import { cookies } from "next/headers";
import { db } from "@/lib/db";

export const CART_COOKIE = "bistrousky_cart";

export interface CartItem {
  variantId: string;
  quantity: number;
}

// ── Čtení / zápis cookie ──────────────────────────────────────────────────

export async function getCartItems(): Promise<CartItem[]> {
  const store = await cookies();
  const raw = store.get(CART_COOKIE)?.value;
  if (!raw) return [];
  try {
    return JSON.parse(raw) as CartItem[];
  } catch {
    return [];
  }
}

export async function setCartItems(items: CartItem[]) {
  const store = await cookies();
  store.set(CART_COOKIE, JSON.stringify(items), {
    httpOnly: true,
    sameSite: "lax",
    path: "/",
    maxAge: 60 * 60 * 24 * 30, // 30 dní
  });
}

// ── Košík s daty z DB ─────────────────────────────────────────────────────

export interface CartItemFull {
  variantId: string;
  quantity: number;
  variant: {
    id: string;
    name: string;
    price: number;
    stock: number;
    product: {
      id: string;
      name: string;
      slug: string;
      image: string | null;
    };
  };
}

export async function getCart(): Promise<CartItemFull[]> {
  const items = await getCartItems();
  if (items.length === 0) return [];

  const variantIds = items.map((i) => i.variantId);
  const variants = await db.productVariant.findMany({
    where: { id: { in: variantIds } },
    include: {
      product: { select: { id: true, name: true, slug: true, image: true } },
    },
  });

  return items
    .map((item) => {
      const variant = variants.find((v) => v.id === item.variantId);
      if (!variant) return null;
      return { variantId: item.variantId, quantity: item.quantity, variant };
    })
    .filter(Boolean) as CartItemFull[];
}

export function cartTotal(items: CartItemFull[]): number {
  return items.reduce((sum, item) => sum + item.variant.price * item.quantity, 0);
}