feature to import and update shopify store products in my website

my website already has store plugin with multiple sellers, written in cakephp I need to add feature, each seller can enter his shopify store url and password and import products to my website and instead of add to cart button my website will have "Buy Online" button when customer clicks "Buy Online" it will open product from shopify stores and it should auto update when a product is removed from shopify it should remove from my site price change, inventory update also should update