WordPress / WooCommerce / Automatically add product to the cart

woo_auto_add_product_to_cart.php

/******************************************************************************/
/* Automatically adding the product to the cart.
/* https://www.tychesoftwares.com/how-to-automatically-add-a-product-to-your-woocommerce-cart-in-3-different-scenarios/
/******************************************************************************/

function auto_add_product_to_cart() {

    if ( ! is_admin() ) {

        $product_id = 2623;  // Product ID which will get added to cart. Should be dynamic.
        $found  = false;

        //check if product already in cart
        if ( sizeof( WC()->cart->get_cart() ) > 0 ) {

            foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
                $_product = $values['data'];
                if ( $_product->get_id() == $product_id ) $found = true;
            }

            // If product not found, add it
            if ( ! $found ) WC()->cart->add_to_cart( $product_id );

        } else {

            // If no products in cart, add it
            WC()->cart->add_to_cart( $product_id );

        }

    }

}

//add_action( 'init', 'auto_add_product_to_cart' );