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.productUuid) || 0;
			const quantityDifference = cartItem.quantity - apiQuantity;

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

		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,
	};
}