OrderProcessor_how_to_approve.php

<?php

class OrderProcessor
{
    public function processOrder($orderId, $items, $customerEmail)
    {
        // Check if product exists
        foreach ($items as $item) {
            $sql = "SELECT quantity FROM products WHERE id = " . $item['id'];
            $result = mysqli_query($GLOBALS['db_connection'], $sql);
            $row = mysqli_fetch_assoc($result);
            if ($row['quantity'] < $item['quantity']) {
                die("Not enough stock for product " . $item['id']);
            }
        }

        // Create a new order
        $totalPrice = 0;
        foreach ($items as $item) {
            $totalPrice += $item['price'] * $item['quantity'];
        }
        $sql = "INSERT INTO orders (customer_email, total_price, status) VALUES ('$customerEmail', $totalPrice, 'pending')";
        mysqli_query($GLOBALS['db_connection'], $sql);
        $orderId = mysqli_insert_id($GLOBALS['db_connection']);

        // Update product amount
        foreach ($items as $item) {
            $sql = "UPDATE products SET quantity = quantity - " . $item['quantity'] . " WHERE id = " . $item['id'];
            mysqli_query($GLOBALS['db_connection'], $sql);
        }

        // Send email
        mail($customerEmail, "Order Confirmation", "Your order #$orderId has been placed. Total: $totalPrice");

        return "Order processed successfully";
    }
}

// Run

$processor = new OrderProcessor();
$result = $processor->processOrder(1, array(
    array('id' => 1, 'quantity' => 2, 'price' => 10),
    array('id' => 2, 'quantity' => 1, 'price' => 20)
), "customer@example.com");
echo $result;