const net = require('net');
const eol = require('os').EOL;
const crypto = require('crypto');

const HASH_ALG = 'sha256';
const NAME_LEN = 10;

var srvr = net.createServer();
var clientList = [];

srvr.on('connection', function (client) {
  client.name = calcName(client.remoteAddress, client.remotePort);
  client.write('Welcome, ' + client.name + eol);
  clientList.push(client);

  client.on("data", function (data) {
    if (data.at(0) !== "\\".charCodeAt(0)) {
      broadcast(data, client);
      return;
    }
    command = data
      .subarray(1)
      .toString()
      .split(/[\s\r\n]+/)
      .filter((s) => s.length > 0);
    console.log(command);
    switch (command[0]) {
      case "list":
        const list = clientList.map((c) => c.name).join(eol);
        client.write("Connected Users" + eol + list + eol);
        break;
      case "rename":
        if (command.length !== 2) {
          client.write("Usage: \\rename <newname>" + eol);
          break;
        }
        const oldName = client.name;
        client.name = command[1];
        client.write("You are now known as " + client.name + eol);
        broadcast(oldName + " is now known as " + client.name + eol, client);
        break;
      case "private":
        if (command.length < 3) {
          client.write("Usage: \\private <name> <msg>" + eol);
          break;
        }
        const targetName = command[1];
        const msg = command.slice(2).join(" ");
        const targetClient = clientList.find((c) => c.name === targetName);
        if (targetClient) {
          targetClient.write("(Private) " + client.name + " says " + msg + eol);
          client.write("(Private) To " + targetClient.name + ": " + msg + eol);
        } else {
          client.write("User " + targetName + " not found." + eol);
        }
        break;
      default:
        client.write("Unknown command: " + command[0] + eol);
    }
  });
});

function calcName(remoteAddress, remotePort) {
  let data = remoteAddress + ":" + remotePort;
  let h = crypto.createHash(HASH_ALG).update(data).digest('hex')
  return h.substring(0, NAME_LEN);
}

function broadcast(data, client) {
  for (var i in clientList) {
    if (client !== clientList[i]) {
      clientList[i].write(client.name + " says " + data);
    }
  }
}

srvr.listen(9000);