import { Server } from "socket.io";

let io;
const userSocketMap = new Map(); // userId -> socketId

// Initialize Socket.IO
export const initSocket = (server) => {
	io = new Server(server, {
		cors: {
			origin: "*", // Adjust as needed for production
			methods: ["GET", "POST"],
		},
	});

	io.on("connection", (socket) => {
		console.log("A user connected:", socket.id);

		// Event for user to register their ID
		socket.on("register", (userId) => {
			if (userId) {
				userSocketMap.set(userId, socket.id);
				console.log(`Registered user ${userId} to socket ${socket.id}`);
			}
		});

		socket.on("disconnect", () => {
			console.log("User disconnected:", socket.id);
			// Optional: Remove user from map. This is inefficient O(N).
			// Better: keep reverse map or just iterate. Map iteration is okay for small scale.
			for (const [userId, socketId] of userSocketMap.entries()) {
				if (socketId === socket.id) {
					userSocketMap.delete(userId);
					console.log(`Unregistered user ${userId}`);
					break;
				}
			}
		});
	});

	return io;
};

// Get the IO instance
export const getIO = () => {
	if (!io) {
		throw new Error("Socket.io not initialized!");
	}
	return io;
};

// Get socket ID for a user
export const getSocketId = (userId) => {
	return userSocketMap.get(userId);
};