import {mkdir, readFile, writeFile} from 'node:fs/promises';
import {dirname, join} from 'node:path';

import {WebSocketServer} from 'ws';

import Server from '@/net/server/server.js';
import {getSession} from '@/session.server.js';

import Engine from './engine.js';

const wss = new WebSocketServer({
  noServer: true,
});

function onUpgrade(request, socket, head) {
  const {pathname} = new URL(request.url, 'wss://base.url');
  if (pathname === '/ws') {
    wss.handleUpgrade(request, socket, head, function done(ws) {
      wss.emit('connection', ws, request);
    });
  }
  else {
    socket.destroy();
  }
}

let engine;
let onConnect;

function createOnConnect(engine) {
  onConnect = async (ws, request) => {
    ws.on('close', async () => {
      await engine.disconnectPlayer(ws);
    })
    ws.on('message', (packed) => {
      engine.server.accept(ws, new DataView(packed.buffer, packed.byteOffset, packed.length));
    });
    const session = await getSession(request.headers['cookie']);
    await engine.connectPlayer(ws, session.get('id'));
  };
  wss.on('connection', onConnect);
}

class SocketServer extends Server {
  async ensurePath(path) {
    await mkdir(path, {recursive: true});
  }
  static qualify(path) {
    return join(import.meta.dirname, 'data', 'remote', 'UNIVERSE', path);
  }
  async readData(path) {
    const qualified = this.constructor.qualify(path);
    await this.ensurePath(dirname(qualified));
    return readFile(qualified);
  }
  async writeData(path, view) {
    const qualified = this.constructor.qualify(path);
    await this.ensurePath(dirname(qualified));
    await writeFile(qualified, view);
  }
  transmit(ws, packed) { ws.send(packed); }
}

async function createEngine(Engine) {
  engine = new Engine(SocketServer);
  await engine.load();
  engine.start();
  return engine;
}

async function remakeServer(Engine) {
  if (onConnect) {
    wss.off('connection', onConnect);
  }
  if (engine) {
    for (const [connection] of engine.connectedPlayers) {
      connection.close();
    }
  }
  createOnConnect(await createEngine(Engine));
}

(async () => {
  await remakeServer(Engine);
})();

if (import.meta.hot) {
  import.meta.hot.accept('./engine.js', async ({default: Engine}) => {
    await remakeServer(Engine);
  });
}

export default async function listen(server) {
  server.on('upgrade', onUpgrade);
}