// server.js
// Simple WebSocket server for multiplayer demo
// npm install ws
const WebSocket = require('ws');
const port = process.env.PORT || 8080;
const wss = new WebSocket.Server({ port });

console.log('Multiplayer server running on port', port);

// State: map clientId -> { ws, username, lastSeen, pos, rot }
const clients = new Map();

function broadcast(data, exceptWs = null) {
  const raw = JSON.stringify(data);
  for (const c of clients.values()) {
    if (c.ws.readyState === WebSocket.OPEN && c.ws !== exceptWs) {
      c.ws.send(raw);
    }
  }
}

wss.on('connection', (ws) => {
  const clientId = Math.random().toString(36).slice(2,10);
  clients.set(clientId, { ws, clientId, username: 'anon', lastSeen: Date.now() });

  // Send welcome + assigned id
  ws.send(JSON.stringify({ t: 'welcome', id: clientId }));

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

    const me = clients.get(clientId);
    me.lastSeen = Date.now();

    switch (msg.t) {
      case 'join':
        // {t:'join', username}
        me.username = (msg.username || 'anon').substring(0,32);
        // send current players to the new client
        const roster = [];
        for (const c of clients.values()) {
          if (c.clientId !== clientId && c.ws.readyState === WebSocket.OPEN) {
            roster.push({
              id: c.clientId,
              username: c.username,
              pos: c.pos || null,
              rot: c.rot || null
            });
          }
        }
        ws.send(JSON.stringify({ t:'roster', players: roster }));
        // tell others about me
        broadcast({ t:'player-joined', id: clientId, username: me.username }, ws);
        break;

      case 'update':
        // {t:'update', pos:{x,y,z}, rot:{x,y,z}}
        me.pos = msg.pos;
        me.rot = msg.rot;
        // broadcast to others
        broadcast({ t:'update', id: clientId, pos: msg.pos || null, rot: msg.rot || null }, ws);
        break;

      case 'place-block':
        // {t:'place-block', x,y,z, blockType}
        // broadcast action so others can replicate the block placement
        broadcast({ t:'place-block', id: clientId, x: msg.x, y: msg.y, z: msg.z, blockType: msg.blockType }, ws);
        break;

      case 'chat':
        // {t:'chat', text}
        const text = String(msg.text || '').slice(0,200);
        broadcast({ t:'chat', id: clientId, username: me.username || 'anon', text });
        break;

      default:
        // ignore
        break;
    }
  });

  ws.on('close', () => {
    clients.delete(clientId);
    broadcast({ t:'player-left', id: clientId }, ws);
  });

  ws.on('error', (e) => {
    console.error('ws err', e);
  });
});

// Periodic cleanup of dead clients (in case)
setInterval(() => {
  const now = Date.now();
  for (const [id, c] of clients.entries()) {
    if (!c.ws || c.ws.readyState !== WebSocket.OPEN || (now - c.lastSeen) > (1000*60*5)) {
      try { c.ws.terminate(); } catch(e){}
      clients.delete(id);
      broadcast({ t:'player-left', id });
    }
  }
}, 30_000);