How do I integrate Shop For Good with our Headless CMS?

const getCart = async () => {
  /*
  This method should return a content of the cart in the Shopify Ajax Cart API format
  */
    return {}
  }

  const manageDonationProduct = async (variantId, quantity, attributes) => {
  /*
  a product with the specified variant should be either added to the cart,
   removed from it or its quantity should be changed.
   attributes is a json object like {_dk_charities: '755'} - the same as 
   for the Shopify Ajax Cart API. This is a specific for the product
  */    
  }

  const updateCartAttributes = async (attributes) => {
    /*
    set attributes on the cart level, json object like {__dk_user_notification_out_in: 'false'}
    */
  }
  
  window.dkExternalEndpoints = {
      manageDonationProduct: manageDonationProduct,
      getCart: getCart,
      updateCartAttributes: updateCartAttributes,
      domain: "amymyersmd.myshopify.com"
  };

window.dkExternalEndpoints = {
  domain: 'dailykarmademo.myshopify.com',
  getCart: async () => {
    const domain = 'https://dailykarmademo.myshopify.com';
    const response = await fetch(`${domain}/cart.js`, {
      method: 'GET',
      headers: {
        'Content-Type': 'application/json',
      },
    });
    const data = await response.json();
    return data;
  },
  manageDonationProduct: async (variantId, quantity, attributes) => {
    const domain = 'https://dailykarmademo.myshopify.com';
    const cart = await window.dkExternalEndpoints.getCart();
    const line = cart?.items?.find((l) => l.variant_id === variantId);
    const response = await fetch(`${domain}/cart/${quantity === 0 ? 'change' : 'add'}.js`, {
      method: 'POST',
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        id: line ? line.key : variantId,
        quantity: +quantity,
        properties: attributes,
      }),
    });
    return response;
  },
  updateCartAttributes: async (attributes) => {
    const domain = 'https://dailykarmademo.myshopify.com';
    const response = await fetch(`${domain}/cart/update.js`, {
      method: 'POST',
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({ attributes }),
    });
  },
};