Add guest cart drawer, Continue handoff, and shared customer login.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/customer.ts

@@ -0,0 +1,59 @@
+import { BUSINESS_ORIGIN, CUSTOMER_ORIGIN } from "./site";
+
+export const GUEST_CART_URL_PARAM = "guestCart";
+
+export type GuestCartLine = {
+  id: string;
+  name: string;
+  slug?: string;
+  price: number;
+  quantity: number;
+  image?: string | null;
+};
+
+export function encodeGuestCartForUrl(items: GuestCartLine[]): string {
+  const payload = items.map(({ id, name, slug, price, quantity, image }) => ({
+    id,
+    name,
+    ...(slug ? { slug } : {}),
+    price,
+    quantity,
+    image: image ?? null,
+  }));
+  const json = JSON.stringify(payload);
+  return btoa(unescape(encodeURIComponent(json)))
+    .replace(/\+/g, "-")
+    .replace(/\//g, "_")
+    .replace(/=+$/, "");
+}
+
+export function customerDashboardUrl(path = "/"): string {
+  const normalized = path.startsWith("/") ? path : `/${path}`;
+  return `${CUSTOMER_ORIGIN}${normalized}`;
+}
+
+export function businessDashboardUrl(): string {
+  return `${BUSINESS_ORIGIN}/`;
+}
+
+export function customerLoginUrl(redirectPath = "/", cartItems?: GuestCartLine[]): string {
+  let redirect = redirectPath.startsWith("/") ? redirectPath : `/${redirectPath}`;
+  if (cartItems && cartItems.length > 0) {
+    const join = redirect.includes("#") ? "&" : "#";
+    redirect = `${redirect}${join}${GUEST_CART_URL_PARAM}=${encodeGuestCartForUrl(cartItems)}`;
+  }
+  const url = new URL("/login", CUSTOMER_ORIGIN);
+  url.searchParams.set("redirect", redirect);
+  return url.toString();
+}
+
+export function customerContinueCheckoutUrl(isAuthenticated: boolean, cartItems: GuestCartLine[] = []): string {
+  if (isAuthenticated) {
+    const url = new URL("/checkout/cart", CUSTOMER_ORIGIN);
+    if (cartItems.length > 0) {
+      url.hash = `${GUEST_CART_URL_PARAM}=${encodeGuestCartForUrl(cartItems)}`;
+    }
+    return url.toString();
+  }
+  return customerLoginUrl("/checkout/cart", cartItems);
+}