import { Server as SocketIOServer } from 'socket.io';
import type { Server as HttpServer } from 'http';
import { validateSession, sessionCookieName } from '$lib/server/auth.js';

let io: SocketIOServer | null = null;

export function initSocketIO(server: HttpServer): SocketIOServer {
	io = new SocketIOServer(server, {
		cors: {
			origin: process.env.ORIGIN || 'http://localhost:5173',
			credentials: true
		}
	});

	// Auth middleware — validate session cookie
	io.use(async (socket, next) => {
		const cookieHeader = socket.handshake.headers.cookie;
		if (!cookieHeader) {
			// Allow anonymous connections (for public boards)
			socket.data.user = null;
			return next();
		}

		const cookies = parseCookies(cookieHeader);
		const sessionId = cookies[sessionCookieName()];
		if (!sessionId) {
			socket.data.user = null;
			return next();
		}

		const session = await validateSession(sessionId);
		if (session) {
			socket.data.user = session.user;
		} else {
			socket.data.user = null;
		}
		next();
	});

	io.on('connection', (socket) => {
		// Join board room
		socket.on('join-board', (boardId: string) => {
			socket.join(`board:${boardId}`);
			// Broadcast presence
			socket.to(`board:${boardId}`).emit('user-joined', {
				user: socket.data.user
					? { id: socket.data.user.id, name: socket.data.user.name }
					: null,
				socketId: socket.id
			});
		});

		// Leave board room
		socket.on('leave-board', (boardId: string) => {
			socket.leave(`board:${boardId}`);
			socket.to(`board:${boardId}`).emit('user-left', {
				socketId: socket.id
			});
		});

		socket.on('disconnect', () => {
			// Socket.IO handles room cleanup automatically
		});
	});

	return io;
}

export function getIO(): SocketIOServer | null {
	return io;
}

/**
 * Emit an event to all clients in a board room.
 */
export function emitToBoardRoom(boardId: string, event: string, data: unknown) {
	if (io) {
		io.to(`board:${boardId}`).emit(event, data);
	}
}

/**
 * Emit a notification to a specific user across all their connections.
 */
export function emitToUser(userId: string, event: string, data: unknown) {
	if (io) {
		io.to(`user:${userId}`).emit(event, data);
	}
}

function parseCookies(cookieHeader: string): Record<string, string> {
	const cookies: Record<string, string> = {};
	cookieHeader.split(';').forEach((cookie) => {
		const [name, ...rest] = cookie.trim().split('=');
		cookies[name] = decodeURIComponent(rest.join('='));
	});
	return cookies;
}