import { NextResponse } from "next/server";
import dbConnect from "@/lib/mongodb";
import Cart from "@/models/Cart";
import { verifyToken } from "@/lib/auth";

export async function GET(request) {
  try {
    const token = request.headers.get("authorization")?.split(" ")[1];
    if (!token) {
      return NextResponse.json([]);
    }

    const decoded = verifyToken(token);
    await dbConnect();

    const cartItems = await Cart.find({ userId: decoded.userId }).populate(
      "productId"
    );
    return NextResponse.json(cartItems);
  } catch (error) {
    return NextResponse.json([]);
  }
}

export async function POST(request) {
  try {
    const token = request.headers.get("authorization")?.split(" ")[1];
    if (!token) {
      return NextResponse.json({ error: "未登录" }, { status: 401 });
    }

    const decoded = verifyToken(token);
    const { productId, quantity } = await request.json();

    await dbConnect();

    // 检查购物车是否已存在该商品
    let cartItem = await Cart.findOne({
      userId: decoded.userId,
      productId: productId,
    });

    if (cartItem) {
      // 如果存在，更新数量
      cartItem.quantity += quantity;
      await cartItem.save();
    } else {
      // 如果不存在，创建新的购物车项
      cartItem = await Cart.create({
        userId: decoded.userId,
        productId: productId,
        quantity: quantity,
      });
    }

    return NextResponse.json({ message: "添加成功", cartItem });
  } catch (error) {
    return NextResponse.json({ error: "添加失败" }, { status: 500 });
  }
}

export async function DELETE(request) {
  try {
    const token = request.headers.get("authorization")?.split(" ")[1];
    if (!token) {
      return NextResponse.json({ error: "未登录" }, { status: 401 });
    }

    const decoded = verifyToken(token);
    const { cartItemId } = await request.json();

    await dbConnect();
    await Cart.findByIdAndDelete(cartItemId);

    return NextResponse.json({ message: "删除成功" });
  } catch (error) {
    return NextResponse.json({ error: "删除失败" }, { status: 500 });
  }
}

export async function PUT(request) {
  try {
    const token = request.headers.get("authorization")?.split(" ")[1];
    if (!token) {
      return NextResponse.json({ error: "未登录" }, { status: 401 });
    }

    const decoded = verifyToken(token);
    const { cartItemId, quantity } = await request.json();

    await dbConnect();

    const cartItem = await Cart.findById(cartItemId);
    if (!cartItem) {
      return NextResponse.json({ error: "购物车商品不存在" }, { status: 404 });
    }

    cartItem.quantity = quantity;
    await cartItem.save();

    return NextResponse.json({ message: "更新成功", cartItem });
  } catch (error) {
    return NextResponse.json({ error: "更新失败" }, { status: 500 });
  }
}