'use client';

import {
  createContext,
  useContext,
  useEffect,
  useState,
  ReactNode,
} from 'react';
import type { CartItem } from '@/types';

interface CartContextValue {
  items: CartItem[];
  addItem: (item: Omit<CartItem, 'quantity'>, quantity?: number) => void;
  removeItem: (productId: string) => void;
  updateQuantity: (productId: string, quantity: number) => void;
  clearCart: () => void;
  total: number;
  count: number;
}

const CartContext = createContext<CartContextValue | null>(null);

const CART_KEY = 'lom-shop-cart';

export function CartProvider({ children }: { children: ReactNode }) {
  const [items, setItems] = useState<CartItem[]>([]);
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setMounted(true);
    try {
      const raw = localStorage.getItem(CART_KEY);
      if (raw) setItems(JSON.parse(raw));
    } catch {
      // ignore
    }
  }, []);

  useEffect(() => {
    if (mounted) {
      localStorage.setItem(CART_KEY, JSON.stringify(items));
    }
  }, [items, mounted]);

  const addItem = (item: Omit<CartItem, 'quantity'>, quantity = 1) => {
    setItems((prev) => {
      const existing = prev.find((i) => i.productId === item.productId);
      if (existing) {
        return prev.map((i) =>
          i.productId === item.productId
            ? { ...i, quantity: i.quantity + quantity }
            : i
        );
      }
      return [...prev, { ...item, quantity }];
    });
  };

  const removeItem = (productId: string) => {
    setItems((prev) => prev.filter((i) => i.productId !== productId));
  };

  const updateQuantity = (productId: string, quantity: number) => {
    if (quantity < 1) {
      removeItem(productId);
      return;
    }
    setItems((prev) =>
      prev.map((i) =>
        i.productId === productId ? { ...i, quantity } : i
      )
    );
  };

  const clearCart = () => setItems([]);

  const total = items.reduce((sum, i) => sum + i.price * i.quantity, 0);
  const count = items.reduce((sum, i) => sum + i.quantity, 0);

  return (
    <CartContext.Provider
      value={{ items, addItem, removeItem, updateQuantity, clearCart, total, count }}
    >
      {children}
    </CartContext.Provider>
  );
}

export function useCart() {
  const ctx = useContext(CartContext);
  if (!ctx) throw new Error('useCart must be used within CartProvider');
  return ctx;
}