WooCommerce - Auto add item to cart

<?php
  // Auto add-to-cart
  // code goes in functions.php for your child theme
  add_action( 'init', 'add_product_to_cart' );
  function add_product_to_cart() {
    if ( ! is_admin() ) {
      global $woocommerce;
      $product_id = 30; // your product ID here
      $free_product_id = 2287; // your free product ID here
      $found = false;
      // check if product already in cart
      if ( sizeof( $woocommerce->cart->get_cart() ) > 0 ) {
        foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $values ) {
          $_product = $values['data'];
          if ( $_product->id == $product_id ){
            $found = true;
          }
        }
        // if product not found, add it
        if ( $found ) $woocommerce->cart->add_to_cart( $free_product_id );
      }
    }
  }