set_coupon.php

<?php
require('connection.inc.php');
require('function.inc.php');

$coupon_str = get_safe_value($con, $_POST['coupon_str']);

$res = mysqli_query($con, "select * from coupon_master where coupon_code='$coupon_str' and status=1");
$count = mysqli_num_rows($res);

$jsonArr = array();
$cart_total = '0';
if (isset($_SESSION['COUPON_ID'])) {
    unset($_SESSION['COUPON_ID']);
    unset($_SESSION['COUPON_CODE']);
    unset($_SESSION['COUPON_VALUE']);
}
foreach ($_SESSION['cart'] as $key => $val) {
    $productArr = get_product($con, '', '', $key);
    $price = $productArr[0]['price'];
    $qty = $val['qty'];
    $cart_total = $cart_total + ($price * $qty);
}
if ($count > 0) {
    $coupon_details = mysqli_fetch_assoc($res);
    $id = $coupon_details['id'];
    $coupon_value = number_format($coupon_details['coupon_value'], 2);
    $coupon_type = $coupon_details['coupon_type'];
    $cart_min_value = $coupon_details['cart_min_value'];

    if ($cart_min_value > $cart_total) {
        $jsonArr = array('is_error' => 'yes', 'result' => $cart_total, 'dd' => 'Cart total value must be ' . $cart_min_value);
    } else {
        if ($coupon_type == 'Rupee') {
            $final_price = $cart_total - $coupon_value;
        } else {
            $final_price = $cart_total - (($cart_total * $coupon_value) / 100);
        }
        $dd_float = $cart_total - $final_price;
        $dd = number_format($dd_float, 2);
        $_SESSION['COUPON_ID'] = $id;
        $_SESSION['FINAL_PRICE'] = $final_price;
        $_SESSION['COUPON_VALUE'] = $dd;
        $_SESSION['COUPON_CODE'] = $coupon_str;
        $jsonArr = array('is_error' => 'no', 'result' => $final_price, 'dd' => $dd);
    }
} else {
    $jsonArr = array('is_error' => 'yes', 'result' => $cart_total, 'dd' => 'Coupon code not found');
}
echo json_encode($jsonArr);