'use client';

import React, { createContext, useContext, useState, useCallback, useEffect } from 'react';
import {
  createCart,
  getCart,
  addCartLines,
  removeCartLines,
  updateCartLines,
} from '@/hooks/use-shopify-cart';

const CART_ID_KEY = 'cartId';

interface CartLine {
  id: string;
  quantity: number;
  merchandise: {
    id: string;
    title: string;
    price: {
      amount: string;
      currencyCode: string;
    };
    selectedOptions?: Array<{
      name: string;
      value: string;
    }>;
    image?: {
      url: string;
      altText?: string | null;
    };
    product: {
      id: string;
      title: string;
      handle: string;
      vendor?: string;
    };
  };
}

interface ShopifyCart {
  id: string;
  lines: {
    edges: Array<{
      node: CartLine;
    }>;
  };
  cost: {
    totalAmount: {
      amount: string;
      currencyCode: string;
    };
    subtotalAmount?: {
      amount: string;
      currencyCode: string;
    };
    totalTaxAmount?: {
      amount: string;
      currencyCode: string;
    };
  };
  checkoutUrl: string;
}

interface CartContextType {
  isOpen: boolean;
  openCart: () => void;
  closeCart: () => void;
  toggleCart: () => void;
  cartId: string | null;
  cart: ShopifyCart | null;
  items: CartLine[];
  itemCount: number;
  totalAmount: number;
  checkoutUrl: string | null;
  loading: boolean;
  error: string | null;
  addItem: (variantId: string, quantity?: number) => Promise<ShopifyCart>;
  removeItem: (lineId: string) => Promise<ShopifyCart>;
  updateItemQuantity: (lineId: string, quantity: number) => Promise<ShopifyCart>;
  refreshCart: () => Promise<void>;
}

export const CartContext = createContext<CartContextType | null>(null);

export const ShopifyProvider: React.FC<{ children: React.ReactNode }> = ({ children }) => {
  const [isOpen, setIsOpen] = useState(false);
  const [cartId, setCartId] = useState<string | null>(null);
  const [cart, setCart] = useState<ShopifyCart | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const storeCartId = useCallback((id: string) => {
    localStorage.setItem(CART_ID_KEY, id);
    setCartId(id);
  }, []);

  const refreshCart = useCallback(async () => {
    const storedCartId = localStorage.getItem(CART_ID_KEY);
    if (!storedCartId) {
      setLoading(false);
      return;
    }

    try {
      setLoading(true);
      setError(null);
      const fetchedCart = await getCart(storedCartId);
      if (fetchedCart) {
        setCart(fetchedCart);
        setCartId(storedCartId);
      } else {
        localStorage.removeItem(CART_ID_KEY);
        setCartId(null);
        setCart(null);
      }
    } catch (err) {
      console.error('Error fetching cart:', err);
      localStorage.removeItem(CART_ID_KEY);
      setCartId(null);
      setCart(null);
      setError('Failed to fetch cart');
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    refreshCart();
  }, [refreshCart]);

  const getOrCreateCart = useCallback(async (): Promise<string> => {
    if (cartId) return cartId;

    const storedCartId = localStorage.getItem(CART_ID_KEY);
    if (storedCartId) {
      setCartId(storedCartId);
      return storedCartId;
    }

    try {
      const newCart = await createCart();
      setCart(newCart);
      storeCartId(newCart.id);
      return newCart.id;
    } catch (err) {
      console.error('Failed to create cart:', err);
      throw err;
    }
  }, [cartId, storeCartId]);

  const openCart = useCallback(() => {
    setIsOpen(true);
  }, []);

  const closeCart = useCallback(() => {
    setIsOpen(false);
  }, []);

  const toggleCart = useCallback(() => {
    setIsOpen((prev) => !prev);
  }, []);

  const addItem = useCallback(async (variantId: string, quantity: number = 1): Promise<ShopifyCart> => {
    try {
      setLoading(true);
      setError(null);

      const currentCartId = await getOrCreateCart();
      const updatedCart = await addCartLines(currentCartId, [
        { merchandiseId: variantId, quantity },
      ]);

      setCart(updatedCart);
      return updatedCart;
    } catch (err) {
      const errorMessage = err instanceof Error ? err.message : 'Failed to add item to cart';
      setError(errorMessage);
      throw err;
    } finally {
      setLoading(false);
    }
  }, [getOrCreateCart]);

  const removeItem = useCallback(async (lineId: string): Promise<ShopifyCart> => {
    if (!cartId) {
      throw new Error('No cart exists');
    }

    try {
      setLoading(true);
      setError(null);

      const updatedCart = await removeCartLines(cartId, [lineId]);
      setCart(updatedCart);
      return updatedCart;
    } catch (err) {
      const errorMessage = err instanceof Error ? err.message : 'Failed to remove item from cart';
      setError(errorMessage);
      throw err;
    } finally {
      setLoading(false);
    }
  }, [cartId]);

  const updateItemQuantity = useCallback(async (lineId: string, quantity: number): Promise<ShopifyCart> => {
    if (!cartId) {
      throw new Error('No cart exists');
    }

    if (quantity <= 0) {
      return removeItem(lineId);
    }

    try {
      setLoading(true);
      setError(null);

      const updatedCart = await updateCartLines(cartId, [
        { id: lineId, quantity },
      ]);
      setCart(updatedCart);
      return updatedCart;
    } catch (err) {
      const errorMessage = err instanceof Error ? err.message : 'Failed to update item quantity';
      setError(errorMessage);
      throw err;
    } finally {
      setLoading(false);
    }
  }, [cartId, removeItem]);

  const items = cart?.lines?.edges?.map((edge) => edge.node) ?? [];
  const itemCount = items.reduce((sum, item) => sum + item.quantity, 0);
  const totalAmount = parseFloat(cart?.cost?.totalAmount?.amount ?? '0');
  const checkoutUrl = cart?.checkoutUrl ?? null;

  return (
    <CartContext.Provider value={{
      isOpen,
      openCart,
      closeCart,
      toggleCart,
      cartId,
      cart,
      items,
      itemCount,
      totalAmount,
      checkoutUrl,
      loading,
      error,
      addItem,
      removeItem,
      updateItemQuantity,
      refreshCart,
    }}>
      {children}
    </CartContext.Provider>
  );
};

// Alias for backwards compatibility
export const CartProvider = ShopifyProvider;

export default ShopifyProvider;