CouponManagementInterface.php

<?php
/**
 *
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace Magento\Quote\Api;

/**
 * Coupon management service interface.
 * @api
 * @since 100.0.2
 */
interface CouponManagementInterface
{
    /**
     * Returns information for a coupon in a specified cart.
     *
     * @param int $cartId The cart ID.
     * @return string The coupon code data.
     * @throws \Magento\Framework\Exception\NoSuchEntityException The specified cart does not exist.
     */
    public function get($cartId);

    /**
     * Adds a coupon by code to a specified cart.
     *
     * @param int $cartId The cart ID.
     * @param string $couponCode The coupon code data.
     * @return bool
     * @throws \Magento\Framework\Exception\NoSuchEntityException The specified cart does not exist.
     * @throws \Magento\Framework\Exception\CouldNotSaveException The specified coupon could not be added.
     */
    public function set($cartId, $couponCode);

    /**
     * Deletes a coupon from a specified cart.
     *
     * @param int $cartId The cart ID.
     * @return bool
     * @throws \Magento\Framework\Exception\NoSuchEntityException The specified cart does not exist.
     * @throws \Magento\Framework\Exception\CouldNotDeleteException The specified coupon could not be deleted.
     */
    public function remove($cartId);
}