"use client";

import React, { useEffect } from "react";
import { useRouter } from "next/navigation";

export default function Cart() {
  const router = useRouter();
  const [cartItems, setCartItems] = React.useState([]);
  const [loading, setLoading] = React.useState(true);
  const [error, setError] = React.useState(null);
  const [recommendProducts, setRecommendProducts] = React.useState([]);

  useEffect(() => {
    const fetchCartItems = async () => {
      try {
        const token = localStorage.getItem("token");
        if (!token) {
          setCartItems([]);
          setLoading(false);
          return;
        }

        const res = await fetch("/api/cart", {
          headers: {
            Authorization: `Bearer ${token}`,
          },
        });

        if (!res.ok) {
          throw new Error("获取购物车失败");
        }
        const data = await res.json();
        setCartItems(data);
      } catch (err) {
        setError(err.message);
      } finally {
        setLoading(false);
      }
    };

    fetchCartItems();
  }, []);

  useEffect(() => {
    const fetchRecommendProducts = async () => {
      try {
        const res = await fetch("/api/products");
        if (!res.ok) {
          throw new Error("获取推荐商品失败");
        }
        const data = await res.json();
        // 随机获取4个商品作为推荐
        const shuffled = data.sort(() => 0.5 - Math.random());
        setRecommendProducts(shuffled.slice(0, 4));
      } catch (err) {
        console.error("获取推荐商品失败:", err);
      }
    };

    fetchRecommendProducts();
  }, []);

  const calculateTotal = () => {
    return cartItems.reduce(
      (total, item) => total + item.productId.price * item.quantity,
      0
    );
  };

  const handleCheckout = () => {
    const productParams = cartItems
      .map((item) => `${item.productId._id}:${item.quantity}`)
      .join(",");
    router.push(`/checkout?items=${productParams}`);
  };

  const handleDelete = async (itemId) => {
    try {
      const token = localStorage.getItem("token");
      if (!token) {
        router.push("/login");
        return;
      }

      const res = await fetch("/api/cart", {
        method: "DELETE",
        headers: {
          "Content-Type": "application/json",
          Authorization: `Bearer ${token}`,
        },
        body: JSON.stringify({ cartItemId: itemId }),
      });

      if (!res.ok) {
        throw new Error("删除失败");
      }

      // 更新本地状态
      setCartItems(cartItems.filter((item) => item._id !== itemId));
    } catch (error) {
      console.error("删除失败:", error);
    }
  };

  const handleUpdateQuantity = async (itemId, newQuantity) => {
    try {
      const token = localStorage.getItem("token");
      if (!token) {
        router.push("/login");
        return;
      }

      const res = await fetch("/api/cart", {
        method: "PUT",
        headers: {
          "Content-Type": "application/json",
          Authorization: `Bearer ${token}`,
        },
        body: JSON.stringify({
          cartItemId: itemId,
          quantity: newQuantity,
        }),
      });

      if (!res.ok) {
        throw new Error("更新数量失败");
      }

      // 更新本地状态
      setCartItems(
        cartItems.map((item) =>
          item._id === itemId ? { ...item, quantity: newQuantity } : item
        )
      );
    } catch (error) {
      console.error("更新失败:", error);
    }
  };

  if (loading) {
    return <div className="p-4">加载中...</div>;
  }

  if (error) {
    return <div className="p-4 text-red-500">错误: {error}</div>;
  }

  return (
    <div className="p-4">
      <h1 className="text-2xl font-bold mb-4">购物车</h1>

      {cartItems.length === 0 ? (
        <div className="text-center py-8">
          <p>购物车为空</p>
          <p className="text-gray-500">赶紧去逛逛，购买心仪的商品吧</p>
        </div>
      ) : (
        <>
          <div className="space-y-4">
            {cartItems.map((item) => (
              <div key={item._id} className="flex items-center border-b pb-4">
                <img
                  src={item.productId.imageUrl}
                  alt={item.productId.title}
                  className="w-24 h-24 object-cover rounded"
                />
                <div className="ml-4 flex-1">
                  <h3 className="font-medium">{item.productId.title}</h3>
                  <p className="text-red-500">
                    ¥{item.productId.price.toFixed(2)}
                  </p>
                  <div className="flex items-center justify-between mt-2">
                    <div className="flex items-center">
                      <button
                        className="px-2 py-1 border"
                        onClick={() =>
                          handleUpdateQuantity(
                            item._id,
                            Math.max(1, item.quantity - 1)
                          )
                        }
                      >
                        -
                      </button>
                      <span className="px-4">{item.quantity}</span>
                      <button
                        className="px-2 py-1 border"
                        onClick={() =>
                          handleUpdateQuantity(item._id, item.quantity + 1)
                        }
                      >
                        +
                      </button>
                    </div>
                    <button
                      onClick={() => handleDelete(item._id)}
                      className="text-red-500 text-sm"
                    >
                      删除
                    </button>
                  </div>
                </div>
              </div>
            ))}
          </div>

          <div className="mt-6 flex justify-between items-center">
            <span className="text-lg">总计：</span>
            <span className="text-xl text-red-500 font-bold">
              ¥{calculateTotal().toFixed(2)}
            </span>
          </div>

          <button
            onClick={handleCheckout}
            className="w-full bg-red-500 text-white py-3 rounded-lg mt-4"
          >
            结算
          </button>
        </>
      )}

      {/* 推荐商品板块 - 移到条件渲染外部 */}
      <div className="mt-8">
        <h2 className="text-xl font-bold mb-4">猜你喜欢</h2>
        <div className="grid grid-cols-2 gap-4">
          {recommendProducts.map((product) => (
            <div
              key={product._id}
              className="bg-white rounded-lg overflow-hidden shadow-sm cursor-pointer"
              onClick={() => router.push(`/good/${product._id}`)}
            >
              <img
                src={product.imageUrl}
                alt={product.title}
                className="w-full aspect-square object-cover"
              />
              <div className="p-2">
                <h3 className="text-sm font-medium line-clamp-2">
                  {product.title}
                </h3>
                <div className="mt-2 flex items-center justify-between">
                  <span className="text-red-500">¥{product.price}</span>
                  {product.isVip && (
                    <span className="text-xs px-1 text-yellow-600 border border-yellow-600 rounded">
                      VIP
                    </span>
                  )}
                </div>
              </div>
            </div>
          ))}
        </div>
      </div>
    </div>
  );
}