schon/storefront/app/composables/orders/useOrderSync.ts

import { useOrderOverwrite } from '@composables/orders/useOrderOverwrite';

export function useOrderSync() {
  const cartStore = useCartStore();
  const userStore = useUserStore();
  const { $appHelpers } = useNuxtApp();

  const { overwriteOrder } = useOrderOverwrite();

  const isAuthenticated = computed(() => userStore.isAuthenticated);
  const orderUuid = computed(() => cartStore.currentOrder?.uuid);

  const cookieCart = useCookie($appHelpers.COOKIES_CART_KEY, {
    default: () => [],
    path: '/',
  });

  async function syncOrder() {
    if (!isAuthenticated.value || !orderUuid.value) {
      return;
    }

    const cookieCartItems = cookieCart.value || [];

    if (cookieCartItems.length === 0) {
      return;
    }

    const apiCartProducts = cartStore.currentOrder?.orderProducts?.edges || [];

    const apiProductMap = new Map(
        apiCartProducts.map(e => [e.node.product.uuid, e.node.quantity])
    );

    const productsToSync = [];

    for (const cartItem of cookieCartItems) {
      const apiQuantity = apiProductMap.get(cartItem.product.uuid) || 0;
      const quantityDifference = cartItem.quantity - apiQuantity;

      if (quantityDifference > 0) {
        for (let i = 0; i < quantityDifference; i++) {
          productsToSync.push({ uuid: cartItem.product.uuid });
        }
      }
    }

    if (productsToSync.length === 0) {
      cookieCart.value = [];
      return;
    }

    try {
      await overwriteOrder({
        type: 'bulk',
        bulkAction: 'add',
        isBulkSync: true,
        products: productsToSync
      });
    } catch (err) {
      console.error('Failed to sync cart:', err);
    }
  }

  return {
    syncOrder,
  };
}