<?php 
session_start();

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

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $sr_no = $_POST['sr_no'];
    $quantity = $_POST['quantity'];
    $name = $_POST['name'];
    $price = $_POST['price'];
    $image = $_POST['image'];

    $product = [
        'id' => $sr_no,
        "quantity" => $quantity,
        "name" => $name,
        "price" => $price,
        "image" => $image
    ];

    if (isset($_POST['add_product'])) {
        $ids = array_column($_SESSION['cart'], 'id');

        if (!in_array($product['id'], $ids)) {
            $_SESSION['cart'][] = $product;
            echo "<script>
                alert('Item Added!');
                history.back();
            </script>";
        } else {
            echo "<script>
                alert('Item Already Added!');
                history.back();
            </script>";
        }
    }
    
    if (isset($_POST['checkout_product'])) {
        $ids = array_column($_SESSION['cart'], 'id');

        if (!in_array($product['id'], $ids)) {
            $_SESSION['cart'][] = $product;
        }

        // Prepare the data to be passed
        $totalQuantity = 0;
        $productQuantities = [];
        $productNames = [];
        $total = 0;

        foreach ($_SESSION['cart'] as $value) {
            $subtotal = $value['price'] * $value['quantity'];
            $total += $subtotal;
            $totalQuantity += $value['quantity'];
            $productQuantities[] = $value['quantity'];
            $productNames[] = $value['name'];
        }

        $total = number_format($total, 2);

        $totalQuantityEncoded = urlencode($totalQuantity);
        $productQuantitiesEncoded = urlencode(implode(',', $productQuantities));
        $productNamesEncoded = urlencode(implode(', ', $productNames));
        $totalEncoded = urlencode($total);

        // Redirect to checkout.html with POST data in query parameters
        echo "<script>
            window.location.href = 'checkout.html?total_quantity=$totalQuantityEncoded&product_quantities=$productQuantitiesEncoded&product_names=$productNamesEncoded&total_price=$totalEncoded';
        </script>";
    }

    if (isset($_POST['remove_product'])) {
        foreach ($_SESSION['cart'] as $key => $re_product) {
            if ($re_product['name'] == $_POST['name']) {
                unset($_SESSION['cart'][$key]);
                $_SESSION['cart'] = array_values($_SESSION['cart']);
                echo "<script>
                    alert('Item Removed!');
                    window.location.href = 'cart.php';
                </script>";
            }
        }
    }

    if (isset($_POST['mod_quantity'])) {
        foreach ($_SESSION['cart'] as $key => $re_product) {
            if ($re_product['name'] == $_POST['name']) {
                $_SESSION['cart'][$key]['quantity'] = $_POST['mod_quantity'];
                echo "<script>
                    window.location.href = 'cart.php';
                </script>";
            }
        }
    }
}
?>