php - wordpress remove gift product on cart total change

Question

using the code found on Internet, works perfectly, but it needs to be updated with extra function.

now: if total sum gets 100+ free gift is added. if user removes some products and total gets lower than 100, free gift still stays there

should be: if user removes products and total gets lower than 100, free gift is removed

function aapc_add_product_to_cart() {
    global $woocommerce;
    
    $cart_total = 100;  

    if ( $woocommerce->cart->total >= $cart_total ) {
        if ( ! is_admin() ) {
            $free_product_id = 6663;  // Product Id of the free product which will get added to cart
           
            $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() == $free_product_id )
                        $found = true;                  
                }
                // if product not found, add it
                if ( ! $found )
                    WC()->cart->add_to_cart( $free_product_id );
            } else {
                // if no products in cart, add it
       WC()->cart->add_to_cart( $free_product_id );
            }        
        }
    }        
}

add_action( 'template_redirect', 'aapc_add_product_to_cart' );

Answer 1

this works

    add_action( 'woocommerce_before_calculate_totals', 'add_or_remove_cart_items', 10, 1 );
    function add_or_remove_cart_items( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // ONLY for logged users (and avoiding the hook repetition) 
    if ( ! is_user_logged_in() && did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
        return;

    $threshold_amount = 99.9; // The threshold amount for cart total
    $free_product_id  = 6663; // ID of the free product
    $cart_items_total = 0; // Initializing

    // Loop through cart items
    foreach ( $cart->get_cart() as $cart_item_key => $cart_item ){
        // Check if the free product is in cart
        if ( $cart_item['data']->get_id() == $free_product_id ) {
            $free_item_key = $cart_item_key;
        }
        // Get cart subtotal incl. tax from items (with discounts if any)
        $cart_items_total += $cart_item['line_total'] + $cart_item['line_tax'];
    }

    // If Cart total is up to the defined amount and if the free products is not in cart, we add it.
    if ( $cart_items_total >= $threshold_amount && ! isset($free_item_key) ) {
        $cart->add_to_cart( $free_product_id );
    }
    // If cart total is below the defined amount and free product is in cart, we remove it.
    elseif ( $cart_items_total remove_cart_item( $free_item_key );
    }
}