Add Buy Now Button

/**
 * Snippet Name:     Add Buy Now Button
 * Snippet Author:   coding-bunny.com
 * Description:      Adds a "Buy Now" button to single product pages that empties the cart, adds the current product, and redirects to checkout.
 * Version:          1.1.0
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

function cbbnb_buy_now_btn() {
    global $product;
    if ( ! $product || ! $product->is_purchasable() || ! $product->is_in_stock() ) {
        return;
    }
    $nonce = wp_create_nonce( 'cbbnb_buy_now_nonce' );
    printf(
        '<button id="cbbnb-buy-now" type="submit" name="cbbnb-buy-now" value="%d" data-nonce="%s" class="single_add_to_cart_button cbbnb_buy_now_btn button alt">%s</button>',
        esc_attr( $product->get_id() ),
        esc_attr( $nonce ),
        esc_html__( 'Buy Now', 'cbbnb' )
    );
}
add_action( 'woocommerce_after_add_to_cart_button', 'cbbnb_buy_now_btn' );

function cbbnb_buy_now_handle() {
    if ( ! isset( $_REQUEST['cbbnb-buy-now'] ) ) {
        return;
    }
    $nonce = isset( $_REQUEST['_wpnonce'] ) ? sanitize_text_field( wp_unslash( $_REQUEST['_wpnonce'] ) ) : '';
    if ( ! wp_verify_nonce( $nonce, 'cbbnb_buy_now_nonce' ) ) {
        wp_die(
            esc_html__( 'Security check failed. Please try again.', 'cbbnb' ),
            esc_html__( 'Security Error', 'cbbnb' ),
            array( 'response' => 403 )
        );
    }
    $product_id = absint( $_REQUEST['cbbnb-buy-now'] );
    if ( ! $product_id ) {
        wc_add_notice( __( 'Invalid product.', 'cbbnb' ), 'error' );
        return;
    }
    $product = wc_get_product( $product_id );
    if ( ! $product || ! $product->is_purchasable() || ! $product->is_in_stock() ) {
        wc_add_notice( __( 'This product cannot be purchased.', 'cbbnb' ), 'error' );
        return;
    }
    $quantity = isset( $_REQUEST['quantity'] ) ? absint( $_REQUEST['quantity'] ) : 1;
    if ( $quantity < 1 ) {
        $quantity = 1;
    }
    if ( ! $product->has_enough_stock( $quantity ) ) {
        wc_add_notice( __( 'Not enough stock available.', 'cbbnb' ), 'error' );
        return;
    }
    try {
        WC()->cart->empty_cart();
        if ( isset( $_REQUEST['variation_id'] ) && $_REQUEST['variation_id'] ) {
            $variation_id = absint( $_REQUEST['variation_id'] );
            $variation = wc_get_product( $variation_id );
            if ( ! $variation || ! $variation->is_purchasable() ) {
                wc_add_notice( __( 'Invalid product variation.', 'cbbnb' ), 'error' );
                return;
            }
            $attributes = array();
            if ( isset( $_REQUEST['attribute'] ) && is_array( $_REQUEST['attribute'] ) ) {
                foreach ( $_REQUEST['attribute'] as $key => $value ) {
                    $attributes[ sanitize_key( $key ) ] = sanitize_text_field( wp_unslash( $value ) );
                }
            }
            $cart_item_key = WC()->cart->add_to_cart(
                $product_id,
                $quantity,
                $variation_id,
                $attributes
            );
        } else {
            $cart_item_key = WC()->cart->add_to_cart( $product_id, $quantity );
        }
        if ( ! $cart_item_key ) {
            wc_add_notice( __( 'Failed to add product to cart.', 'cbbnb' ), 'error' );
            return;
        }
        wp_safe_redirect( wc_get_checkout_url() );
        exit;
    } catch ( Exception $e ) {
        if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
            error_log( 'Buy Now Button Error: ' . $e->getMessage() );
        }
        wc_add_notice( __( 'An error occurred. Please try again.', 'cbbnb' ), 'error' );
        return;
    }
}
add_action( 'wp_loaded', 'cbbnb_buy_now_handle' );

function cbbnb_buy_now_js() {
    if ( ! is_product() ) {
        return;
    }
    ?>
    <script type="text/javascript">
    jQuery(document).ready(function($) {
        $('#cbbnb-buy-now').on('click', function(e) {
            var $form = $(this).closest('form.cart');
            var nonce = $(this).data('nonce');
            if (nonce && !$form.find('input[name="_wpnonce"]').length) {
                $form.append('<input type="hidden" name="_wpnonce" value="' + nonce + '">');
            }
        });
    });
    </script>
    <?php
}
add_action( 'wp_footer', 'cbbnb_buy_now_js' );

function cbbnb_buy_now_css() {
    if ( ! is_product() ) {
        return;
    }
    ?>
    <style type="text/css">
    .cbbnb_buy_now_btn {
        margin-left: 10px !important;
        background-color: #ff6b35 !important;
        border-color: #ff6b35 !important;
    }
    .cbbnb_buy_now_btn:hover {
        background-color: #e55a2b !important;
        border-color: #e55a2b !important;
    }
    </style>
    <?php
}
add_action( 'wp_head', 'cbbnb_buy_now_css' );