Add variation to cart.php

<?php
class Wishlist_Plus_Product {
	public function __construct() {
		add_action( 'woocommerce_single_product_summary', array( $this, 'add_button_hook' ), 35 );
		add_action( 'woocommerce_after_shop_loop_item', array( $this, 'add_button_hook' ), 100 );
		add_action( 'wp_footer', array( $this, 'wishlist_modal_template' ), 100 );
	}

	public function wishlist_modal_template() {
		if ( wishlist_plus()->get_limit() <= 1 ) {
			return;
		}
		?>
		<div id="wislist-plus-overlay"></div>
		<div id="wislist-plus-modal" class="wislist-plus-modal">
			<div class="wlp-modal-inner">
				<div class="wlp-modal-heading"><?php _e( 'Add to...', 'wishlist-plus' ); ?><span class="wlp-modal-close">
					<span class="wlp-modal-x"></span>
				</span></div>
				<ul>
					<?php foreach ( (array) wishlist_plus()->get_user_wishlists() as $item ) { ?>
					<li id="mdwlid-<?php echo esc_attr( $item->list_id ); ?>">
						<label><input class="wishlist-plus-add-list" value="<?php echo esc_attr( $item->list_id ); ?>" type="checkbox"/> <span><?php echo esc_html( $item->list_name ); ?></span></label>
					</li>
					<?php } ?>
				</ul>
				<a href="#" rel="nofolow" class="wlp-modal-add-list"><?php _e( 'Create new wishlist', 'wishlist-plus' ); ?></a>
				<form class="wlp-modal-form">
					<div class="wpl-field">
						<label><?php _e( 'Name', 'wishlist-plus' ); ?></label>
						<input type="text" class="wpl-input new-wishlist-name">
					</div>
					<input type="button" class="wpl-button" value="<?php esc_attr_e( 'Create', 'wishlist-plus' ); ?>">
				</form>
			</div>
		</div>
		<?php
	}

	public function add_button_hook() {
		global $product;
		echo $this->add_button( $product, null );
	}

	function add_button( $product = false, $varian_id = false ) {
		if ( ! $product instanceof WC_Product ) {
			$product = wc_get_product( $product );
		}

		if ( ! $product instanceof WC_Product ) {
			return false;
		}

		$id = $product->get_id();
		$link = wishlist_plus()->get_wishlist_page_url(
			array(
				'add_wishlist' => $id,
				'varian_id' => $varian_id,
			)
		);

		$atts = array(
			'class' => 'wishlist-plus-add-btn add-to-wishlist p_' . $id,
			'rel' => 'nofollow',
			'href' => $link,
			'data-product_id' => $id,
			'data-varian_id' => $varian_id,
			'title' => wp_sprintf( __( 'Add &ldquo;%s&rdquo; to wishlist', 'wishlist-plus' ), $product->get_name() ),
		);
		$atts = array_filter( $atts );
		$atts = apply_filters( 'wishlist_plus_button_args', $atts, $this );

		$string = array();
		foreach ( $atts as $k => $value ) {
			$string[ $k ] = "{$k}='" . esc_attr( $value ) . "'";
		}

		$button = '<a ' . join( ' ', $string ) . '>' . __( 'Add to wishlist #', 'wishlist-plus' ) . $id . '</a>';
		return $button;
	}

}