import { NextResponse } from "next/server";
import { atomicUpdateRoom } from "@/lib/roomRepository";
import { notify } from "@/lib/roomEvents";
import { apiHandler, ApiError, requireUserId } from "@/lib/api";

export const POST = apiHandler(async (req, { params }) => {
  const { id } = await params;
  const { userId, restaurantId, action } = await req.json();

  requireUserId(userId);
  if (restaurantId == null || !action) {
    throw new ApiError("restaurantId and action are required");
  }
  if (action !== "like" && action !== "pass") {
    throw new ApiError("action must be 'like' or 'pass'");
  }

  const rid = String(restaurantId);

  const updated = await atomicUpdateRoom(id, (data) => {
    if (!data.users.includes(userId)) {
      throw new ApiError("你不是该房间的成员", 403);
    }

    const restaurantIndex = data.restaurants.findIndex((r) => r.id === rid);
    if (restaurantIndex < 0) {
      throw new ApiError("restaurantId 不存在于该房间候选列表", 400);
    }
    const alreadySwiped =
      restaurantIndex < (data.swipeCounts[userId] ?? 0);

    if (alreadySwiped) return data;

    if (action === "like") {
      if (!data.likes[rid]) {
        data.likes[rid] = [];
      }
      if (!data.likes[rid].includes(userId)) {
        data.likes[rid].push(userId);
      }

      if (data.likes[rid].length === data.users.length) {
        data.match = rid;
      }
    }

    data.swipeCounts[userId] = (data.swipeCounts[userId] ?? 0) + 1;

    return data;
  });

  if (!updated) throw new ApiError("房间不存在或已过期", 404);

  notify(id);

  return NextResponse.json({
    match: updated.match,
    likeCount: updated.likes[rid]?.length ?? 0,
  });
});