A fledgling Socket Server lib

socket-server.js

const crypto = require('crypto');
const net = require('net');

function createConnectionId() {
  return crypto.randomBytes(16).toString('hex');
};

function create() {
  // TODO(john): Timeout & Delete these after idling?
  const connectedClients = {};
  const handlers = [];
  const errHandlers = [];
  const server = net.createServer((connection) => {
    connection.id = createConnectionId();
    connectedClients[connection.id] = connection;
    connection.on('close', () => {
      delete connectedClients[connection.id];
      console.log(`[INFO][TCP] ${connection.id} - connection closed`);
    });
    connection.on('error', (e) => {
      // TODO(john): determine whether an error implies disconnected?
      console.log(`[ERROR][TCP] ${connection.id} - ${e}`);
    });

    connection.on('data', async (data) => {
      let error = null;
      let handled = true;
      const next = (err) => {
        handled = false;
        error = err;
      };
      async function execute(handler) {
        // TODO(john): Finish implementing separate error handlers
        const payload = { connection, data, next };
        if (error && handler.length === 2) {
          await handler(error, payload);
        } else if (!error && handler.length === 1) {
          await handler(payload);
        } else {
          console.log(`[INFO][TCP] ${connection.id} unhandled: ${handler}(${handler.length})`);
        }
        return handled;
      }

      for (let i = 0; i < handlers.length; i++) {
        const handler = handlers[i];
        if (await execute(handler)) {
          break;
        }
      }
    });
  });
  return {
    use(handler) {
      if (handler.length === 1) {
        handlers.push(handler);
      } else if (handler.length === 2) {
        errHandlers.push(handler);
      }
    },
    handlers,
    connectedClients,
    server,
  };
}

module.exports.create = create;