php - WooCommerce check cart contents on add to cart -

i have 1 product display, offer 2 options it: payment plan (handled through subscription plugin) , single payment. have them displayed on site grouped , both options have "add cart" button. don't want either option in cart @ same time other. either,

a) empty cart before each time add cart clicked.

or

b) check if cart contains product (via productid), , remove payment plan if full pay selected, or vice versa. here i've come option, i'm bit lost , it's not functioning quite right.

        global $woocommerce;         if ($product_id = 66){             foreach ( $woocommerce->cart->get_cart() $cart_item_key => $cart_item ) {                  echo $cart_item_key;                  if($cart_item['product_id'] == '69'){                     //remove single product                     $woocommerce->cart->remove_cart_item($cart_item_key);                  }             }         }         elseif ($product_id = 69){             foreach ( $woocommerce->cart->get_cart() $cart_item_key => $cart_item ) {                  echo $cart_item_key;                  if($cart_item['product_id'] == '66'){                     //remove single product                     $woocommerce->cart->remove_cart_item($cart_item_key);                  }             }         } 

i'm thinking of adding add_to_cart method before try/catch throw errors. can me figure better solution?

emptying cart easy

add_filter( 'woocommerce_add_to_cart_validation', 'so_31392001_empty_cart', 10, 3 );  function so_31392001_empty_cart( $valid, $product_id, $quantity ) {      wc()->cart->empty_cart();      return $valid; }