OpenCart 🇺🇦

if (isset($this->session->data['coupon'])) {
	$this->language->load('total/coupon');

	$this->load->model('checkout/coupon');

	$coupon_info = $this->model_checkout_coupon->getCoupon($this->session->data['coupon']);

	if ($coupon_info) {
		$discount_total = 0;

		if (!$coupon_info['product']) {
			$sub_total = $this->cart->getSubTotal();
		} else {
			$sub_total = 0;

			foreach ($this->cart->getProducts() as $product) {
				if (in_array($product['product_id'], $coupon_info['product'])) {
					$sub_total += $product['total'];
				}
			}					
		}

		if ($coupon_info['type'] == 'F') {
			$coupon_info['discount'] = min($coupon_info['discount'], $sub_total);
		}

		foreach ($this->cart->getProducts() as $product) {
			$discount = 0;

			if (!$coupon_info['product']) {
				$status = true;
			} else {
				if (in_array($product['product_id'], $coupon_info['product'])) {
					$status = true;
				} else {
					$status = false;
				}
			}

			if ($status) {
				if ($coupon_info['type'] == 'F') {
					$discount = $coupon_info['discount'] * ($product['total'] / $sub_total);
				} elseif ($coupon_info['type'] == 'P') {
					$discount = $product['total'] / 100 * $coupon_info['discount'];
				}

				if ($product['tax_class_id']) {
					$tax_rates = $this->tax->getRates($product['total'] - ($product['total'] - $discount), $product['tax_class_id']);

					foreach ($tax_rates as $tax_rate) {
						if ($tax_rate['type'] == 'P') {
							$taxes[$tax_rate['tax_rate_id']] -= $tax_rate['amount'];
						}
					}
				}
			}

			$discount_total += $discount;
		}

		if ($coupon_info['shipping'] && isset($this->session->data['shipping_method'])) {
			if (!empty($this->session->data['shipping_method']['tax_class_id'])) {
				$tax_rates = $this->tax->getRates($this->session->data['shipping_method']['cost'], $this->session->data['shipping_method']['tax_class_id']);

				foreach ($tax_rates as $tax_rate) {
					if ($tax_rate['type'] == 'P') {
						$taxes[$tax_rate['tax_rate_id']] -= $tax_rate['amount'];
					}
				}
			}

			$discount_total += $this->session->data['shipping_method']['cost'];				
		}				

		$total_data[] = array(
			'code'       => 'coupon',
			'title'      => sprintf($this->language->get('text_coupon'), $this->session->data['coupon']),
			'text'       => $this->currency->format(-$discount_total),
			'value'      => -$discount_total,
			'sort_order' => $this->config->get('coupon_sort_order')
		);

		$total -= $discount_total;
	} 
}

$code = '';

$start = strpos($order_total['title'], '(') + 1;
$end = strrpos($order_total['title'], ')');

if ($start && $end) {  
	$code = substr($order_total['title'], $start, $end - $start);
}	

$this->load->model('checkout/coupon');

$coupon_info = $this->model_checkout_coupon->getCoupon($code);

if ($coupon_info) {
	$this->model_checkout_coupon->redeem($coupon_info['coupon_id'], $order_info['order_id'], $order_info['customer_id'], $order_total['value']);	
}