// The front door for duels between people. Plain HTTP for actions, a
// websocket only to say "something changed, fetch the view again".
//
//   POST /api/rooms                 {name, size?}      create a duel and take seat A
//   POST /api/rooms/:id/join        {name}             take the next seat
//   POST /api/rooms/:id/bot         {token}            seat a bot (any seated player may)
//   GET  /api/rooms/:id?token=      the view for that seat
//   POST /api/rooms/:id/turn        {token, input}     this seat's move
//   WS   /ws?room=:id&token=        {type:"update", seq} whenever the room changes
//
// Caddy serves the static site and proxies /api and /ws here.

import { createServer, type IncomingMessage, type ServerResponse } from 'node:http';
import { WebSocketServer, WebSocket } from 'ws';
import { RoomError, Rooms } from './rooms';
import { Store } from './store';

const PORT = Number(process.env.PORT ?? 8788);
const HOST = process.env.HOST ?? '127.0.0.1';
const DATA_DIR = process.env.WH_DATA_DIR ?? './data/rooms';
const BODY_LIMIT = 16 * 1024;

const rooms = new Rooms(new Store(DATA_DIR));

function send(res: ServerResponse, status: number, body: unknown): void {
	const json = JSON.stringify(body);
	res.writeHead(status, { 'content-type': 'application/json; charset=utf-8', 'cache-control': 'no-store' });
	res.end(json);
}

function readBody(req: IncomingMessage): Promise<Record<string, unknown>> {
	return new Promise((resolve, reject) => {
		let size = 0;
		const chunks: Buffer[] = [];
		req.on('data', (chunk: Buffer) => {
			size += chunk.length;
			if (size > BODY_LIMIT) {
				reject(new RoomError('That is more than a turn needs.', 413));
				req.destroy();
				return;
			}
			chunks.push(chunk);
		});
		req.on('end', () => {
			if (chunks.length === 0) return resolve({});
			try {
				resolve(JSON.parse(Buffer.concat(chunks).toString('utf8')));
			} catch {
				reject(new RoomError('The request was not JSON.'));
			}
		});
		req.on('error', reject);
	});
}

async function handle(req: IncomingMessage, res: ServerResponse): Promise<void> {
	const url = new URL(req.url ?? '/', 'http://localhost');
	const parts = url.pathname.split('/').filter(Boolean);
	if (parts[0] !== 'api' || parts[1] !== 'rooms') throw new RoomError('Not here.', 404);

	if (parts.length === 2 && req.method === 'POST') {
		const body = await readBody(req);
		const { room, seat } = rooms.create(String(body.name ?? ''), Number(body.size ?? 2));
		return send(res, 201, { seat: seat.id, token: seat.token, view: rooms.view(room, seat.id) });
	}

	const room = rooms.get(parts[2] ?? '');
	const action = parts[3];
	if (!action && req.method === 'GET') {
		const seat = rooms.seatOf(room, url.searchParams.get('token') ?? undefined);
		return send(res, 200, rooms.view(room, seat.id));
	}
	if (req.method !== 'POST') throw new RoomError('Not here.', 404);
	const body = await readBody(req);
	if (action === 'join') {
		const seat = rooms.join(room, String(body.name ?? ''));
		return send(res, 200, { seat: seat.id, token: seat.token, view: rooms.view(room, seat.id) });
	}
	if (action === 'bot') {
		rooms.addBot(room, typeof body.token === 'string' ? body.token : undefined);
		const seat = rooms.seatOf(room, body.token as string);
		return send(res, 200, rooms.view(room, seat.id));
	}
	if (action === 'turn') {
		const token = typeof body.token === 'string' ? body.token : undefined;
		rooms.submit(room, token, body.input);
		const seat = rooms.seatOf(room, token);
		return send(res, 200, rooms.view(room, seat.id));
	}
	throw new RoomError('Not here.', 404);
}

const server = createServer((req, res) => {
	handle(req, res).catch((err: unknown) => {
		if (err instanceof RoomError) return send(res, err.status, { error: err.message });
		console.error(err);
		send(res, 500, { error: 'Something went wrong on the server.' });
	});
});

const wss = new WebSocketServer({ noServer: true });
server.on('upgrade', (req, socket, head) => {
	const url = new URL(req.url ?? '/', 'http://localhost');
	if (url.pathname !== '/ws') return socket.destroy();
	let seatId: string;
	let roomId: string;
	try {
		roomId = url.searchParams.get('room') ?? '';
		seatId = rooms.seatOf(rooms.get(roomId), url.searchParams.get('token') ?? undefined).id;
	} catch {
		return socket.destroy();
	}
	wss.handleUpgrade(req, socket, head, (ws: WebSocket) => {
		const unsubscribe = rooms.subscribe(roomId, (room) => {
			if (ws.readyState === WebSocket.OPEN) ws.send(JSON.stringify({ type: 'update', seq: room.seq }));
		});
		ws.on('close', unsubscribe);
		ws.send(JSON.stringify({ type: 'hello', seat: seatId }));
	});
});

server.listen(PORT, HOST, () => {
	console.log(`waving-hands server listening on http://${HOST}:${PORT}, rooms in ${DATA_DIR}`);
});