import { WebSocket, WebSocketServer } from 'ws';
import { ulid } from 'ulid';

const wss = new WebSocketServer({ port: 8080 });

const rooms = new Map<string, Set<string>>();
const sockets = new Map<string, WebSocket>();

wss.on('connection', (ws) => {
    let peerId = ulid();

    const join = (room: string) => {
        if (!rooms.has(room)) {
            rooms.set(room, new Set([peerId]));
        } else {
            rooms.get(room)!.add(peerId);
        }
    };

    const unjoinAll = () => {
        rooms.entries().forEach(([room, peers]) => {
            peers.delete(peerId);
            if (!peers.size) rooms.delete(room);
        });
    };

    ws.on('message', (message) => {
        try {
            const text = message.toString('utf8');
            const data = JSON.parse(text);

            if (data.type === 'self') {
                ws.send(JSON.stringify({
                    type: 'self',
                    id: peerId.toString(),
                }));

                return;
            }

            if (data.type === 'join' && typeof data.room === 'string') {
                unjoinAll();
                join(data.room);

                const peers = rooms.get(data.room) ?? [];
                peers.forEach((peer) => {
                    sockets.get(peer)!.send(JSON.stringify({
                        type: 'peers',
                        peers: peers,
                    }));
                });

                return;
            }

            if (data.type === 'offer' && typeof data.peer === 'string' && typeof data.offer === 'object') {
                const otherWS = sockets.get(data.peer);
                if (!otherWS) return;

                otherWS.send(JSON.stringify({
                    type: 'offer',
                    from: peerId,
                    offer: data.offer,
                }));

                return;
            }

            if (data.type === 'accept' && typeof data.peer === 'string' && typeof data.counterOffer === 'object') {
                const otherWS = sockets.get(data.peer);
                if (!otherWS) return;

                otherWS.send(JSON.stringify({
                    type: 'accept',
                    from: peerId,
                    counterOffer: data.counterOffer,
                }));

                return;
            }

            throw 0;
        } catch (e) {
            ws.send(JSON.stringify({
                type: 'error',
                message: 'Bad Request',
            }));
        }
    });

    ws.on('close', () => {
        unjoinAll();
        sockets.delete(peerId);
    });
});