WooCommerce - Add a product page button

<?php
  // WooCommerce - Add a product page button
  add_action( 'woocommerce_after_shop_loop_item', 'replace_add_to_cart', 10 );
  function replace_add_to_cart() {
    global $product;
    $link = $product->get_permalink();
    $link = esc_attr( $link );
    print '<a rel="nofollow" href="'.$link.'" data-quantity="1" data-product_id="168" data-product_sku="" class="button product_type_simple add_to_cart_button">SHOP NOW</a>'.PHP_EOL;
  }