const { WebSocketServer } = require("ws");

const PORT = 3000;
const wss = new WebSocketServer({ port: PORT });

// rooms: { roomId: { host: WebSocket, viewer: WebSocket } }
const rooms = {};

console.log(`Pulsar signalling server listening on ws://localhost:${PORT}`);

wss.on("connection", (ws) => {
  ws.roomId = null;
  ws.role = null; // "host" or "viewer"

  ws.on("message", (raw) => {
    let msg;
    try {
      msg = JSON.parse(raw);
    } catch {
      return;
    }

    const { type, roomId, data } = msg;

    switch (type) {
      case "create": {
        if (!roomId) return;
        if (rooms[roomId]) {
          ws.send(JSON.stringify({ type: "error", message: "Room already exists" }));
          return;
        }
        rooms[roomId] = { host: ws, viewer: null };
        ws.roomId = roomId;
        ws.role = "host";
        ws.send(JSON.stringify({ type: "created", roomId }));
        console.log(`Room created: ${roomId}`);
        break;
      }

      case "join": {
        if (!roomId || !rooms[roomId]) {
          ws.send(JSON.stringify({ type: "error", message: "Room not found" }));
          return;
        }

        const room = rooms[roomId];

        if (room.viewer) {
          ws.send(JSON.stringify({ type: "error", message: "Room full" }));
          return;
        }

        room.viewer = ws;
        ws.roomId = roomId;
        ws.role = "viewer";

        ws.send(JSON.stringify({ type: "joined", roomId }));
        room.host.send(JSON.stringify({ type: "peer_joined" }));
        console.log(`Viewer joined room: ${roomId}`);
        break;
      }

      case "signal": {
        if (!ws.roomId || !rooms[ws.roomId]) return;

        const room = rooms[ws.roomId];
        const target = ws.role === "host" ? room.viewer : room.host;

        if (target && target.readyState === 1) {
          target.send(JSON.stringify({ type: "signal", data }));
        }
        break;
      }

      default:
        break;
    }
  });

  ws.on("close", () => {
    if (!ws.roomId || !rooms[ws.roomId]) return;

    const room = rooms[ws.roomId];

    if (ws.role === "host") {
      // notify viewer if connected
      if (room.viewer && room.viewer.readyState === 1) {
        room.viewer.send(JSON.stringify({ type: "host_disconnected" }));
      }
      delete rooms[ws.roomId];
      console.log(`Room closed: ${ws.roomId}`);
    } else if (ws.role === "viewer") {
      room.viewer = null;
      if (room.host && room.host.readyState === 1) {
        room.host.send(JSON.stringify({ type: "peer_disconnected" }));
      }
      console.log(`Viewer left room: ${ws.roomId}`);
    }
  });

  ws.on("error", (err) => {
    console.error("WebSocket error:", err.message);
  });
});