Add Checkbox to Apply Coupon at Add to Cart Button

/**
 * Snippet Name:      Add Checkbox to Apply Coupon at Add to Cart Button
 * Snippet Author:    coding-bunny.com
 * Description:       Adds a checkbox near the add-to-cart button on WooCommerce product pages for applying a discount coupon.
 */

/**
 * Display a coupon checkbox below the add-to-cart button
 */
add_action( 'woocommerce_after_add_to_cart_button', 'cb_coupon_checkbox', 10 );
function cb_coupon_checkbox() {
    echo '<p style="display: inline-block; margin-top:20px;">
            <span style="background-color: #2d2d2d; color: white; font-weight: bold; padding: 5px 10px; border-radius: 3px;">
                BLACK FRIDAY
            </span> 
            <label style="color: #2d2d2d;">
                <input type="checkbox" name="cb_apply_coupon" value="1"/> 
                Save 10% by activating the discount code!
            </label>
          </p>';
}

/**
 * Apply the coupon when the checkbox is selected
 *
 * @param string $cart_item_key Cart item key.
 * @param int $product_id Product ID.
 * @param int $quantity Quantity of the product.
 * @param int $variation_id Variation ID.
 * @param array $variation Variation details.
 * @param array $cart_item_data Additional cart item data.
 */
add_action( 'woocommerce_add_to_cart', 'cb_apply_coupon_on_checkbox_check', 10, 6 );
function cb_apply_coupon_on_checkbox_check( $cart_item_key, $product_id, $quantity, $variation_id, $variation, $cart_item_data ) {
    if ( isset( $_POST['cb_apply_coupon'] ) && $_POST['cb_apply_coupon'] == 1 ) {
        $coupon_code = 'discount10'; // Replace with your actual coupon code
        
        // Apply the coupon only if it is not already applied
        if ( ! WC()->cart->has_discount( $coupon_code ) ) {
            WC()->cart->apply_coupon( $coupon_code );
        }
    }
}