'use client';

import React, { createContext, useContext, useEffect, useState } from 'react';

export interface CartItem {
  id: string;
  name: string;
  price: number;
  quantity: number;
  image: string;
  category: string;
}

interface CartContextType {
  cartItems: CartItem[];
  addToCart: (item: Omit<CartItem, 'quantity'>, quantity?: number) => void;
  removeFromCart: (id: string) => void;
  updateQuantity: (id: string, quantity: number) => void;
  clearCart: () => void;
  cartCount: number;
  cartSubtotal: number;
  taxEstimation: number;
  cartTotal: number;
}

const CartContext = createContext<CartContextType | undefined>(undefined);

export function CartProvider({ children }: { children: React.ReactNode }) {
  const [cartItems, setCartItems] = useState<CartItem[]>([]);
  const [isLoaded, setIsLoaded] = useState(false);

  // Load cart items on mount
  useEffect(() => {
    try {
      const storedCart = localStorage.getItem('uvu_cart');
      if (storedCart) {
        setCartItems(JSON.parse(storedCart));
      }
    } catch (e) {
      console.error('Failed to load cart from localStorage:', e);
    }
    setIsLoaded(true);
  }, []);

  // Save cart items whenever they change
  useEffect(() => {
    if (!isLoaded) return;
    try {
      localStorage.setItem('uvu_cart', JSON.stringify(cartItems));
    } catch (e) {
      console.error('Failed to save cart to localStorage:', e);
    }
  }, [cartItems, isLoaded]);

  const addToCart = (item: Omit<CartItem, 'quantity'>, quantity = 1) => {
    setCartItems((prevItems) => {
      const existingItem = prevItems.find((i) => i.id === item.id);
      if (existingItem) {
        return prevItems.map((i) =>
          i.id === item.id ? { ...i, quantity: i.quantity + quantity } : i
        );
      }
      return [...prevItems, { ...item, quantity }];
    });
  };

  const removeFromCart = (id: string) => {
    setCartItems((prevItems) => prevItems.filter((item) => item.id !== id));
  };

  const updateQuantity = (id: string, quantity: number) => {
    if (quantity <= 0) {
      removeFromCart(id);
      return;
    }
    setCartItems((prevItems) =>
      prevItems.map((item) => (item.id === id ? { ...item, quantity } : item))
    );
  };

  const clearCart = () => {
    setCartItems([]);
  };

  const cartCount = cartItems.reduce((acc, item) => acc + item.quantity, 0);
  const cartSubtotal = cartItems.reduce((acc, item) => acc + item.price * item.quantity, 0);
  // UVU is a government University and is tax-exempt. Therefore, no sales tax is charged (0%).
  // We keep taxEstimation as a variable/property for backward compatibility with types and other components.
  const taxEstimation = 0;
  const cartTotal = cartSubtotal + taxEstimation;

  return (
    <CartContext.Provider
      value={{
        cartItems,
        addToCart,
        removeFromCart,
        updateQuantity,
        clearCart,
        cartCount,
        cartSubtotal,
        taxEstimation,
        cartTotal,
      }}
    >
      {children}
    </CartContext.Provider>
  );
}

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