// NEONSTRIKE — multiplayer server. Static files + WebSocket rooms.
// Zero config: `node server/index.js` and go.
const http = require('http');
const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { WebSocketServer } = require('ws');

const PUBLIC_DIR = path.join(__dirname, '..', 'public');
const PORT = Number(process.env.PORT) || 3002;

const MAPS = ['vector', 'foundry', 'canopy'];
const MAX_PLAYERS = 8;
const KILL_TARGET = 15;
// unambiguous alphabet: no 0/O/1/I
const CODE_ALPHABET = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';

const MIME = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.png': 'image/png',
};

// code -> room { code, map, players: Map<id, player>, resetTimer }
const rooms = new Map();

function uid(n) {
  return crypto.randomBytes(n).toString('base64url').slice(0, n);
}

function roomCode() {
  let code;
  do {
    code = '';
    for (let i = 0; i < 4; i++) {
      code += CODE_ALPHABET[crypto.randomInt(CODE_ALPHABET.length)];
    }
  } while (rooms.has(code));
  return code;
}

function send(ws, msg) {
  if (ws.readyState === 1) ws.send(JSON.stringify(msg));
}

function broadcast(room, msg, exceptId) {
  const raw = JSON.stringify(msg);
  for (const p of room.players.values()) {
    if (p.id !== exceptId && p.ws.readyState === 1) p.ws.send(raw);
  }
}

function scoreList(room) {
  return [...room.players.values()].map((p) => ({
    id: p.id,
    name: p.name,
    kills: p.kills,
    deaths: p.deaths,
  }));
}

function createRoom(ws, msg) {
  const name = String(msg.name || 'player').slice(0, 24);
  const map = MAPS.includes(msg.map) ? msg.map : MAPS[0];
  const room = { code: roomCode(), map, players: new Map(), resetTimer: null };
  rooms.set(room.code, room);
  const player = makePlayer(ws, name);
  room.players.set(player.id, player);
  ws._room = room;
  ws._playerId = player.id;
  send(ws, { t: 'created', code: room.code, id: player.id });
}

function makePlayer(ws, name) {
  return { id: uid(8), ws, name, hp: 100, kills: 0, deaths: 0, lastState: null };
}

function joinRoom(ws, msg) {
  const code = String(msg.code || '').toUpperCase();
  const room = rooms.get(code);
  if (!room) { send(ws, { t: 'error', msg: 'Room not found' }); return; }
  if (room.players.size >= MAX_PLAYERS) { send(ws, { t: 'error', msg: 'Room is full' }); return; }
  const name = String(msg.name || 'player').slice(0, 24);
  const player = makePlayer(ws, name);
  room.players.set(player.id, player);
  ws._room = room;
  ws._playerId = player.id;
  send(ws, {
    t: 'joined',
    id: player.id,
    code: room.code,
    map: room.map,
    players: scoreList(room).filter((p) => p.id !== player.id),
  });
  // snapshot of where everyone currently is
  for (const p of room.players.values()) {
    if (p.id !== player.id && p.lastState) send(ws, { t: 'state', id: p.id, ...p.lastState });
  }
  broadcast(room, { t: 'player_join', id: player.id, name: player.name }, player.id);
}

function leaveRoom(ws) {
  const room = ws._room;
  if (!room) return;
  const id = ws._playerId;
  ws._room = null;
  ws._playerId = null;
  if (!room.players.delete(id)) return;
  broadcast(room, { t: 'player_leave', id });
  if (room.players.size === 0) {
    if (room.resetTimer) clearTimeout(room.resetTimer);
    rooms.delete(room.code);
  }
}

function handleHit(room, shooter, msg) {
  const victim = room.players.get(String(msg.target || ''));
  if (!victim || victim.id === shooter.id || victim.hp <= 0) return;
  const dmg = Math.max(0, Math.min(200, Number(msg.dmg) || 0));
  const head = !!msg.head;
  victim.hp = Math.max(0, victim.hp - dmg);
  broadcast(room, { t: 'damage', id: victim.id, hp: victim.hp, from: shooter.id });
  if (victim.hp <= 0) {
    shooter.kills++;
    victim.deaths++;
    broadcast(room, { t: 'death', id: victim.id, by: shooter.id, head });
    broadcast(room, { t: 'scores', players: scoreList(room) });
    if (shooter.kills >= KILL_TARGET && !room.resetTimer) {
      broadcast(room, { t: 'match_over', winner: { id: shooter.id, name: shooter.name } });
      room.resetTimer = setTimeout(() => {
        room.resetTimer = null;
        for (const p of room.players.values()) { p.kills = 0; p.deaths = 0; }
        broadcast(room, { t: 'scores', players: scoreList(room) });
      }, 5000);
    }
  }
}

function handleMessage(ws, msg) {
  if (msg.t === 'create') { leaveRoom(ws); createRoom(ws, msg); return; }
  if (msg.t === 'join') { leaveRoom(ws); joinRoom(ws, msg); return; }

  const room = ws._room;
  if (!room) return;
  const player = room.players.get(ws._playerId);
  if (!player || player.ws !== ws) return;

  switch (msg.t) {
    case 'state': {
      const { t, ...rest } = msg;
      player.lastState = rest;
      broadcast(room, { t: 'state', id: player.id, ...rest }, player.id);
      break;
    }
    case 'shoot': {
      broadcast(room, { t: 'shoot', id: player.id, weapon: msg.weapon }, player.id);
      break;
    }
    case 'hit': {
      handleHit(room, player, msg);
      break;
    }
    case 'respawn': {
      if (player.hp > 0) break;
      player.hp = 100;
      broadcast(room, { t: 'respawned', id: player.id, hp: 100 });
      break;
    }
    case 'leave': {
      leaveRoom(ws);
      break;
    }
  }
}

// ---------------- http static server ----------------

const server = http.createServer((req, res) => {
  let urlPath;
  try {
    urlPath = decodeURIComponent(req.url.split('?')[0]);
  } catch (e) {
    res.writeHead(400); res.end('bad request'); return;
  }
  if (urlPath === '/') urlPath = '/index.html';
  const filePath = path.join(PUBLIC_DIR, urlPath);
  if (!filePath.startsWith(PUBLIC_DIR)) { res.writeHead(403); res.end('forbidden'); return; }
  const mime = MIME[path.extname(filePath).toLowerCase()];
  fs.readFile(filePath, (err, data) => {
    if (err || !mime) { res.writeHead(404); res.end('not found'); return; }
    res.writeHead(200, { 'Content-Type': mime });
    res.end(data);
  });
});

// ---------------- websocket wiring ----------------

const wss = new WebSocketServer({ server, path: '/ws', perMessageDeflate: false });

wss.on('connection', (ws) => {
  ws.isAlive = true;
  ws.on('pong', () => { ws.isAlive = true; });

  ws.on('message', (raw) => {
    try {
      const msg = JSON.parse(raw);
      if (!msg || typeof msg !== 'object' || typeof msg.t !== 'string') return;
      handleMessage(ws, msg);
    } catch (e) {
      // never crash on malformed input
    }
  });

  ws.on('close', () => leaveRoom(ws));
  ws.on('error', () => leaveRoom(ws));
});

// heartbeat: drop dead sockets so rooms don't fill with ghosts
setInterval(() => {
  for (const ws of wss.clients) {
    if (!ws.isAlive) { try { ws.terminate(); } catch (e) {} continue; }
    ws.isAlive = false;
    try { ws.ping(); } catch (e) {}
  }
}, 20000);

server.listen(PORT, () => {
  console.log(`NEONSTRIKE server running at http://localhost:${PORT}`);
});