schon/storefront/app/composables/wishlist/useWishlistSync.ts

import {useWishlistOverwrite} from "@composables/wishlist/useWishlistOverwrite";

export function useWishlistSync() {
  const wishlistStore = useWishlistStore();
  const userStore = useUserStore();
  const { $appHelpers } = useNuxtApp();

  const { overwriteWishlist } = useWishlistOverwrite();

  const isAuthenticated = computed(() => userStore.isAuthenticated);
  const wishlistUuid = computed(() => wishlistStore.wishlist?.uuid);

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

  async function syncWishlist() {
    if (!isAuthenticated.value || !wishlistUuid.value) {
      return;
    }

    const cookieProducts = cookieWishlist.value || [];

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

    const apiProductUuids = wishlistStore.wishlist?.products?.edges.map(e => e.node.uuid) || [];

    const productsToAdd = cookieProducts.filter(
        (product) => !apiProductUuids.includes(product.uuid)
    );

    if (productsToAdd.length === 0) {
      cookieWishlist.value = [];
      return;
    }

    try {
      await overwriteWishlist({
        type: 'bulk',
        bulkAction: 'add',
        isBulkSync: true,
        products: productsToAdd.map(p => ({ uuid: p.uuid }))
      })

      if (bulkResult?.data?.bulkWishlistAction?.wishlist) {
        wishlistStore.setWishlist(bulkResult.data.bulkWishlistAction.wishlist);

        cookieWishlist.value = [];
      }
    } catch (err) {
      console.error('Failed to sync wishlist:', err);
    }
  }

  watch(syncError, (err) => {
    if (!err) return;
    console.error('useWishlistSync error:', err);
  });

  return {
    syncWishlist,
  };
}