A way to get a valid json for the order api call

<?php

class token {
        public $data_key;
        public $issuer_id;
}

class recur {
        public $bill_now;
        public $recur_amount;
        public $start_date;
        public $recur_unit;
        public $recur_period;
        public $number_of_recurs;
}

class item {
        public $url;
        public $description;
        public $product_code;
        public $unit_cost;
        public $quantity;
}

class tax {
        public $amount;
        public $description;
        public $rate;
}

class cart {
        function __construct() {
                $this->tax = new tax();
        }

        public $items = array(); // for item objects
        public $subtotal;
        public $tax;
}

class contactdetails {
        public $first_name;
        public $last_name;
        public $email;
        public $phone;
}

class address {
        public $address_1;
        public $address_2;
        public $city;
        public $province;
        public $country;
        public $postal_code;
}

class order {
        function __construct() {
                // just to simply init things for you
                $this->recur = new recur();
                $this->cart = new cart();
                $this->contact_details = new contactdetails();
                $this->shipping_details = new address();
                $this->billing_details = new address();
        }

        public $store_id;
        public $api_token;
        public $checkout_id;
        public $txn_total;
        public $environment;
        public $action;
        public $token = array(); // for token objects
        public $ask_cvv;
        public $order_no;
        public $cust_id;
        public $dynamic_descriptor;
        public $language;
        public $recur;
        public $cart;
        public $contact_details;
        public $shipping_details;
        public $billing_details;
}

$order = new order();

// To add new items do, we assume $itemid is posted together with $quantity
// $item = new item();
// $item->url = "https://domain.example.net/item/$itemid";
// $item->description = fetch_item_description_from_db($itemid);
// $item->product_code = $itemid;
// $item->unit_cost = fetch_item_unit_cost_from_db($itmeid);
// $item->quantity = $quantity;
// don't forget to calculate the tax and add it to the $order->cart->tax->amount
// update also $order->txn_total and also $order->cart->subtotal
// $order->cart->items[] = $item;

// we add two tokens
$token1 = new token();
$token1->data_key = "1234";
$token1->issuer_id = "645sddfvdrt4tefd";
$order->token[] = $token1;
$token2 = new token();
$token2->data_key = "5678";
$token2->issuer_id = "645sddfvdrt4tefd";
$order->token[] = $token2;

// we add two items, we do not update other values in this example
$item1 = new item();
$item1->product_code = "1";
$item1->url = "https://example.net/item?id=1";
$item1->description = "item 1";
$item1->unit_cost = "100";
$item1->quantity = "1";
$order->cart->items[] = $item1;
$item2 = new item();
$item2->product_code = "2";
$item2->url = "https://example.net/item?id=2";
$item2->description = "item 2";
$item2->unit_cost = "200";
$item2->quantity = "1";
$order->cart->items[] = $item2;

echo json_encode($order, JSON_PRETTY_PRINT);
echo "\n";

?>