apply_coupon.php

<?php
session_start();
include_once("admin/class/adminback.php");
$obj = new adminback();

if (isset($_POST['coupon_code']) && isset($_POST['total'])) {
    $coupon_code = $_POST['coupon_code'];
    $total_amount = $_POST['total'];
    
    // Validate the coupon code
    $query = "SELECT * FROM `coupon` WHERE `coupon_code` = '$coupon_code' AND `status` = 1";
    $result = $obj->execute_query($query);
    
    if (mysqli_num_rows($result) > 0) {
        $coupon = mysqli_fetch_assoc($result);
        $discount_percentage = $coupon['discount'];
        
        // Calculate the discounted amount
        $discount_amount = $total_amount * ($discount_percentage / 100);
        $discounted_amount = $total_amount - $discount_amount;
        
        // Update the session variables
        $_SESSION['subtotal'] = $discounted_amount;
        $_SESSION['coupon_code'] = $coupon_code;
        $_SESSION['discount_amount'] = $discount_amount;
        
        // Return the discount amount as JSON response
        echo json_encode(['discount_amount' => $discount_amount]);
    } else {
        // Invalid coupon code
        echo json_encode(['error' => 'Invalid coupon code']);
    }
}
?>