import type { CartItem } from "@/lib/cart-types";

/** Must match customer dashboard `GUEST_CART_STORAGE_KEY`. */
export const MESHKEE_GUEST_CART_KEY = "meshkee-guest-cart";
export const LEGACY_GUEST_CART_KEY = "sanihome-guest-cart";
export const GUEST_CART_URL_PARAM = "guestCart";

export type MeshkeeGuestCartItem = {
  id: string;
  name: string;
  slug?: string;
  price: number;
  originalPrice?: number;
  image: string | null;
  quantity: number;
};

function cookieDomain(): string | undefined {
  if (typeof window === "undefined") return undefined;
  const host = window.location.hostname.toLowerCase();
  if (host === "localhost" || host === "127.0.0.1") return undefined;
  const parts = host.split(".").filter(Boolean);
  if (parts.length < 2) return undefined;
  return `.${parts.slice(-2).join(".")}`;
}

function parseItems(raw: string | null): CartItem[] {
  if (!raw) return [];
  try {
    const parsed = JSON.parse(raw) as CartItem[];
    return Array.isArray(parsed) ? parsed : [];
  } catch {
    return [];
  }
}

/** Map storefront cart lines to the shared guest-cart shape (id = variant id). */
export function toMeshkeeGuestItems(items: CartItem[]): MeshkeeGuestCartItem[] {
  const result: MeshkeeGuestCartItem[] = [];
  for (const item of items) {
    const variantId = (item.storeItemVariantId || item.id || "").trim();
    if (!variantId) continue;
    result.push({
      id: variantId,
      name: item.name || "محصول",
      ...(item.slug ? { slug: item.slug } : {}),
      price: item.price,
      image: item.image ?? null,
      quantity: Math.max(1, Math.floor(item.quantity) || 1),
    });
  }
  return result;
}

export function encodeGuestCartForUrl(items: CartItem[]): string {
  const payload = toMeshkeeGuestItems(items);
  const json = JSON.stringify(payload);
  return btoa(unescape(encodeURIComponent(json)))
    .replace(/\+/g, "-")
    .replace(/\//g, "_")
    .replace(/=+$/, "");
}

function writeSharedCookie(items: MeshkeeGuestCartItem[]) {
  if (typeof document === "undefined") return;
  const domain = cookieDomain();
  const maxAge = 60 * 60 * 24 * 30;
  const encoded = encodeURIComponent(
    JSON.stringify(
      items.map(({ id, name, slug, price, originalPrice, quantity }) => ({
        id,
        name,
        slug,
        price,
        originalPrice,
        quantity,
        image: null as string | null,
      })),
    ),
  );
  if (encoded.length > 3500) return;
  let cookie = `${MESHKEE_GUEST_CART_KEY}=${encoded}; path=/; max-age=${maxAge}; SameSite=Lax`;
  if (domain) cookie += `; domain=${domain}`;
  document.cookie = cookie;
}

export function readGuestCart(): CartItem[] {
  if (typeof window === "undefined") return [];
  const primary = parseItems(localStorage.getItem(MESHKEE_GUEST_CART_KEY));
  if (primary.length > 0) return primary;
  const legacy = parseItems(localStorage.getItem(LEGACY_GUEST_CART_KEY));
  if (legacy.length > 0) {
    writeGuestCart(legacy);
    return legacy;
  }
  return [];
}

export function writeGuestCart(items: CartItem[]) {
  if (typeof window === "undefined") return;
  const raw = JSON.stringify(items);
  localStorage.setItem(MESHKEE_GUEST_CART_KEY, raw);
  localStorage.removeItem(LEGACY_GUEST_CART_KEY);
  try {
    writeSharedCookie(toMeshkeeGuestItems(items));
  } catch {
    // ignore cookie failures
  }
}

export function clearGuestCart() {
  if (typeof window === "undefined") return;
  localStorage.removeItem(MESHKEE_GUEST_CART_KEY);
  localStorage.removeItem(LEGACY_GUEST_CART_KEY);
  const domain = cookieDomain();
  let cookie = `${MESHKEE_GUEST_CART_KEY}=; path=/; max-age=0; SameSite=Lax`;
  if (domain) cookie += `; domain=${domain}`;
  document.cookie = cookie;
}