] = new stdClass;
$value = $_SESSION['product'][$prod];
$subtotal=$value * $_SESSION['icms'][$prod];

$result['subtotal'] =  number_format($value * $_SESSION['icms'][$prod], 2, '.', ''); /* subtotal result here */
$result['cost'] = $_SESSION['icms'][$prod] ;/* Product cost here */
$subtotal= number_format($value *$_SESSION['icms'][$prod], 2, '.', ''); //this session is created in calculates.php
$result['valor_total'] =  $_SESSION['total']= $total +=  $subtotal;
$all_products +=$value;
$_SESSION['total_products']= $all_products;

$result['items'] =  $total_in_cart;


//$result['all_items'] = $_SESSION['total_products'];

//$result['items'] = 999;
//$result->items =$_SESSION['products'];

echo json_encode($result);



function add_prod($prod, $prodname){
  //add function
$_SESSION['product'][$prod] = 1;
$_SESSION['products']++;
return ['result'=>'success' ];
}
//add +1 function
function plus_prod($prod, $prodname){
  $_SESSION['product'][$prod]++;
  return ['result'=>'success', 'val'=> $_SESSION['product'][$prod]];

}
//minus -1 function
function remove_prod($prod, $prodname){
  //sua função para remove
$_SESSION['product'][$prod]--;
$_SESSION['product'][$prod]-1;
  return ['result'=>'success', 'val'=> $_SESSION['product'][$prod]];
}
//delete function
function delete_prod($prod, $prodname){
  //sua função para delete
unset($_SESSION['product'][$prod]);
unset($_SESSION['icms'][$prod]);
$_SESSION['total_products']--;
$_SESSION['products']--;
  return ['result'=>'success'];
}